perf evlist: Fix event ID retrieval for group format read case

We need to fail the event ID retrieval in case both following conditions
are true:

  - we are on kernel with no PERF_EVENT_IOC_ID support
  - PERF_FORMAT_GROUP read format is set

The PERF_FORMAT_GROUP read format bit is the killer for retrieving event
ID out of the read syscall, because we have no guarantee of the event
placement within leader kernel sibling list.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-e93pgyj20rqx48qzw10vj4r4@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index df77a44fe276a78b6ba27ab17593a89a81c6620d..10fcc0372aa9e457b3145c8a0d3774c10fc063e5 100644 (file)
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -314,6 +314,13 @@ static int perf_evlist__id_add_fd(struct perf_evlist *evlist,
 
        /* Legacy way to get event id.. All hail to old kernels! */
 
+       /*
+        * This way does not work with group format read, so bail
+        * out in that case.
+        */
+       if (perf_evlist__read_format(evlist) & PERF_FORMAT_GROUP)
+               return -1;
+
        if (!(evsel->attr.read_format & PERF_FORMAT_ID) ||
            read(fd, &read_data, sizeof(read_data)) == -1)
                return -1;