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| author | Masami Hiramatsu <mhiramat@kernel.org> | 2018-11-05 18:00:43 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-12-05 09:19:49 +0100 |
| commit | dee3f77032077225a2346ffd142091c7c41fe939 (patch) | |
| tree | 6d7eee851c29926feff52bd297266cd550063ecc /include | |
| parent | 67547b9b46602759a4d29ee6d8655837a94e5b68 (diff) | |
| download | linux-stable-dee3f77032077225a2346ffd142091c7c41fe939.tar.gz linux-stable-dee3f77032077225a2346ffd142091c7c41fe939.tar.bz2 linux-stable-dee3f77032077225a2346ffd142091c7c41fe939.zip | |
tracing: Lock event_mutex before synth_event_mutex
[ Upstream commit fc800a10be26017f8f338bc8e500d48e3e6429d9 ]
synthetic event is using synth_event_mutex for protecting
synth_event_list, and event_trigger_write() path acquires
locks as below order.
event_trigger_write(event_mutex)
->trigger_process_regex(trigger_cmd_mutex)
->event_hist_trigger_func(synth_event_mutex)
On the other hand, synthetic event creation and deletion paths
call trace_add_event_call() and trace_remove_event_call()
which acquires event_mutex. In that case, if we keep the
synth_event_mutex locked while registering/unregistering synthetic
events, its dependency will be inversed.
To avoid this issue, current synthetic event is using a 2 phase
process to create/delete events. For example, it searches existing
events under synth_event_mutex to check for event-name conflicts, and
unlocks synth_event_mutex, then registers a new event under event_mutex
locked. Finally, it locks synth_event_mutex and tries to add the
new event to the list. But it can introduce complexity and a chance
for name conflicts.
To solve this simpler, this introduces trace_add_event_call_nolock()
and trace_remove_event_call_nolock() which don't acquire
event_mutex inside. synthetic event can lock event_mutex before
synth_event_mutex to solve the lock dependency issue simpler.
Link: http://lkml.kernel.org/r/154140844377.17322.13781091165954002713.stgit@devbox
Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/trace_events.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 78a010e19ed4..0643c083ed86 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -529,6 +529,8 @@ extern int trace_event_raw_init(struct trace_event_call *call); extern int trace_define_field(struct trace_event_call *call, const char *type, const char *name, int offset, int size, int is_signed, int filter_type); +extern int trace_add_event_call_nolock(struct trace_event_call *call); +extern int trace_remove_event_call_nolock(struct trace_event_call *call); extern int trace_add_event_call(struct trace_event_call *call); extern int trace_remove_event_call(struct trace_event_call *call); extern int trace_event_get_offsets(struct trace_event_call *call); |