cifs: take cifs_tcp_ses_lock for status checks

While checking/updating status for tcp ses, smb ses or tcon,
we take GlobalMid_Lock. This doesn't make any sense.
Replaced it with cifs_tcp_ses_lock.

Ideally, we should take a spin lock per struct.
But since tcp ses, smb ses and tcon objects won't add up to a lot,
I think there should not be too much contention.

Also, in few other places, these are checked without locking.
Added locking for these.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

12 files changed, 164 insertions, 43 deletions

diff --git a/fs/cifs/cifs_swn.c b/fs/cifs/cifs_swn.c
index 23a1ed2fb769..8f386dd9939e 100644
--- a/fs/cifs/cifs_swn.c
+++ b/fs/cifs/cifs_swn.c
@@ -498,10 +498,10 @@ static int cifs_swn_reconnect(struct cifs_tcon *tcon, struct sockaddr_storage *a
 		goto unlock;
 	}
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	if (tcon->ses->server->tcpStatus != CifsExiting)
 		tcon->ses->server->tcpStatus = CifsNeedReconnect;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 unlock:
 	mutex_unlock(&tcon->ses->server->srv_mutex);
diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
index d118282071b3..0912d8bbbac1 100644
--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -141,9 +141,13 @@ int cifs_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server,
 	if ((cifs_pdu == NULL) || (server == NULL))
 		return -EINVAL;
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (!(cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) ||
-	    server->tcpStatus == CifsNeedNegotiate)
+	    server->tcpStatus == CifsNeedNegotiate) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return rc;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	if (!server->session_estab) {
 		memcpy(cifs_pdu->Signature.SecuritySignature, "BSRSPYL", 8);
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 23d76ae713f0..4ba35faff79c 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -586,7 +586,7 @@ struct TCP_Server_Info {
 	char server_RFC1001_name[RFC1001_NAME_LEN_WITH_NULL];
 	struct smb_version_operations	*ops;
 	struct smb_version_values	*vals;
-	/* updates to tcpStatus protected by GlobalMid_Lock */
+	/* updates to tcpStatus protected by cifs_tcp_ses_lock */
 	enum statusEnum tcpStatus; /* what we think the status is */
 	char *hostname; /* hostname portion of UNC string */
 	struct socket *ssocket;
@@ -924,7 +924,7 @@ struct cifs_ses {
 	struct mutex session_mutex;
 	struct TCP_Server_Info *server;	/* pointer to server info */
 	int ses_count;		/* reference counter */
-	enum statusEnum status;  /* updates protected by GlobalMid_Lock */
+	enum statusEnum status;  /* updates protected by cifs_tcp_ses_lock */
 	unsigned overrideSecFlg;  /* if non-zero override global sec flags */
 	char *serverOS;		/* name of operating system underlying server */
 	char *serverNOS;	/* name of network operating system of server */
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 7b1d0d71f3f1..3ef2796e2f24 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -120,15 +120,18 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	 * only tree disconnect, open, and write, (and ulogoff which does not
 	 * have tcon) are allowed as we start force umount
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if (tcon->tidStatus == CifsExiting) {
 		if (smb_command != SMB_COM_WRITE_ANDX &&
 		    smb_command != SMB_COM_OPEN_ANDX &&
 		    smb_command != SMB_COM_TREE_DISCONNECT) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			cifs_dbg(FYI, "can not send cmd %d while umounting\n",
 				 smb_command);
 			return -ENODEV;
 		}
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	retries = server->nr_targets;
 
@@ -148,8 +151,12 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 		}
 
 		/* are we still trying to reconnect? */
-		if (server->tcpStatus != CifsNeedReconnect)
+		spin_lock(&cifs_tcp_ses_lock);
+		if (server->tcpStatus != CifsNeedReconnect) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			break;
+		}
+		spin_unlock(&cifs_tcp_ses_lock);
 
 		if (retries && --retries)
 			continue;
@@ -186,11 +193,14 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	 * and the server never sends an answer the socket will be closed
 	 * and tcpStatus set to reconnect.
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedReconnect) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		rc = -EHOSTDOWN;
 		mutex_unlock(&ses->session_mutex);
 		goto out;
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	/*
 	 * need to prevent multiple threads trying to simultaneously
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 7b478f5db9d6..815f629933de 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -467,9 +467,12 @@ reconnect_dfs_server(struct TCP_Server_Info *server,
 	dfs_cache_free_tgts(&tl);
 
 	/* Need to set up echo worker again once connection has been established */
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedNegotiate)
 		mod_delayed_work(cifsiod_wq, &server->echo, 0);
 
+	spin_unlock(&cifs_tcp_ses_lock);
+
 	wake_up(&server->response_q);
 	return rc;
 }
@@ -571,15 +574,18 @@ server_unresponsive(struct TCP_Server_Info *server)
 	 * 65s kernel_recvmsg times out, and we see that we haven't gotten
 	 *     a response in >60s.
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if ((server->tcpStatus == CifsGood ||
 	    server->tcpStatus == CifsNeedNegotiate) &&
 	    (!server->ops->can_echo || server->ops->can_echo(server)) &&
 	    time_after(jiffies, server->lstrp + 3 * server->echo_interval)) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		cifs_server_dbg(VFS, "has not responded in %lu seconds. Reconnecting...\n",
 			 (3 * server->echo_interval) / HZ);
 		cifs_reconnect(server, false);
 		return true;
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	return false;
 }
@@ -624,13 +630,18 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg)
 		else
 			length = sock_recvmsg(server->ssocket, smb_msg, 0);
 
-		if (server->tcpStatus == CifsExiting)
+		spin_lock(&cifs_tcp_ses_lock);
+		if (server->tcpStatus == CifsExiting) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			return -ESHUTDOWN;
+		}
 
 		if (server->tcpStatus == CifsNeedReconnect) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			cifs_reconnect(server, false);
 			return -ECONNABORTED;
 		}
+		spin_unlock(&cifs_tcp_ses_lock);
 
 		if (length == -ERESTARTSYS ||
 		    length == -EAGAIN ||
@@ -808,9 +819,9 @@ static void clean_demultiplex_info(struct TCP_Server_Info *server)
 	cancel_delayed_work_sync(&server->echo);
 	cancel_delayed_work_sync(&server->resolve);
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	server->tcpStatus = CifsExiting;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 	wake_up_all(&server->response_q);
 
 	/* check if we have blocked requests that need to free */
@@ -1427,9 +1438,9 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
 	else
 		cancel_delayed_work_sync(&server->reconnect);
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	server->tcpStatus = CifsExiting;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	cifs_crypto_secmech_release(server);
 
@@ -1582,7 +1593,9 @@ smbd_connected:
 	 * to the struct since the kernel thread not created yet
 	 * no need to spinlock this update of tcpStatus
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	tcp_ses->tcpStatus = CifsNeedNegotiate;
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	if ((ctx->max_credits < 20) || (ctx->max_credits > 60000))
 		tcp_ses->max_credits = SMB2_MAX_CREDITS_AVAILABLE;
@@ -1799,15 +1812,13 @@ void cifs_put_smb_ses(struct cifs_ses *ses)
 		spin_unlock(&cifs_tcp_ses_lock);
 		return;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
 
 	/* ses_count can never go negative */
 	WARN_ON(ses->ses_count < 0);
 
-	spin_lock(&GlobalMid_Lock);
 	if (ses->status == CifsGood)
 		ses->status = CifsExiting;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	cifs_free_ipc(ses);
 
@@ -3075,12 +3086,15 @@ static int mount_get_conns(struct mount_ctx *mnt_ctx)
 		 * for just this mount.
 		 */
 		reset_cifs_unix_caps(xid, tcon, cifs_sb, ctx);
+		spin_lock(&cifs_tcp_ses_lock);
 		if ((tcon->ses->server->tcpStatus == CifsNeedReconnect) &&
 		    (le64_to_cpu(tcon->fsUnixInfo.Capability) &
 		     CIFS_UNIX_TRANSPORT_ENCRYPTION_MANDATORY_CAP)) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			rc = -EACCES;
 			goto out;
 		}
+		spin_unlock(&cifs_tcp_ses_lock);
 	} else
 		tcon->unix_ext = 0; /* server does not support them */
 
@@ -3755,7 +3769,9 @@ CIFSTCon(const unsigned int xid, struct cifs_ses *ses,
 	if (rc == 0) {
 		bool is_unicode;
 
+		spin_lock(&cifs_tcp_ses_lock);
 		tcon->tidStatus = CifsGood;
+		spin_unlock(&cifs_tcp_ses_lock);
 		tcon->need_reconnect = false;
 		tcon->tid = smb_buffer_response->Tid;
 		bcc_ptr = pByteArea(smb_buffer_response);
@@ -3859,12 +3875,12 @@ cifs_negotiate_protocol(const unsigned int xid, struct cifs_ses *ses,
 
 	rc = server->ops->negotiate(xid, ses, server);
 	if (rc == 0) {
-		spin_lock(&GlobalMid_Lock);
+		spin_lock(&cifs_tcp_ses_lock);
 		if (server->tcpStatus == CifsNeedNegotiate)
 			server->tcpStatus = CifsGood;
 		else
 			rc = -EHOSTDOWN;
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&cifs_tcp_ses_lock);
 	}
 
 	return rc;
diff --git a/fs/cifs/netmisc.c b/fs/cifs/netmisc.c
index fa9fbd6a819c..43b16b6d108c 100644
--- a/fs/cifs/netmisc.c
+++ b/fs/cifs/netmisc.c
@@ -896,10 +896,10 @@ map_and_check_smb_error(struct mid_q_entry *mid, bool logErr)
 		if (class == ERRSRV && code == ERRbaduid) {
 			cifs_dbg(FYI, "Server returned 0x%x, reconnecting session...\n",
 				code);
-			spin_lock(&GlobalMid_Lock);
+			spin_lock(&cifs_tcp_ses_lock);
 			if (mid->server->tcpStatus != CifsExiting)
 				mid->server->tcpStatus = CifsNeedReconnect;
-			spin_unlock(&GlobalMid_Lock);
+			spin_unlock(&cifs_tcp_ses_lock);
 		}
 	}
 
diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index 61fc8cb1ec8f..03ba30843950 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -369,10 +369,10 @@ void cifs_ses_mark_for_reconnect(struct cifs_ses *ses)
 	int i;
 
 	for (i = 0; i < ses->chan_count; i++) {
-		spin_lock(&GlobalMid_Lock);
+		spin_lock(&cifs_tcp_ses_lock);
 		if (ses->chans[i].server->tcpStatus != CifsExiting)
 			ses->chans[i].server->tcpStatus = CifsNeedReconnect;
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&cifs_tcp_ses_lock);
 	}
 }
 
@@ -1052,9 +1052,9 @@ sess_establish_session(struct sess_data *sess_data)
 	spin_unlock(&ses->chan_lock);
 
 	/* Even if one channel is active, session is in good state */
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	ses->status = CifsGood;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	return 0;
 }
diff --git a/fs/cifs/smb1ops.c b/fs/cifs/smb1ops.c
index 5366202d343d..54319a789c92 100644
--- a/fs/cifs/smb1ops.c
+++ b/fs/cifs/smb1ops.c
@@ -163,7 +163,7 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 {
 	__u64 mid = 0;
 	__u16 last_mid, cur_mid;
-	bool collision;
+	bool collision, reconnect;
 
 	spin_lock(&GlobalMid_Lock);
 
@@ -215,7 +215,7 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 		 * an eventual reconnect to clean out the pending_mid_q.
 		 */
 		if (num_mids > 32768)
-			server->tcpStatus = CifsNeedReconnect;
+			reconnect = true;
 
 		if (!collision) {
 			mid = (__u64)cur_mid;
@@ -225,6 +225,13 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 		cur_mid++;
 	}
 	spin_unlock(&GlobalMid_Lock);
+
+	if (reconnect) {
+		spin_lock(&cifs_tcp_ses_lock);
+		server->tcpStatus = CifsNeedReconnect;
+		spin_unlock(&cifs_tcp_ses_lock);
+	}
+
 	return mid;
 }
 
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index b33b0f391a23..c2368c9110b0 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -121,9 +121,13 @@ smb2_add_credits(struct TCP_Server_Info *server,
 			 optype, scredits, add);
 	}
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedReconnect
-	    || server->tcpStatus == CifsExiting)
+	    || server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	switch (rc) {
 	case -1:
@@ -208,11 +212,15 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
 				return rc;
 			spin_lock(&server->req_lock);
 		} else {
+			spin_unlock(&server->req_lock);
+			spin_lock(&cifs_tcp_ses_lock);
 			if (server->tcpStatus == CifsExiting) {
-				spin_unlock(&server->req_lock);
+				spin_unlock(&cifs_tcp_ses_lock);
 				return -ENOENT;
 			}
+			spin_unlock(&cifs_tcp_ses_lock);
 
+			spin_lock(&server->req_lock);
 			scredits = server->credits;
 			/* can deadlock with reopen */
 			if (scredits <= 8) {
@@ -4983,10 +4991,12 @@ static void smb2_decrypt_offload(struct work_struct *work)
 
 			mid->callback(mid);
 		} else {
+			spin_lock(&cifs_tcp_ses_lock);
 			spin_lock(&GlobalMid_Lock);
 			if (dw->server->tcpStatus == CifsNeedReconnect) {
 				mid->mid_state = MID_RETRY_NEEDED;
 				spin_unlock(&GlobalMid_Lock);
+				spin_unlock(&cifs_tcp_ses_lock);
 				mid->callback(mid);
 			} else {
 				mid->mid_state = MID_REQUEST_SUBMITTED;
@@ -4994,6 +5004,7 @@ static void smb2_decrypt_offload(struct work_struct *work)
 				list_add_tail(&mid->qhead,
 					&dw->server->pending_mid_q);
 				spin_unlock(&GlobalMid_Lock);
+				spin_unlock(&cifs_tcp_ses_lock);
 			}
 		}
 		cifs_mid_q_entry_release(mid);
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 9e7b213dbef5..0c18b6f4f9eb 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -162,6 +162,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	if (smb2_command == SMB2_TREE_CONNECT || smb2_command == SMB2_IOCTL)
 		return 0;
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (tcon->tidStatus == CifsExiting) {
 		/*
 		 * only tree disconnect, open, and write,
@@ -171,11 +172,13 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		if ((smb2_command != SMB2_WRITE) &&
 		   (smb2_command != SMB2_CREATE) &&
 		   (smb2_command != SMB2_TREE_DISCONNECT)) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			cifs_dbg(FYI, "can not send cmd %d while umounting\n",
 				 smb2_command);
 			return -ENODEV;
 		}
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 	if ((!tcon->ses) || (tcon->ses->status == CifsExiting) ||
 	    (!tcon->ses->server) || !server)
 		return -EIO;
@@ -214,8 +217,12 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		}
 
 		/* are we still trying to reconnect? */
-		if (server->tcpStatus != CifsNeedReconnect)
+		spin_lock(&cifs_tcp_ses_lock);
+		if (server->tcpStatus != CifsNeedReconnect) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			break;
+		}
+		spin_unlock(&cifs_tcp_ses_lock);
 
 		if (retries && --retries)
 			continue;
@@ -255,11 +262,14 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	 * and the server never sends an answer the socket will be closed
 	 * and tcpStatus set to reconnect.
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedReconnect) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		rc = -EHOSTDOWN;
 		mutex_unlock(&ses->session_mutex);
 		goto out;
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	/*
 	 * need to prevent multiple threads trying to simultaneously
@@ -1386,9 +1396,9 @@ SMB2_sess_establish_session(struct SMB2_sess_data *sess_data)
 	spin_unlock(&ses->chan_lock);
 
 	/* Even if one channel is active, session is in good state */
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	ses->status = CifsGood;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	return rc;
 }
@@ -1917,7 +1927,9 @@ SMB2_tcon(const unsigned int xid, struct cifs_ses *ses, const char *tree,
 	tcon->share_flags = le32_to_cpu(rsp->ShareFlags);
 	tcon->capabilities = rsp->Capabilities; /* we keep caps little endian */
 	tcon->maximal_access = le32_to_cpu(rsp->MaximalAccess);
+	spin_lock(&cifs_tcp_ses_lock);
 	tcon->tidStatus = CifsGood;
+	spin_unlock(&cifs_tcp_ses_lock);
 	tcon->need_reconnect = false;
 	tcon->tid = le32_to_cpu(rsp->hdr.Id.SyncId.TreeId);
 	strlcpy(tcon->treeName, tree, sizeof(tcon->treeName));
@@ -3854,11 +3866,14 @@ SMB2_echo(struct TCP_Server_Info *server)
 
 	cifs_dbg(FYI, "In echo request\n");
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedNegotiate) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		/* No need to send echo on newly established connections */
 		mod_delayed_work(cifsiod_wq, &server->reconnect, 0);
 		return rc;
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	rc = smb2_plain_req_init(SMB2_ECHO, NULL, server,
 				 (void **)&req, &total_len);
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index 112adf153807..b70a49b4edc0 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -634,8 +634,12 @@ smb2_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 
 	if (!is_signed)
 		return 0;
-	if (server->tcpStatus == CifsNeedNegotiate)
+	spin_lock(&cifs_tcp_ses_lock);
+	if (server->tcpStatus == CifsNeedNegotiate) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return 0;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 	if (!is_binding && !server->session_estab) {
 		strncpy(shdr->Signature, "BSRSPYL", 8);
 		return 0;
@@ -751,30 +755,41 @@ static int
 smb2_get_mid_entry(struct cifs_ses *ses, struct TCP_Server_Info *server,
 		   struct smb2_hdr *shdr, struct mid_q_entry **mid)
 {
-	if (server->tcpStatus == CifsExiting)
+	spin_lock(&cifs_tcp_ses_lock);
+	if (server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return -ENOENT;
+	}
 
 	if (server->tcpStatus == CifsNeedReconnect) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");
 		return -EAGAIN;
 	}
 
 	if (server->tcpStatus == CifsNeedNegotiate &&
-	   shdr->Command != SMB2_NEGOTIATE)
+	   shdr->Command != SMB2_NEGOTIATE) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return -EAGAIN;
+	}
 
 	if (ses->status == CifsNew) {
 		if ((shdr->Command != SMB2_SESSION_SETUP) &&
-		    (shdr->Command != SMB2_NEGOTIATE))
+		    (shdr->Command != SMB2_NEGOTIATE)) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			return -EAGAIN;
+		}
 		/* else ok - we are setting up session */
 	}
 
 	if (ses->status == CifsExiting) {
-		if (shdr->Command != SMB2_LOGOFF)
+		if (shdr->Command != SMB2_LOGOFF) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			return -EAGAIN;
+		}
 		/* else ok - we are shutting down the session */
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	*mid = smb2_mid_entry_alloc(shdr, server);
 	if (*mid == NULL)
@@ -847,9 +862,13 @@ smb2_setup_async_request(struct TCP_Server_Info *server, struct smb_rqst *rqst)
 			(struct smb2_hdr *)rqst->rq_iov[0].iov_base;
 	struct mid_q_entry *mid;
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedNegotiate &&
-	   shdr->Command != SMB2_NEGOTIATE)
+	   shdr->Command != SMB2_NEGOTIATE) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return ERR_PTR(-EAGAIN);
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	smb2_seq_num_into_buf(server, shdr);
 
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 1d81681d9b97..1c400ca26383 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -430,9 +430,9 @@ unmask:
 		 * be taken as the remainder of this one. We need to kill the
 		 * socket so the server throws away the partial SMB
 		 */
-		spin_lock(&GlobalMid_Lock);
+		spin_lock(&cifs_tcp_ses_lock);
 		server->tcpStatus = CifsNeedReconnect;
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&cifs_tcp_ses_lock);
 		trace_smb3_partial_send_reconnect(server->CurrentMid,
 						  server->conn_id, server->hostname);
 	}
@@ -578,10 +578,14 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
 				return -ERESTARTSYS;
 			spin_lock(&server->req_lock);
 		} else {
+			spin_unlock(&server->req_lock);
+
+			spin_lock(&cifs_tcp_ses_lock);
 			if (server->tcpStatus == CifsExiting) {
-				spin_unlock(&server->req_lock);
+				spin_unlock(&cifs_tcp_ses_lock);
 				return -ENOENT;
 			}
+			spin_unlock(&cifs_tcp_ses_lock);
 
 			/*
 			 * For normal commands, reserve the last MAX_COMPOUND
@@ -596,6 +600,7 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
 			 * for servers that are slow to hand out credits on
 			 * new sessions.
 			 */
+			spin_lock(&server->req_lock);
 			if (!optype && num_credits == 1 &&
 			    server->in_flight > 2 * MAX_COMPOUND &&
 			    *credits <= MAX_COMPOUND) {
@@ -723,28 +728,36 @@ cifs_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
 static int allocate_mid(struct cifs_ses *ses, struct smb_hdr *in_buf,
 			struct mid_q_entry **ppmidQ)
 {
+	spin_lock(&cifs_tcp_ses_lock);
 	if (ses->server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return -ENOENT;
 	}
 
 	if (ses->server->tcpStatus == CifsNeedReconnect) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");
 		return -EAGAIN;
 	}
 
 	if (ses->status == CifsNew) {
 		if ((in_buf->Command != SMB_COM_SESSION_SETUP_ANDX) &&
-			(in_buf->Command != SMB_COM_NEGOTIATE))
+			(in_buf->Command != SMB_COM_NEGOTIATE)) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			return -EAGAIN;
+		}
 		/* else ok - we are setting up session */
 	}
 
 	if (ses->status == CifsExiting) {
 		/* check if SMB session is bad because we are setting it up */
-		if (in_buf->Command != SMB_COM_LOGOFF_ANDX)
+		if (in_buf->Command != SMB_COM_LOGOFF_ANDX) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			return -EAGAIN;
+		}
 		/* else ok - we are shutting down session */
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	*ppmidQ = AllocMidQEntry(in_buf, ses->server);
 	if (*ppmidQ == NULL)
@@ -1085,8 +1098,12 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 		return -EIO;
 	}
 
-	if (server->tcpStatus == CifsExiting)
+	spin_lock(&cifs_tcp_ses_lock);
+	if (server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return -ENOENT;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	/*
 	 * Wait for all the requests to become available.
@@ -1189,11 +1206,17 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 	/*
 	 * Compounding is never used during session establish.
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if ((ses->status == CifsNew) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP)) {
+		spin_unlock(&cifs_tcp_ses_lock);
+
 		mutex_lock(&server->srv_mutex);
 		smb311_update_preauth_hash(ses, server, rqst[0].rq_iov, rqst[0].rq_nvec);
 		mutex_unlock(&server->srv_mutex);
+
+		spin_lock(&cifs_tcp_ses_lock);
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	for (i = 0; i < num_rqst; i++) {
 		rc = wait_for_response(server, midQ[i]);
@@ -1256,15 +1279,19 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 	/*
 	 * Compounding is never used during session establish.
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if ((ses->status == CifsNew) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP)) {
 		struct kvec iov = {
 			.iov_base = resp_iov[0].iov_base,
 			.iov_len = resp_iov[0].iov_len
 		};
+		spin_unlock(&cifs_tcp_ses_lock);
 		mutex_lock(&server->srv_mutex);
 		smb311_update_preauth_hash(ses, server, &iov, 1);
 		mutex_unlock(&server->srv_mutex);
+		spin_lock(&cifs_tcp_ses_lock);
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 out:
 	/*
@@ -1353,8 +1380,12 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
 		return -EIO;
 	}
 
-	if (server->tcpStatus == CifsExiting)
+	spin_lock(&cifs_tcp_ses_lock);
+	if (server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return -ENOENT;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	/* Ensure that we do not send more than 50 overlapping requests
 	   to the same server. We may make this configurable later or
@@ -1494,8 +1525,12 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
 		return -EIO;
 	}
 
-	if (server->tcpStatus == CifsExiting)
+	spin_lock(&cifs_tcp_ses_lock);
+	if (server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return -ENOENT;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	/* Ensure that we do not send more than 50 overlapping requests
 	   to the same server. We may make this configurable later or
@@ -1553,10 +1588,12 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
 		 (server->tcpStatus != CifsNew)));
 
 	/* Were we interrupted by a signal ? */
+	spin_lock(&cifs_tcp_ses_lock);
 	if ((rc == -ERESTARTSYS) &&
 		(midQ->mid_state == MID_REQUEST_SUBMITTED) &&
 		((server->tcpStatus == CifsGood) ||
 		 (server->tcpStatus == CifsNew))) {
+		spin_unlock(&cifs_tcp_ses_lock);
 
 		if (in_buf->Command == SMB_COM_TRANSACTION2) {
 			/* POSIX lock. We send a NT_CANCEL SMB to cause the
@@ -1595,7 +1632,9 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
 
 		/* We got the response - restart system call. */
 		rstart = 1;
+		spin_lock(&cifs_tcp_ses_lock);
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	rc = cifs_sync_mid_result(midQ, server);
 	if (rc != 0)