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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>
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@ -860,17 +860,27 @@ static void ftrace_trace_stack(struct trace_array *tr,
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static void ftrace_trace_userstack(struct trace_array *tr,
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unsigned long flags, int pc);
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void trace_buffer_unlock_commit(struct trace_array *tr,
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static inline void __trace_buffer_unlock_commit(struct trace_array *tr,
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struct ring_buffer_event *event,
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unsigned long flags, int pc)
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unsigned long flags, int pc,
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int wake)
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{
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ring_buffer_unlock_commit(tr->buffer, event);
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ftrace_trace_stack(tr, flags, 6, pc);
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ftrace_trace_userstack(tr, flags, pc);
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if (wake)
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trace_wake_up();
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}
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void trace_buffer_unlock_commit(struct trace_array *tr,
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struct ring_buffer_event *event,
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unsigned long flags, int pc)
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{
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__trace_buffer_unlock_commit(tr, event, flags, pc, 1);
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}
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struct ring_buffer_event *
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trace_current_buffer_lock_reserve(unsigned char type, unsigned long len,
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unsigned long flags, int pc)
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@ -882,7 +892,13 @@ trace_current_buffer_lock_reserve(unsigned char type, unsigned long len,
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void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
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unsigned long flags, int pc)
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{
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return trace_buffer_unlock_commit(&global_trace, event, flags, pc);
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return __trace_buffer_unlock_commit(&global_trace, event, flags, pc, 1);
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}
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void trace_nowake_buffer_unlock_commit(struct ring_buffer_event *event,
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unsigned long flags, int pc)
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{
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return __trace_buffer_unlock_commit(&global_trace, event, flags, pc, 0);
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}
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void
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@ -483,6 +483,8 @@ trace_current_buffer_lock_reserve(unsigned char type, unsigned long len,
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unsigned long flags, int pc);
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void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
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unsigned long flags, int pc);
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void trace_nowake_buffer_unlock_commit(struct ring_buffer_event *event,
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unsigned long flags, int pc);
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struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
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struct trace_array_cpu *data);
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@ -222,7 +222,7 @@ static void ftrace_raw_event_##call(proto) \
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\
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assign; \
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\
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trace_current_buffer_unlock_commit(event, irq_flags, pc); \
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trace_nowake_buffer_unlock_commit(event, irq_flags, pc); \
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\
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if (call->preds && !filter_match_preds(call, entry)) \
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ring_buffer_event_discard(event); \
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