diff options
author | Hans Verkuil <hans.verkuil@cisco.com> | 2016-08-02 08:13:57 -0300 |
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committer | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2016-08-22 13:14:21 -0300 |
commit | 2ab25d35a91098ef0f42d478cc37f6a5591a4ab0 (patch) | |
tree | d23b665dc4fb9977e9abf443626279a3364a0d5a /drivers/staging/media/cec/cec-core.c | |
parent | 62148f0930a8e9bd5c5614f8387222f0220d7d47 (diff) | |
download | op-kernel-dev-2ab25d35a91098ef0f42d478cc37f6a5591a4ab0.zip op-kernel-dev-2ab25d35a91098ef0f42d478cc37f6a5591a4ab0.tar.gz |
[media] cec: improve locking
- The global lock was used in cec_get_device when it should have
used the devnode lock.
- cec_put_device also took the global lock, but since the release
function takes that lock as well this could lead to a deadlock.
Just don't take the lock here since there is no reason for it.
- cec_devnode_register() should take the global lock when clearing
the bit in the global bitmap.
- In cec_devnode_unregister() place the devnode->(un)register tests
and assignments under the devnode lock as well: this has to be
in a critical block.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Diffstat (limited to 'drivers/staging/media/cec/cec-core.c')
-rw-r--r-- | drivers/staging/media/cec/cec-core.c | 25 |
1 files changed, 14 insertions, 11 deletions
diff --git a/drivers/staging/media/cec/cec-core.c b/drivers/staging/media/cec/cec-core.c index 73792d0..3b1e4d2 100644 --- a/drivers/staging/media/cec/cec-core.c +++ b/drivers/staging/media/cec/cec-core.c @@ -51,31 +51,29 @@ int cec_get_device(struct cec_devnode *devnode) { /* * Check if the cec device is available. This needs to be done with - * the cec_devnode_lock held to prevent an open/unregister race: + * the devnode->lock held to prevent an open/unregister race: * without the lock, the device could be unregistered and freed between * the devnode->registered check and get_device() calls, leading to * a crash. */ - mutex_lock(&cec_devnode_lock); + mutex_lock(&devnode->lock); /* * return ENXIO if the cec device has been removed * already or if it is not registered anymore. */ if (!devnode->registered) { - mutex_unlock(&cec_devnode_lock); + mutex_unlock(&devnode->lock); return -ENXIO; } /* and increase the device refcount */ get_device(&devnode->dev); - mutex_unlock(&cec_devnode_lock); + mutex_unlock(&devnode->lock); return 0; } void cec_put_device(struct cec_devnode *devnode) { - mutex_lock(&cec_devnode_lock); put_device(&devnode->dev); - mutex_unlock(&cec_devnode_lock); } /* Called when the last user of the cec device exits. */ @@ -84,11 +82,10 @@ static void cec_devnode_release(struct device *cd) struct cec_devnode *devnode = to_cec_devnode(cd); mutex_lock(&cec_devnode_lock); - /* Mark device node number as free */ clear_bit(devnode->minor, cec_devnode_nums); - mutex_unlock(&cec_devnode_lock); + cec_delete_adapter(to_cec_adapter(devnode)); } @@ -160,7 +157,9 @@ static int __must_check cec_devnode_register(struct cec_devnode *devnode, cdev_del: cdev_del(&devnode->cdev); clr_bit: + mutex_lock(&cec_devnode_lock); clear_bit(devnode->minor, cec_devnode_nums); + mutex_unlock(&cec_devnode_lock); return ret; } @@ -177,17 +176,21 @@ static void cec_devnode_unregister(struct cec_devnode *devnode) { struct cec_fh *fh; + mutex_lock(&devnode->lock); + /* Check if devnode was never registered or already unregistered */ - if (!devnode->registered || devnode->unregistered) + if (!devnode->registered || devnode->unregistered) { + mutex_unlock(&devnode->lock); return; + } - mutex_lock(&devnode->lock); list_for_each_entry(fh, &devnode->fhs, list) wake_up_interruptible(&fh->wait); - mutex_unlock(&devnode->lock); devnode->registered = false; devnode->unregistered = true; + mutex_unlock(&devnode->lock); + device_del(&devnode->dev); cdev_del(&devnode->cdev); put_device(&devnode->dev); |