From 3f35f82e04923affb3283b451b6d66880f266a5a Mon Sep 17 00:00:00 2001 From: Emanuele Giuseppe Esposito Date: Wed, 7 Dec 2022 14:18:33 +0100 Subject: [PATCH] block: assert that graph read and writes are performed correctly Remove the old assert_bdrv_graph_writable, and replace it with the new version using graph-lock API. See the function documentation for more information. Signed-off-by: Emanuele Giuseppe Esposito Signed-off-by: Kevin Wolf Message-Id: <20221207131838.239125-14-kwolf@redhat.com> Reviewed-by: Emanuele Giuseppe Esposito Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- block.c | 4 ++-- block/graph-lock.c | 11 +++++++++++ include/block/block_int-global-state.h | 17 ----------------- include/block/graph-lock.h | 15 +++++++++++++++ 4 files changed, 28 insertions(+), 19 deletions(-) diff --git a/block.c b/block.c index bdffadcdaa72..ff53b41af324 100644 --- a/block.c +++ b/block.c @@ -1406,7 +1406,7 @@ static void bdrv_child_cb_attach(BdrvChild *child) { BlockDriverState *bs = child->opaque; - assert_bdrv_graph_writable(bs); + assert_bdrv_graph_writable(); QLIST_INSERT_HEAD(&bs->children, child, next); if (bs->drv->is_filter || (child->role & BDRV_CHILD_FILTERED)) { /* @@ -1452,7 +1452,7 @@ static void bdrv_child_cb_detach(BdrvChild *child) bdrv_backing_detach(child); } - assert_bdrv_graph_writable(bs); + assert_bdrv_graph_writable(); QLIST_REMOVE(child, next); if (child == bs->backing) { assert(child != bs->file); diff --git a/block/graph-lock.c b/block/graph-lock.c index e033c6d9acd2..c4d9d2c274d8 100644 --- a/block/graph-lock.c +++ b/block/graph-lock.c @@ -259,3 +259,14 @@ void bdrv_graph_rdunlock_main_loop(void) GLOBAL_STATE_CODE(); assert(!qemu_in_coroutine()); } + +void assert_bdrv_graph_readable(void) +{ + assert(qemu_in_main_thread() || reader_count()); +} + +void assert_bdrv_graph_writable(void) +{ + assert(qemu_in_main_thread()); + assert(qatomic_read(&has_writer)); +} diff --git a/include/block/block_int-global-state.h b/include/block/block_int-global-state.h index b49f4eb35bf9..2f0993f6e9ca 100644 --- a/include/block/block_int-global-state.h +++ b/include/block/block_int-global-state.h @@ -310,21 +310,4 @@ void bdrv_remove_aio_context_notifier(BlockDriverState *bs, */ void bdrv_drain_all_end_quiesce(BlockDriverState *bs); -/** - * Make sure that the function is running under both drain and BQL. - * The latter protects from concurrent writings - * from the GS API, while the former prevents concurrent reads - * from I/O. - */ -static inline void assert_bdrv_graph_writable(BlockDriverState *bs) -{ - /* - * TODO: this function is incomplete. Because the users of this - * assert lack the necessary drains, check only for BQL. - * Once the necessary drains are added, - * assert also for qatomic_read(&bs->quiesce_counter) > 0 - */ - assert(qemu_in_main_thread()); -} - #endif /* BLOCK_INT_GLOBAL_STATE_H */ diff --git a/include/block/graph-lock.h b/include/block/graph-lock.h index b27d8a5fb199..85e8a53b7353 100644 --- a/include/block/graph-lock.h +++ b/include/block/graph-lock.h @@ -135,6 +135,21 @@ void coroutine_fn bdrv_graph_co_rdunlock(void); void bdrv_graph_rdlock_main_loop(void); void bdrv_graph_rdunlock_main_loop(void); +/* + * assert_bdrv_graph_readable: + * Make sure that the reader is either the main loop, + * or there is at least a reader helding the rdlock. + * In this way an incoming writer is aware of the read and waits. + */ +void assert_bdrv_graph_readable(void); + +/* + * assert_bdrv_graph_writable: + * Make sure that the writer is the main loop and has set @has_writer, + * so that incoming readers will pause. + */ +void assert_bdrv_graph_writable(void); + typedef struct GraphLockable { } GraphLockable; /*