[qemu-xen staging] block/nbd: nbd_co_reconnect_loop(): don't sleep if drained

[patchbot@xxxxxxx]

commit 12c75e20a269ac917f4a76936d7142264e522233
Author:     Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx>
AuthorDate: Mon Jul 27 21:47:50 2020 +0300
Commit:     Eric Blake <eblake@xxxxxxxxxx>
CommitDate: Tue Jul 28 09:54:43 2020 -0500

    block/nbd: nbd_co_reconnect_loop(): don't sleep if drained
    
    We try to go to wakeable sleep, so that, if drain begins it will break
    the sleep. But what if nbd_client_co_drain_begin() already called and
    s->drained is already true? We'll go to sleep, and drain will have to
    wait for the whole timeout. Let's improve it.
    
    Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx>
    Reviewed-by: Eric Blake <eblake@xxxxxxxxxx>
    Message-Id: <20200727184751.15704-5-vsementsov@xxxxxxxxxxxxx>
    Signed-off-by: Eric Blake <eblake@xxxxxxxxxx>
---
 block/nbd.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/block/nbd.c b/block/nbd.c
index 620c97be6b..7bb881fef4 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -341,8 +341,6 @@ static coroutine_fn void nbd_co_reconnect_loop(BDRVNBDState 
*s)
             qemu_co_queue_restart_all(&s->free_sema);
         }
 
-        qemu_co_sleep_ns_wakeable(QEMU_CLOCK_REALTIME, timeout,
-                                  &s->connection_co_sleep_ns_state);
         if (s->drained) {
             bdrv_dec_in_flight(s->bs);
             s->wait_drained_end = true;
@@ -354,9 +352,12 @@ static coroutine_fn void 
nbd_co_reconnect_loop(BDRVNBDState *s)
                 qemu_coroutine_yield();
             }
             bdrv_inc_in_flight(s->bs);
-        }
-        if (timeout < max_timeout) {
-            timeout *= 2;
+        } else {
+            qemu_co_sleep_ns_wakeable(QEMU_CLOCK_REALTIME, timeout,
+                                      &s->connection_co_sleep_ns_state);
+            if (timeout < max_timeout) {
+                timeout *= 2;
+            }
         }
 
         nbd_reconnect_attempt(s);
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#staging