block: remove outdated AioContext locking comments

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>

2 files changed, 0 insertions, 12 deletions

diff --git a/block/block-backend.c b/block/block-backend.c
index f412bed274..209eb07528 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -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)
 {
diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
index 16f48388d3..50c358e8cd 100644
--- a/block/export/vhost-user-blk-server.c
+++ b/block/export/vhost-user-blk-server.c
@@ -278,7 +278,6 @@ static void vu_blk_exp_resize(void *opaque)
     vu_config_change_msg(&vexp->vu_server.vu_dev);
 }
 
-/* Called with vexp->export.ctx acquired */
 static void vu_blk_drained_begin(void *opaque)
 {
     VuBlkExport *vexp = opaque;
@@ -287,7 +286,6 @@ static void vu_blk_drained_begin(void *opaque)
     vhost_user_server_detach_aio_context(&vexp->vu_server);
 }
 
-/* Called with vexp->export.blk AioContext acquired */
 static void vu_blk_drained_end(void *opaque)
 {
     VuBlkExport *vexp = opaque;
@@ -300,8 +298,6 @@ static void vu_blk_drained_end(void *opaque)
  * Ensures that bdrv_drained_begin() waits until in-flight requests complete
  * and the server->co_trip coroutine has terminated. It will be restarted in
  * vhost_user_server_attach_aio_context().
- *
- * Called with vexp->export.ctx acquired.
  */
 static bool vu_blk_drained_poll(void *opaque)
 {