diff options
| author | Alistair Strachan <alistair.strachan@imgtec.com> | 2014-02-04 16:08:36 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-07 09:03:16 -0800 |
| commit | 5cf045f54d31894ec59ee741e01fa258be2ba0fb (patch) | |
| tree | 1820fb33350fdd10a8bf56bd9b1eebcea8f76836 /drivers | |
| parent | bbd9ae8a05e05a608ff9158cf3b95be7b857a6fa (diff) | |
staging: sync: Fix a race condition between release_obj and print_obj
Before this change, a timeline would only be removed from the timeline
list *after* the sync driver had its release_obj() called. However, the
driver's release_obj() may free resources needed by print_obj().
Although the timeline list is locked when print_obj() is called, it is
not locked when release_obj() is called. If one CPU was in print_obj()
when another was in release_obj(), the print_obj() may make unsafe
accesses.
It is not actually necessary to hold the timeline list lock when calling
release_obj() if the call is made after the timeline is unlinked from
the list, since there is no possibility another thread could be in --
or enter -- print_obj() for that timeline.
This change moves the release_obj() call to after the timeline is
unlinked, preventing the above race from occurring.
Cc: Colin Cross <ccross@android.com>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Alistair Strachan <alistair.strachan@imgtec.com>
[jstultz: minor commit subject tweak]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/staging/android/sync.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c index 38e5d3b5ed9b..b7fcaab0acea 100644 --- a/drivers/staging/android/sync.c +++ b/drivers/staging/android/sync.c @@ -79,13 +79,13 @@ static void sync_timeline_free(struct kref *kref) container_of(kref, struct sync_timeline, kref); unsigned long flags; - if (obj->ops->release_obj) - obj->ops->release_obj(obj); - spin_lock_irqsave(&sync_timeline_list_lock, flags); list_del(&obj->sync_timeline_list); spin_unlock_irqrestore(&sync_timeline_list_lock, flags); + if (obj->ops->release_obj) + obj->ops->release_obj(obj); + kfree(obj); } |