On Tue, Mar 19, 2013 at 8:50 PM, Victor Buciuc <victor.buciuc@xxxxxxxxx> wrote: > On Tue, Mar 19, 2013 at 5:34 PM, Arlie Stephens <arlie@xxxxxxxxxxxx> wrote: >> Hi Folks, >> >> I'm trying to understand the linux way of doing things, so as to write >> code which will be easier for experienced linux kernel people to >> understand. Yesterday I wound up in a 3 engineer discussion about >> something conceptually simple, that just didn't want to be done with >> the tools at hand; what's worse, the only ways I could see to do it >> were (a) do my own linked lists or (b) write some routines that relied >> kind of heavily on the never-mentioned-in-documentation details of >> linux/list.h I'll probably go with option (b), as that seems less >> insane, but I thought I might as well ask here as well. >> >> Here's the problem. I have a collection of resources. Call them >> A,B,C,D but note that resources get added at run time, so I don't know >> how many to expect. I want to go through them in a round robin >> fashion, but not all at once. On the first request, I use A. On a >> later request I use B, etc. This seems to me to map naturally to a >> circular linked list, with a "cursor" - a pointer of some kind to the >> next one I want to use. To make my specific situation more >> interesting, I actually have multiple cursors - that may or may not >> happen to point to the same node at any given time, but usually will >> not. >> >> This is where I wish I could draw pictures in ascii emails ;-) >> Perhaps the following will come through halfway sanely: >> >> C1 C2 C3 >> V / V >> A<->B<->C-<->D >> ^------------^ >> > > Hi, > > Another option might be to not iterate through the list but to simply > move the element you're processing to the end of the list using > list_rotate_left[1]. > And you could use list_next_entry[2] to get the next entry after the > head. You'll > have to check that the list is empty, tough. > > This would cost you some extra operations but you'll use the existing interface. > > [1] http://lxr.linux.no/linux+v3.8.3/include/linux/list.h#L214 > [2] http://lxr.linux.no/linux+v3.8.3/include/linux/list.h#L361 > > Regards, > Victor Buciuc. Forgot to send to the list. Regards, Victor Buciuc. _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
