perf_event: Make software events work again

Commit 6bde9b6ce0127e2a56228a2071536d422be31336 ("perf: Add
group scheduling transactional APIs") added code to allow a
group to be scheduled in a single transaction.  However, it
introduced a bug in handling events whose pmu does not implement
transactions -- at the end of scheduling in the events in the
group, in the non-transactional case the code now falls through
to the group_error label, and proceeds to unschedule all the
events in the group and return failure.

This fixes it by returning 0 (success) in the non-transactional
case.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: eranian@gmail.com
LKML-Reference: <20100508105800.GB10650@brick.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index bb06382..180151f 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -664,13 +664,13 @@ group_sched_in(struct perf_event *group_event,
                }
        }
 
-       if (txn) {
-               ret = pmu->commit_txn(pmu);
-               if (!ret) {
-                       pmu->cancel_txn(pmu);
+       if (!txn)
+               return 0;
 
-                       return 0;
-               }
+       ret = pmu->commit_txn(pmu);
+       if (!ret) {
+               pmu->cancel_txn(pmu);
+               return 0;
        }
 
 group_error: