[libvirt] [PATCH] remote: Fix locking in stream APIs
Remote driver needs to make sure the driver lock is released before
entering client IO loop as that may block indefinitely in poll(). As a
direct consequence of not following this in stream APIs, tunneled
migration to a destination host which becomes non-responding may block
qemu driver. Luckily, if keepalive is turned for p2p migrations, both
remote and qemu drivers will get automagically unblocked after keepalive
timeout.
---
src/remote/remote_driver.c | 40 ++++++++++++++++++++++++++++------------
1 file changed, 28 insertions(+), 12 deletions(-)
diff --git a/src/remote/remote_driver.c b/src/remote/remote_driver.c
index 3314f80..acae5d0 100644
--- a/src/remote/remote_driver.c
+++ b/src/remote/remote_driver.c
@@ -3976,12 +3976,14 @@ remoteStreamSend(virStreamPtr st,
VIR_DEBUG("st=%p data=%p nbytes=%zu", st, data, nbytes);
struct private_data *priv = st->conn->privateData;
virNetClientStreamPtr privst = st->privateData;
- int rv = -1;
-
- remoteDriverLock(priv);
+ int rv;
if (virNetClientStreamRaiseError(privst))
- goto cleanup;
+ return -1;
+
+ remoteDriverLock(priv);
+ priv->localUses++;
+ remoteDriverUnlock(priv);
rv = virNetClientStreamSendPacket(privst,
priv->client,
@@ -3989,9 +3991,9 @@ remoteStreamSend(virStreamPtr st,
data,
nbytes);
-cleanup:
+ remoteDriverLock(priv);
+ priv->localUses--;
remoteDriverUnlock(priv);
-
return rv;
}
@@ -4004,12 +4006,14 @@ remoteStreamRecv(virStreamPtr st,
VIR_DEBUG("st=%p data=%p nbytes=%zu", st, data, nbytes);
struct private_data *priv = st->conn->privateData;
virNetClientStreamPtr privst = st->privateData;
- int rv = -1;
-
- remoteDriverLock(priv);
+ int rv;
if (virNetClientStreamRaiseError(privst))
- goto cleanup;
+ return -1;
+
+ remoteDriverLock(priv);
+ priv->localUses++;
+ remoteDriverUnlock(priv);
rv = virNetClientStreamRecvPacket(privst,
priv->client,
@@ -4019,9 +4023,9 @@ remoteStreamRecv(virStreamPtr st,
VIR_DEBUG("Done %d", rv);
-cleanup:
+ remoteDriverLock(priv);
+ priv->localUses--;
remoteDriverUnlock(priv);
-
return rv;
}
@@ -4138,12 +4142,18 @@ remoteStreamFinish(virStreamPtr st)
if (virNetClientStreamRaiseError(privst))
goto cleanup;
+ priv->localUses++;
+ remoteDriverUnlock(priv);
+
ret = virNetClientStreamSendPacket(privst,
priv->client,
VIR_NET_OK,
NULL,
0);
+ remoteDriverLock(priv);
+ priv->localUses--;
+
cleanup:
virNetClientRemoveStream(priv->client, privst);
virNetClientStreamFree(privst);
@@ -4167,12 +4177,18 @@ remoteStreamAbort(virStreamPtr st)
if (virNetClientStreamRaiseError(privst))
goto cleanup;
+ priv->localUses++;
+ remoteDriverUnlock(priv);
+
ret = virNetClientStreamSendPacket(privst,
priv->client,
VIR_NET_ERROR,
NULL,
0);
+ remoteDriverLock(priv);
+ priv->localUses--;
+
cleanup:
virNetClientRemoveStream(priv->client, privst);
virNetClientStreamFree(privst);
--
1.7.11.1