[media] media-device: get rid of the spinlock
Right now, the lock schema for media_device struct is messy,
since sometimes, it is protected via a spin lock, while, for
media graph traversal, it is protected by a mutex.
Solve this conflict by always using a mutex.
As a side effect, this prevents a bug when the media notifiers
is called at atomic context, while running the notifier callback:
BUG: sleeping function called from invalid context at mm/slub.c:1289
in_atomic(): 1, irqs_disabled(): 0, pid: 3479, name: modprobe
4 locks held by modprobe/3479:
#0: (&dev->mutex){......}, at: [<ffffffff81ce8933>] __driver_attach+0xa3/0x160
#1: (&dev->mutex){......}, at: [<ffffffff81ce8941>] __driver_attach+0xb1/0x160
#2: (register_mutex#5){+.+.+.}, at: [<ffffffffa10596c7>] usb_audio_probe+0x257/0x1c90 [snd_usb_audio]
#3: (&(&mdev->lock)->rlock){+.+.+.}, at: [<ffffffffa0e6051b>] media_device_register_entity+0x1cb/0x700 [media]
CPU: 2 PID: 3479 Comm: modprobe Not tainted 4.5.0-rc3+ #49
Hardware name: /NUC5i7RYB, BIOS RYBDWi35.86A.0350.2015.0812.1722 08/12/2015
0000000000000000 ffff8803b3f6f288 ffffffff81933901 ffff8803c4bae000
ffff8803c4bae5c8 ffff8803b3f6f2b0 ffffffff811c6af5 ffff8803c4bae000
ffffffff8285d7f6 0000000000000509 ffff8803b3f6f2f0 ffffffff811c6ce5
Call Trace:
[<ffffffff81933901>] dump_stack+0x85/0xc4
[<ffffffff811c6af5>] ___might_sleep+0x245/0x3a0
[<ffffffff811c6ce5>] __might_sleep+0x95/0x1a0
[<ffffffff8155aade>] kmem_cache_alloc_trace+0x20e/0x300
[<ffffffffa0e66e3d>] ? media_add_link+0x4d/0x140 [media]
[<ffffffffa0e66e3d>] media_add_link+0x4d/0x140 [media]
[<ffffffffa0e69931>] media_create_pad_link+0xa1/0x600 [media]
[<ffffffffa0fe11b3>] au0828_media_graph_notify+0x173/0x360 [au0828]
[<ffffffffa0e68a6a>] ? media_gobj_create+0x1ba/0x480 [media]
[<ffffffffa0e606fb>] media_device_register_entity+0x3ab/0x700 [media]
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index 6e43c95..898a3cf 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -90,18 +90,13 @@
id &= ~MEDIA_ENT_ID_FLAG_NEXT;
- spin_lock(&mdev->lock);
-
media_device_for_each_entity(entity, mdev) {
if (((media_entity_id(entity) == id) && !next) ||
((media_entity_id(entity) > id) && next)) {
- spin_unlock(&mdev->lock);
return entity;
}
}
- spin_unlock(&mdev->lock);
-
return NULL;
}
@@ -431,6 +426,7 @@
struct media_device *dev = to_media_device(devnode);
long ret;
+ mutex_lock(&dev->graph_mutex);
switch (cmd) {
case MEDIA_IOC_DEVICE_INFO:
ret = media_device_get_info(dev,
@@ -443,29 +439,24 @@
break;
case MEDIA_IOC_ENUM_LINKS:
- mutex_lock(&dev->graph_mutex);
ret = media_device_enum_links(dev,
(struct media_links_enum __user *)arg);
- mutex_unlock(&dev->graph_mutex);
break;
case MEDIA_IOC_SETUP_LINK:
- mutex_lock(&dev->graph_mutex);
ret = media_device_setup_link(dev,
(struct media_link_desc __user *)arg);
- mutex_unlock(&dev->graph_mutex);
break;
case MEDIA_IOC_G_TOPOLOGY:
- mutex_lock(&dev->graph_mutex);
ret = media_device_get_topology(dev,
(struct media_v2_topology __user *)arg);
- mutex_unlock(&dev->graph_mutex);
break;
default:
ret = -ENOIOCTLCMD;
}
+ mutex_unlock(&dev->graph_mutex);
return ret;
}
@@ -590,12 +581,12 @@
if (!ida_pre_get(&mdev->entity_internal_idx, GFP_KERNEL))
return -ENOMEM;
- spin_lock(&mdev->lock);
+ mutex_lock(&mdev->graph_mutex);
ret = ida_get_new_above(&mdev->entity_internal_idx, 1,
&entity->internal_idx);
if (ret < 0) {
- spin_unlock(&mdev->lock);
+ mutex_unlock(&mdev->graph_mutex);
return ret;
}
@@ -615,9 +606,6 @@
(notify)->notify(entity, notify->notify_data);
}
- spin_unlock(&mdev->lock);
-
- mutex_lock(&mdev->graph_mutex);
if (mdev->entity_internal_idx_max
>= mdev->pm_count_walk.ent_enum.idx_max) {
struct media_entity_graph new = { .top = 0 };
@@ -680,9 +668,9 @@
if (mdev == NULL)
return;
- spin_lock(&mdev->lock);
+ mutex_lock(&mdev->graph_mutex);
__media_device_unregister_entity(entity);
- spin_unlock(&mdev->lock);
+ mutex_unlock(&mdev->graph_mutex);
}
EXPORT_SYMBOL_GPL(media_device_unregister_entity);
@@ -703,7 +691,6 @@
INIT_LIST_HEAD(&mdev->pads);
INIT_LIST_HEAD(&mdev->links);
INIT_LIST_HEAD(&mdev->entity_notify);
- spin_lock_init(&mdev->lock);
mutex_init(&mdev->graph_mutex);
ida_init(&mdev->entity_internal_idx);
@@ -752,9 +739,9 @@
int __must_check media_device_register_entity_notify(struct media_device *mdev,
struct media_entity_notify *nptr)
{
- spin_lock(&mdev->lock);
+ mutex_lock(&mdev->graph_mutex);
list_add_tail(&nptr->list, &mdev->entity_notify);
- spin_unlock(&mdev->lock);
+ mutex_unlock(&mdev->graph_mutex);
return 0;
}
EXPORT_SYMBOL_GPL(media_device_register_entity_notify);
@@ -771,9 +758,9 @@
void media_device_unregister_entity_notify(struct media_device *mdev,
struct media_entity_notify *nptr)
{
- spin_lock(&mdev->lock);
+ mutex_lock(&mdev->graph_mutex);
__media_device_unregister_entity_notify(mdev, nptr);
- spin_unlock(&mdev->lock);
+ mutex_unlock(&mdev->graph_mutex);
}
EXPORT_SYMBOL_GPL(media_device_unregister_entity_notify);
@@ -787,11 +774,11 @@
if (mdev == NULL)
return;
- spin_lock(&mdev->lock);
+ mutex_lock(&mdev->graph_mutex);
/* Check if mdev was ever registered at all */
if (!media_devnode_is_registered(&mdev->devnode)) {
- spin_unlock(&mdev->lock);
+ mutex_unlock(&mdev->graph_mutex);
return;
}
@@ -811,7 +798,7 @@
kfree(intf);
}
- spin_unlock(&mdev->lock);
+ mutex_unlock(&mdev->graph_mutex);
device_remove_file(&mdev->devnode.dev, &dev_attr_model);
media_devnode_unregister(&mdev->devnode);