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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 <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237759847-21025-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
hifive-unleashed-5.1
Frederic Weisbecker 2009-03-22 23:10:46 +01:00 committed by Ingo Molnar
parent 9bd7d099ab
commit 07edf71213
3 changed files with 24 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
kernel/trace/trace.c
View File

@ -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

2
kernel/trace/trace.h
View File

@ -483,6 +483,8 @@ trace_current_buffer_lock_reserve(unsigned char type, unsigned long len,
unsigned long flags, int pc);
void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
unsigned long flags, int pc);
void trace_nowake_buffer_unlock_commit(struct ring_buffer_event *event,
unsigned long flags, int pc);
struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
struct trace_array_cpu *data);

2
kernel/trace/trace_events_stage_3.h
View File

@ -222,7 +222,7 @@ static void ftrace_raw_event_##call(proto) \
\
assign; \
\
trace_current_buffer_unlock_commit(event, irq_flags, pc); \
trace_nowake_buffer_unlock_commit(event, irq_flags, pc); \
\
if (call->preds && !filter_match_preds(call, entry)) \
ring_buffer_event_discard(event); \