From 07edf7121374609709ef1b0889f6e7b8d6a62ec1 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Sun, 22 Mar 2009 23:10:46 +0100 Subject: tracing/events: don't use wake up for events Impact: fix hard-lockup with sched switch events Some ftrace events, such as sched wakeup, can be traced while the runqueue lock is hold. Since they are using trace_current_buffer_unlock_commit(), they call wake_up() which can try to grab the runqueue lock too, resulting in a deadlock. Now for all event, we call a new helper: trace_nowake_buffer_unlock_commit() which do pretty the same than trace_current_buffer_unlock_commit() except than it doesn't call trace_wake_up(). Reported-by: Ingo Molnar Signed-off-by: Frederic Weisbecker Cc: Steven Rostedt LKML-Reference: <1237759847-21025-4-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- kernel/trace/trace.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) (limited to 'kernel/trace/trace.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index e6fac0ffe6f0..6bad12819eb6 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -860,15 +860,25 @@ static void ftrace_trace_stack(struct trace_array *tr, static void ftrace_trace_userstack(struct trace_array *tr, unsigned long flags, int pc); -void trace_buffer_unlock_commit(struct trace_array *tr, - struct ring_buffer_event *event, - unsigned long flags, int pc) +static inline void __trace_buffer_unlock_commit(struct trace_array *tr, + struct ring_buffer_event *event, + unsigned long flags, int pc, + int wake) { ring_buffer_unlock_commit(tr->buffer, event); ftrace_trace_stack(tr, flags, 6, pc); ftrace_trace_userstack(tr, flags, pc); - trace_wake_up(); + + if (wake) + trace_wake_up(); +} + +void trace_buffer_unlock_commit(struct trace_array *tr, + struct ring_buffer_event *event, + unsigned long flags, int pc) +{ + __trace_buffer_unlock_commit(tr, event, flags, pc, 1); } struct ring_buffer_event * @@ -882,7 +892,13 @@ trace_current_buffer_lock_reserve(unsigned char type, unsigned long len, void trace_current_buffer_unlock_commit(struct ring_buffer_event *event, unsigned long flags, int pc) { - return trace_buffer_unlock_commit(&global_trace, event, flags, pc); + return __trace_buffer_unlock_commit(&global_trace, event, flags, pc, 1); +} + +void trace_nowake_buffer_unlock_commit(struct ring_buffer_event *event, + unsigned long flags, int pc) +{ + return __trace_buffer_unlock_commit(&global_trace, event, flags, pc, 0); } void -- cgit v1.2.2