[PATCH 6.12 201/244] tracing: Switch trace_osnoise.c code over to use guard() and __free()

Greg Kroah-Hartman
2026-03-31T16:54:46Z

From: Steven Rostedt <rostedt@goodmis.org>

[ Upstream commit 930d2b32c0af6895ba4c6ca6404e7f7b6dc214ed ]

The osnoise_hotplug_workfn() grabs two mutexes and cpu_read_lock(). It has
various gotos to handle unlocking them. Switch them over to guard() and
let the compiler worry about it.

The osnoise_cpus_read() has a temporary mask_str allocated and there's
some gotos to make sure it gets freed on error paths. Switch that over to
__free() to let the compiler worry about it.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/20241225222931.517329690@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Stable-dep-of: 1f9885732248 ("tracing: Fix potential deadlock in cpu hotplug with osnoise")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/trace/trace_osnoise.c | 40 +++++++++++++---------------------------
1 file changed, 13 insertions(+), 27 deletions(-)

--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -2099,26 +2099,21 @@ static void osnoise_hotplug_workfn(struc
{
unsigned int cpu = smp_processor_id();

- mutex_lock(&trace_types_lock);
+ guard(mutex)(&trace_types_lock);

if (!osnoise_has_registered_instances())
- goto out_unlock_trace;
+ return;

- mutex_lock(&interface_lock);
- cpus_read_lock();
+ guard(mutex)(&interface_lock);
+ guard(cpus_read_lock)();

if (!cpu_online(cpu))
- goto out_unlock;
+ return;
+
if (!cpumask_test_cpu(cpu, &osnoise_cpumask))
- goto out_unlock;
+ return;

start_kthread(cpu);
-
-out_unlock:
- cpus_read_unlock();
- mutex_unlock(&interface_lock);
-out_unlock_trace:
- mutex_unlock(&trace_types_lock);
}

static DECLARE_WORK(osnoise_hotplug_work, osnoise_hotplug_workfn);
@@ -2316,31 +2311,22 @@ static ssize_t
osnoise_cpus_read(struct file *filp, char __user *ubuf, size_t count,
loff_t *ppos)
{
- char *mask_str;
+ char *mask_str __free(kfree) = NULL;
int len;

- mutex_lock(&interface_lock);
+ guard(mutex)(&interface_lock);

len = snprintf(NULL, 0, "%*pbl\n", cpumask_pr_args(&osnoise_cpumask)) + 1;
mask_str = kmalloc(len, GFP_KERNEL);
- if (!mask_str) {
- count = -ENOMEM;
- goto out_unlock;
- }
+ if (!mask_str)
+ return -ENOMEM;

len = snprintf(mask_str, len, "%*pbl\n", cpumask_pr_args(&osnoise_cpumask));
- if (len >= count) {
- count = -EINVAL;
- goto out_free;
- }
+ if (len >= count)
+ return -EINVAL;

count = simple_read_from_buffer(ubuf, count, ppos, mask_str, len);

-out_free:
- kfree(mask_str);
-out_unlock:
- mutex_unlock(&interface_lock);
-
return count;
}