smb: client: fix potential race in cifs_put_tcon()

smb: client: fix potential race in cifs_put_tcon()

[ Upstream commit c32b624fa4f7ca5a2ff217a0b1b2f1352bb4ec11 ]

dfs_cache_refresh() delayed worker could race with cifs_put_tcon(), so
make sure to call list_replace_init() on @tcon->dfs_ses_list after
kworker is cancelled or finished.

Fixes: 4f42a8b54b5c ("smb: client: fix DFS interlink failover")
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>