From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Alexander Potapenko , Arnaldo Carvalho de Melo , Arnaldo Carvalho de Melo , Eric Dumazet , Jiri Olsa , Kostya Serebryany , Linus Torvalds , Sasha Levin , Stephane Eranian , Thomas Gleixner , Vince Weaver , Ingo Molnar , Sasha Levin Subject: [PATCH AUTOSEL 3.18 84/98] perf: Fix PERF_EVENT_IOC_PERIOD deadlock Date: Thu, 25 Oct 2018 10:18:39 -0400 Message-Id: <20181025141853.214051-84-sashal@kernel.org> In-Reply-To: <20181025141853.214051-1-sashal@kernel.org> References: <20181025141853.214051-1-sashal@kernel.org> List-ID: From: Peter Zijlstra [ Upstream commit 642c2d671ceff40e9453203ea0c66e991e11e249 ] Dmitry reported a fairly silly recursive lock deadlock for PERF_EVENT_IOC_PERIOD, fix this by explicitly doing the inactive part of __perf_event_period() instead of calling that function. Reported-by: Dmitry Vyukov Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Alexander Potapenko Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Eric Dumazet Cc: Jiri Olsa Cc: Kostya Serebryany Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Sasha Levin Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Fixes: c7999c6f3fed ("perf: Fix PERF_EVENT_IOC_PERIOD migration race") Link: http://lkml.kernel.org/r/20151130115615.GJ17308@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- kernel/events/core.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 1f08f691de59..7b2f9d432fe7 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3929,7 +3929,14 @@ static int perf_event_period(struct perf_event *event, u64 __user *arg) goto retry; } - __perf_event_period(&pe); + if (event->attr.freq) { + event->attr.sample_freq = value; + } else { + event->attr.sample_period = value; + event->hw.sample_period = value; + } + + local64_set(&event->hw.period_left, 0); raw_spin_unlock_irq(&ctx->lock); return 0; -- 2.17.1