From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752703AbcGRXeY (ORCPT ); Mon, 18 Jul 2016 19:34:24 -0400 Received: from merlin.infradead.org ([205.233.59.134]:52405 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752282AbcGRXdg (ORCPT ); Mon, 18 Jul 2016 19:33:36 -0400 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Mark Rutland , Adrian Hunter , Alexander Shishkin , He Kuang , Kan Liang , Peter Zijlstra , Wang Nan , Arnaldo Carvalho de Melo Subject: [PATCH 10/15] perf stat: Balance opening and reading events Date: Mon, 18 Jul 2016 20:33:13 -0300 Message-Id: <1468884798-14932-11-git-send-email-acme@kernel.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1468884798-14932-1-git-send-email-acme@kernel.org> References: <1468884798-14932-1-git-send-email-acme@kernel.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by merlin.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mark Rutland In create_perf_stat_counter, when a target CPU has not been provided, we call __perf_evsel__open with empty_cpu_map, and open a single FD per thread. However, in read_counter we assume that we opened events for the product of threads and CPUs described in the evsel's cpu_map. Thus, if an evsel has a cpu_map with more than one entry, we will attempt to access FDs that we didn't open. This could result in a number of problems (e.g. blocking while reading from STDIN if the fd memory happened to be initialised to zero). This is problematic for systems were a logical CPU PMU covers some arbitrary subset of CPUs. The cpu_map of any evsel for that PMU will be initialised based on the cpumask exposed through sysfs, even if the user requests per-thread events. Signed-off-by: Mark Rutland Acked-by: Jiri Olsa Cc: Adrian Hunter Cc: Alexander Shishkin Cc: He Kuang Cc: Kan Liang Cc: Mark Rutland Cc: Peter Zijlstra Cc: Wang Nan Link: http://lkml.kernel.org/r/1468577293-19667-2-git-send-email-mark.rutland@arm.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-stat.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index 8c5a3bfdfdd7..0c16d20d7e32 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -290,8 +290,12 @@ perf_evsel__write_stat_event(struct perf_evsel *counter, u32 cpu, u32 thread, static int read_counter(struct perf_evsel *counter) { int nthreads = thread_map__nr(evsel_list->threads); - int ncpus = perf_evsel__nr_cpus(counter); - int cpu, thread; + int ncpus, cpu, thread; + + if (target__has_cpu(&target)) + ncpus = perf_evsel__nr_cpus(counter); + else + ncpus = 1; if (!counter->supported) return -ENOENT; -- 2.7.4