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authorSakari Ailus <sakari.ailus@linux.intel.com>2018-11-05 09:35:44 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-11-27 16:10:50 +0100
commit817266cb8d45b74a695fb8a27e12b17cf087d7b1 (patch)
treee7a2c17e9294437090cb15463a1edd0cc05cc2dd /drivers/media
parenta17989cb9bb03c75bb57dddc0f044100fd4d856e (diff)
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media: v4l: event: Add subscription to list before calling "add" operation
commit 92539d3eda2c090b382699bbb896d4b54e9bdece upstream. Patch ad608fbcf166 changed how events were subscribed to address an issue elsewhere. As a side effect of that change, the "add" callback was called before the event subscription was added to the list of subscribed events, causing the first event queued by the add callback (and possibly other events arriving soon afterwards) to be lost. Fix this by adding the subscription to the list before calling the "add" callback, and clean up afterwards if that fails. Fixes: ad608fbcf166 ("media: v4l: event: Prevent freeing event subscriptions while accessed") Reported-by: Dave Stevenson <dave.stevenson@raspberrypi.org> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Tested-by: Dave Stevenson <dave.stevenson@raspberrypi.org> Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com> Tested-by: Hans Verkuil <hans.verkuil@cisco.com> Cc: stable@vger.kernel.org (for 4.14 and up) Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/media')
-rw-r--r--drivers/media/v4l2-core/v4l2-event.c43
1 files changed, 24 insertions, 19 deletions
diff --git a/drivers/media/v4l2-core/v4l2-event.c b/drivers/media/v4l2-core/v4l2-event.c
index 568dd4affb33..011907eff660 100644
--- a/drivers/media/v4l2-core/v4l2-event.c
+++ b/drivers/media/v4l2-core/v4l2-event.c
@@ -193,6 +193,22 @@ int v4l2_event_pending(struct v4l2_fh *fh)
}
EXPORT_SYMBOL_GPL(v4l2_event_pending);
+static void __v4l2_event_unsubscribe(struct v4l2_subscribed_event *sev)
+{
+ struct v4l2_fh *fh = sev->fh;
+ unsigned int i;
+
+ lockdep_assert_held(&fh->subscribe_lock);
+ assert_spin_locked(&fh->vdev->fh_lock);
+
+ /* Remove any pending events for this subscription */
+ for (i = 0; i < sev->in_use; i++) {
+ list_del(&sev->events[sev_pos(sev, i)].list);
+ fh->navailable--;
+ }
+ list_del(&sev->list);
+}
+
int v4l2_event_subscribe(struct v4l2_fh *fh,
const struct v4l2_event_subscription *sub, unsigned elems,
const struct v4l2_subscribed_event_ops *ops)
@@ -225,27 +241,23 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
+ if (!found_ev)
+ list_add(&sev->list, &fh->subscribed);
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
if (found_ev) {
/* Already listening */
kvfree(sev);
- goto out_unlock;
- }
-
- if (sev->ops && sev->ops->add) {
+ } else if (sev->ops && sev->ops->add) {
ret = sev->ops->add(sev, elems);
if (ret) {
+ spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+ __v4l2_event_unsubscribe(sev);
+ spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
kvfree(sev);
- goto out_unlock;
}
}
- spin_lock_irqsave(&fh->vdev->fh_lock, flags);
- list_add(&sev->list, &fh->subscribed);
- spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
-
-out_unlock:
mutex_unlock(&fh->subscribe_lock);
return ret;
@@ -280,7 +292,6 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh,
{
struct v4l2_subscribed_event *sev;
unsigned long flags;
- int i;
if (sub->type == V4L2_EVENT_ALL) {
v4l2_event_unsubscribe_all(fh);
@@ -292,14 +303,8 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh,
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
sev = v4l2_event_subscribed(fh, sub->type, sub->id);
- if (sev != NULL) {
- /* Remove any pending events for this subscription */
- for (i = 0; i < sev->in_use; i++) {
- list_del(&sev->events[sev_pos(sev, i)].list);
- fh->navailable--;
- }
- list_del(&sev->list);
- }
+ if (sev != NULL)
+ __v4l2_event_unsubscribe(sev);
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);