From 4af4c9550ccaaf0b53013ff730bc15068ffe6abc Mon Sep 17 00:00:00 2001 From: David Ahern Date: Fri, 27 May 2011 09:58:34 -0600 Subject: [PATCH] perf events: initialize fd array to -1 instead of 0 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 file changed, 10 insertions(+) diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index ee0fe0dffa71..cca29ededb5b 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; } -- 2.20.1