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block: Move recursion to bdrv_set_aio_context()

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Instead of having two recursions, in bdrv_attach_aio_context() and in
bdrv_detach_aio_context(), just having one recursion is enough. Said
functions are only about a single node now.

It is important that the recursion doesn't happen between detaching and
attaching a context to the current node because the nested call will
drain the node, and draining with a NULL context would segfault.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2019-05-06 19:17:58 +02:00
parent a3a683c33d
commit 0d83708a1d
1 changed files with 7 additions and 8 deletions
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15
block.c
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@ -5679,7 +5679,6 @@ static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban)
static void bdrv_detach_aio_context(BlockDriverState *bs)
{
BdrvAioNotifier *baf, *baf_tmp;
BdrvChild *child;
assert(!bs->walking_aio_notifiers);
bs->walking_aio_notifiers = true;
@ -5698,9 +5697,6 @@ static void bdrv_detach_aio_context(BlockDriverState *bs)
if (bs->drv && bs->drv->bdrv_detach_aio_context) {
bs->drv->bdrv_detach_aio_context(bs);
}
QLIST_FOREACH(child, &bs->children, next) {
bdrv_detach_aio_context(child->bs);
}
if (bs->quiesce_counter) {
aio_enable_external(bs->aio_context);
@ -5712,7 +5708,6 @@ static void bdrv_attach_aio_context(BlockDriverState *bs,
AioContext *new_context)
{
BdrvAioNotifier *ban, *ban_tmp;
BdrvChild *child;
if (bs->quiesce_counter) {
aio_disable_external(new_context);
@ -5720,9 +5715,6 @@ static void bdrv_attach_aio_context(BlockDriverState *bs,
bs->aio_context = new_context;
QLIST_FOREACH(child, &bs->children, next) {
bdrv_attach_aio_context(child->bs, new_context);
}
if (bs->drv && bs->drv->bdrv_attach_aio_context) {
bs->drv->bdrv_attach_aio_context(bs, new_context);
}
@ -5744,11 +5736,18 @@ static void bdrv_attach_aio_context(BlockDriverState *bs,
* the same as the current context of bs). */
void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context)
{
BdrvChild *child;
if (bdrv_get_aio_context(bs) == new_context) {
return;
}
bdrv_drained_begin(bs);
QLIST_FOREACH(child, &bs->children, next) {
bdrv_set_aio_context(child->bs, new_context);
}
bdrv_detach_aio_context(bs);
/* This function executes in the old AioContext so acquire the new one in