requests[].receiving is set by nbd_receive_replies() under the receive_mutex;
Read it under the same mutex as well. Waking up receivers on errors happens
after each reply finishes processing, in nbd_co_receive_one_chunk().
If there is no currently-active reply, there are two cases:
* either there is no active request at all, in which case no
element of request[] can have .receiving = true
* or nbd_receive_replies() must be running and waiting for receive_mutex;
in that case it will get back to nbd_co_receive_one_chunk() because
the socket has been shutdown, and all waiting coroutines will wake up
in turn.
Signed-off-by: Paolo Bonzini
---
block/nbd.c | 15 +++
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/block/nbd.c b/block/nbd.c
index 6d80bd59e2..8954243f50 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -132,6 +132,7 @@ static void nbd_clear_bdrvstate(BlockDriverState *bs)
s->x_dirty_bitmap = NULL;
}
+/* Called with s->receive_mutex taken. */
static bool coroutine_fn nbd_recv_coroutine_wake_one(NBDClientRequest *req)
{
if (req->receiving) {
@@ -143,12 +144,13 @@ static bool coroutine_fn
nbd_recv_coroutine_wake_one(NBDClientRequest *req)
return false;
}
-static void coroutine_fn nbd_recv_coroutines_wake(BDRVNBDState *s, bool all)
+static void coroutine_fn nbd_recv_coroutines_wake(BDRVNBDState *s)
{
int i;
+QEMU_LOCK_GUARD(>receive_mutex);
for (i = 0; i < MAX_NBD_REQUESTS; i++) {
-if (nbd_recv_coroutine_wake_one(>requests[i]) && !all) {
+if (nbd_recv_coroutine_wake_one(>requests[i])) {
return;
}
}
@@ -169,8 +171,6 @@ static void coroutine_fn
nbd_channel_error_locked(BDRVNBDState *s, int ret)
} else {
s->state = NBD_CLIENT_QUIT;
}
-
-nbd_recv_coroutines_wake(s, true);
}
static void coroutine_fn nbd_channel_error(BDRVNBDState *s, int ret)
@@ -433,11 +433,10 @@ static coroutine_fn int nbd_receive_replies(BDRVNBDState
*s, uint64_t handle)
qemu_coroutine_yield();
/*
- * We may be woken for 3 reasons:
+ * We may be woken for 2 reasons:
* 1. From this function, executing in parallel coroutine, when our
*handle is received.
- * 2. From nbd_channel_error(), when connection is lost.
- * 3. From nbd_co_receive_one_chunk(), when previous request is
+ * 2. From nbd_co_receive_one_chunk(), when previous request is
*finished and s->reply.handle set to 0.
* Anyway, it's OK to lock the mutex and go to the next iteration.
*/
@@ -931,7 +930,7 @@ static coroutine_fn int nbd_co_receive_one_chunk(
}
s->reply.handle = 0;
-nbd_recv_coroutines_wake(s, false);
+nbd_recv_coroutines_wake(s);
return ret;
}
--
2.35.1
