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[Qemu-devel] [PATCH 1/7] block/nbd: Fix hang in .bdrv_close()
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH 1/7] block/nbd: Fix hang in .bdrv_close() |
Date: |
Fri, 12 Jul 2019 19:35:54 +0200 |
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 <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
---
block/nbd.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/block/nbd.c b/block/nbd.c
index 81edabbf35..8f5ee86842 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -61,6 +61,7 @@ typedef struct BDRVNBDState {
CoMutex send_mutex;
CoQueue free_sema;
Coroutine *connection_co;
+ Coroutine *teardown_co;
int in_flight;
NBDClientRequest requests[MAX_NBD_REQUESTS];
@@ -135,7 +136,15 @@ static void nbd_teardown_connection(BlockDriverState *bs)
qio_channel_shutdown(s->ioc,
QIO_CHANNEL_SHUTDOWN_BOTH,
NULL);
- 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);
nbd_client_detach_aio_context(bs);
object_unref(OBJECT(s->sioc));
@@ -207,6 +216,9 @@ static coroutine_fn void nbd_connection_entry(void *opaque)
bdrv_dec_in_flight(s->bs);
s->connection_co = NULL;
+ if (s->teardown_co) {
+ aio_co_wake(s->teardown_co);
+ }
aio_wait_kick();
}
--
2.21.0