Merge: CIFS: fix livelocks in smb2_reconnect() when server abruptly shuts down [rhel-10.1]

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/655

JIRA: https://issues.redhat.com/browse/RHEL-85526

Signed-off-by: Paulo Alcantara <paalcant@redhat.com>

Approved-by: Jay Shin <jaeshin@redhat.com>
Approved-by: Benjamin Coddington <bcodding@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: CKI GitLab Kmaint Pipeline Bot <26919896-cki-kmaint-pipeline-bot@users.noreply.gitlab.com>

Author: CKI KWF Bot

fs/smb/client/cifssmb.c

@@ -114,19 +114,23 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 
 	mutex_lock(&ses->session_mutex);
 	/*
-	 * Recheck after acquire mutex. If another thread is negotiating
-	 * and the server never sends an answer the socket will be closed
-	 * and tcpStatus set to reconnect.
+	 * Handle the case where a concurrent thread failed to negotiate or
+	 * killed a channel.
 	 */
 	spin_lock(&server->srv_lock);
-	if (server->tcpStatus == CifsNeedReconnect) {
+	switch (server->tcpStatus) {
+	case CifsExiting:
 		spin_unlock(&server->srv_lock);
 		mutex_unlock(&ses->session_mutex);
-
-		if (tcon->retry)
-			goto again;
-		rc = -EHOSTDOWN;
-		goto out;
+		return -EHOSTDOWN;
+	case CifsNeedReconnect:
+		spin_unlock(&server->srv_lock);
+		mutex_unlock(&ses->session_mutex);
+		if (!tcon->retry)
+			return -EHOSTDOWN;
+		goto again;
+	default:
+		break;
 	}
 	spin_unlock(&server->srv_lock);
 
@@ -152,16 +156,20 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	spin_unlock(&ses->ses_lock);
 
 	rc = cifs_negotiate_protocol(0, ses, server);
-	if (!rc) {
-		rc = cifs_setup_session(0, ses, server, ses->local_nls);
-		if ((rc == -EACCES) || (rc == -EHOSTDOWN) || (rc == -EKEYREVOKED)) {
-			/*
-			 * Try alternate password for next reconnect if an alternate
-			 * password is available.
-			 */
-			if (ses->password2)
-				swap(ses->password2, ses->password);
-		}
+	if (rc) {
+		mutex_unlock(&ses->session_mutex);
+		if (!tcon->retry)
+			return -EHOSTDOWN;
+		goto again;
+	}
+	rc = cifs_setup_session(0, ses, server, ses->local_nls);
+	if ((rc == -EACCES) || (rc == -EHOSTDOWN) || (rc == -EKEYREVOKED)) {
+		/*
+		 * Try alternate password for next reconnect if an alternate
+		 * password is available.
+		 */
+		if (ses->password2)
+			swap(ses->password2, ses->password);
 	}
 
 	/* do we need to reconnect tcon? */

fs/smb/client/smb2pdu.c

@@ -300,32 +300,23 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 
 	mutex_lock(&ses->session_mutex);
 	/*
-	 * if this is called by delayed work, and the channel has been disabled
-	 * in parallel, the delayed work can continue to execute in parallel
-	 * there's a chance that this channel may not exist anymore
+	 * Handle the case where a concurrent thread failed to negotiate or
+	 * killed a channel.
 	 */
 	spin_lock(&server->srv_lock);
-	if (server->tcpStatus == CifsExiting) {
+	switch (server->tcpStatus) {
+	case CifsExiting:
 		spin_unlock(&server->srv_lock);
 		mutex_unlock(&ses->session_mutex);
-		rc = -EHOSTDOWN;
-		goto out;
-	}
-
-	/*
-	 * Recheck after acquire mutex. If another thread is negotiating
-	 * and the server never sends an answer the socket will be closed
-	 * and tcpStatus set to reconnect.
-	 */
-	if (server->tcpStatus == CifsNeedReconnect) {
+		return -EHOSTDOWN;
+	case CifsNeedReconnect:
 		spin_unlock(&server->srv_lock);
 		mutex_unlock(&ses->session_mutex);
-
-		if (tcon->retry)
-			goto again;
-
-		rc = -EHOSTDOWN;
-		goto out;
+		if (!tcon->retry)
+			return -EHOSTDOWN;
+		goto again;
+	default:
+		break;
 	}
 	spin_unlock(&server->srv_lock);
 
@@ -350,43 +341,41 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	spin_unlock(&ses->ses_lock);
 
 	rc = cifs_negotiate_protocol(0, ses, server);
-	if (!rc) {
-		/*
-		 * if server stopped supporting multichannel
-		 * and the first channel reconnected, disable all the others.
-		 */
-		if (ses->chan_count > 1 &&
-		    !(server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) {
-			rc = cifs_chan_skip_or_disable(ses, server,
-						       from_reconnect);
-			if (rc) {
-				mutex_unlock(&ses->session_mutex);
-				goto out;
-			}
-		}
-
-		rc = cifs_setup_session(0, ses, server, ses->local_nls);
-		if ((rc == -EACCES) || (rc == -EKEYEXPIRED) || (rc == -EKEYREVOKED)) {
-			/*
-			 * Try alternate password for next reconnect (key rotation
-			 * could be enabled on the server e.g.) if an alternate
-			 * password is available and the current password is expired,
-			 * but do not swap on non pwd related errors like host down
-			 */
-			if (ses->password2)
-				swap(ses->password2, ses->password);
-		}
-
-		if ((rc == -EACCES) && !tcon->retry) {
-			mutex_unlock(&ses->session_mutex);
-			rc = -EHOSTDOWN;
-			goto failed;
-		} else if (rc) {
+	if (rc) {
+		mutex_unlock(&ses->session_mutex);
+		if (!tcon->retry)
+			return -EHOSTDOWN;
+		goto again;
+	}
+	/*
+	 * if server stopped supporting multichannel
+	 * and the first channel reconnected, disable all the others.
+	 */
+	if (ses->chan_count > 1 &&
+	    !(server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) {
+		rc = cifs_chan_skip_or_disable(ses, server,
+					       from_reconnect);
+		if (rc) {
 			mutex_unlock(&ses->session_mutex);
 			goto out;
 		}
-	} else {
+	}
+
+	rc = cifs_setup_session(0, ses, server, ses->local_nls);
+	if ((rc == -EACCES) || (rc == -EKEYEXPIRED) || (rc == -EKEYREVOKED)) {
+		/*
+		 * Try alternate password for next reconnect (key rotation
+		 * could be enabled on the server e.g.) if an alternate
+		 * password is available and the current password is expired,
+		 * but do not swap on non pwd related errors like host down
+		 */
+		if (ses->password2)
+			swap(ses->password2, ses->password);
+	}
+	if (rc) {
 		mutex_unlock(&ses->session_mutex);
+		if (rc == -EACCES && !tcon->retry)
+			return -EHOSTDOWN;
 		goto out;
 	}
 
@@ -490,7 +479,6 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	case SMB2_IOCTL:
 		rc = -EAGAIN;
 	}
-failed:
 	return rc;
 }