tracing: Switch trace_osnoise.c code over to use guard() and __free()

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>

diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index b9f96c77527db8670516a7cd9d1abbc1144b88e5..b25c30b05dd058998cbb6f1653b725bcd0b65194 100644 (file)
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -2083,26 +2083,21 @@ static void osnoise_hotplug_workfn(struct work_struct *dummy)
 {
        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);
@@ -2300,31 +2295,22 @@ 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;
 }