This function, in addition to be called by a generated_co_wrapper, is also called by the blk_* API. The strategy is to always take the lock at the function called when the coroutine is created, to avoid recursive locking.
Protecting bdrv_co_pdiscard{_snapshot}() implies that the following BlockDriver callbacks always called with graph rdlock taken: - bdrv_co_pdiscard - bdrv_aio_pdiscard - bdrv_co_pdiscard_snapshot Signed-off-by: Emanuele Giuseppe Esposito <eespo...@redhat.com> --- block/block-backend.c | 1 + block/io.c | 2 ++ include/block/block_int-common.h | 3 +++ 3 files changed, 6 insertions(+) diff --git a/block/block-backend.c b/block/block-backend.c index d660772375..211a813523 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -1716,6 +1716,7 @@ blk_co_do_pdiscard(BlockBackend *blk, int64_t offset, int64_t bytes) IO_CODE(); blk_wait_while_drained(blk); + GRAPH_RDLOCK_GUARD(); ret = blk_check_byte_request(blk, offset, bytes); if (ret < 0) { diff --git a/block/io.c b/block/io.c index c9b451fecd..bc9f47538c 100644 --- a/block/io.c +++ b/block/io.c @@ -2885,6 +2885,7 @@ int coroutine_fn bdrv_co_pdiscard(BdrvChild *child, int64_t offset, int head, tail, align; BlockDriverState *bs = child->bs; IO_CODE(); + assert_bdrv_graph_readable(); if (!bs || !bs->drv || !bdrv_is_inserted(bs)) { return -ENOMEDIUM; @@ -3488,6 +3489,7 @@ bdrv_co_pdiscard_snapshot(BlockDriverState *bs, int64_t offset, int64_t bytes) BlockDriver *drv = bs->drv; int ret; IO_CODE(); + assert_bdrv_graph_readable(); if (!drv) { return -ENOMEDIUM; diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index 568c2d3092..7c34a8e40f 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -486,6 +486,7 @@ struct BlockDriver { BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque); BlockAIOCB *(*bdrv_aio_flush)(BlockDriverState *bs, BlockCompletionFunc *cb, void *opaque); + /* Called with graph rdlock taken. */ BlockAIOCB *(*bdrv_aio_pdiscard)(BlockDriverState *bs, int64_t offset, int bytes, BlockCompletionFunc *cb, void *opaque); @@ -559,6 +560,7 @@ struct BlockDriver { */ int coroutine_fn (*bdrv_co_pwrite_zeroes)(BlockDriverState *bs, int64_t offset, int64_t bytes, BdrvRequestFlags flags); + /* Called with graph rdlock taken. */ int coroutine_fn (*bdrv_co_pdiscard)(BlockDriverState *bs, int64_t offset, int64_t bytes); @@ -647,6 +649,7 @@ struct BlockDriver { int coroutine_fn (*bdrv_co_snapshot_block_status)(BlockDriverState *bs, bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum, int64_t *map, BlockDriverState **file); + /* Called with graph rdlock taken. */ int coroutine_fn (*bdrv_co_pdiscard_snapshot)(BlockDriverState *bs, int64_t offset, int64_t bytes); -- 2.31.1