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authorSteven Rostedt (Google) <rostedt@goodmis.org>2022-11-24 00:43:23 +0300
committerSteven Rostedt (Google) <rostedt@goodmis.org>2022-11-24 03:05:50 +0300
commitef38c79a522b660f7f71d45dad2d6244bc741841 (patch)
tree74676f7bf6dfd660112239b0cf31e77486bd6715 /kernel
parent022632f6c43a86f2135642dccd5686de318e861d (diff)
downloadlinux-ef38c79a522b660f7f71d45dad2d6244bc741841.tar.xz
tracing: Fix race where histograms can be called before the event
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/ Link: https://lore.kernel.org/linux-trace-kernel/20221123164323.03450c3a@gandalf.local.home Cc: Tom Zanussi <zanussi@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> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace_events_hist.c3
1 files changed, 3 insertions, 0 deletions
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) {