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tracing: Fix potential deadlock in cpu hotplug with osnoise 

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: bce29ac9ce ("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>
This commit is contained in:
Luo Haiyang 2026-03-26 14:19:53 +08:00 committed by Steven Rostedt (Google)
parent 50b35c9e50
commit 1f98857322
1 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
kernel/trace/trace_osnoise.c
View File

@ -2073,8 +2073,8 @@ 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;
@ -2237,11 +2237,11 @@ 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;
@ -2257,8 +2257,8 @@ 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();
@ -2345,16 +2345,16 @@ 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();