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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 <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221207131838.239125-14-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Emanuele Giuseppe Esposito 2022-12-07 14:18:33 +01:00 committed by Kevin Wolf
parent 1af8239235
commit 3f35f82e04
4 changed files with 28 additions and 19 deletions
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4
block.c
View File

@ -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);

11
block/graph-lock.c
View File

@ -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));
}

17
include/block/block_int-global-state.h
View File

@ -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 */

15
include/block/graph-lock.h
View File

@ -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;
/*