From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932621AbeBPJt7 (ORCPT ); Fri, 16 Feb 2018 04:49:59 -0500 Received: from terminus.zytor.com ([198.137.202.136]:48125 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932579AbeBPJtz (ORCPT ); Fri, 16 Feb 2018 04:49:55 -0500 Date: Fri, 16 Feb 2018 01:34:54 -0800 From: tip-bot for Kan Liang Message-ID: Cc: tglx@linutronix.de, peterz@infradead.org, acme@redhat.com, wangnan0@huawei.com, kan.liang@intel.com, hpa@zytor.com, namhyung@kernel.org, yao.jin@linux.intel.com, jolsa@kernel.org, linux-kernel@vger.kernel.org, mingo@kernel.org, ak@linux.intel.com Reply-To: mingo@kernel.org, ak@linux.intel.com, linux-kernel@vger.kernel.org, yao.jin@linux.intel.com, jolsa@kernel.org, wangnan0@huawei.com, namhyung@kernel.org, hpa@zytor.com, kan.liang@intel.com, peterz@infradead.org, acme@redhat.com, tglx@linutronix.de In-Reply-To: <1516310792-208685-3-git-send-email-kan.liang@intel.com> References: <1516310792-208685-3-git-send-email-kan.liang@intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] perf mmap: Recalculate size for overwrite mode Git-Commit-ID: dc6c35c679e96987dc83a003f30bc2cc33c84c00 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: dc6c35c679e96987dc83a003f30bc2cc33c84c00 Gitweb: https://git.kernel.org/tip/dc6c35c679e96987dc83a003f30bc2cc33c84c00 Author: Kan Liang AuthorDate: Thu, 18 Jan 2018 13:26:17 -0800 Committer: Arnaldo Carvalho de Melo CommitDate: Thu, 15 Feb 2018 09:51:57 -0300 perf mmap: Recalculate size for overwrite mode In perf_mmap__push(), the 'size' need to be recalculated, otherwise the invalid data might be pushed to the record in overwrite mode. The issue is introduced by commit 7fb4b407a124 ("perf mmap: Don't discard prev in backward mode"). When the ring buffer is full in overwrite mode, backward_rb_find_range() will be called to recalculate the 'start' and 'end'. The 'size' needs to be recalculated accordingly. Unconditionally recalculate the 'size', not just for full ring buffer in overwrite mode. Because: - There is no harmful to recalculate the 'size' for other cases. - The code of calculating 'start' and 'end' will be factored out later. The new function does not need to return 'size'. Signed-off-by: Kan Liang Acked-by: Jiri Olsa Cc: Andi Kleen Cc: Jin Yao Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Wang Nan Fixes: 7fb4b407a124 ("perf mmap: Don't discard prev in backward mode") Link: http://lkml.kernel.org/r/1516310792-208685-3-git-send-email-kan.liang@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/mmap.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c index 05076e6..97cf4fa 100644 --- a/tools/perf/util/mmap.c +++ b/tools/perf/util/mmap.c @@ -302,6 +302,8 @@ int perf_mmap__push(struct perf_mmap *md, bool overwrite, return -1; } + size = end - start; + if ((start & md->mask) + size != (end & md->mask)) { buf = &data[start & md->mask]; size = md->mask + 1 - (start & md->mask);