Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757300Ab1E0Vpv (ORCPT ); Fri, 27 May 2011 17:45:51 -0400 Received: from casper.infradead.org ([85.118.1.10]:45726 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756461Ab1E0Vpp (ORCPT ); Fri, 27 May 2011 17:45:45 -0400 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, David Ahern , Frederic Weisbecker , Ingo Molnar , Paul Mackerras , Peter Zijlstra , Thomas Gleixner , Arnaldo Carvalho de Melo Subject: [PATCH 2/5] perf events: initialize fd array to -1 instead of 0 Date: Fri, 27 May 2011 18:45:33 -0300 Message-Id: <1306532736-3790-3-git-send-email-acme@infradead.org> X-Mailer: git-send-email 1.6.2.5 In-Reply-To: <1306532736-3790-1-git-send-email-acme@infradead.org> References: <1306532736-3790-1-git-send-email-acme@infradead.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.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 Content-Length: 2243 Lines: 61 From: David Ahern perf_evsel__alloc_fd allocates an array of file descriptors with the memory initialized to 0. The array has dimensions for cpus and threads. Later, __perf_evsel__open calls sys_perf_event_open for each cpu and thread dimensions. If the open fails for any of the cpus or threads then the fd's for this event are closed and the fd entry in the array is set to -1. Now, if the first attempt fails for the event (e.g., the event is not supported) the remaining dimensions (cpu > 0 and thread > 0) are not touched and left at the initialized value of 0. builtin-stat catches ENOENT and ENOSYS failures and allows the command to continue. The end result is that stat attempts to read from an fd of 0 which of course is stdin and so the command hangs until you type ctrl-D. Resolve by initializing the array to -1 since an fd < 0 is already handled. Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1306511914-8016-1-git-send-email-dsahern@gmail.com Signed-off-by: David Ahern Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evsel.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-) diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index ee0fe0d..cca29ed 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -35,7 +35,17 @@ struct perf_evsel *perf_evsel__new(struct perf_event_attr *attr, int idx) int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads) { + int cpu, thread; evsel->fd = xyarray__new(ncpus, nthreads, sizeof(int)); + + if (evsel->fd) { + for (cpu = 0; cpu < ncpus; cpu++) { + for (thread = 0; thread < nthreads; thread++) { + FD(evsel, cpu, thread) = -1; + } + } + } + return evsel->fd != NULL ? 0 : -ENOMEM; } -- 1.6.2.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/