From: Yan, Zheng Date: Fri, 15 Jun 2012 06:31:31 +0000 (+0800) Subject: perf: Avoid race between cpu hotplug and installing event X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=fbfc623f8231c8d8c78aab5841e9c6e5811ab638;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git perf: Avoid race between cpu hotplug and installing event perf_event_open() requires the cpu on which to install event is online, but the cpu can go offline after perf_event_open checks that. Add a get_online_cpus()/put_online_cpus() pair to avoid the race. Signed-off-by: Zheng Yan Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1339741902-8449-3-git-send-email-zheng.z.yan@intel.com Signed-off-by: Ingo Molnar --- diff --git a/kernel/events/core.c b/kernel/events/core.c index d7d71d6ec972..31d182e01549 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6252,6 +6252,8 @@ SYSCALL_DEFINE5(perf_event_open, } } + get_online_cpus(); + event = perf_event_alloc(&attr, cpu, task, group_leader, NULL, NULL, NULL); if (IS_ERR(event)) { @@ -6391,6 +6393,8 @@ SYSCALL_DEFINE5(perf_event_open, perf_unpin_context(ctx); mutex_unlock(&ctx->mutex); + put_online_cpus(); + event->owner = current; mutex_lock(¤t->perf_event_mutex); @@ -6419,6 +6423,7 @@ err_context: err_alloc: free_event(event); err_task: + put_online_cpus(); if (task) put_task_struct(task); err_group_fd: