perf: Fix event multiplexing for exclusive groups

Commit 9e6302056f80 ("perf: Use hrtimers for event multiplexing")
placed the hrtimer (re)start call in the wrong place.  Instead of
capturing all scheduling failures, it only considered the PMU failure.

The result is that groups using perf_event_attr::exclusive are no
longer rotated.

Fixes: 9e6302056f80 ("perf: Use hrtimers for event multiplexing")
Reported-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201029162902.038667689@infradead.org

diff --git a/kernel/events/core.c b/kernel/events/core.c
index f0e526866a1c1704d355ac6b41d5e97962a863a8..00be48acdc360b3e50df310de55773215489e238 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2612,7 +2612,6 @@ group_error:
 
 error:
        pmu->cancel_txn(pmu);
-       perf_mux_hrtimer_restart(cpuctx);
        return -EAGAIN;
 }
 
@@ -3672,6 +3671,7 @@ static int merge_sched_in(struct perf_event *event, void *data)
 
                *can_add_hw = 0;
                ctx->rotate_necessary = 1;
+               perf_mux_hrtimer_restart(cpuctx);
        }
 
        return 0;