pktcdvd: debugfs functions return NULL on error

My static checker complains correctly that this is potential NULL
dereference because debugfs functions return NULL on error.  They return
an ERR_PTR if they are configured out.

We don't need to check for ERR_PTR because if debugfs is stubbed out the
dummy functions won't complain about that.  We don't need to check the
values before calling debugfs_remove() because that accepts ERR_PTRs and
NULL pointers.

We don't need to set pkt->dfs_f_info to NULL in pkt_debugfs_dev_new()
because it was initialized with kzalloc() so I have removed that.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/block/pktcdvd.c

@@ -473,45 +473,31 @@ static void pkt_debugfs_dev_new(struct pktcdvd_device *pd)
 {
 	if (!pkt_debugfs_root)
 		return;
-	pd->dfs_f_info = NULL;
 	pd->dfs_d_root = debugfs_create_dir(pd->name, pkt_debugfs_root);
-	if (IS_ERR(pd->dfs_d_root)) {
-		pd->dfs_d_root = NULL;
+	if (!pd->dfs_d_root)
 		return;
-	}
+
 	pd->dfs_f_info = debugfs_create_file("info", S_IRUGO,
 				pd->dfs_d_root, pd, &debug_fops);
-	if (IS_ERR(pd->dfs_f_info)) {
-		pd->dfs_f_info = NULL;
-		return;
-	}
 }
 
 static void pkt_debugfs_dev_remove(struct pktcdvd_device *pd)
 {
 	if (!pkt_debugfs_root)
 		return;
-	if (pd->dfs_f_info)
 	debugfs_remove(pd->dfs_f_info);
-	pd->dfs_f_info = NULL;
-	if (pd->dfs_d_root)
 	debugfs_remove(pd->dfs_d_root);
+	pd->dfs_f_info = NULL;
 	pd->dfs_d_root = NULL;
 }
 
 static void pkt_debugfs_init(void)
 {
 	pkt_debugfs_root = debugfs_create_dir(DRIVER_NAME, NULL);
-	if (IS_ERR(pkt_debugfs_root)) {
-		pkt_debugfs_root = NULL;
-		return;
-	}
 }
 
 static void pkt_debugfs_cleanup(void)
 {
-	if (!pkt_debugfs_root)
-		return;
 	debugfs_remove(pkt_debugfs_root);
 	pkt_debugfs_root = NULL;
 }