CIFS: Fix race condition on RFC1002_NEGATIVE_SESSION_RESPONSE
This patch fixes a race condition that occurs when connecting
to a NT 3.51 host without specifying a NetBIOS name.
In that case a RFC1002_NEGATIVE_SESSION_RESPONSE is received
and the SMB negotiation is reattempted, but under some conditions
it leads SendReceive() to hang forever while waiting for srv_mutex.
This, in turn, sets the calling process to an uninterruptible sleep
state and makes it unkillable.
The solution is to unlock the srv_mutex acquired in the demux
thread *before* going to sleep (after the reconnect error) and
before reattempting the connection.
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index f3bfe08..8383d5e 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -386,6 +386,7 @@
rc = generic_ip_connect(server);
if (rc) {
cifs_dbg(FYI, "reconnect error %d\n", rc);
+ mutex_unlock(&server->srv_mutex);
msleep(3000);
} else {
atomic_inc(&tcpSesReconnectCount);
@@ -393,8 +394,8 @@
if (server->tcpStatus != CifsExiting)
server->tcpStatus = CifsNeedNegotiate;
spin_unlock(&GlobalMid_Lock);
+ mutex_unlock(&server->srv_mutex);
}
- mutex_unlock(&server->srv_mutex);
} while (server->tcpStatus == CifsNeedReconnect);
return rc;