perf_events: Fix stale ->cgrp pointer in update_cgrp_time_from_cpuctx()

This patch solves a stale pointer problem in
update_cgrp_time_from_cpuctx(). The cpuctx->cgrp
was not cleared on all possible event exit paths,
including:

   close()
     perf_release()
       perf_release_kernel()
         list_del_event()

This patch fixes list_del_event() to clear cpuctx->cgrp
when there are no cgroup events left in the context.

[ This second version makes the code compile when
  CONFIG_CGROUP_PERF is not enabled. We unconditionally define
  perf_cpu_context->cgrp. ]

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: peterz@infradead.org
Cc: perfmon2-devel@lists.sf.net
Cc: paulus@samba.org
Cc: davem@davemloft.net
LKML-Reference: <20110323150306.GA1580@quad>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 0 insertions, 2 deletions

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index f495c0147240..311b4dc785a1 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -938,9 +938,7 @@ struct perf_cpu_context {
         struct list_head                rotation_list;
         int                             jiffies_interval;
         struct pmu                      *active_pmu;
-#ifdef CONFIG_CGROUP_PERF
         struct perf_cgroup              *cgrp;
-#endif
 };
 
 struct perf_output_handle {