* [PATCH] list.h: add list_for_each_struct_entry macro @ 2010-01-18 16:23 Jiri Pirko 2010-01-18 17:17 ` Ben Hutchings 0 siblings, 1 reply; 5+ messages in thread From: Jiri Pirko @ 2010-01-18 16:23 UTC (permalink / raw) To: linux-kernel; +Cc: bhutchings, davem, netdev When preparing to upcoming migration of mc_list (list of multicast MACs) to list_head, the need of traversing the list over one structure member appeared. I thought I'll do it locally but I decided that an intruduction the macro in list.h would be much clearer. Please kindly for a review. Jirka Signed-off-by: Jiri Pirko <jpirko@redhat.com> diff --git a/include/linux/list.h b/include/linux/list.h index 969f6e9..8350a94 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -420,6 +420,22 @@ static inline void list_splice_tail_init(struct list_head *list, pos = list_entry(pos->member.prev, typeof(*pos), member)) /** + * list_for_each_struct_entry - iterate over list of given type using + * the struct member. + * @pos: the type * to use as a loop cursor. + * @head: the head for your list. + * @type: the type of the struct. + * @posmember: the name ot the loop cursor within the struct. + * @member: the name of the list_struct within the struct. + */ +#define list_for_each_struct_entry(pos, head, type, posmember, member) \ + for (pos = list_entry((head)->next, type, member)->posmember; \ + prefetch(container_of(pos, type, posmember)->member.next), \ + &container_of(pos, type, posmember)->member != (head); \ + pos = list_entry(container_of(pos, type, posmember)->member.next, \ + type, member)->posmember) + +/** * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue() * @pos: the type * to use as a start point * @head: the head of the list ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] list.h: add list_for_each_struct_entry macro 2010-01-18 16:23 [PATCH] list.h: add list_for_each_struct_entry macro Jiri Pirko @ 2010-01-18 17:17 ` Ben Hutchings 2010-01-18 21:07 ` Jiri Pirko 0 siblings, 1 reply; 5+ messages in thread From: Ben Hutchings @ 2010-01-18 17:17 UTC (permalink / raw) To: Jiri Pirko; +Cc: linux-kernel, davem, netdev On Mon, 2010-01-18 at 17:23 +0100, Jiri Pirko wrote: > When preparing to upcoming migration of mc_list (list of multicast MACs) > to list_head, the need of traversing the list over one structure member > appeared. I thought I'll do it locally but I decided that an intruduction > the macro in list.h would be much clearer. Please kindly for a review. > > Jirka > > Signed-off-by: Jiri Pirko <jpirko@redhat.com> > > diff --git a/include/linux/list.h b/include/linux/list.h > index 969f6e9..8350a94 100644 > --- a/include/linux/list.h > +++ b/include/linux/list.h > @@ -420,6 +420,22 @@ static inline void list_splice_tail_init(struct list_head *list, > pos = list_entry(pos->member.prev, typeof(*pos), member)) > > /** > + * list_for_each_struct_entry - iterate over list of given type using > + * the struct member. > + * @pos: the type * to use as a loop cursor. > + * @head: the head for your list. > + * @type: the type of the struct. > + * @posmember: the name ot the loop cursor within the struct. > + * @member: the name of the list_struct within the struct. > + */ > +#define list_for_each_struct_entry(pos, head, type, posmember, member) \ > + for (pos = list_entry((head)->next, type, member)->posmember; \ Surely &list_entry(...)->posmember ? > + prefetch(container_of(pos, type, posmember)->member.next), \ > + &container_of(pos, type, posmember)->member != (head); \ It seems a bit dodgy to do this pointer arithmetic on a list node which might be the list head. > + pos = list_entry(container_of(pos, type, posmember)->member.next, \ > + type, member)->posmember) My version: #define list_for_each_struct_entry(pos, head, type, posmember, member) \ for (pos = list_empty(head) ? NULL : \ &list_first_entry(head, type, member)->posmember; \ prefetch(container_of(pos, type, posmember)->member.next), pos; \ pos = list_is_last(&container_of(pos, type, posmember)->member, \ head) ? NULL : \ &list_entry(container_of(pos, type, posmember)->member.next, \ type, member)->posmember) Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked. ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] list.h: add list_for_each_struct_entry macro 2010-01-18 17:17 ` Ben Hutchings @ 2010-01-18 21:07 ` Jiri Pirko 2010-01-18 21:14 ` Ben Hutchings 0 siblings, 1 reply; 5+ messages in thread From: Jiri Pirko @ 2010-01-18 21:07 UTC (permalink / raw) To: Ben Hutchings; +Cc: linux-kernel, davem, netdev Mon, Jan 18, 2010 at 06:17:13PM CET, bhutchings@solarflare.com wrote: >On Mon, 2010-01-18 at 17:23 +0100, Jiri Pirko wrote: >> When preparing to upcoming migration of mc_list (list of multicast MACs) >> to list_head, the need of traversing the list over one structure member >> appeared. I thought I'll do it locally but I decided that an intruduction >> the macro in list.h would be much clearer. Please kindly for a review. >> >> Jirka >> >> Signed-off-by: Jiri Pirko <jpirko@redhat.com> >> >> diff --git a/include/linux/list.h b/include/linux/list.h >> index 969f6e9..8350a94 100644 >> --- a/include/linux/list.h >> +++ b/include/linux/list.h >> @@ -420,6 +420,22 @@ static inline void list_splice_tail_init(struct list_head *list, >> pos = list_entry(pos->member.prev, typeof(*pos), member)) >> >> /** >> + * list_for_each_struct_entry - iterate over list of given type using >> + * the struct member. >> + * @pos: the type * to use as a loop cursor. >> + * @head: the head for your list. >> + * @type: the type of the struct. >> + * @posmember: the name ot the loop cursor within the struct. >> + * @member: the name of the list_struct within the struct. >> + */ >> +#define list_for_each_struct_entry(pos, head, type, posmember, member) \ >> + for (pos = list_entry((head)->next, type, member)->posmember; \ > >Surely &list_entry(...)->posmember ? Ugh, right, I tested this with char * so it worked well. Got i corrected now so I can repost. > >> + prefetch(container_of(pos, type, posmember)->member.next), \ >> + &container_of(pos, type, posmember)->member != (head); \ > >It seems a bit dodgy to do this pointer arithmetic on a list node which >might be the list head. Well I tried to be as much close to other traverse macros as it could be. > >> + pos = list_entry(container_of(pos, type, posmember)->member.next, \ >> + type, member)->posmember) > >My version: > >#define list_for_each_struct_entry(pos, head, type, posmember, member) \ > for (pos = list_empty(head) ? NULL : \ > &list_first_entry(head, type, member)->posmember; \ > prefetch(container_of(pos, type, posmember)->member.next), pos; \ > pos = list_is_last(&container_of(pos, type, posmember)->member, \ > head) ? NULL : \ > &list_entry(container_of(pos, type, posmember)->member.next, \ > type, member)->posmember) > At the first glance, this would take even more cputime for lists longer than 2 or so, wouldn't it? Jirka >Ben. > >-- >Ben Hutchings, Senior Software Engineer, Solarflare Communications >Not speaking for my employer; that's the marketing department's job. >They asked us to note that Solarflare product names are trademarked. > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] list.h: add list_for_each_struct_entry macro 2010-01-18 21:07 ` Jiri Pirko @ 2010-01-18 21:14 ` Ben Hutchings 2010-01-18 21:30 ` Jiri Pirko 0 siblings, 1 reply; 5+ messages in thread From: Ben Hutchings @ 2010-01-18 21:14 UTC (permalink / raw) To: Jiri Pirko; +Cc: linux-kernel, davem, netdev On Mon, 2010-01-18 at 22:07 +0100, Jiri Pirko wrote: > Mon, Jan 18, 2010 at 06:17:13PM CET, bhutchings@solarflare.com wrote: [...] > >#define list_for_each_struct_entry(pos, head, type, posmember, member) \ > > for (pos = list_empty(head) ? NULL : \ > > &list_first_entry(head, type, member)->posmember; \ > > prefetch(container_of(pos, type, posmember)->member.next), pos; \ > > pos = list_is_last(&container_of(pos, type, posmember)->member, \ > > head) ? NULL : \ > > &list_entry(container_of(pos, type, posmember)->member.next, \ > > type, member)->posmember) > > > > At the first glance, this would take even more cputime for lists longer > than 2 or so, wouldn't it? If you're concerned about speed, measure it, don't guess. Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked. ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] list.h: add list_for_each_struct_entry macro 2010-01-18 21:14 ` Ben Hutchings @ 2010-01-18 21:30 ` Jiri Pirko 0 siblings, 0 replies; 5+ messages in thread From: Jiri Pirko @ 2010-01-18 21:30 UTC (permalink / raw) To: Ben Hutchings; +Cc: linux-kernel, davem, netdev Mon, Jan 18, 2010 at 10:14:18PM CET, bhutchings@solarflare.com wrote: >On Mon, 2010-01-18 at 22:07 +0100, Jiri Pirko wrote: >> Mon, Jan 18, 2010 at 06:17:13PM CET, bhutchings@solarflare.com wrote: >[...] >> >#define list_for_each_struct_entry(pos, head, type, posmember, member) \ >> > for (pos = list_empty(head) ? NULL : \ >> > &list_first_entry(head, type, member)->posmember; \ >> > prefetch(container_of(pos, type, posmember)->member.next), pos; \ >> > pos = list_is_last(&container_of(pos, type, posmember)->member, \ >> > head) ? NULL : \ >> > &list_entry(container_of(pos, type, posmember)->member.next, \ >> > type, member)->posmember) >> > >> >> At the first glance, this would take even more cputime for lists longer >> than 2 or so, wouldn't it? > >If you're concerned about speed, measure it, don't guess. Well I just see extra code "list_is_last(&container_of(pos, type, posmember)->member, head)" to be done in each iteration. Also I do not see additional value in doing this. (Unlike in checking list_empty(head)). Anyway, if you want to use this optimization, I guess more code in list.h could use this. Jirka > >Ben. > >-- >Ben Hutchings, Senior Software Engineer, Solarflare Communications >Not speaking for my employer; that's the marketing department's job. >They asked us to note that Solarflare product names are trademarked. > ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2010-01-18 21:30 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2010-01-18 16:23 [PATCH] list.h: add list_for_each_struct_entry macro Jiri Pirko 2010-01-18 17:17 ` Ben Hutchings 2010-01-18 21:07 ` Jiri Pirko 2010-01-18 21:14 ` Ben Hutchings 2010-01-18 21:30 ` Jiri Pirko
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