Commit 6cc041e9 authored by Paulo Alcantara's avatar Paulo Alcantara Committed by Steve French
Browse files

cifs: avoid races in parallel reconnects in smb1 



Prevent multiple threads of doing negotiate, session setup and tree
connect by holding @ses->session_mutex in cifs_reconnect_tcon() while
reconnecting session and tcon.

Signed-off-by: default avatarPaulo Alcantara (SUSE) <pc@manguebit.com>
Reviewed-by: default avatarRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 179a88a8

fs/cifs/cifssmb.c

+15 −6
Original line number Diff line number Diff line
@@ -71,7 +71,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command) 
	int rc;

	struct cifs_ses *ses;

	struct TCP_Server_Info *server;

	struct nls_table *nls_codepage;

	struct nls_table *nls_codepage = NULL;



	/*

	 * SMBs NegProt, SessSetup, uLogoff do not have tcon yet so check for
@@ -99,6 +99,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command) 
	}

	spin_unlock(&tcon->tc_lock);



again:

	rc = cifs_wait_for_server_reconnect(server, tcon->retry);

	if (rc)

		return rc;
@@ -110,8 +111,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command) 
	}

	spin_unlock(&ses->chan_lock);



	nls_codepage = load_nls_default();



	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
@@ -120,29 +120,38 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command) 
	spin_lock(&server->srv_lock);

	if (server->tcpStatus == CifsNeedReconnect) {

		spin_unlock(&server->srv_lock);

		mutex_lock(&ses->session_mutex);



		if (tcon->retry)

			goto again;

		rc = -EHOSTDOWN;

		goto out;

	}

	spin_unlock(&server->srv_lock);



	nls_codepage = load_nls_default();



	/*

	 * need to prevent multiple threads trying to simultaneously

	 * reconnect the same SMB session

	 */

	spin_lock(&ses->ses_lock);

	spin_lock(&ses->chan_lock);

	if (!cifs_chan_needs_reconnect(ses, server)) {

	if (!cifs_chan_needs_reconnect(ses, server) &&

	    ses->ses_status == SES_GOOD) {

		spin_unlock(&ses->chan_lock);

		spin_unlock(&ses->ses_lock);



		/* this means that we only need to tree connect */

		if (tcon->need_reconnect)

			goto skip_sess_setup;



		rc = -EHOSTDOWN;

		mutex_unlock(&ses->session_mutex);

		goto out;

	}

	spin_unlock(&ses->chan_lock);

	spin_unlock(&ses->ses_lock);



	mutex_lock(&ses->session_mutex);

	rc = cifs_negotiate_protocol(0, ses, server);

	if (!rc)

		rc = cifs_setup_session(0, ses, server, nls_codepage);