[perfmon2] [PATCH] Fix error with buffer size and number of events in a group

[Corey A. <cja...@li...>]

perf_get_group_nevents was returning the wrong number of events
when the group was the last in the list - it always returned 1
instead of the true number.

Also, when reading up event groups, only a "max size" (sz) was
being passed to the read() function, which resulted in getting
fewer bytes than requested and a resulting warning when groups with
fewer events follow groups with more events.

Signed-off-by: Corey Ashford <cja...@li...>
---
 perf_examples/perf_util.c |    2 +-
 perf_examples/task.c      |    6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/perf_examples/perf_util.c b/perf_examples/perf_util.c
index 9c99b15..b84f0e2 100644
--- a/perf_examples/perf_util.c
+++ b/perf_examples/perf_util.c
@@ -161,7 +161,7 @@ perf_get_group_nevents(perf_event_desc_t *fds, int num, int idx)
 			return i - leader;
 		}
 	}
-	return 1;
+	return i - leader;
 }
 
 int
diff --git a/perf_examples/task.c b/perf_examples/task.c
index c66e3ed..75de973 100644
--- a/perf_examples/task.c
+++ b/perf_examples/task.c
@@ -99,14 +99,14 @@ read_groups(perf_event_desc_t *fds, int num)
 		if (!values)
 			err(1, "cannot allocate memory for values\n");
 
-		ret = read(fds[evt].fd, values, sz);
-		if (ret != sz) { /* unsigned */
+		ret = read(fds[evt].fd, values, new_sz);
+		if (ret != new_sz) { /* unsigned */
 			if (ret == -1)
 				err(1, "cannot read values event %s", fds[evt].name);
 
 			/* likely pinned and could not be loaded */
 			warnx("could not read event %d, tried to read %d bytes, but got %d",
-				evt, (int)sz, ret);
+				evt, (int)new_sz, ret);
 		}
 
 		/*
-- 
1.7.0.4