From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Laight Date: Mon, 7 Mar 2022 15:26:48 +0000 Subject: [PATCH 0/6] Remove usage of list iterator past the loop body In-Reply-To: <20220307150037.GD3293@kadam> References: <20220228110822.491923-1-jakobkoschel@gmail.com> <20220307150037.GD3293@kadam> Message-ID: List-Id: To: linux-aspeed@lists.ozlabs.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit From: Dan Carpenter > Sent: 07 March 2022 15:01 > > Updating this API is risky because some places rely on the old behavior > and not all of them have been updated. Here are some additional places > you might want to change. I really can't help thinking that trying to merge this patch is actually impossible. It affects far too many different parts of the tree. Since (I believe) this is a doubly linked list with forwards and backwards pointers that point to a 'node' (not that there is a nice comment to that effect in the header - and there are lots of ways to do linked lists) the 'head' pretty much has to be a 'node'. I'd write the following new defines (but I might be using the old names here): list_first(head, field) First item, NULL if empty. list_last(head, field) Last item NULL if empty. list_next(head, item, field) Item after 'item', NULL if last. list_prev(head, item. field) Item before 'item', NULL if first. You get (something like): #define list_first(head, field) \ head->next == &head ? NULL : list_item(head->next, field) (probably needs typeof(item) from somewhere). The iterator loop is then just: #define loop_iterate(item, head, field) \ for (item = list_first(head, field); item; \ item = list_next(head, item, field) I'm not sure, but making the 'head' be a structure that contains a single member that is a 'node' might help type checking. Then all the code that uses the current defines can slowly be moved over (probably a couple of releases) before the existing defines are deleted. That should simplify all the open-coded search loops that are just as likely to be buggy (possibly more so). David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)