[CIFS] Fix oops when slow oplock process races with unmount

If a tcon is being freed in call tconInfoFree, clean up any entries that may
exist in global oplock queue as the tcon structure hanging off of those entries
will be invalid and can cause oops while accesing any elements in the
tcon structure.

Signed-off-by: Shirish Pargaonkar <shirishp@us.ibm.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 8dbfa97..e171067 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3527,6 +3527,7 @@
 			FreeXid(xid);
 			return 0;
 		}
+		DeleteTconOplockQEntries(cifs_sb->tcon);
 		tconInfoFree(cifs_sb->tcon);
 		if ((ses) && (ses->server)) {
 			/* save off task so we do not refer to ses later */