diff options
Diffstat (limited to 'block/graph-lock.c')
| -rw-r--r-- | block/graph-lock.c | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/block/graph-lock.c b/block/graph-lock.c index f357a2c..58a7990 100644 --- a/block/graph-lock.c +++ b/block/graph-lock.c @@ -163,17 +163,29 @@ void bdrv_graph_wrlock(BlockDriverState *bs) void bdrv_graph_wrunlock(void) { GLOBAL_STATE_CODE(); - QEMU_LOCK_GUARD(&aio_context_list_lock); assert(qatomic_read(&has_writer)); + WITH_QEMU_LOCK_GUARD(&aio_context_list_lock) { + /* + * No need for memory barriers, this works in pair with + * the slow path of rdlock() and both take the lock. + */ + qatomic_store_release(&has_writer, 0); + + /* Wake up all coroutines that are waiting to read the graph */ + qemu_co_enter_all(&reader_queue, &aio_context_list_lock); + } + /* - * No need for memory barriers, this works in pair with - * the slow path of rdlock() and both take the lock. + * Run any BHs that were scheduled during the wrlock section and that + * callers might expect to have finished (in particular, this is important + * for bdrv_schedule_unref()). + * + * Do this only after restarting coroutines so that nested event loops in + * BHs don't deadlock if their condition relies on the coroutine making + * progress. */ - qatomic_store_release(&has_writer, 0); - - /* Wake up all coroutine that are waiting to read the graph */ - qemu_co_enter_all(&reader_queue, &aio_context_list_lock); + aio_bh_poll(qemu_get_aio_context()); } void coroutine_fn bdrv_graph_co_rdlock(void) |