[PATCH 3.16 156/245] kernel/trace: Fix do not unregister tracepoints when register sched_migrate_task fail

Ben Hutchings
2020-04-23T23:07:52Z

From: Kaitao Cheng <pilgrimtao@gmail.com>

commit 50f9ad607ea891a9308e67b81f774c71736d1098 upstream.

In the function, if register_trace_sched_migrate_task() returns error,
sched_switch/sched_wakeup_new/sched_wakeup won't unregister. That is
why fail_deprobe_sched_switch was added.

Link: http://lkml.kernel.org/r/20191231133530.2794-1-pilgrimtao@gmail.com

Fixes: 478142c39c8c2 ("tracing: do not grab lock in wakeup latency function tracing")
Signed-off-by: Kaitao Cheng <pilgrimtao@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
kernel/trace/trace_sched_wakeup.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -567,7 +567,7 @@ static void start_wakeup_tracer(struct t
if (ret) {
pr_info("wakeup trace: Couldn't activate tracepoint"
" probe to kernel_sched_migrate_task\n");
- return;
+ goto fail_deprobe_sched_switch;
}

wakeup_reset(tr);
@@ -585,6 +585,8 @@ static void start_wakeup_tracer(struct t
printk(KERN_ERR "failed to start wakeup tracer\n");

return;
+fail_deprobe_sched_switch:
+ unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
fail_deprobe_wake_new:
unregister_trace_sched_wakeup_new(probe_wakeup, NULL);