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authorMark Rutland <mark.rutland@arm.com>2016-07-15 12:08:10 +0200
committerArnaldo Carvalho de Melo <acme@redhat.com>2016-07-19 00:41:14 +0200
commit00e727bb389359c81101b03d34fec8cc7be5168d (patch)
tree93f2d7b207e4eeec77501a02bd9f721a14edb5a8 /tools
parenttools: Copy linux/{hash,poison}.h and check for drift (diff)
downloadlinux-00e727bb389359c81101b03d34fec8cc7be5168d.tar.xz
linux-00e727bb389359c81101b03d34fec8cc7be5168d.zip
perf stat: Balance opening and reading events
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 <mark.rutland@arm.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: He Kuang <hekuang@huawei.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wang Nan <wangnan0@huawei.com> Link: http://lkml.kernel.org/r/1468577293-19667-2-git-send-email-mark.rutland@arm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/builtin-stat.c8
1 files 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;