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Gaurav Kohli cb71229f64 timers: Clear timer_base::must_forward_clk with timer_base::lock held 
[ Upstream commit 363e934d88 ]

timer_base::must_forward_clock is indicating that the base clock might be
stale due to a long idle sleep.

The forwarding of the base clock takes place in the timer softirq or when a
timer is enqueued to a base which is idle. If the enqueue of timer to an
idle base happens from a remote CPU, then the following race can happen:

  CPU0					CPU1
  run_timer_softirq			mod_timer

					base = lock_timer_base(timer);
  base->must_forward_clk = false
					if (base->must_forward_clk)
				       	    forward(base); -> skipped

					enqueue_timer(base, timer, idx);
					-> idx is calculated high due to
					   stale base
					unlock_timer_base(timer);
  base = lock_timer_base(timer);
  forward(base);

The root cause is that timer_base::must_forward_clk is cleared outside the
timer_base::lock held region, so the remote queuing CPU observes it as
cleared, but the base clock is still stale. This can cause large
granularity values for timers, i.e. the accuracy of the expiry time
suffers.

Prevent this by clearing the flag with timer_base::lock held, so that the
forwarding takes place before the cleared flag is observable by a remote
CPU.

Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john.stultz@linaro.org
Cc: sboyd@kernel.org
Cc: linux-arm-msm@vger.kernel.org
Link: https://lkml.kernel.org/r/1533199863-22748-1-git-send-email-gkohli@codeaurora.org
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2018-09-19 22:43:39 +02:00
..
bpf bpf: hash map: decrement counter on error 2018-08-24 13:09:12 +02:00
cgroup cgroup: fix rule checking for threaded mode switching 2018-03-28 18:24:37 +02:00
configs ANDROID: binder: add hwbinder,vndbinder to BINDER_DEVICES. 2017-08-22 18:43:23 -07:00
debug kdb: make "mdr" command repeat 2018-05-30 07:52:41 +02:00
events perf/core: Fix perf_output_read_group() 2018-05-30 07:52:34 +02:00
gcov License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
irq genirq: Make force irq threading setup more robust 2018-08-09 12:16:38 +02:00
livepatch livepatch: Validate module/old func name length 2018-09-09 19:55:58 +02:00
locking locking/rtmutex: Allow specifying a subclass for nested locking 2018-09-05 09:26:29 +02:00
power PM / sleep: wakeup: Fix build error caused by missing SRCU support 2018-09-09 19:55:58 +02:00
printk printk/tracing: Do not trace printk_nmi_enter() 2018-09-09 19:55:57 +02:00
rcu rcu: Call touch_nmi_watchdog() while printing stall warnings 2018-05-30 07:52:39 +02:00
sched sched/deadline: Fix switching to -deadline 2018-09-15 09:45:35 +02:00
time timers: Clear timer_base::must_forward_clk with timer_base::lock held 2018-09-19 22:43:39 +02:00
trace uprobes: Use synchronize_rcu() not synchronize_sched() 2018-09-09 19:55:58 +02:00
.gitignore
…
Kconfig.freezer
…
Kconfig.hz
…
Kconfig.locks
…
Kconfig.preempt
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Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
acct.c kernel/acct.c: fix the acct->needcheck check in check_free_space() 2018-01-10 09:31:17 +01:00
async.c kernel/async.c: revert "async: simplify lowest_in_progress()" 2018-02-16 20:23:05 +01:00
audit.c audit: return on memory error to avoid null pointer dereference 2018-05-30 07:52:39 +02:00
audit.h ipc: mqueue: Replace timespec with timespec64 2017-09-03 20:21:24 -04:00
audit_fsnotify.c Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2017-05-03 11:05:15 -07:00
audit_tree.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
audit_watch.c audit/stable-4.13 PR 20170816 2017-08-16 16:48:34 -07:00
auditfilter.c audit: allow not equal op for audit by executable 2018-08-03 07:50:39 +02:00
auditsc.c audit: fix potential null dereference 'context->module.name' 2018-08-06 16:20:49 +02:00
backtracetest.c
…
bounds.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
capability.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
compat.c compat: fix 4-byte infoleak via uninitialized struct field 2018-05-16 10:10:26 +02:00
configs.c
…
context_tracking.c
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cpu.c cpu/hotplug: Prevent state corruption on error rollback 2018-09-19 22:43:36 +02:00
cpu_pm.c PM / CPU: replace raw_notifier with atomic_notifier 2017-07-31 13:09:49 +02:00
crash_core.c kdump: write correct address of mem_section into vmcoreinfo 2018-01-17 09:45:27 +01:00
crash_dump.c
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cred.c doc: ReSTify credentials.txt 2017-05-18 10:30:19 -06:00
delayacct.c delayacct: Use raw_spinlocks 2018-08-03 07:50:38 +02:00
dma.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
elfcore.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
exec_domain.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
exit.c kernel/exit.c: export abort() to modules 2018-02-13 10:19:49 +01:00
extable.c extable: Enable RCU if it is not watching in kernel_text_address() 2017-09-23 16:50:20 -04:00
fork.c fork: don't copy inconsistent signal handler state to child 2018-09-15 09:45:27 +02:00
freezer.c
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futex.c futex: Fix OWNER_DEAD fixup 2018-02-03 17:38:47 +01:00
futex_compat.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
groups.c kernel: make groups_sort calling a responsibility group_info allocators 2017-12-20 10:10:18 +01:00
hung_task.c kernel/hung_task.c: show all hung tasks before panic 2018-08-03 07:50:23 +02:00
irq_work.c
…
jump_label.c jump_label: Invoke jump_label_test() via early_initcall() 2017-12-14 09:53:13 +01:00
kallsyms.c kernel/kallsyms.c: replace all_var with IS_ENABLED(CONFIG_KALLSYMS_ALL) 2017-07-10 16:32:34 -07:00
kcmp.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kcov.c kcov: ensure irq code sees a valid area 2018-08-03 07:50:22 +02:00
kexec.c kdump: protect vmcoreinfo data under the crash memory 2017-07-12 16:26:00 -07:00
kexec_core.c x86/mm, kexec: Allow kexec to be used with SME 2017-07-18 11:38:04 +02:00
kexec_file.c kexec_file: adjust declaration of kexec_purgatory 2017-07-12 16:26:02 -07:00
kexec_internal.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kmod.c kmod: move #ifdef CONFIG_MODULES wrapper to Makefile 2017-09-08 18:26:51 -07:00
kprobes.c kprobes: Make list and blacklist root user read only 2018-09-05 09:26:41 +02:00
ksysfs.c kexec: move vmcoreinfo out of the kernel's .bss section 2017-07-12 16:25:59 -07:00
kthread.c kthread, tracing: Don't expose half-written comm when creating kthreads 2018-08-03 07:50:21 +02:00
latencytop.c sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h> 2017-03-02 08:42:39 +01:00
memremap.c mm: Fix devm_memremap_pages() collision handling 2018-09-15 09:45:35 +02:00
module-internal.h
…
module.c init: fix false positives in W+X checking 2018-06-21 04:02:57 +09:00
module_signing.c
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notifier.c kernel/notifier.c: simplify expression 2017-02-24 17:46:56 -08:00
nsproxy.c perf: Add PERF_RECORD_NAMESPACES to include namespaces related info 2017-03-13 15:57:41 -03:00
padata.c padata: Avoid nested calls to cpus_read_lock() in pcrypt_init_padata() 2017-05-26 10:10:37 +02:00
panic.c locking/refcounts, x86/asm: Implement fast refcount overflow protection 2017-08-17 10:40:26 +02:00
params.c kernel/params.c: improve STANDARD_PARAM_DEF readability 2017-10-03 17:54:26 -07:00
pid.c pids: make task_tgid_nr_ns() safe 2017-08-21 12:47:31 -07:00
pid_namespace.c userns,pidns: Verify the userns for new pid namespaces 2017-07-20 07:43:58 -05:00
profile.c sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h> 2017-03-02 08:42:39 +01:00
ptrace.c signal: Remove kernel interal si_code magic 2017-07-24 14:30:28 -05:00
range.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
reboot.c
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relay.c kernel/relay.c: limit kmalloc size to KMALLOC_MAX_SIZE 2018-05-30 07:52:00 +02:00
resource.c resource: fix integer overflow at reallocation 2018-04-24 09:36:22 +02:00
seccomp.c seccomp: Move speculation migitation control to arch code 2018-05-22 18:54:04 +02:00
signal.c sched/core: Introduce set_special_state() 2018-06-21 04:02:54 +09:00
smp.c cpu/hotplug: Fix SMT supported evaluation 2018-08-15 18:13:00 +02:00
smpboot.c watchdog/core, powerpc: Lock cpus across reconfiguration 2017-10-04 10:53:54 +02:00
smpboot.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
softirq.c Mark HI and TASKLET softirq synchronous 2018-08-15 18:12:47 +02:00
stacktrace.c stacktrace/x86: add function for detecting reliable stack traces 2017-03-08 09:18:02 +01:00
stop_machine.c stop_machine: Atomically queue and wake stopper threads 2018-09-05 09:26:36 +02:00
sys.c sys: don't hold uts_sem while accessing userspace memory 2018-09-09 19:56:00 +02:00
sys_ni.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sysctl.c kmemcheck: rip it out 2018-02-22 15:42:24 +01:00
sysctl_binary.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
task_work.c locking/barriers: Convert users of lockless_dereference() to READ_ONCE() 2017-12-25 14:26:21 +01:00
taskstats.c taskstats: add e/u/stime for TGID command 2017-05-08 17:15:12 -07:00
test_kprobes.c
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torture.c torture: Fix typo suppressing CPU-hotplug statistics 2017-07-25 13:04:45 -07:00
tracepoint.c tracepoint: Do not warn on ENOMEM 2018-05-09 09:51:50 +02:00
tsacct.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
ucount.c ucount: Remove the atomicity from ucount->count 2017-03-06 15:26:37 -06:00
uid16.c kernel: make groups_sort calling a responsibility group_info allocators 2017-12-20 10:10:18 +01:00
umh.c kmod: split out umh code into its own file 2017-09-08 18:26:50 -07:00
up.c smp: Avoid using two cache lines for struct call_single_data 2017-08-29 15:14:38 +02:00
user-return-notifier.c
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user.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/user.h> 2017-03-02 08:42:29 +01:00
user_namespace.c userns: move user access out of the mutex 2018-09-09 19:56:00 +02:00
utsname.c sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h> 2017-03-02 08:42:38 +01:00
utsname_sysctl.c sys: don't hold uts_sem while accessing userspace memory 2018-09-09 19:56:00 +02:00
watchdog.c watchdog: Mark watchdog touch functions as notrace 2018-09-05 09:26:42 +02:00
watchdog_hld.c watchdog: Mark watchdog touch functions as notrace 2018-09-05 09:26:42 +02:00
workqueue.c watchdog: Mark watchdog touch functions as notrace 2018-09-05 09:26:42 +02:00
workqueue_internal.h Merge branch 'for-4.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2017-11-06 12:26:49 -08:00