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authorStephane Eranian <eranian@google.com>2011-03-23 16:03:06 +0100
committerIngo Molnar <mingo@elte.hu>2011-03-23 16:07:22 +0100
commit68cacd29167b1926d237bd1b153aa2a990201729 (patch)
treed4359e9e0a1fa88b569e0c8a20aede435d916fee /kernel
parentce2d17ca7f85dcade62cd608601a0d52ccdaf0e6 (diff)
downloadlinux-68cacd29167b1926d237bd1b153aa2a990201729.tar.bz2
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/perf_event.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 3472bb1a070c..0c714226ae0c 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -941,6 +941,7 @@ static void perf_group_attach(struct perf_event *event)
static void
list_del_event(struct perf_event *event, struct perf_event_context *ctx)
{
+ struct perf_cpu_context *cpuctx;
/*
* We can have double detach due to exit/hot-unplug + close.
*/
@@ -949,8 +950,17 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx)
event->attach_state &= ~PERF_ATTACH_CONTEXT;
- if (is_cgroup_event(event))
+ if (is_cgroup_event(event)) {
ctx->nr_cgroups--;
+ cpuctx = __get_cpu_context(ctx);
+ /*
+ * if there are no more cgroup events
+ * then cler cgrp to avoid stale pointer
+ * in update_cgrp_time_from_cpuctx()
+ */
+ if (!ctx->nr_cgroups)
+ cpuctx->cgrp = NULL;
+ }
ctx->nr_events--;
if (event->attr.inherit_stat)