perf/live-mode: Handle payload-less events
Some events, such as the PERF_RECORD_FINISHED_ROUND event consist of
only an event header and no data. In this case, a 0-length payload
will be read, and the 0 return value will be wrongly interpreted as an
'unexpected end of event stream'.
This patch allows for proper handling of data-less events by skipping
0-length reads.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
LKML-Reference: <1273038527.6383.51.camel@tropicana>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 9401909..00ab298 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -696,15 +696,18 @@
p = &event;
p += sizeof(struct perf_event_header);
- err = do_read(self->fd, p, size - sizeof(struct perf_event_header));
- if (err <= 0) {
- if (err == 0) {
- pr_err("unexpected end of event stream\n");
- goto done;
- }
+ if (size - sizeof(struct perf_event_header)) {
+ err = do_read(self->fd, p,
+ size - sizeof(struct perf_event_header));
+ if (err <= 0) {
+ if (err == 0) {
+ pr_err("unexpected end of event stream\n");
+ goto done;
+ }
- pr_err("failed to read event data\n");
- goto out_err;
+ pr_err("failed to read event data\n");
+ goto out_err;
+ }
}
if (size == 0 ||