Messages in this thread Patch in this message | | | Date | Wed, 14 Dec 2022 09:01:38 -0500 | From | Steven Rostedt <> | Subject | [for-next][PATCH 5/8] tracing: Do not synchronize freeing of trigger filter on boot up |
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From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
If a trigger filter on the kernel command line fails to apply (due to syntax error), it will be freed. The freeing will call tracepoint_synchronize_unregister(), but this is not needed during early boot up, and will even trigger a lockdep splat.
Avoid calling the synchronization function when system_state is SYSTEM_BOOTING.
Link: https://lore.kernel.org/linux-trace-kernel/20221213172429.7774f4ba@gandalf.local.home
Cc: Andrew Morton <akpm@linux-foundation.org> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> --- kernel/trace/trace_events_trigger.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c index 19ce9d22bfd7..e535959939d3 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -1085,8 +1085,14 @@ int set_trigger_filter(char *filter_str, rcu_assign_pointer(data->filter, filter); if (tmp) { - /* Make sure the call is done with the filter */ - tracepoint_synchronize_unregister(); + /* + * Make sure the call is done with the filter. + * It is possible that a filter could fail at boot up, + * and then this path will be called. Avoid the synchronization + * in that case. + */ + if (system_state != SYSTEM_BOOTING) + tracepoint_synchronize_unregister(); free_event_filter(tmp); } -- 2.35.1
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