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| author | Stephane Eranian <eranian@google.com> | 2011-03-23 16:03:06 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-03-23 16:07:22 +0100 |
| commit | 68cacd29167b1926d237bd1b153aa2a990201729 (patch) | |
| tree | d4359e9e0a1fa88b569e0c8a20aede435d916fee | |
| parent | ce2d17ca7f85dcade62cd608601a0d52ccdaf0e6 (diff) | |
| download | linux-stable-68cacd29167b1926d237bd1b153aa2a990201729.tar.gz linux-stable-68cacd29167b1926d237bd1b153aa2a990201729.tar.bz2 linux-stable-68cacd29167b1926d237bd1b153aa2a990201729.zip | |
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>
| -rw-r--r-- | include/linux/perf_event.h | 2 | ||||
| -rw-r--r-- | kernel/perf_event.c | 12 |
2 files changed, 11 insertions, 3 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 { 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) |