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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2010-06-03 11:21:20 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-06-03 17:03:08 +0200 |
| commit | c6df8d5ab87a246942d138321e1721edbb69f6e1 (patch) | |
| tree | 4fa2965d148c3e7ea456ab889d278d5c16d25d17 | |
| parent | da3fd1a0010ccc9fe6fd5ae2b9e85e1aacc03e4d (diff) | |
perf: Fix crash in swevents
Frederic reported that because swevents handling doesn't disable IRQs
anymore, we can get a recursion of perf_adjust_period(), once from
overflow handling and once from the tick.
If both call ->disable, we get a double hlist_del_rcu() and trigger
a LIST_POISON2 dereference.
Since we don't actually need to stop/start a swevent to re-programm
the hardware (lack of hardware to program), simply nop out these
callbacks for the swevent pmu.
Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1275557609.27810.35218.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | kernel/perf_event.c | 24 |
1 files changed, 15 insertions, 9 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 858f56fa243..31d6afe9259 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -4055,13 +4055,6 @@ static void perf_swevent_overflow(struct perf_event *event, u64 overflow, } } -static void perf_swevent_unthrottle(struct perf_event *event) -{ - /* - * Nothing to do, we already reset hwc->interrupts. - */ -} - static void perf_swevent_add(struct perf_event *event, u64 nr, int nmi, struct perf_sample_data *data, struct pt_regs *regs) @@ -4276,11 +4269,22 @@ static void perf_swevent_disable(struct perf_event *event) hlist_del_rcu(&event->hlist_entry); } +static void perf_swevent_void(struct perf_event *event) +{ +} + +static int perf_swevent_int(struct perf_event *event) +{ + return 0; +} + static const struct pmu perf_ops_generic = { .enable = perf_swevent_enable, .disable = perf_swevent_disable, + .start = perf_swevent_int, + .stop = perf_swevent_void, .read = perf_swevent_read, - .unthrottle = perf_swevent_unthrottle, + .unthrottle = perf_swevent_void, /* hwc->interrupts already reset */ }; /* @@ -4561,8 +4565,10 @@ static int swevent_hlist_get(struct perf_event *event) static const struct pmu perf_ops_tracepoint = { .enable = perf_trace_enable, .disable = perf_trace_disable, + .start = perf_swevent_int, + .stop = perf_swevent_void, .read = perf_swevent_read, - .unthrottle = perf_swevent_unthrottle, + .unthrottle = perf_swevent_void, }; static int perf_tp_filter_match(struct perf_event *event, |