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| author | Prateek Sood <prsood@codeaurora.org> | 2019-12-10 10:15:16 +0100 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-12-21 22:05:13 +0100 |
| commit | 3a53acf1d9bea11b57c1f6205e3fe73f9d8a3688 (patch) | |
| tree | 21d329444d63cb7ad13f5b296166d201fb26f89e /kernel/trace/trace_events.c | |
| parent | tracing: Have the histogram compare functions convert to u64 first (diff) | |
| download | linux-3a53acf1d9bea11b57c1f6205e3fe73f9d8a3688.tar.xz linux-3a53acf1d9bea11b57c1f6205e3fe73f9d8a3688.zip | |
tracing: Fix lock inversion in trace_event_enable_tgid_record()
Task T2 Task T3
trace_options_core_write() subsystem_open()
mutex_lock(trace_types_lock) mutex_lock(event_mutex)
set_tracer_flag()
trace_event_enable_tgid_record() mutex_lock(trace_types_lock)
mutex_lock(event_mutex)
This gives a circular dependency deadlock between trace_types_lock and
event_mutex. To fix this invert the usage of trace_types_lock and
event_mutex in trace_options_core_write(). This keeps the sequence of
lock usage consistent.
Link: http://lkml.kernel.org/r/0101016eef175e38-8ca71caf-a4eb-480d-a1e6-6f0bbc015495-000000@us-west-2.amazonses.com
Cc: stable@vger.kernel.org
Fixes: d914ba37d7145 ("tracing: Add support for recording tgid of tasks")
Signed-off-by: Prateek Sood <prsood@codeaurora.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace_events.c')
| -rw-r--r-- | kernel/trace/trace_events.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index c6de3cebc127..a5b614cc3887 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -320,7 +320,8 @@ void trace_event_enable_cmd_record(bool enable) struct trace_event_file *file; struct trace_array *tr; - mutex_lock(&event_mutex); + lockdep_assert_held(&event_mutex); + do_for_each_event_file(tr, file) { if (!(file->flags & EVENT_FILE_FL_ENABLED)) @@ -334,7 +335,6 @@ void trace_event_enable_cmd_record(bool enable) clear_bit(EVENT_FILE_FL_RECORDED_CMD_BIT, &file->flags); } } while_for_each_event_file(); - mutex_unlock(&event_mutex); } void trace_event_enable_tgid_record(bool enable) @@ -342,7 +342,8 @@ void trace_event_enable_tgid_record(bool enable) struct trace_event_file *file; struct trace_array *tr; - mutex_lock(&event_mutex); + lockdep_assert_held(&event_mutex); + do_for_each_event_file(tr, file) { if (!(file->flags & EVENT_FILE_FL_ENABLED)) continue; @@ -356,7 +357,6 @@ void trace_event_enable_tgid_record(bool enable) &file->flags); } } while_for_each_event_file(); - mutex_unlock(&event_mutex); } static int __ftrace_event_enable_disable(struct trace_event_file *file, |