fs/proc/proc_sysctl.c: remove redundant link check in proc_sys_link_fill_cache()

proc_sys_link_fill_cache() does not need to check whether we're called
for a link - it's already done by scan().

Link: http://lkml.kernel.org/r/20180228013506.4915-2-danilokrummrich@dk-develop.deSigned-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Luis R . Rodriguez" <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/proc_sysctl.c

@@ -712,12 +712,9 @@ static bool proc_sys_link_fill_cache(struct file *file,
 	if (IS_ERR(head))
 		return false;
 
-	if (S_ISLNK(table->mode)) {
 	/* It is not an error if we can not follow the link ignore it */
-		int err = sysctl_follow_link(&head, &table);
-		if (err)
+	if (sysctl_follow_link(&head, &table))
 		goto out;
-	}
 
 	ret = proc_sys_fill_cache(file, ctx, head, table);
 out: