From: Masami Hiramatsu (Google) <[email protected]>
Since __tracepoint_user_init() calls tracepoint_user_register() without
initializing tuser->tpoint with given tracpoint, it does not register
tracepoint stub function as callback correctly, and tprobe does not work.
Initializing tuser->tpoint correctly before tracepoint_user_register()
so that it sets up tracepoint callback.
I confirmed below example works fine again.
echo "t sched_switch preempt prev_pid=prev->pid next_pid=next->pid" >
/sys/kernel/tracing/dynamic_events
echo 1 > /sys/kernel/tracing/events/tracepoints/sched_switch/enable
cat /sys/kernel/tracing/trace_pipe
Fixes: 2867495dea86 ("tracing: tprobe-events: Register tracepoint when enable
tprobe event")
Reported-by: Beau Belgrave <[email protected]>
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
---
kernel/trace/trace_fprobe.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index b36ade43d4b3..d4e78d1ace12 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -106,13 +106,14 @@ static struct tracepoint_user
*__tracepoint_user_init(const char *name, struct t
if (!tuser->name)
return NULL;
+ /* Register tracepoint if it is loaded. */
if (tpoint) {
+ tuser->tpoint = tpoint;
ret = tracepoint_user_register(tuser);
if (ret)
return ERR_PTR(ret);
}
- tuser->tpoint = tpoint;
tuser->refcount = 1;
INIT_LIST_HEAD(&tuser->list);
list_add(&tuser->list, &tracepoint_user_list);
