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Commit 4afe260b authored by Federico Sauter's avatar Federico Sauter Committed by Steve French
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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.
parent b2910307

fs/cifs/connect.c

+2 −1
Original line number Diff line number Diff line
@@ -386,6 +386,7 @@ cifs_reconnect(struct TCP_Server_Info *server) 
		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 @@ cifs_reconnect(struct TCP_Server_Info *server) 
			if (server->tcpStatus != CifsExiting)

				server->tcpStatus = CifsNeedNegotiate;

			spin_unlock(&GlobalMid_Lock);

		}

			mutex_unlock(&server->srv_mutex);

		}

	} while (server->tcpStatus == CifsNeedReconnect);



	return rc;