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| author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-08-09 15:31:48 -0400 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-08-10 15:12:01 -0400 |
| commit | e0a568dcd18bdaa77877d558700ce4d3bbbb12b8 (patch) | |
| tree | 98962d8b1862aa1422e2e79021a6019a5a232a10 /kernel/trace/trace_events.c | |
| parent | b207de3ec531ff364843708c9fea968700aae8fe (diff) | |
| download | lwn-e0a568dcd18bdaa77877d558700ce4d3bbbb12b8.tar.gz lwn-e0a568dcd18bdaa77877d558700ce4d3bbbb12b8.zip | |
tracing: Fix synchronizing to event changes with tracepoint_synchronize_unregister()
Now that some trace events can be protected by srcu_read_lock(tracepoint_srcu),
we need to make sure all locations that depend on this are also protected.
There were many places that did a synchronize_sched() thinking that it was
enough to protect againts access to trace events. This use to be the case,
but now that we use SRCU for _rcuidle() trace events, they may not be
protected by synchronize_sched(), as they may be called in paths that RCU is
not watching for preempt disable.
Fixes: e6753f23d961d ("tracepoint: Make rcuidle tracepoint callers use SRCU")
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 7b508ce8ac44..808cf29febe2 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -636,7 +636,7 @@ static void __ftrace_clear_event_pids(struct trace_array *tr) rcu_assign_pointer(tr->filtered_pids, NULL); /* Wait till all users are no longer using pid filtering */ - synchronize_sched(); + tracepoint_synchronize_unregister(); trace_free_pid_list(pid_list); } @@ -1622,7 +1622,7 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf, } if (filtered_pids) { - synchronize_sched(); + tracepoint_synchronize_unregister(); trace_free_pid_list(filtered_pids); } else if (pid_list) { /* @@ -3036,8 +3036,8 @@ int event_trace_del_tracer(struct trace_array *tr) /* Disable any running events */ __ftrace_set_clr_event_nolock(tr, NULL, NULL, NULL, 0); - /* Access to events are within rcu_read_lock_sched() */ - synchronize_sched(); + /* Make sure no more events are being executed */ + tracepoint_synchronize_unregister(); down_write(&trace_event_sem); __trace_remove_event_dirs(tr); |