On Wed, Jun 19, 2019 at 08:34:52AM -0300, Jason Gunthorpe wrote: > /** > * list_empty_careful - tests whether a list is empty and not being modified > * @head: the list to test > * > * Description: > * tests whether a list is empty _and_ checks that no other CPU might be > * in the process of modifying either member (next or prev) > * > * NOTE: using list_empty_careful() without synchronization > * can only be safe if the only activity that can happen > * to the list entry is list_del_init(). Eg. it cannot be used > * if another CPU could re-list_add() it. > */ > > Agree it doesn't seem obvious why this is relevant when checking the > list head.. > > Maybe the comment is a bit misleading? >From looking at the commit log in the history tree list_empty_careful was initially added by Linus, and then mingo added that comment later. I don't see how list_del_init would change anything here, so I suspect list_del_init was just used as a short hand for list_del or list_del_init.
