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authorLi Zhe <lizhe.67@bytedance.com>2023-11-23 16:40:22 +0800
committerAndrew Morton <akpm@linux-foundation.org>2023-12-10 17:21:44 -0800
commit9d02330abd3ecdacc43fc6b16a5668e7e94b7562 (patch)
tree019f798651b2d5a714eacf0b0fa3c290324b389f /kernel/watchdog.c
parentb3ba234171cd0d58df0a13c262210ff8b5fd2830 (diff)
softlockup: serialized softlockup's log
If multiple CPUs trigger softlockup at the same time with 'softlockup_all_cpu_backtrace=0', the softlockup's logs will appear staggeredly in dmesg, which will affect the viewing of the logs for developer. Since the code path for outputting softlockup logs is not a kernel hotspot and the performance requirements for the code are not strict, locks are used to serialize the softlockup log output to improve the readability of the logs. Link: https://lkml.kernel.org/r/20231123084022.10302-1-lizhe.67@bytedance.com Signed-off-by: Li Zhe <lizhe.67@bytedance.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Zefan Li <lizefan.x@bytedance.com> Cc: John Ogness <john.ogness@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'kernel/watchdog.c')
-rw-r--r--kernel/watchdog.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 5cd6d4e26915..bf30a6fac665 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -448,6 +448,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
struct pt_regs *regs = get_irq_regs();
int duration;
int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;
+ static DEFINE_SPINLOCK(watchdog_output_lock);
if (!watchdog_enabled)
return HRTIMER_NORESTART;
@@ -514,6 +515,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
/* Start period for the next softlockup warning. */
update_report_ts();
+ spin_lock(&watchdog_output_lock);
pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
smp_processor_id(), duration,
current->comm, task_pid_nr(current));
@@ -523,6 +525,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
show_regs(regs);
else
dump_stack();
+ spin_unlock(&watchdog_output_lock);
if (softlockup_all_cpu_backtrace) {
trigger_allbutcpu_cpu_backtrace(smp_processor_id());