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-rw-r--r--kernel/rcu/rcu.h31
-rw-r--r--kernel/rcu/rcu_segcblist.c25
-rw-r--r--kernel/rcu/rcu_segcblist.h25
-rw-r--r--kernel/rcu/rcuperf.c173
-rw-r--r--kernel/rcu/rcutorture.c139
-rw-r--r--kernel/rcu/srcutree.c11
-rw-r--r--kernel/rcu/tiny.c28
-rw-r--r--kernel/rcu/tree.c304
-rw-r--r--kernel/rcu/tree.h18
-rw-r--r--kernel/rcu/tree_exp.h141
-rw-r--r--kernel/rcu/tree_plugin.h52
-rw-r--r--kernel/rcu/tree_stall.h28
-rw-r--r--kernel/rcu/update.c12
13 files changed, 680 insertions, 307 deletions
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index eabafde2349e..05f936ed167a 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -198,33 +198,6 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head)
}
#endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
-void kfree(const void *);
-
-/*
- * Reclaim the specified callback, either by invoking it (non-lazy case)
- * or freeing it directly (lazy case). Return true if lazy, false otherwise.
- */
-static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head)
-{
- rcu_callback_t f;
- unsigned long offset = (unsigned long)head->func;
-
- rcu_lock_acquire(&rcu_callback_map);
- if (__is_kfree_rcu_offset(offset)) {
- trace_rcu_invoke_kfree_callback(rn, head, offset);
- kfree((void *)head - offset);
- rcu_lock_release(&rcu_callback_map);
- return true;
- } else {
- trace_rcu_invoke_callback(rn, head);
- f = head->func;
- WRITE_ONCE(head->func, (rcu_callback_t)0L);
- f(head);
- rcu_lock_release(&rcu_callback_map);
- return false;
- }
-}
-
#ifdef CONFIG_RCU_STALL_COMMON
extern int rcu_cpu_stall_ftrace_dump;
@@ -281,7 +254,7 @@ void rcu_test_sync_prims(void);
*/
extern void resched_cpu(int cpu);
-#if defined(SRCU) || !defined(TINY_RCU)
+#if defined(CONFIG_SRCU) || !defined(CONFIG_TINY_RCU)
#include <linux/rcu_node_tree.h>
@@ -418,7 +391,7 @@ do { \
#define raw_lockdep_assert_held_rcu_node(p) \
lockdep_assert_held(&ACCESS_PRIVATE(p, lock))
-#endif /* #if defined(SRCU) || !defined(TINY_RCU) */
+#endif /* #if defined(CONFIG_SRCU) || !defined(CONFIG_TINY_RCU) */
#ifdef CONFIG_SRCU
void srcu_init(void);
diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c
index cbc87b804db9..5f4fd3b8777c 100644
--- a/kernel/rcu/rcu_segcblist.c
+++ b/kernel/rcu/rcu_segcblist.c
@@ -20,14 +20,10 @@ void rcu_cblist_init(struct rcu_cblist *rclp)
rclp->head = NULL;
rclp->tail = &rclp->head;
rclp->len = 0;
- rclp->len_lazy = 0;
}
/*
* Enqueue an rcu_head structure onto the specified callback list.
- * This function assumes that the callback is non-lazy because it
- * is intended for use by no-CBs CPUs, which do not distinguish
- * between lazy and non-lazy RCU callbacks.
*/
void rcu_cblist_enqueue(struct rcu_cblist *rclp, struct rcu_head *rhp)
{
@@ -54,7 +50,6 @@ void rcu_cblist_flush_enqueue(struct rcu_cblist *drclp,
else
drclp->tail = &drclp->head;
drclp->len = srclp->len;
- drclp->len_lazy = srclp->len_lazy;
if (!rhp) {
rcu_cblist_init(srclp);
} else {
@@ -62,16 +57,12 @@ void rcu_cblist_flush_enqueue(struct rcu_cblist *drclp,
srclp->head = rhp;
srclp->tail = &rhp->next;
WRITE_ONCE(srclp->len, 1);
- srclp->len_lazy = 0;
}
}
/*
* Dequeue the oldest rcu_head structure from the specified callback
- * list. This function assumes that the callback is non-lazy, but
- * the caller can later invoke rcu_cblist_dequeued_lazy() if it
- * finds otherwise (and if it cares about laziness). This allows
- * different users to have different ways of determining laziness.
+ * list.
*/
struct rcu_head *rcu_cblist_dequeue(struct rcu_cblist *rclp)
{
@@ -161,7 +152,6 @@ void rcu_segcblist_init(struct rcu_segcblist *rsclp)
for (i = 0; i < RCU_CBLIST_NSEGS; i++)
rsclp->tails[i] = &rsclp->head;
rcu_segcblist_set_len(rsclp, 0);
- rsclp->len_lazy = 0;
rsclp->enabled = 1;
}
@@ -173,7 +163,6 @@ void rcu_segcblist_disable(struct rcu_segcblist *rsclp)
{
WARN_ON_ONCE(!rcu_segcblist_empty(rsclp));
WARN_ON_ONCE(rcu_segcblist_n_cbs(rsclp));
- WARN_ON_ONCE(rcu_segcblist_n_lazy_cbs(rsclp));
rsclp->enabled = 0;
}
@@ -253,11 +242,9 @@ bool rcu_segcblist_nextgp(struct rcu_segcblist *rsclp, unsigned long *lp)
* absolutely not OK for it to ever miss posting a callback.
*/
void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp,
- struct rcu_head *rhp, bool lazy)
+ struct rcu_head *rhp)
{
rcu_segcblist_inc_len(rsclp);
- if (lazy)
- rsclp->len_lazy++;
smp_mb(); /* Ensure counts are updated before callback is enqueued. */
rhp->next = NULL;
WRITE_ONCE(*rsclp->tails[RCU_NEXT_TAIL], rhp);
@@ -275,15 +262,13 @@ void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp,
* period. You have been warned.
*/
bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp,
- struct rcu_head *rhp, bool lazy)
+ struct rcu_head *rhp)
{
int i;
if (rcu_segcblist_n_cbs(rsclp) == 0)
return false;
rcu_segcblist_inc_len(rsclp);
- if (lazy)
- rsclp->len_lazy++;
smp_mb(); /* Ensure counts are updated before callback is entrained. */
rhp->next = NULL;
for (i = RCU_NEXT_TAIL; i > RCU_DONE_TAIL; i--)
@@ -307,8 +292,6 @@ bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp,
void rcu_segcblist_extract_count(struct rcu_segcblist *rsclp,
struct rcu_cblist *rclp)
{
- rclp->len_lazy += rsclp->len_lazy;
- rsclp->len_lazy = 0;
rclp->len = rcu_segcblist_xchg_len(rsclp, 0);
}
@@ -361,9 +344,7 @@ void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp,
void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp,
struct rcu_cblist *rclp)
{
- rsclp->len_lazy += rclp->len_lazy;
rcu_segcblist_add_len(rsclp, rclp->len);
- rclp->len_lazy = 0;
rclp->len = 0;
}
diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index 815c2fdd3fcc..5c293afc07b8 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -15,15 +15,6 @@ static inline long rcu_cblist_n_cbs(struct rcu_cblist *rclp)
return READ_ONCE(rclp->len);
}
-/*
- * Account for the fact that a previously dequeued callback turned out
- * to be marked as lazy.
- */
-static inline void rcu_cblist_dequeued_lazy(struct rcu_cblist *rclp)
-{
- rclp->len_lazy--;
-}
-
void rcu_cblist_init(struct rcu_cblist *rclp);
void rcu_cblist_enqueue(struct rcu_cblist *rclp, struct rcu_head *rhp);
void rcu_cblist_flush_enqueue(struct rcu_cblist *drclp,
@@ -59,18 +50,6 @@ static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp)
#endif
}
-/* Return number of lazy callbacks in segmented callback list. */
-static inline long rcu_segcblist_n_lazy_cbs(struct rcu_segcblist *rsclp)
-{
- return rsclp->len_lazy;
-}
-
-/* Return number of lazy callbacks in segmented callback list. */
-static inline long rcu_segcblist_n_nonlazy_cbs(struct rcu_segcblist *rsclp)
-{
- return rcu_segcblist_n_cbs(rsclp) - rsclp->len_lazy;
-}
-
/*
* Is the specified rcu_segcblist enabled, for example, not corresponding
* to an offline CPU?
@@ -106,9 +85,9 @@ struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp);
struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp);
bool rcu_segcblist_nextgp(struct rcu_segcblist *rsclp, unsigned long *lp);
void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp,
- struct rcu_head *rhp, bool lazy);
+ struct rcu_head *rhp);
bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp,
- struct rcu_head *rhp, bool lazy);
+ struct rcu_head *rhp);
void rcu_segcblist_extract_count(struct rcu_segcblist *rsclp,
struct rcu_cblist *rclp);
void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp,
diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index 5f884d560384..da94b89cd531 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -86,6 +86,7 @@ torture_param(bool, shutdown, RCUPERF_SHUTDOWN,
"Shutdown at end of performance tests.");
torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
+torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() perf test?");
static char *perf_type = "rcu";
module_param(perf_type, charp, 0444);
@@ -105,8 +106,8 @@ static atomic_t n_rcu_perf_writer_finished;
static wait_queue_head_t shutdown_wq;
static u64 t_rcu_perf_writer_started;
static u64 t_rcu_perf_writer_finished;
-static unsigned long b_rcu_perf_writer_started;
-static unsigned long b_rcu_perf_writer_finished;
+static unsigned long b_rcu_gp_test_started;
+static unsigned long b_rcu_gp_test_finished;
static DEFINE_PER_CPU(atomic_t, n_async_inflight);
#define MAX_MEAS 10000
@@ -378,10 +379,10 @@ rcu_perf_writer(void *arg)
if (atomic_inc_return(&n_rcu_perf_writer_started) >= nrealwriters) {
t_rcu_perf_writer_started = t;
if (gp_exp) {
- b_rcu_perf_writer_started =
+ b_rcu_gp_test_started =
cur_ops->exp_completed() / 2;
} else {
- b_rcu_perf_writer_started = cur_ops->get_gp_seq();
+ b_rcu_gp_test_started = cur_ops->get_gp_seq();
}
}
@@ -429,10 +430,10 @@ retry:
PERFOUT_STRING("Test complete");
t_rcu_perf_writer_finished = t;
if (gp_exp) {
- b_rcu_perf_writer_finished =
+ b_rcu_gp_test_finished =
cur_ops->exp_completed() / 2;
} else {
- b_rcu_perf_writer_finished =
+ b_rcu_gp_test_finished =
cur_ops->get_gp_seq();
}
if (shutdown) {
@@ -515,8 +516,8 @@ rcu_perf_cleanup(void)
t_rcu_perf_writer_finished -
t_rcu_perf_writer_started,
ngps,
- rcuperf_seq_diff(b_rcu_perf_writer_finished,
- b_rcu_perf_writer_started));
+ rcuperf_seq_diff(b_rcu_gp_test_finished,
+ b_rcu_gp_test_started));
for (i = 0; i < nrealwriters; i++) {
if (!writer_durations)
break;
@@ -584,6 +585,159 @@ rcu_perf_shutdown(void *arg)
return -EINVAL;
}
+/*
+ * kfree_rcu() performance tests: Start a kfree_rcu() loop on all CPUs for number
+ * of iterations and measure total time and number of GP for all iterations to complete.
+ */
+
+torture_param(int, kfree_nthreads, -1, "Number of threads running loops of kfree_rcu().");
+torture_param(int, kfree_alloc_num, 8000, "Number of allocations and frees done in an iteration.");
+torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num allocations and frees.");
+
+static struct task_struct **kfree_reader_tasks;
+static int kfree_nrealthreads;
+static atomic_t n_kfree_perf_thread_started;
+static atomic_t n_kfree_perf_thread_ended;
+
+struct kfree_obj {
+ char kfree_obj[8];
+ struct rcu_head rh;
+};
+
+static int
+kfree_perf_thread(void *arg)
+{
+ int i, loop = 0;
+ long me = (long)arg;
+ struct kfree_obj *alloc_ptr;
+ u64 start_time, end_time;
+
+ VERBOSE_PERFOUT_STRING("kfree_perf_thread task started");
+ set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
+ set_user_nice(current, MAX_NICE);
+
+ start_time = ktime_get_mono_fast_ns();
+
+ if (atomic_inc_return(&n_kfree_perf_thread_started) >= kfree_nrealthreads) {
+ if (gp_exp)
+ b_rcu_gp_test_started = cur_ops->exp_completed() / 2;
+ else
+ b_rcu_gp_test_started = cur_ops->get_gp_seq();
+ }
+
+ do {
+ for (i = 0; i < kfree_alloc_num; i++) {
+ alloc_ptr = kmalloc(sizeof(struct kfree_obj), GFP_KERNEL);
+ if (!alloc_ptr)
+ return -ENOMEM;
+
+ kfree_rcu(alloc_ptr, rh);
+ }
+
+ cond_resched();
+ } while (!torture_must_stop() && ++loop < kfree_loops);
+
+ if (atomic_inc_return(&n_kfree_perf_thread_ended) >= kfree_nrealthreads) {
+ end_time = ktime_get_mono_fast_ns();
+
+ if (gp_exp)
+ b_rcu_gp_test_finished = cur_ops->exp_completed() / 2;
+ else
+ b_rcu_gp_test_finished = cur_ops->get_gp_seq();
+
+ pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld\n",
+ (unsigned long long)(end_time - start_time), kfree_loops,
+ rcuperf_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started));
+ if (shutdown) {
+ smp_mb(); /* Assign before wake. */
+ wake_up(&shutdown_wq);
+ }
+ }
+
+ torture_kthread_stopping("kfree_perf_thread");
+ return 0;
+}
+
+static void
+kfree_perf_cleanup(void)
+{
+ int i;
+
+ if (torture_cleanup_begin())
+ return;
+
+ if (kfree_reader_tasks) {
+ for (i = 0; i < kfree_nrealthreads; i++)
+ torture_stop_kthread(kfree_perf_thread,
+ kfree_reader_tasks[i]);
+ kfree(kfree_reader_tasks);
+ }
+
+ torture_cleanup_end();
+}
+
+/*
+ * shutdown kthread. Just waits to be awakened, then shuts down system.
+ */
+static int
+kfree_perf_shutdown(void *arg)
+{
+ do {
+ wait_event(shutdown_wq,
+ atomic_read(&n_kfree_perf_thread_ended) >=
+ kfree_nrealthreads);
+ } while (atomic_read(&n_kfree_perf_thread_ended) < kfree_nrealthreads);
+
+ smp_mb(); /* Wake before output. */
+
+ kfree_perf_cleanup();
+ kernel_power_off();
+ return -EINVAL;
+}
+
+static int __init
+kfree_perf_init(void)
+{
+ long i;
+ int firsterr = 0;
+
+ kfree_nrealthreads = compute_real(kfree_nthreads);
+ /* Start up the kthreads. */
+ if (shutdown) {
+ init_waitqueue_head(&shutdown_wq);
+ firsterr = torture_create_kthread(kfree_perf_shutdown, NULL,
+ shutdown_task);
+ if (firsterr)
+ goto unwind;
+ schedule_timeout_uninterruptible(1);
+ }
+
+ kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
+ GFP_KERNEL);
+ if (kfree_reader_tasks == NULL) {
+ firsterr = -ENOMEM;
+ goto unwind;
+ }
+
+ for (i = 0; i < kfree_nrealthreads; i++) {
+ firsterr = torture_create_kthread(kfree_perf_thread, (void *)i,
+ kfree_reader_tasks[i]);
+ if (firsterr)
+ goto unwind;
+ }
+
+ while (atomic_read(&n_kfree_perf_thread_started) < kfree_nrealthreads)
+ schedule_timeout_uninterruptible(1);
+
+ torture_init_end();
+ return 0;
+
+unwind:
+ torture_init_end();
+ kfree_perf_cleanup();
+ return firsterr;
+}
+
static int __init
rcu_perf_init(void)
{
@@ -616,6 +770,9 @@ rcu_perf_init(void)
if (cur_ops->init)
cur_ops->init();
+ if (kfree_rcu_test)
+ return kfree_perf_init();
+
nrealwriters = compute_real(nwriters);
nrealreaders = compute_real(nreaders);
atomic_set(&n_rcu_perf_reader_started, 0);
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 121a0507a7ce..1aeecc165b21 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1661,43 +1661,52 @@ static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
struct rcu_fwd_cb {
struct rcu_head rh;
struct rcu_fwd_cb *rfc_next;
+ struct rcu_fwd *rfc_rfp;
int rfc_gps;
};
-static DEFINE_SPINLOCK(rcu_fwd_lock);
-static struct rcu_fwd_cb *rcu_fwd_cb_head;
-static struct rcu_fwd_cb **rcu_fwd_cb_tail = &rcu_fwd_cb_head;
-static long n_launders_cb;
-static unsigned long rcu_fwd_startat;
-static bool rcu_fwd_emergency_stop;
+
#define MAX_FWD_CB_JIFFIES (8 * HZ) /* Maximum CB test duration. */
#define MIN_FWD_CB_LAUNDERS 3 /* This many CB invocations to count. */
#define MIN_FWD_CBS_LAUNDERED 100 /* Number of counted CBs. */
#define FWD_CBS_HIST_DIV 10 /* Histogram buckets/second. */
+#define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
+
struct rcu_launder_hist {
long n_launders;
unsigned long launder_gp_seq;
};
-#define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
-static struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
-static unsigned long rcu_launder_gp_seq_start;
-static void rcu_torture_fwd_cb_hist(void)
+struct rcu_fwd {
+ spinlock_t rcu_fwd_lock;
+ struct rcu_fwd_cb *rcu_fwd_cb_head;
+ struct rcu_fwd_cb **rcu_fwd_cb_tail;
+ long n_launders_cb;
+ unsigned long rcu_fwd_startat;
+ struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
+ unsigned long rcu_launder_gp_seq_start;
+};
+
+struct rcu_fwd *rcu_fwds;
+bool rcu_fwd_emergency_stop;
+
+static void rcu_torture_fwd_cb_hist(struct rcu_fwd *rfp)
{
unsigned long gps;
unsigned long gps_old;
int i;
int j;
- for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)
- if (n_launders_hist[i].n_launders > 0)
+ for (i = ARRAY_SIZE(rfp->n_launders_hist) - 1; i > 0; i--)
+ if (rfp->n_launders_hist[i].n_launders > 0)
break;
pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
- __func__, jiffies - rcu_fwd_startat);
- gps_old = rcu_launder_gp_seq_start;
+ __func__, jiffies - rfp->rcu_fwd_startat);
+ gps_old = rfp->rcu_launder_gp_seq_start;
for (j = 0; j <= i; j++) {
- gps = n_launders_hist[j].launder_gp_seq;
+ gps = rfp->n_launders_hist[j].launder_gp_seq;
pr_cont(" %ds/%d: %ld:%ld",
- j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j].n_launders,
+ j + 1, FWD_CBS_HIST_DIV,
+ rfp->n_launders_hist[j].n_launders,
rcutorture_seq_diff(gps, gps_old));
gps_old = gps;
}
@@ -1711,20 +1720,21 @@ static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
int i;
struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
struct rcu_fwd_cb **rfcpp;
+ struct rcu_fwd *rfp = rfcp->rfc_rfp;
rfcp->rfc_next = NULL;
rfcp->rfc_gps++;
- spin_lock_irqsave(&rcu_fwd_lock, flags);
- rfcpp = rcu_fwd_cb_tail;
- rcu_fwd_cb_tail = &rfcp->rfc_next;
+ spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
+ rfcpp = rfp->rcu_fwd_cb_tail;
+ rfp->rcu_fwd_cb_tail = &rfcp->rfc_next;
WRITE_ONCE(*rfcpp, rfcp);
- WRITE_ONCE(n_launders_cb, n_launders_cb + 1);
- i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
- if (i >= ARRAY_SIZE(n_launders_hist))
- i = ARRAY_SIZE(n_launders_hist) - 1;
- n_launders_hist[i].n_launders++;
- n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
- spin_unlock_irqrestore(&rcu_fwd_lock, flags);
+ WRITE_ONCE(rfp->n_launders_cb, rfp->n_launders_cb + 1);
+ i = ((jiffies - rfp->rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
+ if (i >= ARRAY_SIZE(rfp->n_launders_hist))
+ i = ARRAY_SIZE(rfp->n_launders_hist) - 1;
+ rfp->n_launders_hist[i].n_launders++;
+ rfp->n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
+ spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
}
// Give the scheduler a chance, even on nohz_full CPUs.
@@ -1744,23 +1754,23 @@ static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
* Free all callbacks on the rcu_fwd_cb_head list, either because the
* test is over or because we hit an OOM event.
*/
-static unsigned long rcu_torture_fwd_prog_cbfree(void)
+static unsigned long rcu_torture_fwd_prog_cbfree(struct rcu_fwd *rfp)
{
unsigned long flags;
unsigned long freed = 0;
struct rcu_fwd_cb *rfcp;
for (;;) {
- spin_lock_irqsave(&rcu_fwd_lock, flags);
- rfcp = rcu_fwd_cb_head;
+ spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
+ rfcp = rfp->rcu_fwd_cb_head;
if (!rfcp) {
- spin_unlock_irqrestore(&rcu_fwd_lock, flags);
+ spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
break;
}
- rcu_fwd_cb_head = rfcp->rfc_next;
- if (!rcu_fwd_cb_head)
- rcu_fwd_cb_tail = &rcu_fwd_cb_head;
- spin_unlock_irqrestore(&rcu_fwd_lock, flags);
+ rfp->rcu_fwd_cb_head = rfcp->rfc_next;
+ if (!rfp->rcu_fwd_cb_head)
+ rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
+ spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
kfree(rfcp);
freed++;
rcu_torture_fwd_prog_cond_resched(freed);
@@ -1774,7 +1784,8 @@ static unsigned long rcu_torture_fwd_prog_cbfree(void)
}
/* Carry out need_resched()/cond_resched() forward-progress testing. */
-static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
+static void rcu_torture_fwd_prog_nr(struct rcu_fwd *rfp,
+ int *tested, int *tested_tries)
{
unsigned long cver;
unsigned long dur;
@@ -1804,8 +1815,8 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
sd = cur_ops->stall_dur() + 1;
sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
dur = sd4 + torture_random(&trs) % (sd - sd4);
- WRITE_ONCE(rcu_fwd_startat, jiffies);
- stopat = rcu_fwd_startat + dur;
+ WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
+ stopat = rfp->rcu_fwd_startat + dur;
while (time_before(jiffies, stopat) &&
!shutdown_time_arrived() &&
!READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
@@ -1840,7 +1851,7 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
}
/* Carry out call_rcu() forward-progress testing. */
-static void rcu_torture_fwd_prog_cr(void)
+static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
{
unsigned long cver;
unsigned long flags;
@@ -1864,23 +1875,23 @@ static void rcu_torture_fwd_prog_cr(void)
/* Loop continuously posting RCU callbacks. */
WRITE_ONCE(rcu_fwd_cb_nodelay, true);
cur_ops->sync(); /* Later readers see above write. */
- WRITE_ONCE(rcu_fwd_startat, jiffies);
- stopat = rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
+ WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
+ stopat = rfp->rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
n_launders = 0;
- n_launders_cb = 0;
+ rfp->n_launders_cb = 0; // Hoist initialization for multi-kthread
n_launders_sa = 0;
n_max_cbs = 0;
n_max_gps = 0;
- for (i = 0; i < ARRAY_SIZE(n_launders_hist); i++)
- n_launders_hist[i].n_launders = 0;
+ for (i = 0; i < ARRAY_SIZE(rfp->n_launders_hist); i++)
+ rfp->n_launders_hist[i].n_launders = 0;
cver = READ_ONCE(rcu_torture_current_version);
gps = cur_ops->get_gp_seq();
- rcu_launder_gp_seq_start = gps;
+ rfp->rcu_launder_gp_seq_start = gps;
tick_dep_set_task(current, TICK_DEP_BIT_RCU);
while (time_before(jiffies, stopat) &&
!shutdown_time_arrived() &&
!READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
- rfcp = READ_ONCE(rcu_fwd_cb_head);
+ rfcp = READ_ONCE(rfp->rcu_fwd_cb_head);
rfcpn = NULL;
if (rfcp)
rfcpn = READ_ONCE(rfcp->rfc_next);
@@ -1888,7 +1899,7 @@ static void rcu_torture_fwd_prog_cr(void)
if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
break;
- rcu_fwd_cb_head = rfcpn;
+ rfp->rcu_fwd_cb_head = rfcpn;
n_launders++;
n_launders_sa++;
} else {
@@ -1900,6 +1911,7 @@ static void rcu_torture_fwd_prog_cr(void)
n_max_cbs++;
n_launders_sa = 0;
rfcp->rfc_gps = 0;
+ rfcp->rfc_rfp = rfp;
}
cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
@@ -1910,22 +1922,22 @@ static void rcu_torture_fwd_prog_cr(void)
}
}
stoppedat = jiffies;
- n_launders_cb_snap = READ_ONCE(n_launders_cb);
+ n_launders_cb_snap = READ_ONCE(rfp->n_launders_cb);
cver = READ_ONCE(rcu_torture_current_version) - cver;
gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
- (void)rcu_torture_fwd_prog_cbfree();
+ (void)rcu_torture_fwd_prog_cbfree(rfp);
if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
!shutdown_time_arrived()) {
WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n",
__func__,
- stoppedat - rcu_fwd_startat, jiffies - stoppedat,
+ stoppedat - rfp->rcu_fwd_startat, jiffies - stoppedat,
n_launders + n_max_cbs - n_launders_cb_snap,
n_launders, n_launders_sa,
n_max_gps, n_max_cbs, cver, gps);
- rcu_torture_fwd_cb_hist();
+ rcu_torture_fwd_cb_hist(rfp);
}
schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
@@ -1940,20 +1952,22 @@ static void rcu_torture_fwd_prog_cr(void)
static int rcutorture_oom_notify(struct notifier_block *self,
unsigned long notused, void *nfreed)
{
+ struct rcu_fwd *rfp = rcu_fwds;
+
WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
__func__);
- rcu_torture_fwd_cb_hist();
- rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat)) / 2);
+ rcu_torture_fwd_cb_hist(rfp);
+ rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rfp->rcu_fwd_startat)) / 2);
WRITE_ONCE(rcu_fwd_emergency_stop, true);
smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
pr_info("%s: Freed %lu RCU callbacks.\n",
- __func__, rcu_torture_fwd_prog_cbfree());
+ __func__, rcu_torture_fwd_prog_cbfree(rfp));
rcu_barrier();
pr_info("%s: Freed %lu RCU callbacks.\n",
- __func__, rcu_torture_fwd_prog_cbfree());
+ __func__, rcu_torture_fwd_prog_cbfree(rfp));
rcu_barrier();
pr_info("%s: Freed %lu RCU callbacks.\n",
- __func__, rcu_torture_fwd_prog_cbfree());
+ __func__, rcu_torture_fwd_prog_cbfree(rfp));
smp_mb(); /* Frees before return to avoid redoing OOM. */
(*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
pr_info("%s returning after OOM processing.\n", __func__);
@@ -1967,6 +1981,7 @@ static struct notifier_block rcutorture_oom_nb = {
/* Carry out grace-period forward-progress testing. */
static int rcu_torture_fwd_prog(void *args)
{
+ struct rcu_fwd *rfp = args;
int tested = 0;
int tested_tries = 0;
@@ -1978,8 +1993,8 @@ static int rcu_torture_fwd_prog(void *args)
schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
WRITE_ONCE(rcu_fwd_emergency_stop, false);
register_oom_notifier(&rcutorture_oom_nb);
- rcu_torture_fwd_prog_nr(&tested, &tested_tries);
- rcu_torture_fwd_prog_cr();
+ rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries);
+ rcu_torture_fwd_prog_cr(rfp);
unregister_oom_notifier(&rcutorture_oom_nb);
/* Avoid slow periods, better to test when busy. */
@@ -1995,6 +2010,8 @@ static int rcu_torture_fwd_prog(void *args)
/* If forward-progress checking is requested and feasible, spawn the thread. */
static int __init rcu_torture_fwd_prog_init(void)
{
+ struct rcu_fwd *rfp;
+
if (!fwd_progress)
return 0; /* Not requested, so don't do it. */
if (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0 ||
@@ -2013,8 +2030,12 @@ static int __init rcu_torture_fwd_prog_init(void)
fwd_progress_holdoff = 1;
if (fwd_progress_div <= 0)
fwd_progress_div = 4;
- return torture_create_kthread(rcu_torture_fwd_prog,
- NULL, fwd_prog_task);
+ rfp = kzalloc(sizeof(*rfp), GFP_KERNEL);
+ if (!rfp)
+ return -ENOMEM;
+ spin_lock_init(&rfp->rcu_fwd_lock);
+ rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
+ return torture_create_kthread(rcu_torture_fwd_prog, rfp, fwd_prog_task);
}
/* Callback function for RCU barrier testing. */
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 5dffade2d7cd..657e6a7d1c03 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -530,7 +530,7 @@ static void srcu_gp_end(struct srcu_struct *ssp)
idx = rcu_seq_state(ssp->srcu_gp_seq);
WARN_ON_ONCE(idx != SRCU_STATE_SCAN2);
cbdelay = srcu_get_delay(ssp);
- ssp->srcu_last_gp_end = ktime_get_mono_fast_ns();
+ WRITE_ONCE(ssp->srcu_last_gp_end, ktime_get_mono_fast_ns());
rcu_seq_end(&ssp->srcu_gp_seq);
gpseq = rcu_seq_current(&ssp->srcu_gp_seq);
if (ULONG_CMP_LT(ssp->srcu_gp_seq_needed_exp, gpseq))
@@ -762,6 +762,7 @@ static bool srcu_might_be_idle(struct srcu_struct *ssp)
unsigned long flags;
struct srcu_data *sdp;
unsigned long t;
+ unsigned long tlast;
/* If the local srcu_data structure has callbacks, not idle. */
local_irq_save(flags);
@@ -780,9 +781,9 @@ static bool srcu_might_be_idle(struct srcu_struct *ssp)
/* First, see if enough time has passed since the last GP. */
t = ktime_get_mono_fast_ns();
+ tlast = READ_ONCE(ssp->srcu_last_gp_end);
if (exp_holdoff == 0 ||
- time_in_range_open(t, ssp->srcu_last_gp_end,
- ssp->srcu_last_gp_end + exp_holdoff))
+ time_in_range_open(t, tlast, tlast + exp_holdoff))
return false; /* Too soon after last GP. */
/* Next, check for probable idleness. */
@@ -853,7 +854,7 @@ static void __call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp,
local_irq_save(flags);
sdp = this_cpu_ptr(ssp->sda);
spin_lock_rcu_node(sdp);
- rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp, false);
+ rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp);
rcu_segcblist_advance(&sdp->srcu_cblist,
rcu_seq_current(&ssp->srcu_gp_seq));
s = rcu_seq_snap(&ssp->srcu_gp_seq);
@@ -1052,7 +1053,7 @@ void srcu_barrier(struct srcu_struct *ssp)
sdp->srcu_barrier_head.func = srcu_barrier_cb;
debug_rcu_head_queue(&sdp->srcu_barrier_head);
if (!rcu_segcblist_entrain(&sdp->srcu_cblist,
- &sdp->srcu_barrier_head, 0)) {
+ &sdp->srcu_barrier_head)) {
debug_rcu_head_unqueue(&sdp->srcu_barrier_head);
atomic_dec(&ssp->srcu_barrier_cpu_cnt);
}
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index 477b4eb44af5..dd572ce7c747 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -22,6 +22,7 @@
#include <linux/time.h>
#include <linux/cpu.h>
#include <linux/prefetch.h>
+#include <linux/slab.h>
#include "rcu.h"
@@ -73,6 +74,31 @@ void rcu_sched_clock_irq(int user)
}
}
+/*
+ * Reclaim the specified callback, either by invoking it for non-kfree cases or
+ * freeing it directly (for kfree). Return true if kfreeing, false otherwise.
+ */
+static inline bool rcu_reclaim_tiny(struct rcu_head *head)
+{
+ rcu_callback_t f;
+ unsigned long offset = (unsigned long)head->func;
+
+ rcu_lock_acquire(&rcu_callback_map);
+ if (__is_kfree_rcu_offset(offset)) {
+ trace_rcu_invoke_kfree_callback("", head, offset);
+ kfree((void *)head - offset);
+ rcu_lock_release(&rcu_callback_map);
+ return true;
+ }
+
+ trace_rcu_invoke_callback("", head);
+ f = head->func;
+ WRITE_ONCE(head->func, (rcu_callback_t)0L);
+ f(head);
+ rcu_lock_release(&rcu_callback_map);
+ return false;
+}
+
/* Invoke the RCU callbacks whose grace period has elapsed. */
static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
{
@@ -100,7 +126,7 @@ static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused
prefetch(next);
debug_rcu_head_unqueue(list);
local_bh_disable();
- __rcu_reclaim("", list);
+ rcu_reclaim_tiny(list);
local_bh_enable();
list = next;
}
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index b0e0612392a9..d91c9156fab2 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -43,7 +43,6 @@
#include <uapi/linux/sched/types.h>
#include <linux/prefetch.h>
#include <linux/delay.h>
-#include <linux/stop_machine.h>
#include <linux/random.h>
#include <linux/trace_events.h>
#include <linux/suspend.h>
@@ -55,6 +54,7 @@
#include <linux/oom.h>
#include <linux/smpboot.h>
#include <linux/jiffies.h>
+#include <linux/slab.h>
#include <linux/sched/isolation.h>
#include <linux/sched/clock.h>
#include "../time/tick-internal.h"
@@ -84,7 +84,7 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = {
.dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
.dynticks = ATOMIC_INIT(RCU_DYNTICK_CTRL_CTR),
};
-struct rcu_state rcu_state = {
+static struct rcu_state rcu_state = {
.level = { &rcu_state.node[0] },
.gp_state = RCU_GP_IDLE,
.gp_seq = (0UL - 300UL) << RCU_SEQ_CTR_SHIFT,
@@ -188,7 +188,7 @@ EXPORT_SYMBOL_GPL(rcu_get_gp_kthreads_prio);
* held, but the bit corresponding to the current CPU will be stable
* in most contexts.
*/
-unsigned long rcu_rnp_online_cpus(struct rcu_node *rnp)
+static unsigned long rcu_rnp_online_cpus(struct rcu_node *rnp)
{
return READ_ONCE(rnp->qsmaskinitnext);
}
@@ -294,7 +294,7 @@ static void rcu_dynticks_eqs_online(void)
*
* No ordering, as we are sampling CPU-local information.
*/
-bool rcu_dynticks_curr_cpu_in_eqs(void)
+static bool rcu_dynticks_curr_cpu_in_eqs(void)
{
struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
@@ -305,7 +305,7 @@ bool rcu_dynticks_curr_cpu_in_eqs(void)
* Snapshot the ->dynticks counter with full ordering so as to allow
* stable comparison of this counter with past and future snapshots.
*/
-int rcu_dynticks_snap(struct rcu_data *rdp)
+static int rcu_dynticks_snap(struct rcu_data *rdp)
{
int snap = atomic_add_return(0, &rdp->dynticks);
@@ -529,16 +529,6 @@ static struct rcu_node *rcu_get_root(void)
}
/*
- * Convert a ->gp_state value to a character string.
- */
-static const char *gp_state_getname(short gs)
-{
- if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names))
- return "???";
- return gp_state_names[gs];
-}
-
-/*
* Send along grace-period-related data for rcutorture diagnostics.
*/
void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
@@ -577,7 +567,7 @@ static void rcu_eqs_enter(bool user)
}
lockdep_assert_irqs_disabled();
- trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, rdp->dynticks);
+ trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, atomic_read(&rdp->dynticks));
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
rdp = this_cpu_ptr(&rcu_data);
do_nocb_deferred_wakeup(rdp);
@@ -650,14 +640,15 @@ static __always_inline void rcu_nmi_exit_common(bool irq)
* leave it in non-RCU-idle state.
*/
if (rdp->dynticks_nmi_nesting != 1) {
- trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2, rdp->dynticks);
+ trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2,
+ atomic_read(&rdp->dynticks));
WRITE_ONCE(rdp->dynticks_nmi_nesting, /* No store tearing. */
rdp->dynticks_nmi_nesting - 2);
return;
}
/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
- trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, rdp->dynticks);
+ trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, atomic_read(&rdp->dynticks));
WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
if (irq)
@@ -744,7 +735,7 @@ static void rcu_eqs_exit(bool user)
rcu_dynticks_task_exit();
rcu_dynticks_eqs_exit();
rcu_cleanup_after_idle();
- trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, rdp->dynticks);
+ trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, atomic_read(&rdp->dynticks));
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
WRITE_ONCE(rdp->dynticks_nesting, 1);
WARN_ON_ONCE(rdp->dynticks_nmi_nesting);
@@ -838,7 +829,7 @@ static __always_inline void rcu_nmi_enter_common(bool irq)
}
trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
rdp->dynticks_nmi_nesting,
- rdp->dynticks_nmi_nesting + incby, rdp->dynticks);
+ rdp->dynticks_nmi_nesting + incby, atomic_read(&rdp->dynticks));
WRITE_ONCE(rdp->dynticks_nmi_nesting, /* Prevent store tearing. */
rdp->dynticks_nmi_nesting + incby);
barrier();
@@ -2152,7 +2143,6 @@ static void rcu_do_batch(struct rcu_data *rdp)
/* If no callbacks are ready, just return. */
if (!rcu_segcblist_ready_cbs(&rdp->cblist)) {
trace_rcu_batch_start(rcu_state.name,
- rcu_segcblist_n_lazy_cbs(&rdp->cblist),
rcu_segcblist_n_cbs(&rdp->cblist), 0);
trace_rcu_batch_end(rcu_state.name, 0,
!rcu_segcblist_empty(&rdp->cblist),
@@ -2174,7 +2164,6 @@ static void rcu_do_batch(struct rcu_data *rdp)
if (unlikely(bl > 100))
tlimit = local_clock() + rcu_resched_ns;
trace_rcu_batch_start(rcu_state.name,
- rcu_segcblist_n_lazy_cbs(&rdp->cblist),
rcu_segcblist_n_cbs(&rdp->cblist), bl);
rcu_segcblist_extract_done_cbs(&rdp->cblist, &rcl);
if (offloaded)
@@ -2185,9 +2174,19 @@ static void rcu_do_batch(struct rcu_data *rdp)
tick_dep_set_task(current, TICK_DEP_BIT_RCU);
rhp = rcu_cblist_dequeue(&rcl);
for (; rhp; rhp = rcu_cblist_dequeue(&rcl)) {
+ rcu_callback_t f;
+
debug_rcu_head_unqueue(rhp);
- if (__rcu_reclaim(rcu_state.name, rhp))
- rcu_cblist_dequeued_lazy(&rcl);
+
+ rcu_lock_acquire(&rcu_callback_map);
+ trace_rcu_invoke_callback(rcu_state.name, rhp);
+
+ f = rhp->func;
+ WRITE_ONCE(rhp->func, (rcu_callback_t)0L);
+ f(rhp);
+
+ rcu_lock_release(&rcu_callback_map);
+
/*
* Stop only if limit reached and CPU has something to do.
* Note: The rcl structure counts down from zero.
@@ -2314,14 +2313,11 @@ static void force_qs_rnp(int (*f)(struct rcu_data *rdp))
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
continue;
}
- for_each_leaf_node_possible_cpu(rnp, cpu) {
- unsigned long bit = leaf_node_cpu_bit(rnp, cpu);
- if ((rnp->qsmask & bit) != 0) {
- rdp = per_cpu_ptr(&rcu_data, cpu);
- if (f(rdp)) {
- mask |= bit;
- rcu_disable_urgency_upon_qs(rdp);
- }
+ for_each_leaf_node_cpu_mask(rnp, cpu, rnp->qsmask) {
+ rdp = per_cpu_ptr(&rcu_data, cpu);
+ if (f(rdp)) {
+ mask |= rdp->grpmask;
+ rcu_disable_urgency_upon_qs(rdp);
}
}
if (mask != 0) {
@@ -2480,8 +2476,8 @@ static void rcu_cpu_kthread(unsigned int cpu)
char work, *workp = this_cpu_ptr(&rcu_data.rcu_cpu_has_work);
int spincnt;
+ trace_rcu_utilization(TPS("Start CPU kthread@rcu_run"));
for (spincnt = 0; spincnt < 10; spincnt++) {
- trace_rcu_utilization(TPS("Start CPU kthread@rcu_wait"));
local_bh_disable();
*statusp = RCU_KTHREAD_RUNNING;
local_irq_disable();
@@ -2589,7 +2585,7 @@ static void rcu_leak_callback(struct rcu_head *rhp)
* is expected to specify a CPU.
*/
static void
-__call_rcu(struct rcu_head *head, rcu_callback_t func, bool lazy)
+__call_rcu(struct rcu_head *head, rcu_callback_t func)
{
unsigned long flags;
struct rcu_data *rdp;
@@ -2624,18 +2620,17 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func, bool lazy)
if (rcu_segcblist_empty(&rdp->cblist))
rcu_segcblist_init(&rdp->cblist);
}
+
if (rcu_nocb_try_bypass(rdp, head, &was_alldone, flags))
return; // Enqueued onto ->nocb_bypass, so just leave.
/* If we get here, rcu_nocb_try_bypass() acquired ->nocb_lock. */
- rcu_segcblist_enqueue(&rdp->cblist, head, lazy);
+ rcu_segcblist_enqueue(&rdp->cblist, head);
if (__is_kfree_rcu_offset((unsigned long)func))
trace_rcu_kfree_callback(rcu_state.name, head,
(unsigned long)func,
- rcu_segcblist_n_lazy_cbs(&rdp->cblist),
rcu_segcblist_n_cbs(&rdp->cblist));
else
trace_rcu_callback(rcu_state.name, head,
- rcu_segcblist_n_lazy_cbs(&rdp->cblist),
rcu_segcblist_n_cbs(&rdp->cblist));
/* Go handle any RCU core processing required. */
@@ -2685,23 +2680,225 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func, bool lazy)
*/
void call_rcu(struct rcu_head *head, rcu_callback_t func)
{
- __call_rcu(head, func, 0);
+ __call_rcu(head, func);
}
EXPORT_SYMBOL_GPL(call_rcu);
+
+/* Maximum number of jiffies to wait before draining a batch. */
+#define KFREE_DRAIN_JIFFIES (HZ / 50)
+#define KFREE_N_BATCHES 2
+
+/**
+ * struct kfree_rcu_cpu_work - single batch of kfree_rcu() requests
+ * @rcu_work: Let queue_rcu_work() invoke workqueue handler after grace period
+ * @head_free: List of kfree_rcu() objects waiting for a grace period
+ * @krcp: Pointer to @kfree_rcu_cpu structure
+ */
+
+struct kfree_rcu_cpu_work {
+ struct rcu_work rcu_work;
+ struct rcu_head *head_free;
+ struct kfree_rcu_cpu *krcp;
+};
+
+/**
+ * struct kfree_rcu_cpu - batch up kfree_rcu() requests for RCU grace period
+ * @head: List of kfree_rcu() objects not yet waiting for a grace period
+ * @krw_arr: Array of batches of kfree_rcu() objects waiting for a grace period
+ * @lock: Synchronize access to this structure
+ * @monitor_work: Promote @head to @head_free after KFREE_DRAIN_JIFFIES
+ * @monitor_todo: Tracks whether a @monitor_work delayed work is pending
+ * @initialized: The @lock and @rcu_work fields have been initialized
+ *
+ * This is a per-CPU structure. The reason that it is not included in
+ * the rcu_data structure is to permit this code to be extracted from
+ * the RCU files. Such extraction could allow further optimization of
+ * the interactions with the slab allocators.
+ */
+struct kfree_rcu_cpu {
+ struct rcu_head *head;
+ struct kfree_rcu_cpu_work krw_arr[KFREE_N_BATCHES];
+ spinlock_t lock;
+ struct delayed_work monitor_work;
+ bool monitor_todo;
+ bool initialized;
+};
+
+static DEFINE_PER_CPU(struct kfree_rcu_cpu, krc);
+
+/*
+ * This function is invoked in workqueue context after a grace period.
+ * It frees all the objects queued on ->head_free.
+ */
+static void kfree_rcu_work(struct work_struct *work)
+{
+ unsigned long flags;
+ struct rcu_head *head, *next;
+ struct kfree_rcu_cpu *krcp;
+ struct kfree_rcu_cpu_work *krwp;
+
+ krwp = container_of(to_rcu_work(work),
+ struct kfree_rcu_cpu_work, rcu_work);
+ krcp = krwp->krcp;
+ spin_lock_irqsave(&krcp->lock, flags);
+ head = krwp->head_free;
+ krwp->head_free = NULL;
+ spin_unlock_irqrestore(&krcp->lock, flags);
+
+ // List "head" is now private, so traverse locklessly.
+ for (; head; head = next) {
+ unsigned long offset = (unsigned long)head->func;
+
+ next = head->next;
+ // Potentially optimize with kfree_bulk in future.
+ debug_rcu_head_unqueue(head);
+ rcu_lock_acquire(&rcu_callback_map);
+ trace_rcu_invoke_kfree_callback(rcu_state.name, head, offset);
+
+ if (!WARN_ON_ONCE(!__is_kfree_rcu_offset(offset))) {
+ /* Could be optimized with kfree_bulk() in future. */
+ kfree((void *)head - offset);
+ }
+
+ rcu_lock_release(&rcu_callback_map);
+ cond_resched_tasks_rcu_qs();
+ }
+}
+
+/*
+ * Schedule the kfree batch RCU work to run in workqueue context after a GP.
+ *
+ * This function is invoked by kfree_rcu_monitor() when the KFREE_DRAIN_JIFFIES
+ * timeout has been reached.
+ */
+static inline bool queue_kfree_rcu_work(struct kfree_rcu_cpu *krcp)
+{
+ int i;
+ struct kfree_rcu_cpu_work *krwp = NULL;
+
+ lockdep_assert_held(&krcp->lock);
+ for (i = 0; i < KFREE_N_BATCHES; i++)
+ if (!krcp->krw_arr[i].head_free) {
+ krwp = &(krcp->krw_arr[i]);
+ break;
+ }
+
+ // If a previous RCU batch is in progress, we cannot immediately
+ // queue another one, so return false to tell caller to retry.
+ if (!krwp)
+ return false;
+
+ krwp->head_free = krcp->head;
+ krcp->head = NULL;
+ INIT_RCU_WORK(&krwp->rcu_work, kfree_rcu_work);
+ queue_rcu_work(system_wq, &krwp->rcu_work);
+ return true;
+}
+
+static inline void kfree_rcu_drain_unlock(struct kfree_rcu_cpu *krcp,
+ unsigned long flags)
+{
+ // Attempt to start a new batch.
+ krcp->monitor_todo = false;
+ if (queue_kfree_rcu_work(krcp)) {
+ // Success! Our job is done here.
+ spin_unlock_irqrestore(&krcp->lock, flags);
+ return;
+ }
+
+ // Previous RCU batch still in progress, try again later.
+ krcp->monitor_todo = true;
+ schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES);
+ spin_unlock_irqrestore(&krcp->lock, flags);
+}
+
+/*
+ * This function is invoked after the KFREE_DRAIN_JIFFIES timeout.
+ * It invokes kfree_rcu_drain_unlock() to attempt to start another batch.
+ */
+static void kfree_rcu_monitor(struct work_struct *work)
+{
+ unsigned long flags;
+ struct kfree_rcu_cpu *krcp = container_of(work, struct kfree_rcu_cpu,
+ monitor_work.work);
+
+ spin_lock_irqsave(&krcp->lock, flags);
+ if (krcp->monitor_todo)
+ kfree_rcu_drain_unlock(krcp, flags);
+ else
+ spin_unlock_irqrestore(&krcp->lock, flags);
+}
+
/*
- * Queue an RCU callback for lazy invocation after a grace period.
- * This will likely be later named something like "call_rcu_lazy()",
- * but this change will require some way of tagging the lazy RCU
- * callbacks in the list of pending callbacks. Until then, this
- * function may only be called from __kfree_rcu().
+ * Queue a request for lazy invocation of kfree() after a grace period.
+ *
+ * Each kfree_call_rcu() request is added to a batch. The batch will be drained
+ * every KFREE_DRAIN_JIFFIES number of jiffies. All the objects in the batch
+ * will be kfree'd in workqueue context. This allows us to:
+ *
+ * 1. Batch requests together to reduce the number of grace periods during
+ * heavy kfree_rcu() load.
+ *
+ * 2. It makes it possible to use kfree_bulk() on a large number of
+ * kfree_rcu() requests thus reducing cache misses and the per-object
+ * overhead of kfree().
*/
void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
{
- __call_rcu(head, func, 1);
+ unsigned long flags;
+ struct kfree_rcu_cpu *krcp;
+
+ local_irq_save(flags); // For safely calling this_cpu_ptr().
+ krcp = this_cpu_ptr(&krc);
+ if (krcp->initialized)
+ spin_lock(&krcp->lock);
+
+ // Queue the object but don't yet schedule the batch.
+ if (debug_rcu_head_queue(head)) {
+ // Probable double kfree_rcu(), just leak.
+ WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
+ __func__, head);
+ goto unlock_return;
+ }
+ head->func = func;
+ head->next = krcp->head;
+ krcp->head = head;
+
+ // Set timer to drain after KFREE_DRAIN_JIFFIES.
+ if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING &&
+ !krcp->monitor_todo) {
+ krcp->monitor_todo = true;
+ schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES);
+ }
+
+unlock_return:
+ if (krcp->initialized)
+ spin_unlock(&krcp->lock);
+ local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(kfree_call_rcu);
+void __init kfree_rcu_scheduler_running(void)
+{
+ int cpu;
+ unsigned long flags;
+
+ for_each_online_cpu(cpu) {
+ struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
+
+ spin_lock_irqsave(&krcp->lock, flags);
+ if (!krcp->head || krcp->monitor_todo) {
+ spin_unlock_irqrestore(&krcp->lock, flags);
+ continue;
+ }
+ krcp->monitor_todo = true;
+ schedule_delayed_work_on(cpu, &krcp->monitor_work,
+ KFREE_DRAIN_JIFFIES);
+ spin_unlock_irqrestore(&krcp->lock, flags);
+ }
+}
+
/*
* During early boot, any blocking grace-period wait automatically
* implies a grace period. Later on, this is never the case for PREEMPTION.
@@ -2902,7 +3099,7 @@ static void rcu_barrier_func(void *unused)
debug_rcu_head_queue(&rdp->barrier_head);
rcu_nocb_lock(rdp);
WARN_ON_ONCE(!rcu_nocb_flush_bypass(rdp, NULL, jiffies));
- if (rcu_segcblist_entrain(&rdp->cblist, &rdp->barrier_head, 0)) {
+ if (rcu_segcblist_entrain(&rdp->cblist, &rdp->barrier_head)) {
atomic_inc(&rcu_state.barrier_cpu_count);
} else {
debug_rcu_head_unqueue(&rdp->barrier_head);
@@ -3563,12 +3760,29 @@ static void __init rcu_dump_rcu_node_tree(void)
struct workqueue_struct *rcu_gp_wq;
struct workqueue_struct *rcu_par_gp_wq;
+static void __init kfree_rcu_batch_init(void)
+{
+ int cpu;
+ int i;
+
+ for_each_possible_cpu(cpu) {
+ struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
+
+ spin_lock_init(&krcp->lock);
+ for (i = 0; i < KFREE_N_BATCHES; i++)
+ krcp->krw_arr[i].krcp = krcp;
+ INIT_DELAYED_WORK(&krcp->monitor_work, kfree_rcu_monitor);
+ krcp->initialized = true;
+ }
+}
+
void __init rcu_init(void)
{
int cpu;
rcu_early_boot_tests();
+ kfree_rcu_batch_init();
rcu_bootup_announce();
rcu_init_geometry();
rcu_init_one();
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 055c31781d3a..0c87e4c161c2 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -16,7 +16,6 @@
#include <linux/cpumask.h>
#include <linux/seqlock.h>
#include <linux/swait.h>
-#include <linux/stop_machine.h>
#include <linux/rcu_node_tree.h>
#include "rcu_segcblist.h"
@@ -182,8 +181,8 @@ struct rcu_data {
bool rcu_need_heavy_qs; /* GP old, so heavy quiescent state! */
bool rcu_urgent_qs; /* GP old need light quiescent state. */
bool rcu_forced_tick; /* Forced tick to provide QS. */
+ bool rcu_forced_tick_exp; /* ... provide QS to expedited GP. */
#ifdef CONFIG_RCU_FAST_NO_HZ
- bool all_lazy; /* All CPU's CBs lazy at idle start? */
unsigned long last_accelerate; /* Last jiffy CBs were accelerated. */
unsigned long last_advance_all; /* Last jiffy CBs were all advanced. */
int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
@@ -368,18 +367,6 @@ struct rcu_state {
#define RCU_GP_CLEANUP 7 /* Grace-period cleanup started. */
#define RCU_GP_CLEANED 8 /* Grace-period cleanup complete. */
-static const char * const gp_state_names[] = {
- "RCU_GP_IDLE",
- "RCU_GP_WAIT_GPS",
- "RCU_GP_DONE_GPS",
- "RCU_GP_ONOFF",
- "RCU_GP_INIT",
- "RCU_GP_WAIT_FQS",
- "RCU_GP_DOING_FQS",
- "RCU_GP_CLEANUP",
- "RCU_GP_CLEANED",
-};
-
/*
* In order to export the rcu_state name to the tracing tools, it
* needs to be added in the __tracepoint_string section.
@@ -403,8 +390,6 @@ static const char *tp_rcu_varname __used __tracepoint_string = rcu_name;
#define RCU_NAME rcu_name
#endif /* #else #ifdef CONFIG_TRACING */
-int rcu_dynticks_snap(struct rcu_data *rdp);
-
/* Forward declarations for tree_plugin.h */
static void rcu_bootup_announce(void);
static void rcu_qs(void);
@@ -415,7 +400,6 @@ static bool rcu_preempt_has_tasks(struct rcu_node *rnp);
static int rcu_print_task_exp_stall(struct rcu_node *rnp);
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
static void rcu_flavor_sched_clock_irq(int user);
-void call_rcu(struct rcu_head *head, rcu_callback_t func);
static void dump_blkd_tasks(struct rcu_node *rnp, int ncheck);
static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index d8da6b1a3209..6935a9e2b094 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -21,7 +21,7 @@ static void rcu_exp_gp_seq_start(void)
}
/*
- * Return then value that expedited-grace-period counter will have
+ * Return the value that the expedited-grace-period counter will have
* at the end of the current grace period.
*/
static __maybe_unused unsigned long rcu_exp_gp_seq_endval(void)
@@ -39,7 +39,9 @@ static void rcu_exp_gp_seq_end(void)
}
/*
- * Take a snapshot of the expedited-grace-period counter.
+ * Take a snapshot of the expedited-grace-period counter, which is the
+ * earliest value that will indicate that a full grace period has
+ * elapsed since the current time.
*/
static unsigned long rcu_exp_gp_seq_snap(void)
{
@@ -134,7 +136,7 @@ static void __maybe_unused sync_exp_reset_tree(void)
rcu_for_each_node_breadth_first(rnp) {
raw_spin_lock_irqsave_rcu_node(rnp, flags);
WARN_ON_ONCE(rnp->expmask);
- rnp->expmask = rnp->expmaskinit;
+ WRITE_ONCE(rnp->expmask, rnp->expmaskinit);
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
}
@@ -143,31 +145,26 @@ static void __maybe_unused sync_exp_reset_tree(void)
* Return non-zero if there is no RCU expedited grace period in progress
* for the specified rcu_node structure, in other words, if all CPUs and
* tasks covered by the specified rcu_node structure have done their bit
- * for the current expedited grace period. Works only for preemptible
- * RCU -- other RCU implementation use other means.
- *
- * Caller must hold the specificed rcu_node structure's ->lock
+ * for the current expedited grace period.
*/
-static bool sync_rcu_preempt_exp_done(struct rcu_node *rnp)
+static bool sync_rcu_exp_done(struct rcu_node *rnp)
{
raw_lockdep_assert_held_rcu_node(rnp);
-
return rnp->exp_tasks == NULL &&
READ_ONCE(rnp->expmask) == 0;
}
/*
- * Like sync_rcu_preempt_exp_done(), but this function assumes the caller
- * doesn't hold the rcu_node's ->lock, and will acquire and release the lock
- * itself
+ * Like sync_rcu_exp_done(), but where the caller does not hold the
+ * rcu_node's ->lock.
*/
-static bool sync_rcu_preempt_exp_done_unlocked(struct rcu_node *rnp)
+static bool sync_rcu_exp_done_unlocked(struct rcu_node *rnp)
{
unsigned long flags;
bool ret;
raw_spin_lock_irqsave_rcu_node(rnp, flags);
- ret = sync_rcu_preempt_exp_done(rnp);
+ ret = sync_rcu_exp_done(rnp);
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return ret;
@@ -181,8 +178,6 @@ static bool sync_rcu_preempt_exp_done_unlocked(struct rcu_node *rnp)
* which the task was queued or to one of that rcu_node structure's ancestors,
* recursively up the tree. (Calm down, calm down, we do the recursion
* iteratively!)
- *
- * Caller must hold the specified rcu_node structure's ->lock.
*/
static void __rcu_report_exp_rnp(struct rcu_node *rnp,
bool wake, unsigned long flags)
@@ -190,8 +185,9 @@ static void __rcu_report_exp_rnp(struct rcu_node *rnp,
{
unsigned long mask;
+ raw_lockdep_assert_held_rcu_node(rnp);
for (;;) {
- if (!sync_rcu_preempt_exp_done(rnp)) {
+ if (!sync_rcu_exp_done(rnp)) {
if (!rnp->expmask)
rcu_initiate_boost(rnp, flags);
else
@@ -211,7 +207,7 @@ static void __rcu_report_exp_rnp(struct rcu_node *rnp,
rnp = rnp->parent;
raw_spin_lock_rcu_node(rnp); /* irqs already disabled */
WARN_ON_ONCE(!(rnp->expmask & mask));
- rnp->expmask &= ~mask;
+ WRITE_ONCE(rnp->expmask, rnp->expmask & ~mask);
}
}
@@ -234,14 +230,23 @@ static void __maybe_unused rcu_report_exp_rnp(struct rcu_node *rnp, bool wake)
static void rcu_report_exp_cpu_mult(struct rcu_node *rnp,
unsigned long mask, bool wake)
{
+ int cpu;
unsigned long flags;
+ struct rcu_data *rdp;
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (!(rnp->expmask & mask)) {
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return;
}
- rnp->expmask &= ~mask;
+ WRITE_ONCE(rnp->expmask, rnp->expmask & ~mask);
+ for_each_leaf_node_cpu_mask(rnp, cpu, mask) {
+ rdp = per_cpu_ptr(&rcu_data, cpu);
+ if (!IS_ENABLED(CONFIG_NO_HZ_FULL) || !rdp->rcu_forced_tick_exp)
+ continue;
+ rdp->rcu_forced_tick_exp = false;
+ tick_dep_clear_cpu(cpu, TICK_DEP_BIT_RCU_EXP);
+ }
__rcu_report_exp_rnp(rnp, wake, flags); /* Releases rnp->lock. */
}
@@ -345,8 +350,8 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp)
/* Each pass checks a CPU for identity, offline, and idle. */
mask_ofl_test = 0;
for_each_leaf_node_cpu_mask(rnp, cpu, rnp->expmask) {
- unsigned long mask = leaf_node_cpu_bit(rnp, cpu);
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
+ unsigned long mask = rdp->grpmask;
int snap;
if (raw_smp_processor_id() == cpu ||
@@ -372,12 +377,10 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp)
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
/* IPI the remaining CPUs for expedited quiescent state. */
- for_each_leaf_node_cpu_mask(rnp, cpu, rnp->expmask) {
- unsigned long mask = leaf_node_cpu_bit(rnp, cpu);
+ for_each_leaf_node_cpu_mask(rnp, cpu, mask_ofl_ipi) {
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
+ unsigned long mask = rdp->grpmask;
- if (!(mask_ofl_ipi & mask))
- continue;
retry_ipi:
if (rcu_dynticks_in_eqs_since(rdp, rdp->exp_dynticks_snap)) {
mask_ofl_test |= mask;
@@ -389,10 +392,10 @@ retry_ipi:
}
ret = smp_call_function_single(cpu, rcu_exp_handler, NULL, 0);
put_cpu();
- if (!ret) {
- mask_ofl_ipi &= ~mask;
+ /* The CPU will report the QS in response to the IPI. */
+ if (!ret)
continue;
- }
+
/* Failed, raced with CPU hotplug operation. */
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if ((rnp->qsmaskinitnext & mask) &&
@@ -403,13 +406,12 @@ retry_ipi:
schedule_timeout_uninterruptible(1);
goto retry_ipi;
}
- /* CPU really is offline, so we can ignore it. */
- if (!(rnp->expmask & mask))
- mask_ofl_ipi &= ~mask;
+ /* CPU really is offline, so we must report its QS. */
+ if (rnp->expmask & mask)
+ mask_ofl_test |= mask;
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
/* Report quiescent states for those that went offline. */
- mask_ofl_test |= mask_ofl_ipi;
if (mask_ofl_test)
rcu_report_exp_cpu_mult(rnp, mask_ofl_test, false);
}
@@ -456,29 +458,62 @@ static void sync_rcu_exp_select_cpus(void)
flush_work(&rnp->rew.rew_work);
}
-static void synchronize_sched_expedited_wait(void)
+/*
+ * Wait for the expedited grace period to elapse, within time limit.
+ * If the time limit is exceeded without the grace period elapsing,
+ * return false, otherwise return true.
+ */
+static bool synchronize_rcu_expedited_wait_once(long tlimit)
+{
+ int t;
+ struct rcu_node *rnp_root = rcu_get_root();
+
+ t = swait_event_timeout_exclusive(rcu_state.expedited_wq,
+ sync_rcu_exp_done_unlocked(rnp_root),
+ tlimit);
+ // Workqueues should not be signaled.
+ if (t > 0 || sync_rcu_exp_done_unlocked(rnp_root))
+ return true;
+ WARN_ON(t < 0); /* workqueues should not be signaled. */
+ return false;
+}
+
+/*
+ * Wait for the expedited grace period to elapse, issuing any needed
+ * RCU CPU stall warnings along the way.
+ */
+static void synchronize_rcu_expedited_wait(void)
{
int cpu;
unsigned long jiffies_stall;
unsigned long jiffies_start;
unsigned long mask;
int ndetected;
+ struct rcu_data *rdp;
struct rcu_node *rnp;
struct rcu_node *rnp_root = rcu_get_root();
- int ret;
trace_rcu_exp_grace_period(rcu_state.name, rcu_exp_gp_seq_endval(), TPS("startwait"));
jiffies_stall = rcu_jiffies_till_stall_check();
jiffies_start = jiffies;
+ if (IS_ENABLED(CONFIG_NO_HZ_FULL)) {
+ if (synchronize_rcu_expedited_wait_once(1))
+ return;
+ rcu_for_each_leaf_node(rnp) {
+ for_each_leaf_node_cpu_mask(rnp, cpu, rnp->expmask) {
+ rdp = per_cpu_ptr(&rcu_data, cpu);
+ if (rdp->rcu_forced_tick_exp)
+ continue;
+ rdp->rcu_forced_tick_exp = true;
+ tick_dep_set_cpu(cpu, TICK_DEP_BIT_RCU_EXP);
+ }
+ }
+ WARN_ON_ONCE(1);
+ }
for (;;) {
- ret = swait_event_timeout_exclusive(
- rcu_state.expedited_wq,
- sync_rcu_preempt_exp_done_unlocked(rnp_root),
- jiffies_stall);
- if (ret > 0 || sync_rcu_preempt_exp_done_unlocked(rnp_root))
+ if (synchronize_rcu_expedited_wait_once(jiffies_stall))
return;
- WARN_ON(ret < 0); /* workqueues should not be signaled. */
if (rcu_cpu_stall_suppress)
continue;
panic_on_rcu_stall();
@@ -491,7 +526,7 @@ static void synchronize_sched_expedited_wait(void)
struct rcu_data *rdp;
mask = leaf_node_cpu_bit(rnp, cpu);
- if (!(rnp->expmask & mask))
+ if (!(READ_ONCE(rnp->expmask) & mask))
continue;
ndetected++;
rdp = per_cpu_ptr(&rcu_data, cpu);
@@ -503,17 +538,18 @@ static void synchronize_sched_expedited_wait(void)
}
pr_cont(" } %lu jiffies s: %lu root: %#lx/%c\n",
jiffies - jiffies_start, rcu_state.expedited_sequence,
- rnp_root->expmask, ".T"[!!rnp_root->exp_tasks]);
+ READ_ONCE(rnp_root->expmask),
+ ".T"[!!rnp_root->exp_tasks]);
if (ndetected) {
pr_err("blocking rcu_node structures:");
rcu_for_each_node_breadth_first(rnp) {
if (rnp == rnp_root)
continue; /* printed unconditionally */
- if (sync_rcu_preempt_exp_done_unlocked(rnp))
+ if (sync_rcu_exp_done_unlocked(rnp))
continue;
pr_cont(" l=%u:%d-%d:%#lx/%c",
rnp->level, rnp->grplo, rnp->grphi,
- rnp->expmask,
+ READ_ONCE(rnp->expmask),
".T"[!!rnp->exp_tasks]);
}
pr_cont("\n");
@@ -521,7 +557,7 @@ static void synchronize_sched_expedited_wait(void)
rcu_for_each_leaf_node(rnp) {
for_each_leaf_node_possible_cpu(rnp, cpu) {
mask = leaf_node_cpu_bit(rnp, cpu);
- if (!(rnp->expmask & mask))
+ if (!(READ_ONCE(rnp->expmask) & mask))
continue;
dump_cpu_task(cpu);
}
@@ -540,15 +576,14 @@ static void rcu_exp_wait_wake(unsigned long s)
{
struct rcu_node *rnp;
- synchronize_sched_expedited_wait();
- rcu_exp_gp_seq_end();
- trace_rcu_exp_grace_period(rcu_state.name, s, TPS("end"));
+ synchronize_rcu_expedited_wait();
- /*
- * Switch over to wakeup mode, allowing the next GP, but -only- the
- * next GP, to proceed.
- */
+ // Switch over to wakeup mode, allowing the next GP to proceed.
+ // End the previous grace period only after acquiring the mutex
+ // to ensure that only one GP runs concurrently with wakeups.
mutex_lock(&rcu_state.exp_wake_mutex);
+ rcu_exp_gp_seq_end();
+ trace_rcu_exp_grace_period(rcu_state.name, s, TPS("end"));
rcu_for_each_node_breadth_first(rnp) {
if (ULONG_CMP_LT(READ_ONCE(rnp->exp_seq_rq), s)) {
@@ -559,7 +594,7 @@ static void rcu_exp_wait_wake(unsigned long s)
spin_unlock(&rnp->exp_lock);
}
smp_mb(); /* All above changes before wakeup. */
- wake_up_all(&rnp->exp_wq[rcu_seq_ctr(rcu_state.expedited_sequence) & 0x3]);
+ wake_up_all(&rnp->exp_wq[rcu_seq_ctr(s) & 0x3]);
}
trace_rcu_exp_grace_period(rcu_state.name, s, TPS("endwake"));
mutex_unlock(&rcu_state.exp_wake_mutex);
@@ -785,7 +820,7 @@ static int rcu_print_task_exp_stall(struct rcu_node *rnp)
* implementations, it is still unfriendly to real-time workloads, so is
* thus not recommended for any sort of common-case code. In fact, if
* you are using synchronize_rcu_expedited() in a loop, please restructure
- * your code to batch your updates, and then Use a single synchronize_rcu()
+ * your code to batch your updates, and then use a single synchronize_rcu()
* instead.
*
* This has the same semantics as (but is more brutal than) synchronize_rcu().
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index ebdbdec5911f..c6ea81cd4189 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -488,7 +488,7 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags)
empty_norm = !rcu_preempt_blocked_readers_cgp(rnp);
WARN_ON_ONCE(rnp->completedqs == rnp->gp_seq &&
(!empty_norm || rnp->qsmask));
- empty_exp = sync_rcu_preempt_exp_done(rnp);
+ empty_exp = sync_rcu_exp_done(rnp);
smp_mb(); /* ensure expedited fastpath sees end of RCU c-s. */
np = rcu_next_node_entry(t, rnp);
list_del_init(&t->rcu_node_entry);
@@ -512,7 +512,7 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags)
* Note that rcu_report_unblock_qs_rnp() releases rnp->lock,
* so we must take a snapshot of the expedited state.
*/
- empty_exp_now = sync_rcu_preempt_exp_done(rnp);
+ empty_exp_now = sync_rcu_exp_done(rnp);
if (!empty_norm && !rcu_preempt_blocked_readers_cgp(rnp)) {
trace_rcu_quiescent_state_report(TPS("preempt_rcu"),
rnp->gp_seq,
@@ -1264,10 +1264,9 @@ static void rcu_prepare_for_idle(void)
/*
* This code is invoked when a CPU goes idle, at which point we want
* to have the CPU do everything required for RCU so that it can enter
- * the energy-efficient dyntick-idle mode. This is handled by a
- * state machine implemented by rcu_prepare_for_idle() below.
+ * the energy-efficient dyntick-idle mode.
*
- * The following three proprocessor symbols control this state machine:
+ * The following preprocessor symbol controls this:
*
* RCU_IDLE_GP_DELAY gives the number of jiffies that a CPU is permitted
* to sleep in dyntick-idle mode with RCU callbacks pending. This
@@ -1276,21 +1275,15 @@ static void rcu_prepare_for_idle(void)
* number, be warned: Setting RCU_IDLE_GP_DELAY too high can hang your
* system. And if you are -that- concerned about energy efficiency,
* just power the system down and be done with it!
- * RCU_IDLE_LAZY_GP_DELAY gives the number of jiffies that a CPU is
- * permitted to sleep in dyntick-idle mode with only lazy RCU
- * callbacks pending. Setting this too high can OOM your system.
*
- * The values below work well in practice. If future workloads require
+ * The value below works well in practice. If future workloads require
* adjustment, they can be converted into kernel config parameters, though
* making the state machine smarter might be a better option.
*/
#define RCU_IDLE_GP_DELAY 4 /* Roughly one grace period. */
-#define RCU_IDLE_LAZY_GP_DELAY (6 * HZ) /* Roughly six seconds. */
static int rcu_idle_gp_delay = RCU_IDLE_GP_DELAY;
module_param(rcu_idle_gp_delay, int, 0644);
-static int rcu_idle_lazy_gp_delay = RCU_IDLE_LAZY_GP_DELAY;
-module_param(rcu_idle_lazy_gp_delay, int, 0644);
/*
* Try to advance callbacks on the current CPU, but only if it has been
@@ -1329,8 +1322,7 @@ static bool __maybe_unused rcu_try_advance_all_cbs(void)
/*
* Allow the CPU to enter dyntick-idle mode unless it has callbacks ready
* to invoke. If the CPU has callbacks, try to advance them. Tell the
- * caller to set the timeout based on whether or not there are non-lazy
- * callbacks.
+ * caller about what to set the timeout.
*
* The caller must have disabled interrupts.
*/
@@ -1356,25 +1348,18 @@ int rcu_needs_cpu(u64 basemono, u64 *nextevt)
}
rdp->last_accelerate = jiffies;
- /* Request timer delay depending on laziness, and round. */
- rdp->all_lazy = !rcu_segcblist_n_nonlazy_cbs(&rdp->cblist);
- if (rdp->all_lazy) {
- dj = round_jiffies(rcu_idle_lazy_gp_delay + jiffies) - jiffies;
- } else {
- dj = round_up(rcu_idle_gp_delay + jiffies,
- rcu_idle_gp_delay) - jiffies;
- }
+ /* Request timer and round. */
+ dj = round_up(rcu_idle_gp_delay + jiffies, rcu_idle_gp_delay) - jiffies;
+
*nextevt = basemono + dj * TICK_NSEC;
return 0;
}
/*
- * Prepare a CPU for idle from an RCU perspective. The first major task
- * is to sense whether nohz mode has been enabled or disabled via sysfs.
- * The second major task is to check to see if a non-lazy callback has
- * arrived at a CPU that previously had only lazy callbacks. The third
- * major task is to accelerate (that is, assign grace-period numbers to)
- * any recently arrived callbacks.
+ * Prepare a CPU for idle from an RCU perspective. The first major task is to
+ * sense whether nohz mode has been enabled or disabled via sysfs. The second
+ * major task is to accelerate (that is, assign grace-period numbers to) any
+ * recently arrived callbacks.
*
* The caller must have disabled interrupts.
*/
@@ -1401,17 +1386,6 @@ static void rcu_prepare_for_idle(void)
return;
/*
- * If a non-lazy callback arrived at a CPU having only lazy
- * callbacks, invoke RCU core for the side-effect of recalculating
- * idle duration on re-entry to idle.
- */
- if (rdp->all_lazy && rcu_segcblist_n_nonlazy_cbs(&rdp->cblist)) {
- rdp->all_lazy = false;
- invoke_rcu_core();
- return;
- }
-
- /*
* If we have not yet accelerated this jiffy, accelerate all
* callbacks on this CPU.
*/
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index a6652efedd48..55f9b84790d3 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -263,11 +263,9 @@ static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
{
struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
- sprintf(cp, "last_accelerate: %04lx/%04lx, Nonlazy posted: %c%c%c",
+ sprintf(cp, "last_accelerate: %04lx/%04lx dyntick_enabled: %d",
rdp->last_accelerate & 0xffff, jiffies & 0xffff,
- ".l"[rdp->all_lazy],
- ".L"[!rcu_segcblist_n_nonlazy_cbs(&rdp->cblist)],
- ".D"[!!rdp->tick_nohz_enabled_snap]);
+ !!rdp->tick_nohz_enabled_snap);
}
#else /* #ifdef CONFIG_RCU_FAST_NO_HZ */
@@ -279,6 +277,28 @@ static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
#endif /* #else #ifdef CONFIG_RCU_FAST_NO_HZ */
+static const char * const gp_state_names[] = {
+ [RCU_GP_IDLE] = "RCU_GP_IDLE",
+ [RCU_GP_WAIT_GPS] = "RCU_GP_WAIT_GPS",
+ [RCU_GP_DONE_GPS] = "RCU_GP_DONE_GPS",
+ [RCU_GP_ONOFF] = "RCU_GP_ONOFF",
+ [RCU_GP_INIT] = "RCU_GP_INIT",
+ [RCU_GP_WAIT_FQS] = "RCU_GP_WAIT_FQS",
+ [RCU_GP_DOING_FQS] = "RCU_GP_DOING_FQS",
+ [RCU_GP_CLEANUP] = "RCU_GP_CLEANUP",
+ [RCU_GP_CLEANED] = "RCU_GP_CLEANED",
+};
+
+/*
+ * Convert a ->gp_state value to a character string.
+ */
+static const char *gp_state_getname(short gs)
+{
+ if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names))
+ return "???";
+ return gp_state_names[gs];
+}
+
/*
* Print out diagnostic information for the specified stalled CPU.
*
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 34a7452b25fd..6c4b862f57d6 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -40,6 +40,7 @@
#include <linux/rcupdate_wait.h>
#include <linux/sched/isolation.h>
#include <linux/kprobes.h>
+#include <linux/slab.h>
#define CREATE_TRACE_POINTS
@@ -51,9 +52,7 @@
#define MODULE_PARAM_PREFIX "rcupdate."
#ifndef CONFIG_TINY_RCU
-extern int rcu_expedited; /* from sysctl */
module_param(rcu_expedited, int, 0);
-extern int rcu_normal; /* from sysctl */
module_param(rcu_normal, int, 0);
static int rcu_normal_after_boot;
module_param(rcu_normal_after_boot, int, 0);
@@ -218,6 +217,7 @@ static int __init rcu_set_runtime_mode(void)
{
rcu_test_sync_prims();
rcu_scheduler_active = RCU_SCHEDULER_RUNNING;
+ kfree_rcu_scheduler_running();
rcu_test_sync_prims();
return 0;
}
@@ -853,14 +853,22 @@ static void test_callback(struct rcu_head *r)
DEFINE_STATIC_SRCU(early_srcu);
+struct early_boot_kfree_rcu {
+ struct rcu_head rh;
+};
+
static void early_boot_test_call_rcu(void)
{
static struct rcu_head head;
static struct rcu_head shead;
+ struct early_boot_kfree_rcu *rhp;
call_rcu(&head, test_callback);
if (IS_ENABLED(CONFIG_SRCU))
call_srcu(&early_srcu, &shead, test_callback);
+ rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
+ if (!WARN_ON_ONCE(!rhp))
+ kfree_rcu(rhp, rh);
}
void rcu_early_boot_tests(void)
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.