From 4ef2c464a54b0b618d933641ac0a7012e629fed9 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Wed, 11 Mar 2020 10:51:42 +0000 Subject: [PATCH 01/20] block/nbd: Fix hang in .bdrv_close() RH-Author: Maxim Levitsky Message-id: <20200311105147.13208-2-mlevitsk@redhat.com> Patchwork-id: 94224 O-Subject: [RHEL-AV-8.2.0 qemu-kvm PATCH v2 1/6] block/nbd: Fix hang in .bdrv_close() Bugzilla: 1640894 RH-Acked-by: Stefano Garzarella RH-Acked-by: John Snow RH-Acked-by: Max Reitz From: Max Reitz When nbd_close() is called from a coroutine, the connection_co never gets to run, and thus nbd_teardown_connection() hangs. This is because aio_co_enter() only puts the connection_co into the main coroutine's wake-up queue, so this main coroutine needs to yield and wait for connection_co to terminate. Suggested-by: Kevin Wolf Signed-off-by: Max Reitz Message-Id: <20200122164532.178040-2-mreitz@redhat.com> Reviewed-by: Eric Blake Reviewed-by: Maxim Levitsky Signed-off-by: Max Reitz (cherry picked from commit 78c81a3f108870d325b0a39d88711366afe6f703) Signed-off-by: Maxim Levitsky Signed-off-by: Danilo C. L. de Paula --- block/nbd.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/block/nbd.c b/block/nbd.c index 5f18f78..a73f0d9 100644 --- a/block/nbd.c +++ b/block/nbd.c @@ -70,6 +70,7 @@ typedef struct BDRVNBDState { CoMutex send_mutex; CoQueue free_sema; Coroutine *connection_co; + Coroutine *teardown_co; QemuCoSleepState *connection_co_sleep_ns_state; bool drained; bool wait_drained_end; @@ -203,7 +204,15 @@ static void nbd_teardown_connection(BlockDriverState *bs) qemu_co_sleep_wake(s->connection_co_sleep_ns_state); } } - BDRV_POLL_WHILE(bs, s->connection_co); + if (qemu_in_coroutine()) { + s->teardown_co = qemu_coroutine_self(); + /* connection_co resumes us when it terminates */ + qemu_coroutine_yield(); + s->teardown_co = NULL; + } else { + BDRV_POLL_WHILE(bs, s->connection_co); + } + assert(!s->connection_co); } static bool nbd_client_connecting(BDRVNBDState *s) @@ -395,6 +404,9 @@ static coroutine_fn void nbd_connection_entry(void *opaque) s->ioc = NULL; } + if (s->teardown_co) { + aio_co_wake(s->teardown_co); + } aio_wait_kick(); } -- 1.8.3.1