diff options
| author | Luo Haiyang <luo.haiyang@zte.com.cn> | 2026-03-30 17:25:47 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-04-02 14:07:29 +0300 |
| commit | ef41a85a55022e27cdaebf22a6676910b66f65aa (patch) | |
| tree | eb2f2c5584b6621b138c13168c6ac822a77c356d | |
| parent | 5a9f33294cc047835ffc67926b82084123814699 (diff) | |
| download | linux-ef41a85a55022e27cdaebf22a6676910b66f65aa.tar.xz | |
tracing: Fix potential deadlock in cpu hotplug with osnoise
[ Upstream commit 1f9885732248d22f788e4992c739a98c88ab8a55 ]
The following sequence may leads deadlock in cpu hotplug:
task1 task2 task3
----- ----- -----
mutex_lock(&interface_lock)
[CPU GOING OFFLINE]
cpus_write_lock();
osnoise_cpu_die();
kthread_stop(task3);
wait_for_completion();
osnoise_sleep();
mutex_lock(&interface_lock);
cpus_read_lock();
[DEAD LOCK]
Fix by swap the order of cpus_read_lock() and mutex_lock(&interface_lock).
Cc: stable@vger.kernel.org
Cc: <mathieu.desnoyers@efficios.com>
Cc: <zhang.run@zte.com.cn>
Cc: <yang.tao172@zte.com.cn>
Cc: <ran.xiaokai@zte.com.cn>
Fixes: bce29ac9ce0bb ("trace: Add osnoise tracer")
Link: https://patch.msgid.link/20260326141953414bVSj33dAYktqp9Oiyizq8@zte.com.cn
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Luo Haiyang <luo.haiyang@zte.com.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/trace/trace_osnoise.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 6bf8d18a15b7..3b039374c993 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -2104,8 +2104,8 @@ static void osnoise_hotplug_workfn(struct work_struct *dummy) if (!osnoise_has_registered_instances()) return; - guard(mutex)(&interface_lock); guard(cpus_read_lock)(); + guard(mutex)(&interface_lock); if (!cpu_online(cpu)) return; @@ -2268,11 +2268,11 @@ static ssize_t osnoise_options_write(struct file *filp, const char __user *ubuf, if (running) stop_per_cpu_kthreads(); - mutex_lock(&interface_lock); /* * avoid CPU hotplug operations that might read options. */ cpus_read_lock(); + mutex_lock(&interface_lock); retval = cnt; @@ -2288,8 +2288,8 @@ static ssize_t osnoise_options_write(struct file *filp, const char __user *ubuf, clear_bit(option, &osnoise_options); } - cpus_read_unlock(); mutex_unlock(&interface_lock); + cpus_read_unlock(); if (running) start_per_cpu_kthreads(); @@ -2375,16 +2375,16 @@ osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count, if (running) stop_per_cpu_kthreads(); - mutex_lock(&interface_lock); /* * osnoise_cpumask is read by CPU hotplug operations. */ cpus_read_lock(); + mutex_lock(&interface_lock); cpumask_copy(&osnoise_cpumask, osnoise_cpumask_new); - cpus_read_unlock(); mutex_unlock(&interface_lock); + cpus_read_unlock(); if (running) start_per_cpu_kthreads(); |