[tip:perf/urgent] perf: Fix crash in swevents
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From: tip-bot for Peter Zijlstra on 3 Jun 2010 14:00 Commit-ID: c6df8d5ab87a246942d138321e1721edbb69f6e1 Gitweb: http://git.kernel.org/tip/c6df8d5ab87a246942d138321e1721edbb69f6e1 Author: Peter Zijlstra <a.p.zijlstra(a)chello.nl> AuthorDate: Thu, 3 Jun 2010 11:21:20 +0200 Committer: Ingo Molnar <mingo(a)elte.hu> CommitDate: Thu, 3 Jun 2010 17:03:08 +0200 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(a)gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra(a)chello.nl> LKML-Reference: <1275557609.27810.35218.camel(a)twins> Signed-off-by: Ingo Molnar <mingo(a)elte.hu> --- 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 858f56f..31d6afe 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, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |