From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932503AbcELMuJ (ORCPT ); Thu, 12 May 2016 08:50:09 -0400 Received: from terminus.zytor.com ([198.137.202.10]:41344 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752098AbcELMuF (ORCPT ); Thu, 12 May 2016 08:50:05 -0400 Date: Thu, 12 May 2016 05:49:00 -0700 From: tip-bot for Alexander Shishkin Message-ID: Cc: acme@infradead.org, vincent.weaver@maine.edu, jolsa@redhat.com, mingo@kernel.org, acme@redhat.com, eranian@google.com, bp@alien8.de, stable@vger.kernel.org, hpa@zytor.com, torvalds@linux-foundation.org, alexander.shishkin@linux.intel.com, markus.t.metzger@intel.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, peterz@infradead.org Reply-To: mingo@kernel.org, acme@redhat.com, jolsa@redhat.com, vincent.weaver@maine.edu, acme@infradead.org, eranian@google.com, torvalds@linux-foundation.org, alexander.shishkin@linux.intel.com, bp@alien8.de, stable@vger.kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, tglx@linutronix.de, markus.t.metzger@intel.com In-Reply-To: <1462886313-13660-3-git-send-email-alexander.shishkin@linux.intel.com> References: <1462886313-13660-3-git-send-email-alexander.shishkin@linux.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] perf/core: Disable the event on a truncated AUX record Git-Commit-ID: 9f448cd3cbcec8995935e60b27802ae56aac8cc0 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 9f448cd3cbcec8995935e60b27802ae56aac8cc0 Gitweb: http://git.kernel.org/tip/9f448cd3cbcec8995935e60b27802ae56aac8cc0 Author: Alexander Shishkin AuthorDate: Tue, 10 May 2016 16:18:33 +0300 Committer: Ingo Molnar CommitDate: Thu, 12 May 2016 14:46:11 +0200 perf/core: Disable the event on a truncated AUX record When the PMU driver reports a truncated AUX record, it effectively means that there is no more usable room in the event's AUX buffer (even though there may still be some room, so that perf_aux_output_begin() doesn't take action). At this point the consumer still has to be woken up and the event has to be disabled, otherwise the event will just keep spinning between perf_aux_output_begin() and perf_aux_output_end() until its context gets unscheduled. Again, for cpu-wide events this means never, so once in this condition, they will be forever losing data. Fix this by disabling the event and waking up the consumer in case of a truncated AUX record. Reported-by: Markus Metzger Signed-off-by: Alexander Shishkin Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Borislav Petkov Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: vince@deater.net Link: http://lkml.kernel.org/r/1462886313-13660-3-git-send-email-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar --- kernel/events/ring_buffer.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index c61f0cb..7611d0f 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -347,6 +347,7 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size, bool truncated) { struct ring_buffer *rb = handle->rb; + bool wakeup = truncated; unsigned long aux_head; u64 flags = 0; @@ -375,9 +376,16 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size, aux_head = rb->user_page->aux_head = local_read(&rb->aux_head); if (aux_head - local_read(&rb->aux_wakeup) >= rb->aux_watermark) { - perf_output_wakeup(handle); + wakeup = true; local_add(rb->aux_watermark, &rb->aux_wakeup); } + + if (wakeup) { + if (truncated) + handle->event->pending_disable = 1; + perf_output_wakeup(handle); + } + handle->event = NULL; local_set(&rb->aux_nest, 0);