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block: remove outdated AioContext locking comments

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The AioContext lock no longer exists.

There is one noteworthy change:

  - * More specifically, these functions use BDRV_POLL_WHILE(bs), which
  - * requires the caller to be either in the main thread and hold
  - * the BlockdriverState (bs) AioContext lock, or directly in the
  - * home thread that runs the bs AioContext. Calling them from
  - * another thread in another AioContext would cause deadlocks.
  + * More specifically, these functions use BDRV_POLL_WHILE(bs), which requires
  + * the caller to be either in the main thread or directly in the home thread
  + * that runs the bs AioContext. Calling them from another thread in another
  + * AioContext would cause deadlocks.

I am not sure whether deadlocks are still possible. Maybe they have just
moved to the fine-grained locks that have replaced the AioContext. Since
I am not sure if the deadlocks are gone, I have kept the substance
unchanged and just removed mention of the AioContext.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-ID: <20231205182011.1976568-15-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi
2023-12-05 13:20:11 -05:00
committed by Kevin Wolf
parent e91083cd3f
commit 23c983c8f6
8 changed files with 22 additions and 82 deletions
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block/block-backend.c
-8
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@@ -390,8 +390,6 @@ BlockBackend *blk_new(AioContext *ctx, uint64_t perm, uint64_t shared_perm)
* Both sets of permissions can be changed later using blk_set_perm().
*
* Return the new BlockBackend on success, null on failure.
*
* Callers must hold the AioContext lock of @bs.
*/
BlockBackend *blk_new_with_bs(BlockDriverState *bs, uint64_t perm,
uint64_t shared_perm, Error **errp)
@@ -416,8 +414,6 @@ BlockBackend *blk_new_with_bs(BlockDriverState *bs, uint64_t perm,
* Just as with bdrv_open(), after having called this function the reference to
* @options belongs to the block layer (even on failure).
*
* Called without holding an AioContext lock.
*
* TODO: Remove @filename and @flags; it should be possible to specify a whole
* BDS tree just by specifying the @options QDict (or @reference,
* alternatively). At the time of adding this function, this is not possible,
@@ -872,8 +868,6 @@ BlockBackend *blk_by_public(BlockBackendPublic *public)
/*
* Disassociates the currently associated BlockDriverState from @blk.
*
* The caller must hold the AioContext lock for the BlockBackend.
*/
void blk_remove_bs(BlockBackend *blk)
{
@@ -915,8 +909,6 @@ void blk_remove_bs(BlockBackend *blk)
/*
* Associates a new BlockDriverState with @blk.
*
* Callers must hold the AioContext lock of @bs.
*/
int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error **errp)
{