From: Paul Mackerras Date: Tue, 19 Oct 2010 05:55:35 +0000 (+1100) Subject: perf, powerpc: Fix power_pmu_event_init to not use event->ctx X-Git-Tag: v2.6.37-rc1~214^2~3 X-Git-Url: http://bbs.cooldavid.org/git/?a=commitdiff_plain;h=57fa7214330be2e292ddb1402834ff0b221ef29a;p=net-next-2.6.git perf, powerpc: Fix power_pmu_event_init to not use event->ctx Commit c3f00c70 ("perf: Separate find_get_context() from event initialization") changed the generic perf_event code to call perf_event_alloc, which calls the arch-specific event_init code, before looking up the context for the new event. Unfortunately, power_pmu_event_init uses event->ctx->task to see whether the new event is a per-task event or a system-wide event, and thus crashes since event->ctx is NULL at the point where power_pmu_event_init gets called. (The reason it needs to know whether it is a per-task event is because there are some hardware events on Power systems which only count when the processor is not idle, and there are some fixed-function counters which count such events. For example, the "run cycles" event counts cycles when the processor is not idle. If the user asks to count cycles, we can use "run cycles" if this is a per-task event, since the processor is running when the task is running, by definition. We can't use "run cycles" if the user asks for "cycles" on a system-wide counter.) Fortunately the information we need is in the event->attach_state field, so we just use that instead. Signed-off-by: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Peter Zijlstra Cc: Frederic Weisbecker LKML-Reference: <20101019055535.GA10398@drongo> Signed-off-by: Ingo Molnar Reported-by: Alexey Kardashevskiy Signed-off-by: Ingo Molnar --- diff --git a/arch/powerpc/kernel/perf_event.c b/arch/powerpc/kernel/perf_event.c index 9cb4924b6c0..3129c855933 100644 --- a/arch/powerpc/kernel/perf_event.c +++ b/arch/powerpc/kernel/perf_event.c @@ -1092,7 +1092,7 @@ static int power_pmu_event_init(struct perf_event *event) * XXX we should check if the task is an idle task. */ flags = 0; - if (event->ctx->task) + if (event->attach_state & PERF_ATTACH_TASK) flags |= PPMU_ONLY_COUNT_RUN; /*