Re: [PATCH v15 2/9] namei: LOOKUP_NO_MAGICLINKS: block magic-link resolution

On Tue, Nov 05, 2019 at 08:05:46PM +1100, Aleksa Sarai wrote:

@@ -1078,6 +1079,10 @@ const char *get_link(struct nameidata *nd) } else { res = get(dentry, inode, &last->done); }

• if (nd->flags & LOOKUP_MAGICLINK_JUMPED) {
  

• 	if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS))
  

• 		return ERR_PTR(-ELOOP);
  

• }
  

Minor nit - the first check probably wants unlikely() more than the second one; it's probably noise anyway, but most of the symlinks traversed are not going to be procfs ones, so you get test + branch taken most of the time.

OTOH, that just might compile into fetch nd->flags and with LOOKUP_MAGICLINK_JUMPED | LOOKUP_NO_MAGICLINKS compare with the same constant unlikely branch when equal

Anyway, that's no more than a minor nit and can be dealt with later (if at all)