diff options
| author | Petr Pavlu <petr.pavlu@suse.com> | 2026-02-19 17:27:02 +0100 |
|---|---|---|
| committer | Sasha Levin <sashal@kernel.org> | 2026-03-04 07:21:20 -0500 |
| commit | 1cdff5d564fe8ec12717921e89d220a07f522d26 (patch) | |
| tree | 7df6b3d885f69b3f6278c954d5f668ff0fdf8483 | |
| parent | e4e5026252b4e03c0f31511b2de97d0ec6ffb7aa (diff) | |
tracing: Wake up poll waiters for hist files when removing an event
[ Upstream commit 9678e53179aa7e907360f5b5b275769008a69b80 ]
The event_hist_poll() function attempts to verify whether an event file is
being removed, but this check may not occur or could be unnecessarily
delayed. This happens because hist_poll_wakeup() is currently invoked only
from event_hist_trigger() when a hist command is triggered. If the event
file is being removed, no associated hist command will be triggered and a
waiter will be woken up only after an unrelated hist command is triggered.
Fix the issue by adding a call to hist_poll_wakeup() in
remove_event_file_dir() after setting the EVENT_FILE_FL_FREED flag. This
ensures that a task polling on a hist file is woken up and receives
EPOLLERR.
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://patch.msgid.link/20260219162737.314231-3-petr.pavlu@suse.com
Fixes: 1bd13edbbed6 ("tracing/hist: Add poll(POLLIN) support on hist file")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | include/linux/trace_events.h | 5 | ||||
| -rw-r--r-- | kernel/trace/trace_events.c | 3 |
2 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index fe95d13c5e4d..4035cb450356 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -695,6 +695,11 @@ static inline void hist_poll_wakeup(void) #define hist_poll_wait(file, wait) \ poll_wait(file, &hist_poll_wq, wait) + +#else +static inline void hist_poll_wakeup(void) +{ +} #endif #define __TRACE_EVENT_FLAGS(name, value) \ diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index b26d7bb07e11..106ae22f0464 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -1169,6 +1169,9 @@ static void remove_event_file_dir(struct trace_event_file *file) free_event_filter(file->filter); file->flags |= EVENT_FILE_FL_FREED; event_file_put(file); + + /* Wake up hist poll waiters to notice the EVENT_FILE_FL_FREED flag. */ + hist_poll_wakeup(); } /* |