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tracing/timerlat: Fix duplicated kthread creation due to CPU online/offline

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osnoise_hotplug_workfn() is the asynchronous online callback for
"trace/osnoise:online". It may be congested when a CPU goes online and
offline repeatedly and is invoked for multiple times after a certain
online.

This will lead to kthread leak and timer corruption. Add a check
in start_kthread() to prevent this situation.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20240924094515.3561410-2-liwei391@huawei.com
Fixes: c8895e271f ("trace/osnoise: Support hotplug operations")
Signed-off-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Wei Li 2024-09-24 17:45:11 +08:00 committed by Steven Rostedt (Google)
parent ad686707ea
commit 0bb0a5c12e
1 changed files with 5 additions and 2 deletions
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7
kernel/trace/trace_osnoise.c
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@ -2007,6 +2007,10 @@ static int start_kthread(unsigned int cpu)
void *main = osnoise_main;
char comm[24];
/* Do not start a new thread if it is already running */
if (per_cpu(per_cpu_osnoise_var, cpu).kthread)
return 0;
if (timerlat_enabled()) {
snprintf(comm, 24, "timerlat/%d", cpu);
main = timerlat_main;
@ -2061,11 +2065,10 @@ static int start_per_cpu_kthreads(void)
if (cpumask_test_and_clear_cpu(cpu, &kthread_cpumask)) {
struct task_struct *kthread;
kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread;
kthread = xchg_relaxed(&(per_cpu(per_cpu_osnoise_var, cpu).kthread), NULL);
if (!WARN_ON(!kthread))
kthread_stop(kthread);
}
per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
}
for_each_cpu(cpu, current_mask) {