Do not kill cifsd thread until last smb session on tcp session is

SMBulogged off.  Fixes umounting bug (pointed out by Nick Millington)
when multiple mounts with different userids are mounted to the same
server from the client.  

Signed-off-by: Steve French (sfrench@us.ibm.com)

fs/cifs/AUTHORS

@@ -31,7 +31,7 @@ Thanks to those in the community who have submitted detailed bug reports
 and debug of problems they have found:  Jochen Dolze, David Blaine,
 Rene Scharfe, Martin Josefsson, Alexander Wild, Anthony Liguori,
 Lars Muller, Urban Widmark, Massimiliano Ferrero, Howard Owen,
-Olaf Kirch, Kieron Briggs and others. 
+Olaf Kirch, Kieron Briggs, Nick Millington and others. 
 
 And thanks to the IBM LTC and Power test teams and SuSE testers for
 finding multiple bugs during excellent stress test runs.

fs/cifs/CHANGES

@@ -3,6 +3,9 @@ Version 1.19
 Fix /proc/fs/cifs/Stats and DebugData display to handle larger
 amounts of return data. Properly limit requests to MAX_REQ (50
 is the usual maximum active multiplex SMB/CIFS requests per server).
+Do not kill cifsd (and thus hurt the other SMB session) when more than one
+session to the same server (but with different userids) exists and one
+of the two user's smb sessions is being removed while leaving the other.
 
 
 Version 1.18

fs/cifs/cifssmb.c

@@ -387,6 +387,7 @@ CIFSSMBLogoff(const int xid, struct cifsSesInfo *ses)
 			spin_lock(&GlobalMid_Lock);
 			ses->server->tcpStatus = CifsExiting;
 			spin_unlock(&GlobalMid_Lock);
+			rc = -ESHUTDOWN;
 		}
 	}
 	if (pSMB)

fs/cifs/connect.c

@@ -453,7 +453,7 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
 		spin_unlock(&GlobalMid_Lock);
 		read_unlock(&GlobalSMBSeslock);
 		set_current_state(TASK_INTERRUPTIBLE);
-		/* 1/8th of sec should be more than enough time for them to exit */
+		/* 1/8th of sec is more than enough time for them to exit */
 		schedule_timeout(HZ/8); 
 	}
 
@@ -468,7 +468,8 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
 	}
 	kfree(server);
 
-	cFYI(1, ("About to exit from demultiplex thread"));
+	set_current_state(TASK_INTERRUPTIBLE);
+	schedule_timeout(HZ/4);
 	return 0;
 }
 
@@ -2769,6 +2770,7 @@ cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb)
 	int rc = 0;
 	int xid;
 	struct cifsSesInfo *ses = NULL;
+	struct task_struct *cifsd_task;
 
 	xid = GetXid();
 
@@ -2781,19 +2783,25 @@ cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb)
 		}
 		tconInfoFree(cifs_sb->tcon);
 		if ((ses) && (ses->server)) {
+			/* save off task so we do not refer to ses later */
+			cifsd_task = ses->server->tsk;
 			cFYI(1, ("About to do SMBLogoff "));
 			rc = CIFSSMBLogoff(xid, ses);
 			if (rc == -EBUSY) {
 				FreeXid(xid);
 				return 0;
-			}
- 
-			set_current_state(TASK_INTERRUPTIBLE);
-			schedule_timeout(HZ / 4);	/* give captive thread time to exit */
-			if((ses->server) && (ses->server->ssocket)) {            
-				cFYI(1,("Waking up socket by sending it signal "));
-				send_sig(SIGKILL,ses->server->tsk,1);
-			}
+			} else if (rc == -ESHUTDOWN) {
+			/* should we add wake_up_all(&server->request_q); 
+			   and add a check in  the check inFlight loop
+			   for the session ending */
+				set_current_state(TASK_INTERRUPTIBLE);
+			/* give captive thread time to exit */
+				schedule_timeout(HZ / 4);
+				cFYI(1,("Waking up socket by sending it signal"));
+				send_sig(SIGKILL,cifsd_task,1);
+				rc = 0;
+			} /* else - we have an smb session
+				left on this socket do not kill cifsd */
 		} else
 			cFYI(1, ("No session or bad tcon"));
 	}