motorhead/qemu
1
0
Fork 0
mirror of https://github.com/Motorhead1991/qemu.git synced 2025-08-04 08:13:54 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions

throttle: acquire the ThrottleGroup lock in bdrv_swap()

Browse source 
bdrv_swap() touches the fields of a BlockDriverState that are
protected by the ThrottleGroup lock. Although those fields end up in
their original place, they are temporarily swapped in the process,
so there's a chance that an operation on a member of the same group
happening on a different thread can try to use them.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: d92dc40d7c4f1fc5cda5cbbf4ffb7a4670b79d17.1433779731.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Alberto Garcia 2015-06-08 18:17:45 +02:00 • committed by Stefan Hajnoczi
parent 76f4afb40f
commit db6283385c
3 changed files with 49 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

31
block/throttle-groups.c
View file

@ -33,7 +33,8 @@
* its own locking.
*
* This locking is however handled internally in this file, so it's
* transparent to outside users.
* mostly transparent to outside users (but see the documentation in
* throttle_groups_lock()).
*
* The whole ThrottleGroup structure is private and invisible to
* outside users, that only use it through its ThrottleState.
@ -459,6 +460,34 @@ void throttle_group_unregister_bs(BlockDriverState *bs)
bs->throttle_state = NULL;
}
/* Acquire the lock of this throttling group.
*
* You won't normally need to use this. None of the functions from the
* ThrottleGroup API require you to acquire the lock since all of them
* deal with it internally.
*
* This should only be used in exceptional cases when you want to
* access the protected fields of a BlockDriverState directly
* (e.g. bdrv_swap()).
*
* @bs: a BlockDriverState that is member of the group
*/
void throttle_group_lock(BlockDriverState *bs)
{
ThrottleGroup *tg = container_of(bs->throttle_state, ThrottleGroup, ts);
qemu_mutex_lock(&tg->lock);
}
/* Release the lock of this throttling group.
*
* See the comments in throttle_group_lock().
*/
void throttle_group_unlock(BlockDriverState *bs)
{
ThrottleGroup *tg = container_of(bs->throttle_state, ThrottleGroup, ts);
qemu_mutex_unlock(&tg->lock);
}
static void throttle_groups_init(void)
{
qemu_mutex_init(&throttle_groups_lock);