| Message ID | 20221123164323.03450c3a@gandalf.local.home (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | ef38c79a522b660f7f71d45dad2d6244bc741841 |
| Headers | show |
| Series | tracing: Fix race where histograms can be called before the event | expand |
On Wed, 23 Nov 2022 16:43:23 -0500 Steven Rostedt <rostedt@goodmis.org> wrote: > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > commit 94eedf3dded5 ("tracing: Fix race where eprobes can be called before > the event") fixed an issue where if an event is soft disabled, and the > trigger is being added, there's a small window where the event sees that > there's a trigger but does not see that it requires reading the event yet, > and then calls the trigger with the record == NULL. > > This could be solved with adding memory barriers in the hot path, or to > make sure that all the triggers requiring a record check for NULL. The > latter was chosen. > > Commit 94eedf3dded5 set the eprobe trigger handle to check for NULL, but > the same needs to be done with histograms. > > Link: https://lore.kernel.org/linux-trace-kernel/20221118211809.701d40c0f8a757b0df3c025a@kernel.org/ > > Cc: stable@vger.kernel.org > Fixes: 7491e2c442781 ("tracing: Add a probe that attaches to trace events") > Reported-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> I confirmed that other trigger callbacks only use the event_trigger_data, So this looks good to me. Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Thank you! > --- > kernel/trace/trace_events_hist.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c > index 087c19548049..1c82478e8dff 100644 > --- a/kernel/trace/trace_events_hist.c > +++ b/kernel/trace/trace_events_hist.c > @@ -5143,6 +5143,9 @@ static void event_hist_trigger(struct event_trigger_data *data, > void *key = NULL; > unsigned int i; > > + if (unlikely(!rbe)) > + return; > + > memset(compound_key, 0, hist_data->key_size); > > for_each_hist_key_field(i, hist_data) { > -- > 2.35.1 >
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 087c19548049..1c82478e8dff 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -5143,6 +5143,9 @@ static void event_hist_trigger(struct event_trigger_data *data, void *key = NULL; unsigned int i; + if (unlikely(!rbe)) + return; + memset(compound_key, 0, hist_data->key_size); for_each_hist_key_field(i, hist_data) {