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-rw-r--r--Documentation/RCU/stallwarn.txt16
-rw-r--r--Documentation/RCU/trace.txt32
-rw-r--r--Documentation/memory-barriers.txt46
-rw-r--r--include/linux/compiler.h2
-rw-r--r--include/linux/rculist.h16
-rw-r--r--include/linux/rcupdate.h13
-rw-r--r--include/linux/rcutiny.h45
-rw-r--r--include/linux/rcutree.h11
-rw-r--r--init/Kconfig9
-rw-r--r--kernel/cpu.c56
-rw-r--r--kernel/rcu/rcu.h6
-rw-r--r--kernel/rcu/rcutorture.c66
-rw-r--r--kernel/rcu/tiny.c113
-rw-r--r--kernel/rcu/tiny_plugin.h9
-rw-r--r--kernel/rcu/tree.c289
-rw-r--r--kernel/rcu/tree.h62
-rw-r--r--kernel/rcu/tree_plugin.h271
-rw-r--r--kernel/rcu/tree_trace.c8
-rw-r--r--kernel/softirq.c3
-rw-r--r--lib/Kconfig.debug2
-rwxr-xr-xtools/testing/selftests/rcutorture/bin/cpus2use.sh2
-rwxr-xr-xtools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh18
-rwxr-xr-xtools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh9
-rwxr-xr-xtools/testing/selftests/rcutorture/bin/parse-build.sh20
-rwxr-xr-xtools/testing/selftests/rcutorture/bin/parse-console.sh2
25 files changed, 567 insertions, 559 deletions
diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt
index ed186a902d31..b57c0c1cdac6 100644
--- a/Documentation/RCU/stallwarn.txt
+++ b/Documentation/RCU/stallwarn.txt
@@ -15,7 +15,7 @@ CONFIG_RCU_CPU_STALL_TIMEOUT
21 seconds.
This configuration parameter may be changed at runtime via the
- /sys/module/rcutree/parameters/rcu_cpu_stall_timeout, however
+ /sys/module/rcupdate/parameters/rcu_cpu_stall_timeout, however
this parameter is checked only at the beginning of a cycle.
So if you are 10 seconds into a 40-second stall, setting this
sysfs parameter to (say) five will shorten the timeout for the
@@ -152,6 +152,15 @@ no non-lazy callbacks ("." is printed otherwise, as shown above) and
"D" indicates that dyntick-idle processing is enabled ("." is printed
otherwise, for example, if disabled via the "nohz=" kernel boot parameter).
+If the relevant grace-period kthread has been unable to run prior to
+the stall warning, the following additional line is printed:
+
+ rcu_preempt kthread starved for 2023 jiffies!
+
+Starving the grace-period kthreads of CPU time can of course result in
+RCU CPU stall warnings even when all CPUs and tasks have passed through
+the required quiescent states.
+
Multiple Warnings From One Stall
@@ -187,6 +196,11 @@ o For !CONFIG_PREEMPT kernels, a CPU looping anywhere in the
behavior, you might need to replace some of the cond_resched()
calls with calls to cond_resched_rcu_qs().
+o Anything that prevents RCU's grace-period kthreads from running.
+ This can result in the "All QSes seen" console-log message.
+ This message will include information on when the kthread last
+ ran and how often it should be expected to run.
+
o A CPU-bound real-time task in a CONFIG_PREEMPT kernel, which might
happen to preempt a low-priority task in the middle of an RCU
read-side critical section. This is especially damaging if
diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt
index b63b9bb3bc0c..08651da15448 100644
--- a/Documentation/RCU/trace.txt
+++ b/Documentation/RCU/trace.txt
@@ -56,14 +56,14 @@ rcuboost:
The output of "cat rcu/rcu_preempt/rcudata" looks as follows:
- 0!c=30455 g=30456 pq=1 qp=1 dt=126535/140000000000000/0 df=2002 of=4 ql=0/0 qs=N... b=10 ci=74572 nci=0 co=1131 ca=716
- 1!c=30719 g=30720 pq=1 qp=0 dt=132007/140000000000000/0 df=1874 of=10 ql=0/0 qs=N... b=10 ci=123209 nci=0 co=685 ca=982
- 2!c=30150 g=30151 pq=1 qp=1 dt=138537/140000000000000/0 df=1707 of=8 ql=0/0 qs=N... b=10 ci=80132 nci=0 co=1328 ca=1458
- 3 c=31249 g=31250 pq=1 qp=0 dt=107255/140000000000000/0 df=1749 of=6 ql=0/450 qs=NRW. b=10 ci=151700 nci=0 co=509 ca=622
- 4!c=29502 g=29503 pq=1 qp=1 dt=83647/140000000000000/0 df=965 of=5 ql=0/0 qs=N... b=10 ci=65643 nci=0 co=1373 ca=1521
- 5 c=31201 g=31202 pq=1 qp=1 dt=70422/0/0 df=535 of=7 ql=0/0 qs=.... b=10 ci=58500 nci=0 co=764 ca=698
- 6!c=30253 g=30254 pq=1 qp=1 dt=95363/140000000000000/0 df=780 of=5 ql=0/0 qs=N... b=10 ci=100607 nci=0 co=1414 ca=1353
- 7 c=31178 g=31178 pq=1 qp=0 dt=91536/0/0 df=547 of=4 ql=0/0 qs=.... b=10 ci=109819 nci=0 co=1115 ca=969
+ 0!c=30455 g=30456 pq=1/0 qp=1 dt=126535/140000000000000/0 df=2002 of=4 ql=0/0 qs=N... b=10 ci=74572 nci=0 co=1131 ca=716
+ 1!c=30719 g=30720 pq=1/0 qp=0 dt=132007/140000000000000/0 df=1874 of=10 ql=0/0 qs=N... b=10 ci=123209 nci=0 co=685 ca=982
+ 2!c=30150 g=30151 pq=1/1 qp=1 dt=138537/140000000000000/0 df=1707 of=8 ql=0/0 qs=N... b=10 ci=80132 nci=0 co=1328 ca=1458
+ 3 c=31249 g=31250 pq=1/1 qp=0 dt=107255/140000000000000/0 df=1749 of=6 ql=0/450 qs=NRW. b=10 ci=151700 nci=0 co=509 ca=622
+ 4!c=29502 g=29503 pq=1/0 qp=1 dt=83647/140000000000000/0 df=965 of=5 ql=0/0 qs=N... b=10 ci=65643 nci=0 co=1373 ca=1521
+ 5 c=31201 g=31202 pq=1/0 qp=1 dt=70422/0/0 df=535 of=7 ql=0/0 qs=.... b=10 ci=58500 nci=0 co=764 ca=698
+ 6!c=30253 g=30254 pq=1/0 qp=1 dt=95363/140000000000000/0 df=780 of=5 ql=0/0 qs=N... b=10 ci=100607 nci=0 co=1414 ca=1353
+ 7 c=31178 g=31178 pq=1/0 qp=0 dt=91536/0/0 df=547 of=4 ql=0/0 qs=.... b=10 ci=109819 nci=0 co=1115 ca=969
This file has one line per CPU, or eight for this 8-CPU system.
The fields are as follows:
@@ -188,14 +188,14 @@ o "ca" is the number of RCU callbacks that have been adopted by this
Kernels compiled with CONFIG_RCU_BOOST=y display the following from
/debug/rcu/rcu_preempt/rcudata:
- 0!c=12865 g=12866 pq=1 qp=1 dt=83113/140000000000000/0 df=288 of=11 ql=0/0 qs=N... kt=0/O ktl=944 b=10 ci=60709 nci=0 co=748 ca=871
- 1 c=14407 g=14408 pq=1 qp=0 dt=100679/140000000000000/0 df=378 of=7 ql=0/119 qs=NRW. kt=0/W ktl=9b6 b=10 ci=109740 nci=0 co=589 ca=485
- 2 c=14407 g=14408 pq=1 qp=0 dt=105486/0/0 df=90 of=9 ql=0/89 qs=NRW. kt=0/W ktl=c0c b=10 ci=83113 nci=0 co=533 ca=490
- 3 c=14407 g=14408 pq=1 qp=0 dt=107138/0/0 df=142 of=8 ql=0/188 qs=NRW. kt=0/W ktl=b96 b=10 ci=121114 nci=0 co=426 ca=290
- 4 c=14405 g=14406 pq=1 qp=1 dt=50238/0/0 df=706 of=7 ql=0/0 qs=.... kt=0/W ktl=812 b=10 ci=34929 nci=0 co=643 ca=114
- 5!c=14168 g=14169 pq=1 qp=0 dt=45465/140000000000000/0 df=161 of=11 ql=0/0 qs=N... kt=0/O ktl=b4d b=10 ci=47712 nci=0 co=677 ca=722
- 6 c=14404 g=14405 pq=1 qp=0 dt=59454/0/0 df=94 of=6 ql=0/0 qs=.... kt=0/W ktl=e57 b=10 ci=55597 nci=0 co=701 ca=811
- 7 c=14407 g=14408 pq=1 qp=1 dt=68850/0/0 df=31 of=8 ql=0/0 qs=.... kt=0/W ktl=14bd b=10 ci=77475 nci=0 co=508 ca=1042
+ 0!c=12865 g=12866 pq=1/0 qp=1 dt=83113/140000000000000/0 df=288 of=11 ql=0/0 qs=N... kt=0/O ktl=944 b=10 ci=60709 nci=0 co=748 ca=871
+ 1 c=14407 g=14408 pq=1/0 qp=0 dt=100679/140000000000000/0 df=378 of=7 ql=0/119 qs=NRW. kt=0/W ktl=9b6 b=10 ci=109740 nci=0 co=589 ca=485
+ 2 c=14407 g=14408 pq=1/0 qp=0 dt=105486/0/0 df=90 of=9 ql=0/89 qs=NRW. kt=0/W ktl=c0c b=10 ci=83113 nci=0 co=533 ca=490
+ 3 c=14407 g=14408 pq=1/0 qp=0 dt=107138/0/0 df=142 of=8 ql=0/188 qs=NRW. kt=0/W ktl=b96 b=10 ci=121114 nci=0 co=426 ca=290
+ 4 c=14405 g=14406 pq=1/0 qp=1 dt=50238/0/0 df=706 of=7 ql=0/0 qs=.... kt=0/W ktl=812 b=10 ci=34929 nci=0 co=643 ca=114
+ 5!c=14168 g=14169 pq=1/0 qp=0 dt=45465/140000000000000/0 df=161 of=11 ql=0/0 qs=N... kt=0/O ktl=b4d b=10 ci=47712 nci=0 co=677 ca=722
+ 6 c=14404 g=14405 pq=1/0 qp=0 dt=59454/0/0 df=94 of=6 ql=0/0 qs=.... kt=0/W ktl=e57 b=10 ci=55597 nci=0 co=701 ca=811
+ 7 c=14407 g=14408 pq=1/0 qp=1 dt=68850/0/0 df=31 of=8 ql=0/0 qs=.... kt=0/W ktl=14bd b=10 ci=77475 nci=0 co=508 ca=1042
This is similar to the output discussed above, but contains the following
additional fields:
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index 70a09f8a0383..ca2387ef27ab 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -269,6 +269,50 @@ And there are a number of things that _must_ or _must_not_ be assumed:
STORE *(A + 4) = Y; STORE *A = X;
STORE {*A, *(A + 4) } = {X, Y};
+And there are anti-guarantees:
+
+ (*) These guarantees do not apply to bitfields, because compilers often
+ generate code to modify these using non-atomic read-modify-write
+ sequences. Do not attempt to use bitfields to synchronize parallel
+ algorithms.
+
+ (*) Even in cases where bitfields are protected by locks, all fields
+ in a given bitfield must be protected by one lock. If two fields
+ in a given bitfield are protected by different locks, the compiler's
+ non-atomic read-modify-write sequences can cause an update to one
+ field to corrupt the value of an adjacent field.
+
+ (*) These guarantees apply only to properly aligned and sized scalar
+ variables. "Properly sized" currently means variables that are
+ the same size as "char", "short", "int" and "long". "Properly
+ aligned" means the natural alignment, thus no constraints for
+ "char", two-byte alignment for "short", four-byte alignment for
+ "int", and either four-byte or eight-byte alignment for "long",
+ on 32-bit and 64-bit systems, respectively. Note that these
+ guarantees were introduced into the C11 standard, so beware when
+ using older pre-C11 compilers (for example, gcc 4.6). The portion
+ of the standard containing this guarantee is Section 3.14, which
+ defines "memory location" as follows:
+
+ memory location
+ either an object of scalar type, or a maximal sequence
+ of adjacent bit-fields all having nonzero width
+
+ NOTE 1: Two threads of execution can update and access
+ separate memory locations without interfering with
+ each other.
+
+ NOTE 2: A bit-field and an adjacent non-bit-field member
+ are in separate memory locations. The same applies
+ to two bit-fields, if one is declared inside a nested
+ structure declaration and the other is not, or if the two
+ are separated by a zero-length bit-field declaration,
+ or if they are separated by a non-bit-field member
+ declaration. It is not safe to concurrently update two
+ bit-fields in the same structure if all members declared
+ between them are also bit-fields, no matter what the
+ sizes of those intervening bit-fields happen to be.
+
=========================
WHAT ARE MEMORY BARRIERS?
@@ -750,7 +794,7 @@ In summary:
However, they do -not- guarantee any other sort of ordering:
Not prior loads against later loads, nor prior stores against
later anything. If you need these other forms of ordering,
- use smb_rmb(), smp_wmb(), or, in the case of prior stores and
+ use smp_rmb(), smp_wmb(), or, in the case of prior stores and
later loads, smp_mb().
(*) If both legs of the "if" statement begin with identical stores
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index a1c81f80978e..49811cdddaa5 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -385,7 +385,7 @@ static __always_inline void __assign_once_size(volatile void *p, void *res, int
/* Is this type a native word size -- useful for atomic operations */
#ifndef __native_word
-# define __native_word(t) (sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
+# define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
#endif
/* Compile time object size, -1 for unknown */
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 529bc946f450..a18b16f1dc0e 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -524,11 +524,11 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
* @member: the name of the hlist_node within the struct.
*/
#define hlist_for_each_entry_continue_rcu(pos, member) \
- for (pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
- typeof(*(pos)), member); \
+ for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member); \
pos; \
- pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
- typeof(*(pos)), member))
+ pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member))
/**
* hlist_for_each_entry_continue_rcu_bh - iterate over a hlist continuing after current point
@@ -536,11 +536,11 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
* @member: the name of the hlist_node within the struct.
*/
#define hlist_for_each_entry_continue_rcu_bh(pos, member) \
- for (pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
- typeof(*(pos)), member); \
+ for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member); \
pos; \
- pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
- typeof(*(pos)), member))
+ pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member))
/**
* hlist_for_each_entry_from_rcu - iterate over a hlist continuing from current point
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index ed4f5939a452..78097491cd99 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -331,12 +331,13 @@ static inline void rcu_init_nohz(void)
extern struct srcu_struct tasks_rcu_exit_srcu;
#define rcu_note_voluntary_context_switch(t) \
do { \
+ rcu_all_qs(); \
if (ACCESS_ONCE((t)->rcu_tasks_holdout)) \
ACCESS_ONCE((t)->rcu_tasks_holdout) = false; \
} while (0)
#else /* #ifdef CONFIG_TASKS_RCU */
#define TASKS_RCU(x) do { } while (0)
-#define rcu_note_voluntary_context_switch(t) do { } while (0)
+#define rcu_note_voluntary_context_switch(t) rcu_all_qs()
#endif /* #else #ifdef CONFIG_TASKS_RCU */
/**
@@ -582,11 +583,11 @@ static inline void rcu_preempt_sleep_check(void)
})
#define __rcu_dereference_check(p, c, space) \
({ \
- typeof(*p) *_________p1 = (typeof(*p) *__force)ACCESS_ONCE(p); \
+ /* Dependency order vs. p above. */ \
+ typeof(*p) *________p1 = (typeof(*p) *__force)lockless_dereference(p); \
rcu_lockdep_assert(c, "suspicious rcu_dereference_check() usage"); \
rcu_dereference_sparse(p, space); \
- smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
- ((typeof(*p) __force __kernel *)(_________p1)); \
+ ((typeof(*p) __force __kernel *)(________p1)); \
})
#define __rcu_dereference_protected(p, c, space) \
({ \
@@ -603,10 +604,10 @@ static inline void rcu_preempt_sleep_check(void)
})
#define __rcu_dereference_index_check(p, c) \
({ \
- typeof(p) _________p1 = ACCESS_ONCE(p); \
+ /* Dependency order vs. p above. */ \
+ typeof(p) _________p1 = lockless_dereference(p); \
rcu_lockdep_assert(c, \
"suspicious rcu_dereference_index_check() usage"); \
- smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
(_________p1); \
})
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 0e5366200154..937edaeb150d 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -92,17 +92,49 @@ static inline void rcu_virt_note_context_switch(int cpu)
}
/*
- * Return the number of grace periods.
+ * Return the number of grace periods started.
*/
-static inline long rcu_batches_completed(void)
+static inline unsigned long rcu_batches_started(void)
{
return 0;
}
/*
- * Return the number of bottom-half grace periods.
+ * Return the number of bottom-half grace periods started.
*/
-static inline long rcu_batches_completed_bh(void)
+static inline unsigned long rcu_batches_started_bh(void)
+{
+ return 0;
+}
+
+/*
+ * Return the number of sched grace periods started.
+ */
+static inline unsigned long rcu_batches_started_sched(void)
+{
+ return 0;
+}
+
+/*
+ * Return the number of grace periods completed.
+ */
+static inline unsigned long rcu_batches_completed(void)
+{
+ return 0;
+}
+
+/*
+ * Return the number of bottom-half grace periods completed.
+ */
+static inline unsigned long rcu_batches_completed_bh(void)
+{
+ return 0;
+}
+
+/*
+ * Return the number of sched grace periods completed.
+ */
+static inline unsigned long rcu_batches_completed_sched(void)
{
return 0;
}
@@ -154,7 +186,10 @@ static inline bool rcu_is_watching(void)
return true;
}
-
#endif /* #else defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) */
+static inline void rcu_all_qs(void)
+{
+}
+
#endif /* __LINUX_RCUTINY_H */
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 52953790dcca..d2e583a6aaca 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -81,9 +81,12 @@ void cond_synchronize_rcu(unsigned long oldstate);
extern unsigned long rcutorture_testseq;
extern unsigned long rcutorture_vernum;
-long rcu_batches_completed(void);
-long rcu_batches_completed_bh(void);
-long rcu_batches_completed_sched(void);
+unsigned long rcu_batches_started(void);
+unsigned long rcu_batches_started_bh(void);
+unsigned long rcu_batches_started_sched(void);
+unsigned long rcu_batches_completed(void);
+unsigned long rcu_batches_completed_bh(void);
+unsigned long rcu_batches_completed_sched(void);
void show_rcu_gp_kthreads(void);
void rcu_force_quiescent_state(void);
@@ -97,4 +100,6 @@ extern int rcu_scheduler_active __read_mostly;
bool rcu_is_watching(void);
+void rcu_all_qs(void);
+
#endif /* __LINUX_RCUTREE_H */
diff --git a/init/Kconfig b/init/Kconfig
index f085969ba340..1354ac09b516 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -470,7 +470,6 @@ choice
config TREE_RCU
bool "Tree-based hierarchical RCU"
depends on !PREEMPT && SMP
- select IRQ_WORK
help
This option selects the RCU implementation that is
designed for very large SMP system with hundreds or
@@ -480,7 +479,6 @@ config TREE_RCU
config PREEMPT_RCU
bool "Preemptible tree-based hierarchical RCU"
depends on PREEMPT
- select IRQ_WORK
help
This option selects the RCU implementation that is
designed for very large SMP systems with hundreds or
@@ -676,9 +674,10 @@ config RCU_BOOST
config RCU_KTHREAD_PRIO
int "Real-time priority to use for RCU worker threads"
- range 1 99
- depends on RCU_BOOST
- default 1
+ range 1 99 if RCU_BOOST
+ range 0 99 if !RCU_BOOST
+ default 1 if RCU_BOOST
+ default 0 if !RCU_BOOST
help
This option specifies the SCHED_FIFO priority value that will be
assigned to the rcuc/n and rcub/n threads and is also the value
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 5d220234b3ca..1972b161c61e 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -58,22 +58,23 @@ static int cpu_hotplug_disabled;
static struct {
struct task_struct *active_writer;
- struct mutex lock; /* Synchronizes accesses to refcount, */
+ /* wait queue to wake up the active_writer */
+ wait_queue_head_t wq;
+ /* verifies that no writer will get active while readers are active */
+ struct mutex lock;
/*
* Also blocks the new readers during
* an ongoing cpu hotplug operation.
*/
- int refcount;
- /* And allows lockless put_online_cpus(). */
- atomic_t puts_pending;
+ atomic_t refcount;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
} cpu_hotplug = {
.active_writer = NULL,
+ .wq = __WAIT_QUEUE_HEAD_INITIALIZER(cpu_hotplug.wq),
.lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
- .refcount = 0,
#ifdef CONFIG_DEBUG_LOCK_ALLOC
.dep_map = {.name = "cpu_hotplug.lock" },
#endif
@@ -86,15 +87,6 @@ static struct {
#define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map)
#define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map)
-static void apply_puts_pending(int max)
-{
- int delta;
-
- if (atomic_read(&cpu_hotplug.puts_pending) >= max) {
- delta = atomic_xchg(&cpu_hotplug.puts_pending, 0);
- cpu_hotplug.refcount -= delta;
- }
-}
void get_online_cpus(void)
{
@@ -103,8 +95,7 @@ void get_online_cpus(void)
return;
cpuhp_lock_acquire_read();
mutex_lock(&cpu_hotplug.lock);
- apply_puts_pending(65536);
- cpu_hotplug.refcount++;
+ atomic_inc(&cpu_hotplug.refcount);
mutex_unlock(&cpu_hotplug.lock);
}
EXPORT_SYMBOL_GPL(get_online_cpus);
@@ -116,8 +107,7 @@ bool try_get_online_cpus(void)
if (!mutex_trylock(&cpu_hotplug.lock))
return false;
cpuhp_lock_acquire_tryread();
- apply_puts_pending(65536);
- cpu_hotplug.refcount++;
+ atomic_inc(&cpu_hotplug.refcount);
mutex_unlock(&cpu_hotplug.lock);
return true;
}
@@ -125,20 +115,18 @@ EXPORT_SYMBOL_GPL(try_get_online_cpus);
void put_online_cpus(void)
{
+ int refcount;
+
if (cpu_hotplug.active_writer == current)
return;
- if (!mutex_trylock(&cpu_hotplug.lock)) {
- atomic_inc(&cpu_hotplug.puts_pending);
- cpuhp_lock_release();
- return;
- }
- if (WARN_ON(!cpu_hotplug.refcount))
- cpu_hotplug.refcount++; /* try to fix things up */
+ refcount = atomic_dec_return(&cpu_hotplug.refcount);
+ if (WARN_ON(refcount < 0)) /* try to fix things up */
+ atomic_inc(&cpu_hotplug.refcount);
+
+ if (refcount <= 0 && waitqueue_active(&cpu_hotplug.wq))
+ wake_up(&cpu_hotplug.wq);
- if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
- wake_up_process(cpu_hotplug.active_writer);
- mutex_unlock(&cpu_hotplug.lock);
cpuhp_lock_release();
}
@@ -168,18 +156,20 @@ EXPORT_SYMBOL_GPL(put_online_cpus);
*/
void cpu_hotplug_begin(void)
{
- cpu_hotplug.active_writer = current;
+ DEFINE_WAIT(wait);
+ cpu_hotplug.active_writer = current;
cpuhp_lock_acquire();
+
for (;;) {
mutex_lock(&cpu_hotplug.lock);
- apply_puts_pending(1);
- if (likely(!cpu_hotplug.refcount))
- break;
- __set_current_state(TASK_UNINTERRUPTIBLE);
+ prepare_to_wait(&cpu_hotplug.wq, &wait, TASK_UNINTERRUPTIBLE);
+ if (likely(!atomic_read(&cpu_hotplug.refcount)))
+ break;
mutex_unlock(&cpu_hotplug.lock);
schedule();
}
+ finish_wait(&cpu_hotplug.wq, &wait);
}
void cpu_hotplug_done(void)
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index 07bb02eda844..80adef7d4c3d 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -137,4 +137,10 @@ int rcu_jiffies_till_stall_check(void);
void rcu_early_boot_tests(void);
+/*
+ * This function really isn't for public consumption, but RCU is special in
+ * that context switches can allow the state machine to make progress.
+ */
+extern void resched_cpu(int cpu);
+
#endif /* __LINUX_RCU_H */
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 4d559baf06e0..30d42aa55d83 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -244,7 +244,8 @@ struct rcu_torture_ops {
int (*readlock)(void);
void (*read_delay)(struct torture_random_state *rrsp);
void (*readunlock)(int idx);
- int (*completed)(void);
+ unsigned long (*started)(void);
+ unsigned long (*completed)(void);
void (*deferred_free)(struct rcu_torture *p);
void (*sync)(void);
void (*exp_sync)(void);
@@ -296,11 +297,6 @@ static void rcu_torture_read_unlock(int idx) __releases(RCU)
rcu_read_unlock();
}
-static int rcu_torture_completed(void)
-{
- return rcu_batches_completed();
-}
-
/*
* Update callback in the pipe. This should be invoked after a grace period.
*/
@@ -356,7 +352,7 @@ rcu_torture_cb(struct rcu_head *p)
cur_ops->deferred_free(rp);
}
-static int rcu_no_completed(void)
+static unsigned long rcu_no_completed(void)
{
return 0;
}
@@ -377,7 +373,8 @@ static struct rcu_torture_ops rcu_ops = {
.readlock = rcu_torture_read_lock,
.read_delay = rcu_read_delay,
.readunlock = rcu_torture_read_unlock,
- .completed = rcu_torture_completed,
+ .started = rcu_batches_started,
+ .completed = rcu_batches_completed,
.deferred_free = rcu_torture_deferred_free,
.sync = synchronize_rcu,
.exp_sync = synchronize_rcu_expedited,
@@ -407,11 +404,6 @@ static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
rcu_read_unlock_bh();
}
-static int rcu_bh_torture_completed(void)
-{
- return rcu_batches_completed_bh();
-}
-
static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
{
call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
@@ -423,7 +415,8 @@ static struct rcu_torture_ops rcu_bh_ops = {
.readlock = rcu_bh_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_bh_torture_read_unlock,
- .completed = rcu_bh_torture_completed,
+ .started = rcu_batches_started_bh,
+ .completed = rcu_batches_completed_bh,
.deferred_free = rcu_bh_torture_deferred_free,
.sync = synchronize_rcu_bh,
.exp_sync = synchronize_rcu_bh_expedited,
@@ -466,6 +459,7 @@ static struct rcu_torture_ops rcu_busted_ops = {
.readlock = rcu_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = rcu_torture_read_unlock,
+ .started = rcu_no_completed,
.completed = rcu_no_completed,
.deferred_free = rcu_busted_torture_deferred_free,
.sync = synchronize_rcu_busted,
@@ -510,7 +504,7 @@ static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
srcu_read_unlock(&srcu_ctl, idx);
}
-static int srcu_torture_completed(void)
+static unsigned long srcu_torture_completed(void)
{
return srcu_batches_completed(&srcu_ctl);
}
@@ -564,6 +558,7 @@ static struct rcu_torture_ops srcu_ops = {
.readlock = srcu_torture_read_lock,
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock,
+ .started = NULL,
.completed = srcu_torture_completed,
.deferred_free = srcu_torture_deferred_free,
.sync = srcu_torture_synchronize,
@@ -600,7 +595,8 @@ static struct rcu_torture_ops sched_ops = {
.readlock = sched_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = sched_torture_read_unlock,
- .completed = rcu_no_completed,
+ .started = rcu_batches_started_sched,
+ .completed = rcu_batches_completed_sched,
.deferred_free = rcu_sched_torture_deferred_free,
.sync = synchronize_sched,
.exp_sync = synchronize_sched_expedited,
@@ -638,6 +634,7 @@ static struct rcu_torture_ops tasks_ops = {
.readlock = tasks_torture_read_lock,
.read_delay = rcu_read_delay, /* just reuse rcu's version. */
.readunlock = tasks_torture_read_unlock,
+ .started = rcu_no_completed,
.completed = rcu_no_completed,
.deferred_free = rcu_tasks_torture_deferred_free,
.sync = synchronize_rcu_tasks,
@@ -1015,8 +1012,8 @@ static void rcutorture_trace_dump(void)
static void rcu_torture_timer(unsigned long unused)
{
int idx;
- int completed;
- int completed_end;
+ unsigned long started;
+ unsigned long completed;
static DEFINE_TORTURE_RANDOM(rand);
static DEFINE_SPINLOCK(rand_lock);
struct rcu_torture *p;
@@ -1024,7 +1021,10 @@ static void rcu_torture_timer(unsigned long unused)
unsigned long long ts;
idx = cur_ops->readlock();
- completed = cur_ops->completed();
+ if (cur_ops->started)
+ started = cur_ops->started();
+ else
+ started = cur_ops->completed();
ts = rcu_trace_clock_local();
p = rcu_dereference_check(rcu_torture_current,
rcu_read_lock_bh_held() ||
@@ -1047,14 +1047,16 @@ static void rcu_torture_timer(unsigned long unused)
/* Should not happen, but... */
pipe_count = RCU_TORTURE_PIPE_LEN;
}
- completed_end = cur_ops->completed();
+ completed = cur_ops->completed();
if (pipe_count > 1) {
do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
- completed, completed_end);
+ started, completed);
rcutorture_trace_dump();
}
__this_cpu_inc(rcu_torture_count[pipe_count]);
- completed = completed_end - completed;
+ completed = completed - started;
+ if (cur_ops->started)
+ completed++;
if (completed > RCU_TORTURE_PIPE_LEN) {
/* Should not happen, but... */
completed = RCU_TORTURE_PIPE_LEN;
@@ -1073,8 +1075,8 @@ static void rcu_torture_timer(unsigned long unused)
static int
rcu_torture_reader(void *arg)
{
- int completed;
- int completed_end;
+ unsigned long started;
+ unsigned long completed;
int idx;
DEFINE_TORTURE_RANDOM(rand);
struct rcu_torture *p;
@@ -1093,7 +1095,10 @@ rcu_torture_reader(void *arg)
mod_timer(&t, jiffies + 1);
}
idx = cur_ops->readlock();
- completed = cur_ops->completed();
+ if (cur_ops->started)
+ started = cur_ops->started();
+ else
+ started = cur_ops->completed();
ts = rcu_trace_clock_local();
p = rcu_dereference_check(rcu_torture_current,
rcu_read_lock_bh_held() ||
@@ -1114,14 +1119,16 @@ rcu_torture_reader(void *arg)
/* Should not happen, but... */
pipe_count = RCU_TORTURE_PIPE_LEN;
}
- completed_end = cur_ops->completed();
+ completed = cur_ops->completed();
if (pipe_count > 1) {
do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
- ts, completed, completed_end);
+ ts, started, completed);
rcutorture_trace_dump();
}
__this_cpu_inc(rcu_torture_count[pipe_count]);
- completed = completed_end - completed;
+ completed = completed - started;
+ if (cur_ops->started)
+ completed++;
if (completed > RCU_TORTURE_PIPE_LEN) {
/* Should not happen, but... */
completed = RCU_TORTURE_PIPE_LEN;
@@ -1420,6 +1427,9 @@ static int rcu_torture_barrier(void *arg)
cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
n_rcu_torture_barrier_error++;
+ pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
+ atomic_read(&barrier_cbs_invoked),
+ n_barrier_cbs);
WARN_ON_ONCE(1);
}
n_barrier_successes++;
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index 0db5649f8817..cc9ceca7bde1 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -47,54 +47,14 @@ static void __call_rcu(struct rcu_head *head,
void (*func)(struct rcu_head *rcu),
struct rcu_ctrlblk *rcp);
-static long long rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
-
#include "tiny_plugin.h"
-/* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcu/tree.c. */
-static void rcu_idle_enter_common(long long newval)
-{
- if (newval) {
- RCU_TRACE(trace_rcu_dyntick(TPS("--="),
- rcu_dynticks_nesting, newval));
- rcu_dynticks_nesting = newval;
- return;
- }
- RCU_TRACE(trace_rcu_dyntick(TPS("Start"),
- rcu_dynticks_nesting, newval));
- if (IS_ENABLED(CONFIG_RCU_TRACE) && !is_idle_task(current)) {
- struct task_struct *idle __maybe_unused = idle_task(smp_processor_id());
-
- RCU_TRACE(trace_rcu_dyntick(TPS("Entry error: not idle task"),
- rcu_dynticks_nesting, newval));
- ftrace_dump(DUMP_ALL);
- WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
- current->pid, current->comm,
- idle->pid, idle->comm); /* must be idle task! */
- }
- rcu_sched_qs(); /* implies rcu_bh_inc() */
- barrier();
- rcu_dynticks_nesting = newval;
-}
-
/*
* Enter idle, which is an extended quiescent state if we have fully
- * entered that mode (i.e., if the new value of dynticks_nesting is zero).
+ * entered that mode.
*/
void rcu_idle_enter(void)
{
- unsigned long flags;
- long long newval;
-
- local_irq_save(flags);
- WARN_ON_ONCE((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0);
- if ((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) ==
- DYNTICK_TASK_NEST_VALUE)
- newval = 0;
- else
- newval = rcu_dynticks_nesting - DYNTICK_TASK_NEST_VALUE;
- rcu_idle_enter_common(newval);
- local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(rcu_idle_enter);
@@ -103,55 +63,14 @@ EXPORT_SYMBOL_GPL(rcu_idle_enter);
*/
void rcu_irq_exit(void)
{
- unsigned long flags;
- long long newval;
-
- local_irq_save(flags);
- newval = rcu_dynticks_nesting - 1;
- WARN_ON_ONCE(newval < 0);
- rcu_idle_enter_common(newval);
- local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(rcu_irq_exit);
-/* Common code for rcu_idle_exit() and rcu_irq_enter(), see kernel/rcu/tree.c. */
-static void rcu_idle_exit_common(long long oldval)
-{
- if (oldval) {
- RCU_TRACE(trace_rcu_dyntick(TPS("++="),
- oldval, rcu_dynticks_nesting));
- return;
- }
- RCU_TRACE(trace_rcu_dyntick(TPS("End"), oldval, rcu_dynticks_nesting));
- if (IS_ENABLED(CONFIG_RCU_TRACE) && !is_idle_task(current)) {
- struct task_struct *idle __maybe_unused = idle_task(smp_processor_id());
-
- RCU_TRACE(trace_rcu_dyntick(TPS("Exit error: not idle task"),
- oldval, rcu_dynticks_nesting));
- ftrace_dump(DUMP_ALL);
- WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
- current->pid, current->comm,
- idle->pid, idle->comm); /* must be idle task! */
- }
-}
-
/*
* Exit idle, so that we are no longer in an extended quiescent state.
*/
void rcu_idle_exit(void)
{
- unsigned long flags;
- long long oldval;
-
- local_irq_save(flags);
- oldval = rcu_dynticks_nesting;
- WARN_ON_ONCE(rcu_dynticks_nesting < 0);
- if (rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK)
- rcu_dynticks_nesting += DYNTICK_TASK_NEST_VALUE;
- else
- rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
- rcu_idle_exit_common(oldval);
- local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(rcu_idle_exit);
@@ -160,15 +79,6 @@ EXPORT_SYMBOL_GPL(rcu_idle_exit);
*/
void rcu_irq_enter(void)
{
- unsigned long flags;
- long long oldval;
-
- local_irq_save(flags);
- oldval = rcu_dynticks_nesting;
- rcu_dynticks_nesting++;
- WARN_ON_ONCE(rcu_dynticks_nesting == 0);
- rcu_idle_exit_common(oldval);
- local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(rcu_irq_enter);
@@ -179,23 +89,13 @@ EXPORT_SYMBOL_GPL(rcu_irq_enter);
*/
bool notrace __rcu_is_watching(void)
{
- return rcu_dynticks_nesting;
+ return true;
}
EXPORT_SYMBOL(__rcu_is_watching);
#endif /* defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) */
/*
- * Test whether the current CPU was interrupted from idle. Nested
- * interrupts don't count, we must be running at the first interrupt
- * level.
- */
-static int rcu_is_cpu_rrupt_from_idle(void)
-{
- return rcu_dynticks_nesting <= 1;
-}
-
-/*
* Helper function for rcu_sched_qs() and rcu_bh_qs().
* Also irqs are disabled to avoid confusion due to interrupt handlers
* invoking call_rcu().
@@ -250,7 +150,7 @@ void rcu_bh_qs(void)
void rcu_check_callbacks(int user)
{
RCU_TRACE(check_cpu_stalls());
- if (user || rcu_is_cpu_rrupt_from_idle())
+ if (user)
rcu_sched_qs();
else if (!in_softirq())
rcu_bh_qs();
@@ -357,6 +257,11 @@ static void __call_rcu(struct rcu_head *head,
rcp->curtail = &head->next;
RCU_TRACE(rcp->qlen++);
local_irq_restore(flags);
+
+ if (unlikely(is_idle_task(current))) {
+ /* force scheduling for rcu_sched_qs() */
+ resched_cpu(0);
+ }
}
/*
@@ -383,6 +288,8 @@ EXPORT_SYMBOL_GPL(call_rcu_bh);
void __init rcu_init(void)
{
open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
+ RCU_TRACE(reset_cpu_stall_ticks(&rcu_sched_ctrlblk));
+ RCU_TRACE(reset_cpu_stall_ticks(&rcu_bh_ctrlblk));
rcu_early_boot_tests();
}
diff --git a/kernel/rcu/tiny_plugin.h b/kernel/rcu/tiny_plugin.h
index 858c56569127..f94e209a10d6 100644
--- a/kernel/rcu/tiny_plugin.h
+++ b/kernel/rcu/tiny_plugin.h
@@ -145,17 +145,16 @@ static void check_cpu_stall(struct rcu_ctrlblk *rcp)
rcp->ticks_this_gp++;
j = jiffies;
js = ACCESS_ONCE(rcp->jiffies_stall);
- if (*rcp->curtail && ULONG_CMP_GE(j, js)) {
+ if (rcp->rcucblist && ULONG_CMP_GE(j, js)) {
pr_err("INFO: %s stall on CPU (%lu ticks this GP) idle=%llx (t=%lu jiffies q=%ld)\n",
- rcp->name, rcp->ticks_this_gp, rcu_dynticks_nesting,
+ rcp->name, rcp->ticks_this_gp, DYNTICK_TASK_EXIT_IDLE,
jiffies - rcp->gp_start, rcp->qlen);
dump_stack();
- }
- if (*rcp->curtail && ULONG_CMP_GE(j, js))
ACCESS_ONCE(rcp->jiffies_stall) = jiffies +
3 * rcu_jiffies_till_stall_check() + 3;
- else if (ULONG_CMP_GE(j, js))
+ } else if (ULONG_CMP_GE(j, js)) {
ACCESS_ONCE(rcp->jiffies_stall) = jiffies + rcu_jiffies_till_stall_check();
+ }
}
static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 4c106fcc0d54..48d640ca1a05 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -156,6 +156,10 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
static void invoke_rcu_core(void);
static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp);
+/* rcuc/rcub kthread realtime priority */
+static int kthread_prio = CONFIG_RCU_KTHREAD_PRIO;
+module_param(kthread_prio, int, 0644);
+
/*
* Track the rcutorture test sequence number and the update version
* number within a given test. The rcutorture_testseq is incremented
@@ -215,6 +219,9 @@ static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
#endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
};
+DEFINE_PER_CPU_SHARED_ALIGNED(unsigned long, rcu_qs_ctr);
+EXPORT_PER_CPU_SYMBOL_GPL(rcu_qs_ctr);
+
/*
* Let the RCU core know that this CPU has gone through the scheduler,
* which is a quiescent state. This is called when the need for a
@@ -284,6 +291,22 @@ void rcu_note_context_switch(void)
}
EXPORT_SYMBOL_GPL(rcu_note_context_switch);
+/*
+ * Register a quiesecent state for all RCU flavors. If there is an
+ * emergency, invoke rcu_momentary_dyntick_idle() to do a heavy-weight
+ * dyntick-idle quiescent state visible to other CPUs (but only for those
+ * RCU flavors in desparate need of a quiescent state, which will normally
+ * be none of them). Either way, do a lightweight quiescent state for
+ * all RCU flavors.
+ */
+void rcu_all_qs(void)
+{
+ if (unlikely(raw_cpu_read(rcu_sched_qs_mask)))
+ rcu_momentary_dyntick_idle();
+ this_cpu_inc(rcu_qs_ctr);
+}
+EXPORT_SYMBOL_GPL(rcu_all_qs);
+
static long blimit = 10; /* Maximum callbacks per rcu_do_batch. */
static long qhimark = 10000; /* If this many pending, ignore blimit. */
static long qlowmark = 100; /* Once only this many pending, use blimit. */
@@ -315,18 +338,54 @@ static void force_quiescent_state(struct rcu_state *rsp);
static int rcu_pending(void);
/*
- * Return the number of RCU-sched batches processed thus far for debug & stats.
+ * Return the number of RCU batches started thus far for debug & stats.
+ */
+unsigned long rcu_batches_started(void)
+{
+ return rcu_state_p->gpnum;
+}
+EXPORT_SYMBOL_GPL(rcu_batches_started);
+
+/*
+ * Return the number of RCU-sched batches started thus far for debug & stats.
*/
-long rcu_batches_completed_sched(void)
+unsigned long rcu_batches_started_sched(void)
+{
+ return rcu_sched_state.gpnum;
+}
+EXPORT_SYMBOL_GPL(rcu_batches_started_sched);
+
+/*
+ * Return the number of RCU BH batches started thus far for debug & stats.
+ */
+unsigned long rcu_batches_started_bh(void)
+{
+ return rcu_bh_state.gpnum;
+}
+EXPORT_SYMBOL_GPL(rcu_batches_started_bh);
+
+/*
+ * Return the number of RCU batches completed thus far for debug & stats.
+ */
+unsigned long rcu_batches_completed(void)
+{
+ return rcu_state_p->completed;
+}
+EXPORT_SYMBOL_GPL(rcu_batches_completed);
+
+/*
+ * Return the number of RCU-sched batches completed thus far for debug & stats.
+ */
+unsigned long rcu_batches_completed_sched(void)
{
return rcu_sched_state.completed;
}
EXPORT_SYMBOL_GPL(rcu_batches_completed_sched);
/*
- * Return the number of RCU BH batches processed thus far for debug & stats.
+ * Return the number of RCU BH batches completed thus far for debug & stats.
*/
-long rcu_batches_completed_bh(void)
+unsigned long rcu_batches_completed_bh(void)
{
return rcu_bh_state.completed;
}
@@ -930,17 +989,14 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp,
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
return 1;
} else {
+ if (ULONG_CMP_LT(ACCESS_ONCE(rdp->gpnum) + ULONG_MAX / 4,
+ rdp->mynode->gpnum))
+ ACCESS_ONCE(rdp->gpwrap) = true;
return 0;
}
}
/*
- * This function really isn't for public consumption, but RCU is special in
- * that context switches can allow the state machine to make progress.
- */
-extern void resched_cpu(int cpu);
-
-/*
* Return true if the specified CPU has passed through a quiescent
* state by virtue of being in or having passed through an dynticks
* idle state since the last call to dyntick_save_progress_counter()
@@ -1043,6 +1099,22 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
j1 = rcu_jiffies_till_stall_check();
ACCESS_ONCE(rsp->jiffies_stall) = j + j1;
rsp->jiffies_resched = j + j1 / 2;
+ rsp->n_force_qs_gpstart = ACCESS_ONCE(rsp->n_force_qs);
+}
+
+/*
+ * Complain about starvation of grace-period kthread.
+ */
+static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
+{
+ unsigned long gpa;
+ unsigned long j;
+
+ j = jiffies;
+ gpa = ACCESS_ONCE(rsp->gp_activity);
+ if (j - gpa > 2 * HZ)
+ pr_err("%s kthread starved for %ld jiffies!\n",
+ rsp->name, j - gpa);
}
/*
@@ -1065,11 +1137,13 @@ static void rcu_dump_cpu_stacks(struct rcu_state *rsp)
}
}
-static void print_other_cpu_stall(struct rcu_state *rsp)
+static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
{
int cpu;
long delta;
unsigned long flags;
+ unsigned long gpa;
+ unsigned long j;
int ndetected = 0;
struct rcu_node *rnp = rcu_get_root(rsp);
long totqlen = 0;
@@ -1107,30 +1181,34 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
- /*
- * Now rat on any tasks that got kicked up to the root rcu_node
- * due to CPU offlining.
- */
- rnp = rcu_get_root(rsp);
- raw_spin_lock_irqsave(&rnp->lock, flags);
- ndetected += rcu_print_task_stall(rnp);
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
-
print_cpu_stall_info_end();
for_each_possible_cpu(cpu)
totqlen += per_cpu_ptr(rsp->rda, cpu)->qlen;
pr_cont("(detected by %d, t=%ld jiffies, g=%ld, c=%ld, q=%lu)\n",
smp_processor_id(), (long)(jiffies - rsp->gp_start),
(long)rsp->gpnum, (long)rsp->completed, totqlen);
- if (ndetected == 0)
- pr_err("INFO: Stall ended before state dump start\n");
- else
+ if (ndetected) {
rcu_dump_cpu_stacks(rsp);
+ } else {
+ if (ACCESS_ONCE(rsp->gpnum) != gpnum ||
+ ACCESS_ONCE(rsp->completed) == gpnum) {
+ pr_err("INFO: Stall ended before state dump start\n");
+ } else {
+ j = jiffies;
+ gpa = ACCESS_ONCE(rsp->gp_activity);
+ pr_err("All QSes seen, last %s kthread activity %ld (%ld-%ld), jiffies_till_next_fqs=%ld\n",
+ rsp->name, j - gpa, j, gpa,
+ jiffies_till_next_fqs);
+ /* In this case, the current CPU might be at fault. */
+ sched_show_task(current);
+ }
+ }
/* Complain about tasks blocking the grace period. */
-
rcu_print_detail_task_stall(rsp);
+ rcu_check_gp_kthread_starvation(rsp);
+
force_quiescent_state(rsp); /* Kick them all. */
}
@@ -1155,6 +1233,9 @@ static void print_cpu_stall(struct rcu_state *rsp)
pr_cont(" (t=%lu jiffies g=%ld c=%ld q=%lu)\n",
jiffies - rsp->gp_start,
(long)rsp->gpnum, (long)rsp->completed, totqlen);
+
+ rcu_check_gp_kthread_starvation(rsp);
+
rcu_dump_cpu_stacks(rsp);
raw_spin_lock_irqsave(&rnp->lock, flags);
@@ -1225,7 +1306,7 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY)) {
/* They had a few time units to dump stack, so complain. */
- print_other_cpu_stall(rsp);
+ print_other_cpu_stall(rsp, gpnum);
}
}
@@ -1562,7 +1643,8 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
bool ret;
/* Handle the ends of any preceding grace periods first. */
- if (rdp->completed == rnp->completed) {
+ if (rdp->completed == rnp->completed &&
+ !unlikely(ACCESS_ONCE(rdp->gpwrap))) {
/* No grace period end, so just accelerate recent callbacks. */
ret = rcu_accelerate_cbs(rsp, rnp, rdp);
@@ -1577,7 +1659,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuend"));
}
- if (rdp->gpnum != rnp->gpnum) {
+ if (rdp->gpnum != rnp->gpnum || unlikely(ACCESS_ONCE(rdp->gpwrap))) {
/*
* If the current grace period is waiting for this CPU,
* set up to detect a quiescent state, otherwise don't
@@ -1586,8 +1668,10 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
rdp->gpnum = rnp->gpnum;
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpustart"));
rdp->passed_quiesce = 0;
+ rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_qs_ctr);
rdp->qs_pending = !!(rnp->qsmask & rdp->grpmask);
zero_cpu_stall_ticks(rdp);
+ ACCESS_ONCE(rdp->gpwrap) = false;
}
return ret;
}
@@ -1601,7 +1685,8 @@ static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp)
local_irq_save(flags);
rnp = rdp->mynode;
if ((rdp->gpnum == ACCESS_ONCE(rnp->gpnum) &&
- rdp->completed == ACCESS_ONCE(rnp->completed)) || /* w/out lock. */
+ rdp->completed == ACCESS_ONCE(rnp->completed) &&
+ !unlikely(ACCESS_ONCE(rdp->gpwrap))) || /* w/out lock. */
!raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */
local_irq_restore(flags);
return;
@@ -1621,6 +1706,7 @@ static int rcu_gp_init(struct rcu_state *rsp)
struct rcu_data *rdp;
struct rcu_node *rnp = rcu_get_root(rsp);
+ ACCESS_ONCE(rsp->gp_activity) = jiffies;
rcu_bind_gp_kthread();
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
@@ -1681,6 +1767,7 @@ static int rcu_gp_init(struct rcu_state *rsp)
rnp->grphi, rnp->qsmask);
raw_spin_unlock_irq(&rnp->lock);
cond_resched_rcu_qs();
+ ACCESS_ONCE(rsp->gp_activity) = jiffies;
}
mutex_unlock(&rsp->onoff_mutex);
@@ -1697,6 +1784,7 @@ static int rcu_gp_fqs(struct rcu_state *rsp, int fqs_state_in)
unsigned long maxj;
struct rcu_node *rnp = rcu_get_root(rsp);
+ ACCESS_ONCE(rsp->gp_activity) = jiffies;
rsp->n_force_qs++;
if (fqs_state == RCU_SAVE_DYNTICK) {
/* Collect dyntick-idle snapshots. */
@@ -1735,6 +1823,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
struct rcu_data *rdp;
struct rcu_node *rnp = rcu_get_root(rsp);
+ ACCESS_ONCE(rsp->gp_activity) = jiffies;
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
gp_duration = jiffies - rsp->gp_start;
@@ -1771,6 +1860,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
nocb += rcu_future_gp_cleanup(rsp, rnp);
raw_spin_unlock_irq(&rnp->lock);
cond_resched_rcu_qs();
+ ACCESS_ONCE(rsp->gp_activity) = jiffies;
}
rnp = rcu_get_root(rsp);
raw_spin_lock_irq(&rnp->lock);
@@ -1820,6 +1910,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
if (rcu_gp_init(rsp))
break;
cond_resched_rcu_qs();
+ ACCESS_ONCE(rsp->gp_activity) = jiffies;
WARN_ON(signal_pending(current));
trace_rcu_grace_period(rsp->name,
ACCESS_ONCE(rsp->gpnum),
@@ -1863,9 +1954,11 @@ static int __noreturn rcu_gp_kthread(void *arg)
ACCESS_ONCE(rsp->gpnum),
TPS("fqsend"));
cond_resched_rcu_qs();
+ ACCESS_ONCE(rsp->gp_activity) = jiffies;
} else {
/* Deal with stray signal. */
cond_resched_rcu_qs();
+ ACCESS_ONCE(rsp->gp_activity) = jiffies;
WARN_ON(signal_pending(current));
trace_rcu_grace_period(rsp->name,
ACCESS_ONCE(rsp->gpnum),
@@ -2042,8 +2135,10 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp)
rnp = rdp->mynode;
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
- if (rdp->passed_quiesce == 0 || rdp->gpnum != rnp->gpnum ||
- rnp->completed == rnp->gpnum) {
+ if ((rdp->passed_quiesce == 0 &&
+ rdp->rcu_qs_ctr_snap == __this_cpu_read(rcu_qs_ctr)) ||
+ rdp->gpnum != rnp->gpnum || rnp->completed == rnp->gpnum ||
+ rdp->gpwrap) {
/*
* The grace period in which this quiescent state was
@@ -2052,6 +2147,7 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp)
* within the current grace period.
*/
rdp->passed_quiesce = 0; /* need qs for new gp. */
+ rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_qs_ctr);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
@@ -2096,7 +2192,8 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
* Was there a quiescent state since the beginning of the grace
* period? If no, then exit and wait for the next call.
*/
- if (!rdp->passed_quiesce)
+ if (!rdp->passed_quiesce &&
+ rdp->rcu_qs_ctr_snap == __this_cpu_read(rcu_qs_ctr))
return;
/*
@@ -2227,6 +2324,46 @@ static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
}
/*
+ * All CPUs for the specified rcu_node structure have gone offline,
+ * and all tasks that were preempted within an RCU read-side critical
+ * section while running on one of those CPUs have since exited their RCU
+ * read-side critical section. Some other CPU is reporting this fact with
+ * the specified rcu_node structure's ->lock held and interrupts disabled.
+ * This function therefore goes up the tree of rcu_node structures,
+ * clearing the corresponding bits in the ->qsmaskinit fields. Note that
+ * the leaf rcu_node structure's ->qsmaskinit field has already been
+ * updated
+ *
+ * This function does check that the specified rcu_node structure has
+ * all CPUs offline and no blocked tasks, so it is OK to invoke it
+ * prematurely. That said, invoking it after the fact will cost you
+ * a needless lock acquisition. So once it has done its work, don't
+ * invoke it again.
+ */
+static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
+{
+ long mask;
+ struct rcu_node *rnp = rnp_leaf;
+
+ if (rnp->qsmaskinit || rcu_preempt_has_tasks(rnp))
+ return;
+ for (;;) {
+ mask = rnp->grpmask;
+ rnp = rnp->parent;
+ if (!rnp)
+ break;
+ raw_spin_lock(&rnp->lock); /* irqs already disabled. */
+ smp_mb__after_unlock_lock(); /* GP memory ordering. */
+ rnp->qsmaskinit &= ~mask;
+ if (rnp->qsmaskinit) {
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ return;
+ }
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ }
+}
+
+/*
* The CPU has been completely removed, and some other CPU is reporting
* this fact from process context. Do the remainder of the cleanup,
* including orphaning the outgoing CPU's RCU callbacks, and also
@@ -2236,8 +2373,6 @@ static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
{
unsigned long flags;
- unsigned long mask;
- int need_report = 0;
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */
@@ -2251,40 +2386,15 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
/* Orphan the dead CPU's callbacks, and adopt them if appropriate. */
rcu_send_cbs_to_orphanage(cpu, rsp, rnp, rdp);
rcu_adopt_orphan_cbs(rsp, flags);
+ raw_spin_unlock_irqrestore(&rsp->orphan_lock, flags);
- /* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */
- mask = rdp->grpmask; /* rnp->grplo is constant. */
- do {
- raw_spin_lock(&rnp->lock); /* irqs already disabled. */
- smp_mb__after_unlock_lock();
- rnp->qsmaskinit &= ~mask;
- if (rnp->qsmaskinit != 0) {
- if (rnp != rdp->mynode)
- raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
- break;
- }
- if (rnp == rdp->mynode)
- need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp);
- else
- raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
- mask = rnp->grpmask;
- rnp = rnp->parent;
- } while (rnp != NULL);
-
- /*
- * We still hold the leaf rcu_node structure lock here, and
- * irqs are still disabled. The reason for this subterfuge is
- * because invoking rcu_report_unblock_qs_rnp() with ->orphan_lock
- * held leads to deadlock.
- */
- raw_spin_unlock(&rsp->orphan_lock); /* irqs remain disabled. */
- rnp = rdp->mynode;
- if (need_report & RCU_OFL_TASKS_NORM_GP)
- rcu_report_unblock_qs_rnp(rnp, flags);
- else
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
- if (need_report & RCU_OFL_TASKS_EXP_GP)
- rcu_report_exp_rnp(rsp, rnp, true);
+ /* Remove outgoing CPU from mask in the leaf rcu_node structure. */
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ smp_mb__after_unlock_lock(); /* Enforce GP memory-order guarantee. */
+ rnp->qsmaskinit &= ~rdp->grpmask;
+ if (rnp->qsmaskinit == 0 && !rcu_preempt_has_tasks(rnp))
+ rcu_cleanup_dead_rnp(rnp);
+ rcu_report_qs_rnp(rdp->grpmask, rsp, rnp, flags); /* Rlses rnp->lock. */
WARN_ONCE(rdp->qlen != 0 || rdp->nxtlist != NULL,
"rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, nxtlist=%p\n",
cpu, rdp->qlen, rdp->nxtlist);
@@ -2300,6 +2410,10 @@ static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
{
}
+static void __maybe_unused rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
+{
+}
+
static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
{
}
@@ -2496,12 +2610,6 @@ static void force_qs_rnp(struct rcu_state *rsp,
}
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
- rnp = rcu_get_root(rsp);
- if (rnp->qsmask == 0) {
- raw_spin_lock_irqsave(&rnp->lock, flags);
- smp_mb__after_unlock_lock();
- rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */
- }
}
/*
@@ -2601,7 +2709,7 @@ static void rcu_process_callbacks(struct softirq_action *unused)
* Schedule RCU callback invocation. If the specified type of RCU
* does not support RCU priority boosting, just do a direct call,
* otherwise wake up the per-CPU kernel kthread. Note that because we
- * are running on the current CPU with interrupts disabled, the
+ * are running on the current CPU with softirqs disabled, the
* rcu_cpu_kthread_task cannot disappear out from under us.
*/
static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
@@ -3141,9 +3249,12 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
/* Is the RCU core waiting for a quiescent state from this CPU? */
if (rcu_scheduler_fully_active &&
- rdp->qs_pending && !rdp->passed_quiesce) {
+ rdp->qs_pending && !rdp->passed_quiesce &&
+ rdp->rcu_qs_ctr_snap == __this_cpu_read(rcu_qs_ctr)) {
rdp->n_rp_qs_pending++;
- } else if (rdp->qs_pending && rdp->passed_quiesce) {
+ } else if (rdp->qs_pending &&
+ (rdp->passed_quiesce ||
+ rdp->rcu_qs_ctr_snap != __this_cpu_read(rcu_qs_ctr))) {
rdp->n_rp_report_qs++;
return 1;
}
@@ -3167,7 +3278,8 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
}
/* Has a new RCU grace period started? */
- if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */
+ if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum ||
+ unlikely(ACCESS_ONCE(rdp->gpwrap))) { /* outside lock */
rdp->n_rp_gp_started++;
return 1;
}
@@ -3350,6 +3462,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
} else {
_rcu_barrier_trace(rsp, "OnlineNoCB", cpu,
rsp->n_barrier_done);
+ smp_mb__before_atomic();
atomic_inc(&rsp->barrier_cpu_count);
__call_rcu(&rdp->barrier_head,
rcu_barrier_callback, rsp, cpu, 0);
@@ -3417,9 +3530,6 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
/* Set up local state, ensuring consistent view of global state. */
raw_spin_lock_irqsave(&rnp->lock, flags);
rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
- init_callback_list(rdp);
- rdp->qlen_lazy = 0;
- ACCESS_ONCE(rdp->qlen) = 0;
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE);
WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1);
@@ -3476,6 +3586,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->gpnum = rnp->completed;
rdp->completed = rnp->completed;
rdp->passed_quiesce = 0;
+ rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_qs_ctr);
rdp->qs_pending = 0;
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuonl"));
}
@@ -3567,17 +3678,35 @@ static int rcu_pm_notify(struct notifier_block *self,
static int __init rcu_spawn_gp_kthread(void)
{
unsigned long flags;
+ int kthread_prio_in = kthread_prio;
struct rcu_node *rnp;
struct rcu_state *rsp;
+ struct sched_param sp;
struct task_struct *t;
+ /* Force priority into range. */
+ if (IS_ENABLED(CONFIG_RCU_BOOST) && kthread_prio < 1)
+ kthread_prio = 1;
+ else if (kthread_prio < 0)
+ kthread_prio = 0;
+ else if (kthread_prio > 99)
+ kthread_prio = 99;
+ if (kthread_prio != kthread_prio_in)
+ pr_alert("rcu_spawn_gp_kthread(): Limited prio to %d from %d\n",
+ kthread_prio, kthread_prio_in);
+
rcu_scheduler_fully_active = 1;
for_each_rcu_flavor(rsp) {
- t = kthread_run(rcu_gp_kthread, rsp, "%s", rsp->name);
+ t = kthread_create(rcu_gp_kthread, rsp, "%s", rsp->name);
BUG_ON(IS_ERR(t));
rnp = rcu_get_root(rsp);
raw_spin_lock_irqsave(&rnp->lock, flags);
rsp->gp_kthread = t;
+ if (kthread_prio) {
+ sp.sched_priority = kthread_prio;
+ sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
+ }
+ wake_up_process(t);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
rcu_spawn_nocb_kthreads();
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 8e7b1843896e..119de399eb2f 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -27,7 +27,6 @@
#include <linux/threads.h>
#include <linux/cpumask.h>
#include <linux/seqlock.h>
-#include <linux/irq_work.h>
/*
* Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and
@@ -172,11 +171,6 @@ struct rcu_node {
/* queued on this rcu_node structure that */
/* are blocking the current grace period, */
/* there can be no such task. */
- struct completion boost_completion;
- /* Used to ensure that the rt_mutex used */
- /* to carry out the boosting is fully */
- /* released with no future boostee accesses */
- /* before that rt_mutex is re-initialized. */
struct rt_mutex boost_mtx;
/* Used only for the priority-boosting */
/* side effect, not as a lock. */
@@ -257,9 +251,12 @@ struct rcu_data {
/* in order to detect GP end. */
unsigned long gpnum; /* Highest gp number that this CPU */
/* is aware of having started. */
+ unsigned long rcu_qs_ctr_snap;/* Snapshot of rcu_qs_ctr to check */
+ /* for rcu_all_qs() invocations. */
bool passed_quiesce; /* User-mode/idle loop etc. */
bool qs_pending; /* Core waits for quiesc state. */
bool beenonline; /* CPU online at least once. */
+ bool gpwrap; /* Possible gpnum/completed wrap. */
struct rcu_node *mynode; /* This CPU's leaf of hierarchy */
unsigned long grpmask; /* Mask to apply to leaf qsmask. */
#ifdef CONFIG_RCU_CPU_STALL_INFO
@@ -340,14 +337,10 @@ struct rcu_data {
#ifdef CONFIG_RCU_NOCB_CPU
struct rcu_head *nocb_head; /* CBs waiting for kthread. */
struct rcu_head **nocb_tail;
- atomic_long_t nocb_q_count; /* # CBs waiting for kthread */
- atomic_long_t nocb_q_count_lazy; /* (approximate). */
+ atomic_long_t nocb_q_count; /* # CBs waiting for nocb */
+ atomic_long_t nocb_q_count_lazy; /* invocation (all stages). */
struct rcu_head *nocb_follower_head; /* CBs ready to invoke. */
struct rcu_head **nocb_follower_tail;
- atomic_long_t nocb_follower_count; /* # CBs ready to invoke. */
- atomic_long_t nocb_follower_count_lazy; /* (approximate). */
- int nocb_p_count; /* # CBs being invoked by kthread */
- int nocb_p_count_lazy; /* (approximate). */
wait_queue_head_t nocb_wq; /* For nocb kthreads to sleep on. */
struct task_struct *nocb_kthread;
int nocb_defer_wakeup; /* Defer wakeup of nocb_kthread. */
@@ -356,8 +349,6 @@ struct rcu_data {
struct rcu_head *nocb_gp_head ____cacheline_internodealigned_in_smp;
/* CBs waiting for GP. */
struct rcu_head **nocb_gp_tail;
- long nocb_gp_count;
- long nocb_gp_count_lazy;
bool nocb_leader_sleep; /* Is the nocb leader thread asleep? */
struct rcu_data *nocb_next_follower;
/* Next follower in wakeup chain. */
@@ -488,10 +479,14 @@ struct rcu_state {
/* due to no GP active. */
unsigned long gp_start; /* Time at which GP started, */
/* but in jiffies. */
+ unsigned long gp_activity; /* Time of last GP kthread */
+ /* activity in jiffies. */
unsigned long jiffies_stall; /* Time at which to check */
/* for CPU stalls. */
unsigned long jiffies_resched; /* Time at which to resched */
/* a reluctant CPU. */
+ unsigned long n_force_qs_gpstart; /* Snapshot of n_force_qs at */
+ /* GP start. */
unsigned long gp_max; /* Maximum GP duration in */
/* jiffies. */
const char *name; /* Name of structure. */
@@ -514,13 +509,6 @@ extern struct list_head rcu_struct_flavors;
#define for_each_rcu_flavor(rsp) \
list_for_each_entry((rsp), &rcu_struct_flavors, flavors)
-/* Return values for rcu_preempt_offline_tasks(). */
-
-#define RCU_OFL_TASKS_NORM_GP 0x1 /* Tasks blocking normal */
- /* GP were moved to root. */
-#define RCU_OFL_TASKS_EXP_GP 0x2 /* Tasks blocking expedited */
- /* GP were moved to root. */
-
/*
* RCU implementation internal declarations:
*/
@@ -546,27 +534,16 @@ DECLARE_PER_CPU(char, rcu_cpu_has_work);
/* Forward declarations for rcutree_plugin.h */
static void rcu_bootup_announce(void);
-long rcu_batches_completed(void);
static void rcu_preempt_note_context_switch(void);
static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
#ifdef CONFIG_HOTPLUG_CPU
-static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
- unsigned long flags);
+static bool rcu_preempt_has_tasks(struct rcu_node *rnp);
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
static void rcu_print_detail_task_stall(struct rcu_state *rsp);
static int rcu_print_task_stall(struct rcu_node *rnp);
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
-#ifdef CONFIG_HOTPLUG_CPU
-static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
- struct rcu_node *rnp,
- struct rcu_data *rdp);
-#endif /* #ifdef CONFIG_HOTPLUG_CPU */
static void rcu_preempt_check_callbacks(void);
void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
-#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_PREEMPT_RCU)
-static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
- bool wake);
-#endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_PREEMPT_RCU) */
static void __init __rcu_init_preempt(void);
static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
@@ -622,24 +599,15 @@ static void rcu_dynticks_task_exit(void);
#endif /* #ifndef RCU_TREE_NONCORE */
#ifdef CONFIG_RCU_TRACE
-#ifdef CONFIG_RCU_NOCB_CPU
-/* Sum up queue lengths for tracing. */
+/* Read out queue lengths for tracing. */
static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
{
- *ql = atomic_long_read(&rdp->nocb_q_count) +
- rdp->nocb_p_count +
- atomic_long_read(&rdp->nocb_follower_count) +
- rdp->nocb_p_count + rdp->nocb_gp_count;
- *qll = atomic_long_read(&rdp->nocb_q_count_lazy) +
- rdp->nocb_p_count_lazy +
- atomic_long_read(&rdp->nocb_follower_count_lazy) +
- rdp->nocb_p_count_lazy + rdp->nocb_gp_count_lazy;
-}
+#ifdef CONFIG_RCU_NOCB_CPU
+ *ql = atomic_long_read(&rdp->nocb_q_count);
+ *qll = atomic_long_read(&rdp->nocb_q_count_lazy);
#else /* #ifdef CONFIG_RCU_NOCB_CPU */
-static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
-{
*ql = 0;
*qll = 0;
-}
#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
+}
#endif /* #ifdef CONFIG_RCU_TRACE */
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 3ec85cb5d544..2e850a51bb8f 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -34,10 +34,6 @@
#include "../locking/rtmutex_common.h"
-/* rcuc/rcub kthread realtime priority */
-static int kthread_prio = CONFIG_RCU_KTHREAD_PRIO;
-module_param(kthread_prio, int, 0644);
-
/*
* Control variables for per-CPU and per-rcu_node kthreads. These
* handle all flavors of RCU.
@@ -103,6 +99,8 @@ RCU_STATE_INITIALIZER(rcu_preempt, 'p', call_rcu);
static struct rcu_state *rcu_state_p = &rcu_preempt_state;
static int rcu_preempted_readers_exp(struct rcu_node *rnp);
+static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
+ bool wake);
/*
* Tell them what RCU they are running.
@@ -114,25 +112,6 @@ static void __init rcu_bootup_announce(void)
}
/*
- * Return the number of RCU-preempt batches processed thus far
- * for debug and statistics.
- */
-static long rcu_batches_completed_preempt(void)
-{
- return rcu_preempt_state.completed;
-}
-EXPORT_SYMBOL_GPL(rcu_batches_completed_preempt);
-
-/*
- * Return the number of RCU batches processed thus far for debug & stats.
- */
-long rcu_batches_completed(void)
-{
- return rcu_batches_completed_preempt();
-}
-EXPORT_SYMBOL_GPL(rcu_batches_completed);
-
-/*
* Record a preemptible-RCU quiescent state for the specified CPU. Note
* that this just means that the task currently running on the CPU is
* not in a quiescent state. There might be any number of tasks blocked
@@ -307,15 +286,25 @@ static struct list_head *rcu_next_node_entry(struct task_struct *t,
}
/*
+ * Return true if the specified rcu_node structure has tasks that were
+ * preempted within an RCU read-side critical section.
+ */
+static bool rcu_preempt_has_tasks(struct rcu_node *rnp)
+{
+ return !list_empty(&rnp->blkd_tasks);
+}
+
+/*
* Handle special cases during rcu_read_unlock(), such as needing to
* notify RCU core processing or task having blocked during the RCU
* read-side critical section.
*/
void rcu_read_unlock_special(struct task_struct *t)
{
- int empty;
- int empty_exp;
- int empty_exp_now;
+ bool empty;
+ bool empty_exp;
+ bool empty_norm;
+ bool empty_exp_now;
unsigned long flags;
struct list_head *np;
#ifdef CONFIG_RCU_BOOST
@@ -367,7 +356,8 @@ void rcu_read_unlock_special(struct task_struct *t)
break;
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
}
- empty = !rcu_preempt_blocked_readers_cgp(rnp);
+ empty = !rcu_preempt_has_tasks(rnp);
+ empty_norm = !rcu_preempt_blocked_readers_cgp(rnp);
empty_exp = !rcu_preempted_readers_exp(rnp);
smp_mb(); /* ensure expedited fastpath sees end of RCU c-s. */
np = rcu_next_node_entry(t, rnp);
@@ -387,13 +377,21 @@ void rcu_read_unlock_special(struct task_struct *t)
#endif /* #ifdef CONFIG_RCU_BOOST */
/*
+ * If this was the last task on the list, go see if we
+ * need to propagate ->qsmaskinit bit clearing up the
+ * rcu_node tree.
+ */
+ if (!empty && !rcu_preempt_has_tasks(rnp))
+ rcu_cleanup_dead_rnp(rnp);
+
+ /*
* If this was the last task on the current list, and if
* we aren't waiting on any CPUs, report the quiescent state.
* Note that rcu_report_unblock_qs_rnp() releases rnp->lock,
* so we must take a snapshot of the expedited state.
*/
empty_exp_now = !rcu_preempted_readers_exp(rnp);
- if (!empty && !rcu_preempt_blocked_readers_cgp(rnp)) {
+ if (!empty_norm && !rcu_preempt_blocked_readers_cgp(rnp)) {
trace_rcu_quiescent_state_report(TPS("preempt_rcu"),
rnp->gpnum,
0, rnp->qsmask,
@@ -408,10 +406,8 @@ void rcu_read_unlock_special(struct task_struct *t)
#ifdef CONFIG_RCU_BOOST
/* Unboost if we were boosted. */
- if (drop_boost_mutex) {
+ if (drop_boost_mutex)
rt_mutex_unlock(&rnp->boost_mtx);
- complete(&rnp->boost_completion);
- }
#endif /* #ifdef CONFIG_RCU_BOOST */
/*
@@ -519,99 +515,13 @@ static int rcu_print_task_stall(struct rcu_node *rnp)
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
{
WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp));
- if (!list_empty(&rnp->blkd_tasks))
+ if (rcu_preempt_has_tasks(rnp))
rnp->gp_tasks = rnp->blkd_tasks.next;
WARN_ON_ONCE(rnp->qsmask);
}
#ifdef CONFIG_HOTPLUG_CPU
-/*
- * Handle tasklist migration for case in which all CPUs covered by the
- * specified rcu_node have gone offline. Move them up to the root
- * rcu_node. The reason for not just moving them to the immediate
- * parent is to remove the need for rcu_read_unlock_special() to
- * make more than two attempts to acquire the target rcu_node's lock.
- * Returns true if there were tasks blocking the current RCU grace
- * period.
- *
- * Returns 1 if there was previously a task blocking the current grace
- * period on the specified rcu_node structure.
- *
- * The caller must hold rnp->lock with irqs disabled.
- */
-static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
- struct rcu_node *rnp,
- struct rcu_data *rdp)
-{
- struct list_head *lp;
- struct list_head *lp_root;
- int retval = 0;
- struct rcu_node *rnp_root = rcu_get_root(rsp);
- struct task_struct *t;
-
- if (rnp == rnp_root) {
- WARN_ONCE(1, "Last CPU thought to be offlined?");
- return 0; /* Shouldn't happen: at least one CPU online. */
- }
-
- /* If we are on an internal node, complain bitterly. */
- WARN_ON_ONCE(rnp != rdp->mynode);
-
- /*
- * Move tasks up to root rcu_node. Don't try to get fancy for
- * this corner-case operation -- just put this node's tasks
- * at the head of the root node's list, and update the root node's
- * ->gp_tasks and ->exp_tasks pointers to those of this node's,
- * if non-NULL. This might result in waiting for more tasks than
- * absolutely necessary, but this is a good performance/complexity
- * tradeoff.
- */
- if (rcu_preempt_blocked_readers_cgp(rnp) && rnp->qsmask == 0)
- retval |= RCU_OFL_TASKS_NORM_GP;
- if (rcu_preempted_readers_exp(rnp))
- retval |= RCU_OFL_TASKS_EXP_GP;
- lp = &rnp->blkd_tasks;
- lp_root = &rnp_root->blkd_tasks;
- while (!list_empty(lp)) {
- t = list_entry(lp->next, typeof(*t), rcu_node_entry);
- raw_spin_lock(&rnp_root->lock); /* irqs already disabled */
- smp_mb__after_unlock_lock();
- list_del(&t->rcu_node_entry);
- t->rcu_blocked_node = rnp_root;
- list_add(&t->rcu_node_entry, lp_root);
- if (&t->rcu_node_entry == rnp->gp_tasks)
- rnp_root->gp_tasks = rnp->gp_tasks;
- if (&t->rcu_node_entry == rnp->exp_tasks)
- rnp_root->exp_tasks = rnp->exp_tasks;
-#ifdef CONFIG_RCU_BOOST
- if (&t->rcu_node_entry == rnp->boost_tasks)
- rnp_root->boost_tasks = rnp->boost_tasks;
-#endif /* #ifdef CONFIG_RCU_BOOST */
- raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */
- }
-
- rnp->gp_tasks = NULL;
- rnp->exp_tasks = NULL;
-#ifdef CONFIG_RCU_BOOST
- rnp->boost_tasks = NULL;
- /*
- * In case root is being boosted and leaf was not. Make sure
- * that we boost the tasks blocking the current grace period
- * in this case.
- */
- raw_spin_lock(&rnp_root->lock); /* irqs already disabled */
- smp_mb__after_unlock_lock();
- if (rnp_root->boost_tasks != NULL &&
- rnp_root->boost_tasks != rnp_root->gp_tasks &&
- rnp_root->boost_tasks != rnp_root->exp_tasks)
- rnp_root->boost_tasks = rnp_root->gp_tasks;
- raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */
-#endif /* #ifdef CONFIG_RCU_BOOST */
-
- return retval;
-}
-
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
/*
@@ -771,7 +681,7 @@ sync_rcu_preempt_exp_init(struct rcu_state *rsp, struct rcu_node *rnp)
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
- if (list_empty(&rnp->blkd_tasks)) {
+ if (!rcu_preempt_has_tasks(rnp)) {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
} else {
rnp->exp_tasks = rnp->blkd_tasks.next;
@@ -933,15 +843,6 @@ static void __init rcu_bootup_announce(void)
}
/*
- * Return the number of RCU batches processed thus far for debug & stats.
- */
-long rcu_batches_completed(void)
-{
- return rcu_batches_completed_sched();
-}
-EXPORT_SYMBOL_GPL(rcu_batches_completed);
-
-/*
* Because preemptible RCU does not exist, we never have to check for
* CPUs being in quiescent states.
*/
@@ -960,11 +861,12 @@ static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp)
#ifdef CONFIG_HOTPLUG_CPU
-/* Because preemptible RCU does not exist, no quieting of tasks. */
-static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags)
- __releases(rnp->lock)
+/*
+ * Because there is no preemptible RCU, there can be no readers blocked.
+ */
+static bool rcu_preempt_has_tasks(struct rcu_node *rnp)
{
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ return false;
}
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
@@ -996,23 +898,6 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
WARN_ON_ONCE(rnp->qsmask);
}
-#ifdef CONFIG_HOTPLUG_CPU
-
-/*
- * Because preemptible RCU does not exist, it never needs to migrate
- * tasks that were blocked within RCU read-side critical sections, and
- * such non-existent tasks cannot possibly have been blocking the current
- * grace period.
- */
-static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
- struct rcu_node *rnp,
- struct rcu_data *rdp)
-{
- return 0;
-}
-
-#endif /* #ifdef CONFIG_HOTPLUG_CPU */
-
/*
* Because preemptible RCU does not exist, it never has any callbacks
* to check.
@@ -1031,20 +916,6 @@ void synchronize_rcu_expedited(void)
}
EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
-#ifdef CONFIG_HOTPLUG_CPU
-
-/*
- * Because preemptible RCU does not exist, there is never any need to
- * report on tasks preempted in RCU read-side critical sections during
- * expedited RCU grace periods.
- */
-static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
- bool wake)
-{
-}
-
-#endif /* #ifdef CONFIG_HOTPLUG_CPU */
-
/*
* Because preemptible RCU does not exist, rcu_barrier() is just
* another name for rcu_barrier_sched().
@@ -1080,7 +951,7 @@ void exit_rcu(void)
static void rcu_initiate_boost_trace(struct rcu_node *rnp)
{
- if (list_empty(&rnp->blkd_tasks))
+ if (!rcu_preempt_has_tasks(rnp))
rnp->n_balk_blkd_tasks++;
else if (rnp->exp_tasks == NULL && rnp->gp_tasks == NULL)
rnp->n_balk_exp_gp_tasks++;
@@ -1127,7 +998,8 @@ static int rcu_boost(struct rcu_node *rnp)
struct task_struct *t;
struct list_head *tb;
- if (rnp->exp_tasks == NULL && rnp->boost_tasks == NULL)
+ if (ACCESS_ONCE(rnp->exp_tasks) == NULL &&
+ ACCESS_ONCE(rnp->boost_tasks) == NULL)
return 0; /* Nothing left to boost. */
raw_spin_lock_irqsave(&rnp->lock, flags);
@@ -1175,15 +1047,11 @@ static int rcu_boost(struct rcu_node *rnp)
*/
t = container_of(tb, struct task_struct, rcu_node_entry);
rt_mutex_init_proxy_locked(&rnp->boost_mtx, t);
- init_completion(&rnp->boost_completion);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
/* Lock only for side effect: boosts task t's priority. */
rt_mutex_lock(&rnp->boost_mtx);
rt_mutex_unlock(&rnp->boost_mtx); /* Then keep lockdep happy. */
- /* Wait for boostee to be done w/boost_mtx before reinitializing. */
- wait_for_completion(&rnp->boost_completion);
-
return ACCESS_ONCE(rnp->exp_tasks) != NULL ||
ACCESS_ONCE(rnp->boost_tasks) != NULL;
}
@@ -1416,12 +1284,8 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1)
if ((mask & 0x1) && cpu != outgoingcpu)
cpumask_set_cpu(cpu, cm);
- if (cpumask_weight(cm) == 0) {
+ if (cpumask_weight(cm) == 0)
cpumask_setall(cm);
- for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++)
- cpumask_clear_cpu(cpu, cm);
- WARN_ON_ONCE(cpumask_weight(cm) == 0);
- }
set_cpus_allowed_ptr(t, cm);
free_cpumask_var(cm);
}
@@ -1446,12 +1310,8 @@ static void __init rcu_spawn_boost_kthreads(void)
for_each_possible_cpu(cpu)
per_cpu(rcu_cpu_has_work, cpu) = 0;
BUG_ON(smpboot_register_percpu_thread(&rcu_cpu_thread_spec));
- rnp = rcu_get_root(rcu_state_p);
- (void)rcu_spawn_one_boost_kthread(rcu_state_p, rnp);
- if (NUM_RCU_NODES > 1) {
- rcu_for_each_leaf_node(rcu_state_p, rnp)
- (void)rcu_spawn_one_boost_kthread(rcu_state_p, rnp);
- }
+ rcu_for_each_leaf_node(rcu_state_p, rnp)
+ (void)rcu_spawn_one_boost_kthread(rcu_state_p, rnp);
}
static void rcu_prepare_kthreads(int cpu)
@@ -1605,7 +1465,8 @@ static bool __maybe_unused rcu_try_advance_all_cbs(void)
* completed since we last checked and there are
* callbacks not yet ready to invoke.
*/
- if (rdp->completed != rnp->completed &&
+ if ((rdp->completed != rnp->completed ||
+ unlikely(ACCESS_ONCE(rdp->gpwrap))) &&
rdp->nxttail[RCU_DONE_TAIL] != rdp->nxttail[RCU_NEXT_TAIL])
note_gp_changes(rsp, rdp);
@@ -1898,11 +1759,12 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
ticks_value = rsp->gpnum - rdp->gpnum;
}
print_cpu_stall_fast_no_hz(fast_no_hz, cpu);
- pr_err("\t%d: (%lu %s) idle=%03x/%llx/%d softirq=%u/%u %s\n",
+ pr_err("\t%d: (%lu %s) idle=%03x/%llx/%d softirq=%u/%u fqs=%ld %s\n",
cpu, ticks_value, ticks_title,
atomic_read(&rdtp->dynticks) & 0xfff,
rdtp->dynticks_nesting, rdtp->dynticks_nmi_nesting,
rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
+ ACCESS_ONCE(rsp->n_force_qs) - rsp->n_force_qs_gpstart,
fast_no_hz);
}
@@ -2056,9 +1918,26 @@ static void wake_nocb_leader(struct rcu_data *rdp, bool force)
static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu)
{
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
+ unsigned long ret;
+#ifdef CONFIG_PROVE_RCU
struct rcu_head *rhp;
+#endif /* #ifdef CONFIG_PROVE_RCU */
- /* No-CBs CPUs might have callbacks on any of three lists. */
+ /*
+ * Check count of all no-CBs callbacks awaiting invocation.
+ * There needs to be a barrier before this function is called,
+ * but associated with a prior determination that no more
+ * callbacks would be posted. In the worst case, the first
+ * barrier in _rcu_barrier() suffices (but the caller cannot
+ * necessarily rely on this, not a substitute for the caller
+ * getting the concurrency design right!). There must also be
+ * a barrier between the following load an posting of a callback
+ * (if a callback is in fact needed). This is associated with an
+ * atomic_inc() in the caller.
+ */
+ ret = atomic_long_read(&rdp->nocb_q_count);
+
+#ifdef CONFIG_PROVE_RCU
rhp = ACCESS_ONCE(rdp->nocb_head);
if (!rhp)
rhp = ACCESS_ONCE(rdp->nocb_gp_head);
@@ -2072,8 +1951,9 @@ static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu)
cpu, rhp->func);
WARN_ON_ONCE(1);
}
+#endif /* #ifdef CONFIG_PROVE_RCU */
- return !!rhp;
+ return !!ret;
}
/*
@@ -2095,9 +1975,10 @@ static void __call_rcu_nocb_enqueue(struct rcu_data *rdp,
struct task_struct *t;
/* Enqueue the callback on the nocb list and update counts. */
+ atomic_long_add(rhcount, &rdp->nocb_q_count);
+ /* rcu_barrier() relies on ->nocb_q_count add before xchg. */
old_rhpp = xchg(&rdp->nocb_tail, rhtp);
ACCESS_ONCE(*old_rhpp) = rhp;
- atomic_long_add(rhcount, &rdp->nocb_q_count);
atomic_long_add(rhcount_lazy, &rdp->nocb_q_count_lazy);
smp_mb__after_atomic(); /* Store *old_rhpp before _wake test. */
@@ -2288,9 +2169,6 @@ wait_again:
/* Move callbacks to wait-for-GP list, which is empty. */
ACCESS_ONCE(rdp->nocb_head) = NULL;
rdp->nocb_gp_tail = xchg(&rdp->nocb_tail, &rdp->nocb_head);
- rdp->nocb_gp_count = atomic_long_xchg(&rdp->nocb_q_count, 0);
- rdp->nocb_gp_count_lazy =
- atomic_long_xchg(&rdp->nocb_q_count_lazy, 0);
gotcbs = true;
}
@@ -2338,9 +2216,6 @@ wait_again:
/* Append callbacks to follower's "done" list. */
tail = xchg(&rdp->nocb_follower_tail, rdp->nocb_gp_tail);
*tail = rdp->nocb_gp_head;
- atomic_long_add(rdp->nocb_gp_count, &rdp->nocb_follower_count);
- atomic_long_add(rdp->nocb_gp_count_lazy,
- &rdp->nocb_follower_count_lazy);
smp_mb__after_atomic(); /* Store *tail before wakeup. */
if (rdp != my_rdp && tail == &rdp->nocb_follower_head) {
/*
@@ -2415,13 +2290,11 @@ static int rcu_nocb_kthread(void *arg)
trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu, "WokeNonEmpty");
ACCESS_ONCE(rdp->nocb_follower_head) = NULL;
tail = xchg(&rdp->nocb_follower_tail, &rdp->nocb_follower_head);
- c = atomic_long_xchg(&rdp->nocb_follower_count, 0);
- cl = atomic_long_xchg(&rdp->nocb_follower_count_lazy, 0);
- rdp->nocb_p_count += c;
- rdp->nocb_p_count_lazy += cl;
/* Each pass through the following loop invokes a callback. */
- trace_rcu_batch_start(rdp->rsp->name, cl, c, -1);
+ trace_rcu_batch_start(rdp->rsp->name,
+ atomic_long_read(&rdp->nocb_q_count_lazy),
+ atomic_long_read(&rdp->nocb_q_count), -1);
c = cl = 0;
while (list) {
next = list->next;
@@ -2443,9 +2316,9 @@ static int rcu_nocb_kthread(void *arg)
list = next;
}
trace_rcu_batch_end(rdp->rsp->name, c, !!list, 0, 0, 1);
- ACCESS_ONCE(rdp->nocb_p_count) = rdp->nocb_p_count - c;
- ACCESS_ONCE(rdp->nocb_p_count_lazy) =
- rdp->nocb_p_count_lazy - cl;
+ smp_mb__before_atomic(); /* _add after CB invocation. */
+ atomic_long_add(-c, &rdp->nocb_q_count);
+ atomic_long_add(-cl, &rdp->nocb_q_count_lazy);
rdp->n_nocbs_invoked += c;
}
return 0;
diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c
index 5cdc62e1beeb..fbb6240509ea 100644
--- a/kernel/rcu/tree_trace.c
+++ b/kernel/rcu/tree_trace.c
@@ -46,6 +46,8 @@
#define RCU_TREE_NONCORE
#include "tree.h"
+DECLARE_PER_CPU_SHARED_ALIGNED(unsigned long, rcu_qs_ctr);
+
static int r_open(struct inode *inode, struct file *file,
const struct seq_operations *op)
{
@@ -115,11 +117,13 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
if (!rdp->beenonline)
return;
- seq_printf(m, "%3d%cc=%ld g=%ld pq=%d qp=%d",
+ seq_printf(m, "%3d%cc=%ld g=%ld pq=%d/%d qp=%d",
rdp->cpu,
cpu_is_offline(rdp->cpu) ? '!' : ' ',
ulong2long(rdp->completed), ulong2long(rdp->gpnum),
- rdp->passed_quiesce, rdp->qs_pending);
+ rdp->passed_quiesce,
+ rdp->rcu_qs_ctr_snap == per_cpu(rcu_qs_ctr, rdp->cpu),
+ rdp->qs_pending);
seq_printf(m, " dt=%d/%llx/%d df=%lu",
atomic_read(&rdp->dynticks->dynticks),
rdp->dynticks->dynticks_nesting,
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 501baa9ac1be..8cdb98847c7b 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -656,9 +656,8 @@ static void run_ksoftirqd(unsigned int cpu)
* in the task stack here.
*/
__do_softirq();
- rcu_note_context_switch();
local_irq_enable();
- cond_resched();
+ cond_resched_rcu_qs();
return;
}
local_irq_enable();
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 7a9c93e327f2..a2ca213c71ca 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1258,7 +1258,7 @@ config RCU_CPU_STALL_TIMEOUT
config RCU_CPU_STALL_INFO
bool "Print additional diagnostics on RCU CPU stall"
depends on (TREE_RCU || PREEMPT_RCU) && DEBUG_KERNEL
- default n
+ default y
help
For each stalled CPU that is aware of the current RCU grace
period, print out additional per-CPU diagnostic information
diff --git a/tools/testing/selftests/rcutorture/bin/cpus2use.sh b/tools/testing/selftests/rcutorture/bin/cpus2use.sh
index abe14b7f36e9..bb99cde3f5f9 100755
--- a/tools/testing/selftests/rcutorture/bin/cpus2use.sh
+++ b/tools/testing/selftests/rcutorture/bin/cpus2use.sh
@@ -24,7 +24,7 @@
ncpus=`grep '^processor' /proc/cpuinfo | wc -l`
idlecpus=`mpstat | tail -1 | \
- awk -v ncpus=$ncpus '{ print ncpus * ($7 + $12) / 100 }'`
+ awk -v ncpus=$ncpus '{ print ncpus * ($7 + $NF) / 100 }'`
awk -v ncpus=$ncpus -v idlecpus=$idlecpus < /dev/null '
BEGIN {
cpus2use = idlecpus;
diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh
index d6cc07fc137f..559e01ac86be 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh
@@ -30,6 +30,7 @@ else
echo Unreadable results directory: $i
exit 1
fi
+. tools/testing/selftests/rcutorture/bin/functions.sh
configfile=`echo $i | sed -e 's/^.*\///'`
ngps=`grep ver: $i/console.log 2> /dev/null | tail -1 | sed -e 's/^.* ver: //' -e 's/ .*$//'`
@@ -48,4 +49,21 @@ else
title="$title ($ngpsps per second)"
fi
echo $title
+ nclosecalls=`grep --binary-files=text 'torture: Reader Batch' $i/console.log | tail -1 | awk '{for (i=NF-8;i<=NF;i++) sum+=$i; } END {print sum}'`
+ if test -z "$nclosecalls"
+ then
+ exit 0
+ fi
+ if test "$nclosecalls" -eq 0
+ then
+ exit 0
+ fi
+ # Compute number of close calls per tenth of an hour
+ nclosecalls10=`awk -v nclosecalls=$nclosecalls -v dur=$dur 'BEGIN { print int(nclosecalls * 36000 / dur) }' < /dev/null`
+ if test $nclosecalls10 -gt 5 -a $nclosecalls -gt 1
+ then
+ print_bug $nclosecalls "Reader Batch close calls in" $(($dur/60)) minute run: $i
+ else
+ print_warning $nclosecalls "Reader Batch close calls in" $(($dur/60)) minute run: $i
+ fi
fi
diff --git a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
index 8ca9f21f2efc..5236e073919d 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
@@ -8,9 +8,9 @@
#
# Usage: kvm-test-1-run.sh config builddir resdir minutes qemu-args boot_args
#
-# qemu-args defaults to "-nographic", along with arguments specifying the
-# number of CPUs and other options generated from
-# the underlying CPU architecture.
+# qemu-args defaults to "-enable-kvm -soundhw pcspk -nographic", along with
+# arguments specifying the number of CPUs and other
+# options generated from the underlying CPU architecture.
# boot_args defaults to value returned by the per_version_boot_params
# shell function.
#
@@ -138,7 +138,7 @@ then
fi
# Generate -smp qemu argument.
-qemu_args="-nographic $qemu_args"
+qemu_args="-enable-kvm -soundhw pcspk -nographic $qemu_args"
cpu_count=`configNR_CPUS.sh $config_template`
cpu_count=`configfrag_boot_cpus "$boot_args" "$config_template" "$cpu_count"`
vcpus=`identify_qemu_vcpus`
@@ -168,6 +168,7 @@ then
touch $resdir/buildonly
exit 0
fi
+echo "NOTE: $QEMU either did not run or was interactive" > $builddir/console.log
echo $QEMU $qemu_args -m 512 -kernel $resdir/bzImage -append \"$qemu_append $boot_args\" > $resdir/qemu-cmd
( $QEMU $qemu_args -m 512 -kernel $resdir/bzImage -append "$qemu_append $boot_args"; echo $? > $resdir/qemu-retval ) &
qemu_pid=$!
diff --git a/tools/testing/selftests/rcutorture/bin/parse-build.sh b/tools/testing/selftests/rcutorture/bin/parse-build.sh
index 499d1e598e42..a6b57622c2e5 100755
--- a/tools/testing/selftests/rcutorture/bin/parse-build.sh
+++ b/tools/testing/selftests/rcutorture/bin/parse-build.sh
@@ -26,12 +26,15 @@
#
# Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
-T=$1
+F=$1
title=$2
+T=/tmp/parse-build.sh.$$
+trap 'rm -rf $T' 0
+mkdir $T
. functions.sh
-if grep -q CC < $T
+if grep -q CC < $F
then
:
else
@@ -39,18 +42,21 @@ else
exit 1
fi
-if grep -q "error:" < $T
+if grep -q "error:" < $F
then
print_bug $title build errors:
- grep "error:" < $T
+ grep "error:" < $F
exit 2
fi
-exit 0
-if egrep -q "rcu[^/]*\.c.*warning:|rcu.*\.h.*warning:" < $T
+grep warning: < $F > $T/warnings
+grep "include/linux/*rcu*\.h:" $T/warnings > $T/hwarnings
+grep "kernel/rcu/[^/]*:" $T/warnings > $T/cwarnings
+cat $T/hwarnings $T/cwarnings > $T/rcuwarnings
+if test -s $T/rcuwarnings
then
print_warning $title build errors:
- egrep "rcu[^/]*\.c.*warning:|rcu.*\.h.*warning:" < $T
+ cat $T/rcuwarnings
exit 2
fi
exit 0
diff --git a/tools/testing/selftests/rcutorture/bin/parse-console.sh b/tools/testing/selftests/rcutorture/bin/parse-console.sh
index f962ba4cf68b..d8f35cf116be 100755
--- a/tools/testing/selftests/rcutorture/bin/parse-console.sh
+++ b/tools/testing/selftests/rcutorture/bin/parse-console.sh
@@ -36,7 +36,7 @@ if grep -Pq '\x00' < $file
then
print_warning Console output contains nul bytes, old qemu still running?
fi
-egrep 'Badness|WARNING:|Warn|BUG|===========|Call Trace:|Oops:' < $file | grep -v 'ODEBUG: ' | grep -v 'Warning: unable to open an initial console' > $T
+egrep 'Badness|WARNING:|Warn|BUG|===========|Call Trace:|Oops:|Stall ended before state dump start' < $file | grep -v 'ODEBUG: ' | grep -v 'Warning: unable to open an initial console' > $T
if test -s $T
then
print_warning Assertion failure in $file $title