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The llcc-qcom driver can be compiled as a module, but lacks
MODULE_DEVICE_TABLE() and will therefore not be loaded automatically.
Fix this.
Fixes: a3134fb09e0b ("drivers: soc: Add LLCC driver")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Sai Prakash Ranjan <quic_saipraka@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20220408213336.581661-3-bjorn.andersson@linaro.org
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When building with CONFIG_PM=y and CONFIG_PM_SLEEP=n (such as ARCH=riscv
allmodconfig), the following warnings/errors occur:
drivers/gpu/drm/msm/adreno/adreno_device.c:679:12: error: 'adreno_system_resume' defined but not used [-Werror=unused-function]
679 | static int adreno_system_resume(struct device *dev)
| ^~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/msm/adreno/adreno_device.c:655:12: error: 'adreno_system_suspend' defined but not used [-Werror=unused-function]
655 | static int adreno_system_suspend(struct device *dev)
| ^~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
These functions are only used in SET_SYSTEM_SLEEP_PM_OPS(), which
evaluates to empty when CONFIG_PM_SLEEP is not set, making these
functions unused.
To resolve this, use the SYSTEM_SLEEP_PM_OPS() and RUNTIME_PM_OPS()
macros, which were introduced in commit 1a3c7bb08826 ("PM: core: Add new
*_PM_OPS macros, deprecate old ones"). They are designed to avoid these
compiler warnings while still guarding their use on
CONFIG_PM{,_SLEEP}=y.
Fixes: 7e4167c9e021 ("drm/msm/gpu: Park scheduler threads for system suspend")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20220411181249.2758344-1-nathan@kernel.org
Signed-off-by: Rob Clark <robdclark@chromium.org>
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Tony Nguyen says:
====================
Intel Wired LAN Driver Updates 2022-04-08
Alexander fixes a use after free issue with aRFS for ice driver.
Mateusz reverts a commit that introduced issues related to device
resets for iavf driver.
* '100GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/net-queue:
Revert "iavf: Fix deadlock occurrence during resetting VF interface"
ice: arfs: fix use-after-free when freeing @rx_cpu_rmap
====================
Link: https://lore.kernel.org/r/20220408163411.2415552-1-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Karsten Graul says:
====================
net/smc: fixes 2022-04-08
Patch 1 fixes two usages of snprintf() with non null-terminated
string which results into an out-of-bounds read.
Pach 2 fixes a syzbot finding where a pointer check was missed
before the call to dev_name().
Patch 3 fixes a crash when already released memory is used as
a function pointer.
====================
Link: https://lore.kernel.org/r/20220408151035.1044701-1-kgraul@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Child sockets may inherit the af_ops from the parent listen socket.
When the listen socket is released then the af_ops of the child socket
points to released memory.
Solve that by restoring the original af_ops for child sockets which
inherited the parent af_ops. And clear any inherited user_data of the
parent socket.
Fixes: 8270d9c21041 ("net/smc: Limit backlog connections")
Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Reviewed-by: D. Wythe <alibuda@linux.alibaba.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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dev_name() was called with dev.parent as argument but without to
NULL-check it before.
Solve this by checking the pointer before the call to dev_name().
Fixes: af5f60c7e3d5 ("net/smc: allow PCI IDs as ib device names in the pnet table")
Reported-by: syzbot+03e3e228510223dabd34@syzkaller.appspotmail.com
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Using snprintf() to convert not null-terminated strings to null
terminated strings may cause out of bounds read in the source string.
Therefore use memcpy() and terminate the target string with a null
afterwards.
Fixes: fa0866625543 ("net/smc: add support for user defined EIDs")
Fixes: 3c572145c24e ("net/smc: add generic netlink support for system EID")
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Handle XDP_REDIRECT action in netvsc driver.
Also, transparently pass ndo_xdp_xmit to VF when available.
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Link: https://lore.kernel.org/r/1649362894-20077-1-git-send-email-haiyangz@microsoft.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The function is not generally applicable enough to be included in the core
kernel header. Move it to block since it's the only subsystem using it.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20220327173316.315-1-kbusch@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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commit 4298388574da ("net: macb: restart tx after tx used bit read")
added support for restarting transmission. Restarting tx does not work
in case controller asserts TXUBR interrupt and TQBP is already at the end
of the tx queue. In that situation, restarting tx will immediately cause
assertion of another TXUBR interrupt. The driver will end up in an infinite
interrupt loop which it cannot break out of.
For cases where TQBP is at the end of the tx queue, instead
only clear TX_USED interrupt. As more data gets pushed to the queue,
transmission will resume.
This issue was observed on a Xilinx Zynq-7000 based board.
During stress test of the network interface,
driver would get stuck on interrupt loop within seconds or minutes
causing CPU to stall.
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
Tested-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220407161659.14532-1-tomas.melin@vaisala.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Guillaume Nault says:
====================
ipv4: Convert several tos fields to dscp_t
Continue the work started with commit a410a0cf9885 ("ipv6: Define
dscp_t and stop taking ECN bits into account in fib6-rules") and
convert more structure fields and variables to dscp_t. This series
focuses on struct fib_rt_info, struct fib_entry_notifier_info and their
users (networking drivers).
The purpose of dscp_t is to ensure that ECN bits don't influence IP
route lookups. It does so by ensuring that dscp_t variables have the
ECN bits cleared.
Notes:
* This series is entirely about type annotation and isn't supposed
to have any user visible effect.
* The first two patches have to introduce a few dsfield <-> dscp
conversions in the affected drivers, but those are then removed when
converting the internal driver structures (patches 3-5). In the end,
drivers don't have to handle any conversion.
====================
Link: https://lore.kernel.org/r/cover.1649445279.git.gnault@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Use the new dscp_t type to replace the kern_tos field of struct
prestera_kern_fib_cache. This ensures ECN bits are ignored and makes it
compatible with the dscp fields of struct fib_entry_notifier_info and
struct fib_rt_info.
This also allows sparse to flag potential incorrect uses of DSCP and
ECN bits.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Yevhen Orlov <yevhen.orlov@plvision.eu>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Use the new dscp_t type to replace the tos field of struct
mlxsw_sp_fib4_entry. This ensures ECN bits are ignored and makes it
compatible with the dscp fields of fib_entry_notifier_info and
fib_rt_info.
This also allows sparse to flag potential incorrect uses of DSCP and
ECN bits.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Use the new dscp_t type to replace the tos field of struct
nsim_fib4_rt. This ensures ECN bits are ignored and makes it compatible
with the dscp fields of struct fib_entry_notifier_info and struct
fib_rt_info.
This also allows sparse to flag potential incorrect uses of DSCP and
ECN bits.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Use the new dscp_t type to replace the tos field of struct
fib_entry_notifier_info. This ensures ECN bits are ignored and makes it
compatible with the dscp field of struct fib_rt_info.
This also allows sparse to flag potential incorrect uses of DSCP and
ECN bits.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Use the new dscp_t type to replace the tos field of struct fib_rt_info.
This ensures ECN bits are ignored and makes it compatible with the
fa_dscp field of struct fib_alias.
This also allows sparse to flag potential incorrect uses of DSCP and
ECN bits.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The data transfer mode that corresponds to the 'xfer_mode' parameter for
ata_xfer_mode2shift() is a 8-bit *unsigned* value. Using *unsigned long*
to declare the parameter leads to a problematic implicit *int* to *unsigned
long* cast and was most probably a result of a copy/paste mistake -- use
the 'u8' type instead, as in ata_xfer_mode2mask()...
Found by Linux Verification Center (linuxtesting.org) with the SVACE static
analysis tool.
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
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A report of a 12-jiffy normal RCU CPU stall warning raises interesting
questions about the nature of time on the offending system. This commit
instruments rcu_sched_clock_irq(), which is RCU's hook into the
scheduling-clock interrupt, checking for the jiffies counter going
backwards.
Reported-by: Saravanan D <sarvanand@fb.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Suppose we have a kernel built with both CONFIG_RCU_STRICT_GRACE_PERIOD=y
and CONFIG_PREEMPT=y. Suppose further that an RCU reader from which RCU
core needs a quiescent state ends in rcu_preempt_deferred_qs_irqrestore().
This function will then invoke rcu_report_qs_rdp() in order to immediately
report that quiescent state. Unfortunately, it will not have cleared
that reader's CPU's rcu_data structure's ->cpu_no_qs.b.norm field.
As a result, rcu_report_qs_rdp() will take an early exit because it
will believe that this CPU has not yet encountered a quiescent state,
and there will be no reporting of the current quiescent state.
This commit therefore causes rcu_preempt_deferred_qs_irqrestore() to
clear the ->cpu_no_qs.b.norm field before invoking rcu_report_qs_rdp().
Kudos to Boqun Feng and Neeraj Upadhyay for helping with analysis of
this issue!
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Reported-by: Frederic Weisbecker <frederic@kernel.org>
Reported-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Reported-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Including nolibc.h multiple times results in build errors due to multiple
definitions. Let's add a guard against multiple inclusions.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This arch doesn't provide the old-style select() syscall, we have to
use pselect6().
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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For consecutive numbers the lscpu command collapses the output and just
shows the range with start and end. The processors are numbered that
way on POWER8.
$ sudo ppc64_cpu --smt=8
$ lscpu | grep '^NUMA node'
NUMA node(s): 2
NUMA node0 CPU(s): 0-79
NUMA node8 CPU(s): 80-159
This causes the heuristic to detect the number threads per core, looking
for the number after the first comma, to fail, and QEMU aborts because of
invalid arguments.
$ lscpu | grep '^NUMA node0' | sed -e 's/^[^,-]*(,|\-)\([0-9]*\),.*$/\1/'
NUMA node0 CPU(s): 0-79
But the lscpu command shows the number of threads per core:
$ sudo ppc64_cpu --smt=8
$ lscpu | grep 'Thread(s) per core'
Thread(s) per core: 8
$ sudo ppc64_cpu --smt=off
$ lscpu | grep 'Thread(s) per core'
Thread(s) per core: 1
This commit therefore directly uses that value and replaces use of grep
with "sed -n" and its "p" command.
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit weakens the checks of the kvm.sh script's --torture parameter
and the kvm-recheck.sh script's parsing so that experimental torture tests
may be created without updating these two scripts. The changes required
are to the appropriate Makefile and Kconfig file, plus a directory
whose name begins with "X" must be added to the rcutorture/configs file.
This new directory's name can then be passed in via the kvm.sh script's
--torture parameter.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The torture.sh script normally runs unattended, so there is not much
point in the "ssh" command asking for a password. This commit therefore
adds the "-o Batchmode=yes" argument to each "ssh" command to cause it
to fail rather than ask for a password.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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An "echo" slipped in between an "ssh" and the "ret=$?" that was intended
to collect its exit code, which prevents torture.sh from detecting
"ssh" failure. This commit therefore reassociates the two.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The TASKS_RUDE_RCU does not select IRQ_WORK, which can result in build
failures for kernels that do not otherwise select IRQ_WORK. This commit
therefore causes the TASKS_RUDE_RCU Kconfig option to select IRQ_WORK.
Reported-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcutorture test suite sometimess triggers a random scheduler
preemption call while simulating a read delay. Unfortunately, its
direct call to preempt_schedule() bypasses the static call/key filter
used by CONFIG_PREEMPT_DYNAMIC. This breaks the no-preempt assumption
when the dynamic preemption mode is "none".
For example, rcu_blocking_is_gp() is fooled and abbreviates grace periods
when the CPU runs in no-preempt UP mode.
Fix this by making torture_preempt_schedule() call __preempt_schedule(),
which uses the static call/key.
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcutorture module has an rcu_torture_writer task that repeatedly
performs writes, synchronizations, and deletes. There is a corner-case
check in rcu_torture_writer() wherein if nsynctypes is 0, a warning is
issued and the task waits to be stopped via a call to
torture_kthread_stopping() rather than performing any work.
There should be a return statement following this call to
torture_kthread_stopping(), as the intention with issuing the call to
torture_kthread_stopping() in the first place is to avoid the
rcu_torture_writer task from performing any work. Some of the work may even
be dangerous to perform, such as potentially causing a #DE due to
nsynctypes being used in a modulo operator when querying for sync updates
to issue.
This patch adds the missing return call. As a bonus, it also fixes a
checkpatch warning that was emitted due to the WARN_ONCE() call using the
name of the function rather than __func__.
Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcutorture module is used to run torture tests that validate RCU.
rcutorture takes a variety of module parameters that configure the
functionality of the test. Amongst these parameters are the types of
synchronization mechanisms that the rcu_torture_writer and
rcu_torture_fakewriter tasks may use, and the torture_type of the run which
determines what read and sync operations are used by the various writer and
reader tasks that run throughout the test.
When the module is configured to only use sync types for which the
specified torture_type does not implement the necessary operations, we can
end up in a state where nsynctypes is 0. This is not an erroneous state,
but it currently crashes the kernel with a #DE due to nsynctypes being used
with a modulo operator in rcu_torture_fakewriter().
Here is an example of such a #DE:
$ insmod ./rcutorture.ko gp_cond=1 gp_cond_exp=0 gp_exp=0 gp_poll_exp=0
gp_normal=0 gp_poll=0 gp_poll_exp=0 verbose=9999 torture_type=trivial
...
[ 8536.525096] divide error: 0000 [#1] PREEMPT SMP PTI
[ 8536.525101] CPU: 30 PID: 392138 Comm: rcu_torture_fak Kdump: loaded Tainted: G S 5.17.0-rc1-00179-gc8c42c80febd #24
[ 8536.525105] Hardware name: Quanta Twin Lakes MP/Twin Lakes Passive MP, BIOS F09_3A23 12/08/2020
[ 8536.525106] RIP: 0010:rcu_torture_fakewriter+0xf1/0x2d0 [rcutorture]
[ 8536.525121] Code: 00 31 d2 8d 0c f5 00 00 00 00 48 63 c9 48 f7 f1 48 85 d2 0f 84 79 ff ff ff 48 89 e7 e8 78 78 01 00 48 63 0d 29 ca 00 00 31 d2 <48> f7 f1 8b 04 95 00 05 4e a0 83 f8 06 0f 84 ad 00 00 00 7f 1f 83
[ 8536.525124] RSP: 0018:ffffc9000777fef0 EFLAGS: 00010246
[ 8536.525127] RAX: 00000000223d006e RBX: cccccccccccccccd RCX: 0000000000000000
[ 8536.525130] RDX: 0000000000000000 RSI: ffffffff824315b9 RDI: ffffc9000777fef0
[ 8536.525132] RBP: ffffc9000487bb30 R08: 0000000000000002 R09: 000000000002a580
[ 8536.525134] R10: ffffffff82c5f920 R11: 0000000000000000 R12: ffff8881a2c35d00
[ 8536.525136] R13: ffff8881540c8d00 R14: ffffffffa04d39d0 R15: 0000000000000000
[ 8536.525137] FS: 0000000000000000(0000) GS:ffff88903ff80000(0000) knlGS:0000000000000000
[ 8536.525140] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 8536.525142] CR2: 00007f839f022000 CR3: 0000000002c0a006 CR4: 00000000007706e0
[ 8536.525144] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 8536.525145] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 8536.525147] PKRU: 55555554
[ 8536.525148] Call Trace:
[ 8536.525150] <TASK>
[ 8536.525153] kthread+0xe8/0x110
[ 8536.525161] ? kthread_complete_and_exit+0x20/0x20
[ 8536.525167] ret_from_fork+0x22/0x30
[ 8536.525174] </TASK>
The solution is to gracefully handle the case of nsynctypes being 0 in
rcu_torture_fakewriter() by not performing any work. This is already being
done in rcu_torture_writer(), though there is a missing return on that path
which will be fixed in a subsequent patch.
Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The scftorture test module's scf_handler() function is supposed to provide
three different distributions of short delays (including "no delay") and
one distribution of long delays, if specified by the scftorture.longwait
module parameter. However, the second of the two non-zero-wait short delays
is disabled due to the first such delay's "goto out" not being enclosed in
the "then" clause with the "udelay()".
This commit therefore adjusts the code to provide the intended set of
delays.
Fixes: e9d338a0b179 ("scftorture: Add smp_call_function() torture test")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Tree RCU supports grace-period delays using the rcutree.gp_cleanup_delay,
rcutree.gp_init_delay, and rcutree.gp_preinit_delay kernel boot
parameters. These delays are strictly for debugging purposes, and have
proven quite effective at exposing bugs involving race with CPU-hotplug
operations. However, these delays can result in false positives when
used in conjunction with callback flooding, for example, those generated
by the rcutorture.fwd_progress kernel boot parameter.
This commit therefore suppresses grace-period delays while callback
flooding is in progress.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Currently, the rcupdate.rcu_normal and rcupdate.rcu_expedited kernel
boot parameters are not regularly tested. The potential addition of
polled expedited grace-period APIs increases the amount of code that is
affected by these kernel boot parameters. This commit therefore adds a
"--do-rt" argument to torture.sh to exercise these kernel-boot options.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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If the cpu_possible_mask is sparse (for example, if bits are set only for
CPUs 0, 4, 8, ...), then rcu_tasks_invoke_cbs() will access per-CPU data
for a CPU not in cpu_possible_mask. It makes these accesses while doing
a workqueue-based binary search for non-empty callback lists. Although
this search must pass through CPUs not represented in cpu_possible_mask,
it has no need to check the callback list for such CPUs.
This commit therefore changes the rcu_tasks_invoke_cbs() function's
binary search so as to only check callback lists for CPUs present in
cpu_possible_mask.
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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If the rcupdate.rcu_task_enqueue_lim kernel boot parameter is set to
something greater than 1 and less than nr_cpu_ids, the code attempts to
use a subset of the CPU's RCU Tasks callback lists. This works, but only
if the cpu_possible_mask is contiguous. If there are "holes" in this
mask, the callback-enqueue code might attempt to access a non-existent
per-CPU ->rtcpu variable for a non-existent CPU. For example, if only
CPUs 0, 4, 8, 12, 16 and so on are in cpu_possible_mask, specifying
rcupdate.rcu_task_enqueue_lim=4 would cause the code to attempt to
use callback queues for non-existent CPUs 1, 2, and 3. Because such
systems have existed in the past and might still exist, the code needs
to gracefully handle this situation.
This commit therefore checks to see whether the desired CPU is present
in cpu_possible_mask, and, if not, searches for the next CPU. This means
that the systems administrator of a system with a sparse cpu_possible_mask
will need to account for this sparsity when specifying the value of
the rcupdate.rcu_task_enqueue_lim kernel boot parameter. For example,
setting this parameter to the value 4 will use only CPUs 0 and 4, which
CPU 4 getting three times the callback load of CPU 0.
This commit assumes that bit (nr_cpu_ids - 1) is always set in
cpu_possible_mask.
Link: https://lore.kernel.org/lkml/CANn89iKaNEwyNZ=L_PQnkH0LP_XjLYrr_dpyRKNNoDJaWKdrmg@mail.gmail.com/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Currently, the show_rcu_tasks_generic_gp_kthread() function only looks
at CPU 0's callback lists. Although this is not fatal, it can confuse
debugging efforts in cases where any of the Tasks RCU flavors are in
per-CPU queueing mode. This commit therefore causes this function to
scan all CPUs' callback queues.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The use of hrtimers for RCU-tasks grace-period delays works well in
general, but can result in excessive grace-period delays for some
corner-case workloads. This commit therefore reverts to the use of
timers for non-RT kernels to mitigate those grace-period delays.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The synchronous RCU-tasks grace-period-wait primitives invoke
schedule_timeout_idle() to give readers a chance to exit their
read-side critical sections. Unfortunately, this fails during early
boot on PREEMPT_RT because PREEMPT_RT relies solely on ksoftirqd to run
timer handlers. Because ksoftirqd cannot operate until its kthreads
are spawned, there is a brief period of time following scheduler
initialization where PREEMPT_RT cannot run the timer handlers that
schedule_timeout_idle() relies on, resulting in a hang.
To avoid this boot-time hang, this commit replaces schedule_timeout_idle()
with schedule_hrtimeout(), so that the timer expires in hardirq context.
This is ensures that the timer fires even on PREEMPT_RT throughout the
irqs-enabled portions of boot as well as during runtime.
The timer is set to expire between fract and fract + HZ / 2 jiffies in
order to align with any other timers that might expire during that time,
thus reducing the number of wakeups.
Note that RCU-tasks grace periods are infrequent, so the use of hrtimer
should be fine. In contrast, in common-case code, user of hrtimer
could result in performance issues.
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The main Tasks RCU quiescent state is voluntary context switch. However,
userspace execution is also a valid quiescent state, and is a valuable one
for userspace applications that spin repeatedly executing light-weight
non-sleeping system calls. Currently, such an application can delay a
Tasks RCU grace period for many tens of seconds.
This commit therefore enlists the aid of the scheduler-clock interrupt to
provide a Tasks RCU quiescent state when it interrupted a task executing
in userspace.
[ paulmck: Apply feedback from kernel test robot. ]
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Neil Spring <ntspring@fb.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The waitqueue used by rcu_tasks_kthread() has always only one waiter.
With a guaranteed only one waiter, this can be replaced with rcuwait
which is smaller and simpler. With rcuwait based wake counterpart, the
irqwork function (call_rcu_tasks_iw_wakeup()) can be invoked hardirq
context because it is only a wake up and no sleeping locks are involved
(unlike the wait_queue_head).
As a side effect, this is also one piece of the puzzle to pass the RCU
selftest at early boot on PREEMPT_RT.
Replace wait_queue_head with rcuwait and let the irqwork run in hardirq
context on PREEMPT_RT.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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RCU-tasks stall-warning messages are printed after the grace period is ten
minutes old. Unfortunately, most of us will have rebooted the system in
response to an apparently-hung command long before the ten minutes is up,
and will thus see what looks to be a silent hang.
This commit therefore adds pr_info() messages that are printed earlier.
These should avoid being classified as errors, but should give impatient
users a hint. These are controlled by new rcupdate.rcu_task_stall_info
and rcupdate.rcu_task_stall_info_mult kernel-boot parameters. The former
defines the initial delay in jiffies (defaulting to 10 seconds) and the
latter defines the multiplier (defaulting to 3). Thus, by default, the
first message will appear 10 seconds into the RCU-tasks grace period,
the second 40 seconds in, and the third 160 seconds in. There would be
a fourth at 640 seconds in, but the stall warning message appears 600
seconds in, and once a stall warning is printed for a given grace period,
no further informational messages are printed.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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While booting secondary CPUs, cpus_read_[lock/unlock] is not keeping
online cpumask stable. The transient online mask results in below
calltrace.
[ 0.324121] CPU1: Booted secondary processor 0x0000000001 [0x410fd083]
[ 0.346652] Detected PIPT I-cache on CPU2
[ 0.347212] CPU2: Booted secondary processor 0x0000000002 [0x410fd083]
[ 0.377255] Detected PIPT I-cache on CPU3
[ 0.377823] CPU3: Booted secondary processor 0x0000000003 [0x410fd083]
[ 0.379040] ------------[ cut here ]------------
[ 0.383662] WARNING: CPU: 0 PID: 10 at kernel/workqueue.c:3084 __flush_work+0x12c/0x138
[ 0.384850] Modules linked in:
[ 0.385403] CPU: 0 PID: 10 Comm: rcu_tasks_rude_ Not tainted 5.17.0-rc3-v8+ #13
[ 0.386473] Hardware name: Raspberry Pi 4 Model B Rev 1.4 (DT)
[ 0.387289] pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 0.388308] pc : __flush_work+0x12c/0x138
[ 0.388970] lr : __flush_work+0x80/0x138
[ 0.389620] sp : ffffffc00aaf3c60
[ 0.390139] x29: ffffffc00aaf3d20 x28: ffffffc009c16af0 x27: ffffff80f761df48
[ 0.391316] x26: 0000000000000004 x25: 0000000000000003 x24: 0000000000000100
[ 0.392493] x23: ffffffffffffffff x22: ffffffc009c16b10 x21: ffffffc009c16b28
[ 0.393668] x20: ffffffc009e53861 x19: ffffff80f77fbf40 x18: 00000000d744fcc9
[ 0.394842] x17: 000000000000000b x16: 00000000000001c2 x15: ffffffc009e57550
[ 0.396016] x14: 0000000000000000 x13: ffffffffffffffff x12: 0000000100000000
[ 0.397190] x11: 0000000000000462 x10: ffffff8040258008 x9 : 0000000100000000
[ 0.398364] x8 : 0000000000000000 x7 : ffffffc0093c8bf4 x6 : 0000000000000000
[ 0.399538] x5 : 0000000000000000 x4 : ffffffc00a976e40 x3 : ffffffc00810444c
[ 0.400711] x2 : 0000000000000004 x1 : 0000000000000000 x0 : 0000000000000000
[ 0.401886] Call trace:
[ 0.402309] __flush_work+0x12c/0x138
[ 0.402941] schedule_on_each_cpu+0x228/0x278
[ 0.403693] rcu_tasks_rude_wait_gp+0x130/0x144
[ 0.404502] rcu_tasks_kthread+0x220/0x254
[ 0.405264] kthread+0x174/0x1ac
[ 0.405837] ret_from_fork+0x10/0x20
[ 0.406456] irq event stamp: 102
[ 0.406966] hardirqs last enabled at (101): [<ffffffc0093c8468>] _raw_spin_unlock_irq+0x78/0xb4
[ 0.408304] hardirqs last disabled at (102): [<ffffffc0093b8270>] el1_dbg+0x24/0x5c
[ 0.409410] softirqs last enabled at (54): [<ffffffc0081b80c8>] local_bh_enable+0xc/0x2c
[ 0.410645] softirqs last disabled at (50): [<ffffffc0081b809c>] local_bh_disable+0xc/0x2c
[ 0.411890] ---[ end trace 0000000000000000 ]---
[ 0.413000] smp: Brought up 1 node, 4 CPUs
[ 0.413762] SMP: Total of 4 processors activated.
[ 0.414566] CPU features: detected: 32-bit EL0 Support
[ 0.415414] CPU features: detected: 32-bit EL1 Support
[ 0.416278] CPU features: detected: CRC32 instructions
[ 0.447021] Callback from call_rcu_tasks_rude() invoked.
[ 0.506693] Callback from call_rcu_tasks() invoked.
This commit therefore fixes this issue by applying a single-CPU
optimization to the RCU Tasks Rude grace-period process. The key point
here is that the purpose of this RCU flavor is to force a schedule on
each online CPU since some past event. But the rcu_tasks_rude_wait_gp()
function runs in the context of the RCU Tasks Rude's grace-period kthread,
so there must already have been a context switch on the current CPU since
the call to either synchronize_rcu_tasks_rude() or call_rcu_tasks_rude().
So if there is only a single CPU online, RCU Tasks Rude's grace-period
kthread does not need to anything at all.
It turns out that the rcu_tasks_rude_wait_gp() function's call to
schedule_on_each_cpu() causes problems during early boot. During that
time, there is only one online CPU, namely the boot CPU. Therefore,
applying this single-CPU optimization fixes early-boot instances of
this problem.
Link: https://lore.kernel.org/lkml/20220210184319.25009-1-treasure4paddy@gmail.com/T/
Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Padmanabha Srinivasaiah <treasure4paddy@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcu_spawn_gp_kthread() function is called as an early initcall, which
means that SMP initialization hasn't happened yet and only the boot CPU is
online. Therefore, create only the NOCB kthreads related to the boot CPU.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcu_spawn_gp_kthread() function is called as an early initcall,
which means that SMP initialization hasn't happened yet and only the
boot CPU is online. Therefore, create only the boost kthread for the
leaf node of the boot CPU.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcu_init() function is called way before SMP is initialized and
therefore only the boot CPU should be online at this stage.
Simplify the boot per-cpu initialization accordingly.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit moves the RCU nocb initialization witness within rcu_state
to consolidate RCU's global state.
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcu_is_nocb_cpu() function is no longer used, so this commmit
removes it.
Reported-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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There are two reasons why this isn't the best idea:
- It's an odd area to grab a bit of storage space, hence it's an odd area
to grab storage from.
- It puts the 3rd io_kiocb cacheline into the hot path, where normal hot
path just needs the first two.
Use 'cflags' for joint fd/cflags storage. We only need fd until we
successfully issue, and we only need cflags once a request is done and is
completed.
Fixes: 6bf9c47a3989 ("io_uring: defer file assignment")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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In preparation for fixing a regression with pulling in an extra cacheline
for IO that doesn't usually touch the last cacheline of the io_kiocb,
move the cached location of apoll->events to space shared with some other
completion data. Like cflags, this isn't used until after the request
has been completed, so we can piggy back on top of comp_list.
Fixes: 81459350d581 ("io_uring: cache req->apoll->events in req->cflags")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This commit instruments the acquisitions of the srcu_struct structure's
->lock, enabling the initiation of a transition from SRCU_SIZE_SMALL
to SRCU_SIZE_BIG when sufficient contention is experienced. The
instrumentation counts the number of trylock failures within the confines
of a single jiffy. If that number exceeds the value specified by the
srcutree.small_contention_lim kernel boot parameter (which defaults to
100), and if the value specified by the srcutree.convert_to_big kernel
boot parameter has the 0x10 bit set (defaults to 0), then a transition
will be automatically initiated.
By default, there will never be any transitions, so that none of the
srcu_struct structures ever gains an srcu_node array.
The useful values for srcutree.convert_to_big are:
0x00: Never convert.
0x01: Always convert at init_srcu_struct() time.
0x02: Convert when rcutorture prints its first round of statistics.
0x03: Decide conversion approach at boot given system size.
0x10: Convert if contention is encountered.
0x12: Convert if contention is encountered or when rcutorture prints
its first round of statistics, whichever comes first.
The value 0x11 acts the same as 0x01 because the conversion happens
before there is any chance of contention.
[ paulmck: Apply "static" feedback from kernel test robot. ]
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Bjorn Andersson
Nathan Chancellor
Jakub Kicinski
Karsten Graul
Haiyang Zhang
Keith Busch
Tomas Melin
Guillaume Nault
Sergey Shtylyov
Paul E. McKenney
Willy Tarreau
Paul Menzel
Frederic Weisbecker
David Vernet
Eric Dumazet
Sebastian Andrzej Siewior
Padmanabha Srinivasaiah
Jens Axboe