Messages in this thread | | | Date | Mon, 11 Feb 2013 11:37:15 -0500 | From | "J. Bruce Fields" <> | Subject | Re: [PATCH 0/2] NFSD: fix races in service per-net resources allocation |
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On Mon, Feb 11, 2013 at 10:18:18AM +0400, Stanislav Kinsbursky wrote: > This one looks a bit complicated and confusing to me. Probably because > I'm not that familiar with service transports processing logic. So, > as I can see, we now try to run over all per-net pool-assigned > transports, remove them from "ready" queue and delete one by one. > Then we try to enqueue all temporary sockets. But where in enqueueing > of permanent sockets? I.e. how does they be destroyed with this patch? > Then we once again try to run over all per-net pool-assigned > transports, remove them from "ready" queue and delete one by one. Why > twice? I.e. why not just lose them, then enqueue them and > svc_clean_up_xprts()?
I think you missed the first svc_close_list?:
> > svc_close_list(serv, &serv->sv_permsocks, net); > >+ svc_clean_up_xprts(serv, net); > >+ svc_close_list(serv, &serv->sv_tempsocks, net); > >+ svc_clean_up_xprts(serv, net);
The idea is that before we'd like to close all the listeners first, so that they aren't busy creating more tempsocks while we're trying to close them.
I overlooked a race, though: if another thread was already handling an accept for one of the listeners then it might not get closed by that first svc_clean_up_xprts.
I guess we could do something like:
delay = 0;
again: numclosed = svc_close_list(serv, &serv->sv_permsocks, net); numclosed += svc_close_list(serv, &serv->sv_tempsocks, net); if (numclosed) { svc_clean_up_xprts(serv, net); msleep(delay++); goto again; }
Seems a little cheesy, but if we don't care much about shutdown performance in a rare corner case, maybe it's the simplest way out?
--b
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