cifs: no need to mark smb_ses_list as cifs_demultiplex_thread is exiting

The TCP_Server_Info is refcounted and every SMB session holds a
reference to it. Thus, smb_ses_list is always going to be empty when
cifsd is coming down. This is dead code.
Reviewed-by: Suresh Jayaraman <sjayaraman@suse.de>
Reviewed-by: Pavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/connect.c

@@ -346,7 +346,6 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
 	struct kvec iov;
 	struct socket *csocket = server->ssocket;
 	struct list_head *tmp;
-	struct cifsSesInfo *ses;
 	struct task_struct *task_to_wake = NULL;
 	struct mid_q_entry *mid_entry;
 	char temp;
@@ -677,31 +676,7 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
 	if (smallbuf) /* no sense logging a debug message if NULL */
 		cifs_small_buf_release(smallbuf);
 
-	/*
-	 * BB: we shouldn't have to do any of this. It shouldn't be
-	 * possible to exit from the thread with active SMB sessions
-	 */
-	spin_lock(&cifs_tcp_ses_lock);
-	if (list_empty(&server->pending_mid_q)) {
-		/* loop through server session structures attached to this and
-		    mark them dead */
-		list_for_each(tmp, &server->smb_ses_list) {
-			ses = list_entry(tmp, struct cifsSesInfo,
-					 smb_ses_list);
-			ses->status = CifsExiting;
-			ses->server = NULL;
-		}
-		spin_unlock(&cifs_tcp_ses_lock);
-	} else {
-		/* although we can not zero the server struct pointer yet,
-		since there are active requests which may depnd on them,
-		mark the corresponding SMB sessions as exiting too */
-		list_for_each(tmp, &server->smb_ses_list) {
-			ses = list_entry(tmp, struct cifsSesInfo,
-					 smb_ses_list);
-			ses->status = CifsExiting;
-		}
-
+	if (!list_empty(&server->pending_mid_q)) {
 		spin_lock(&GlobalMid_Lock);
 		list_for_each(tmp, &server->pending_mid_q) {
 			mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
@@ -714,7 +689,6 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
 			}
 		}
 		spin_unlock(&GlobalMid_Lock);
-		spin_unlock(&cifs_tcp_ses_lock);
 		/* 1/8th of sec is more than enough time for them to exit */
 		msleep(125);
 	}
@@ -732,18 +706,6 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
 		coming home not much else we can do but free the memory */
 	}
 
-	/* last chance to mark ses pointers invalid
-	if there are any pointing to this (e.g
-	if a crazy root user tried to kill cifsd
-	kernel thread explicitly this might happen) */
-	/* BB: This shouldn't be necessary, see above */
-	spin_lock(&cifs_tcp_ses_lock);
-	list_for_each(tmp, &server->smb_ses_list) {
-		ses = list_entry(tmp, struct cifsSesInfo, smb_ses_list);
-		ses->server = NULL;
-	}
-	spin_unlock(&cifs_tcp_ses_lock);
-
 	kfree(server->hostname);
 	task_to_wake = xchg(&server->tsk, NULL);
 	kfree(server);