tracing/osnoise: Fix missed cpus_read_unlock() in start_per_cpu_kthreads()

When start_kthread() return error, the cpus_read_unlock() need
to be called.

Link: https://lkml.kernel.org/r/[email protected]

Cc: <[email protected]>
Fixes: c8895e2 ("trace/osnoise: Support hotplug operations")
Acked-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Qiang.Zhang <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

Author: Zqiang1211

kernel/trace/trace_osnoise.c

@@ -1548,7 +1548,7 @@ static int start_kthread(unsigned int cpu)
 static int start_per_cpu_kthreads(struct trace_array *tr)
 {
 	struct cpumask *current_mask = &save_cpumask;
-	int retval;
+	int retval = 0;
 	int cpu;
 
 	cpus_read_lock();
@@ -1568,13 +1568,13 @@ static int start_per_cpu_kthreads(struct trace_array *tr)
 		retval = start_kthread(cpu);
 		if (retval) {
 			stop_per_cpu_kthreads();
-			return retval;
+			break;
 		}
 	}
 
 	cpus_read_unlock();
 
-	return 0;
+	return retval;
 }
 
 #ifdef CONFIG_HOTPLUG_CPU