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>

1 files changed, 25 insertions, 6 deletions

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);