diff options
Diffstat (limited to 'samples/trace_events')
-rw-r--r-- | samples/trace_events/trace-events-sample.c | 14 | ||||
-rw-r--r-- | samples/trace_events/trace-events-sample.h | 1 |
2 files changed, 12 insertions, 3 deletions
diff --git a/samples/trace_events/trace-events-sample.c b/samples/trace_events/trace-events-sample.c index bc7fcf010a5b..5522692100ba 100644 --- a/samples/trace_events/trace-events-sample.c +++ b/samples/trace_events/trace-events-sample.c @@ -78,29 +78,37 @@ static int simple_thread_fn(void *arg) } static DEFINE_MUTEX(thread_mutex); +static int simple_thread_cnt; int foo_bar_reg(void) { + mutex_lock(&thread_mutex); + if (simple_thread_cnt++) + goto out; + pr_info("Starting thread for foo_bar_fn\n"); /* * We shouldn't be able to start a trace when the module is * unloading (there's other locks to prevent that). But * for consistency sake, we still take the thread_mutex. */ - mutex_lock(&thread_mutex); simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn"); + out: mutex_unlock(&thread_mutex); return 0; } void foo_bar_unreg(void) { - pr_info("Killing thread for foo_bar_fn\n"); - /* protect against module unloading */ mutex_lock(&thread_mutex); + if (--simple_thread_cnt) + goto out; + + pr_info("Killing thread for foo_bar_fn\n"); if (simple_tsk_fn) kthread_stop(simple_tsk_fn); simple_tsk_fn = NULL; + out: mutex_unlock(&thread_mutex); } diff --git a/samples/trace_events/trace-events-sample.h b/samples/trace_events/trace-events-sample.h index b3858143f1a9..80b4a70315b6 100644 --- a/samples/trace_events/trace-events-sample.h +++ b/samples/trace_events/trace-events-sample.h @@ -1,3 +1,4 @@ +/* SPDX-License-Identifier: GPL-2.0 */ /* * If TRACE_SYSTEM is defined, that will be the directory created * in the ftrace directory under /sys/kernel/tracing/events/<system> |