cifs: avoid NULL pointer dereference in dbg call

cifs_server_dbg() implies server to be non-NULL so
move call under condition to avoid NULL pointer dereference.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: e79b033 ("cifs: ignore cached share root handle closing errors")
Cc: stable@vger.kernel.org
Signed-off-by: Alexandra Diupina <adiupina@astralinux.ru>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: Alexandra Diupina

fs/smb/client/smb2misc.c

@@ -816,11 +816,12 @@ smb2_handle_cancelled_close(struct cifs_tcon *tcon, __u64 persistent_fid,
 		WARN_ONCE(tcon->tc_count < 0, "tcon refcount is negative");
 		spin_unlock(&cifs_tcp_ses_lock);
 
-		if (tcon->ses)
+		if (tcon->ses) {
 			server = tcon->ses->server;
-
-		cifs_server_dbg(FYI, "tid=0x%x: tcon is closing, skipping async close retry of fid %llu %llu\n",
-				tcon->tid, persistent_fid, volatile_fid);
+			cifs_server_dbg(FYI,
+					"tid=0x%x: tcon is closing, skipping async close retry of fid %llu %llu\n",
+					tcon->tid, persistent_fid, volatile_fid);
+		}
 
 		return 0;
 	}