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Date: Wed, 28 Oct 2020 12:59:51 +0200 From: Ilias Apalodimas <ilias.apalodimas@...aro.org> To: Lorenzo Bianconi <lorenzo@...nel.org> Cc: netdev@...r.kernel.org, bpf@...r.kernel.org, lorenzo.bianconi@...hat.com, davem@...emloft.net, kuba@...nel.org, brouer@...hat.com Subject: Re: [PATCH net-next 1/4] net: xdp: introduce bulking for xdp tx return path On Wed, Oct 28, 2020 at 11:23:04AM +0100, Lorenzo Bianconi wrote: > > Hi Lorenzo, > > Hi Ilias, > > thx for the review. > > > > > On Tue, Oct 27, 2020 at 08:04:07PM +0100, Lorenzo Bianconi wrote: > > [...] > > > > +void xdp_return_frame_bulk(struct xdp_frame *xdpf, > > > + struct xdp_frame_bulk *bq) > > > +{ > > > + struct xdp_mem_info *mem = &xdpf->mem; > > > + struct xdp_mem_allocator *xa, *nxa; > > > + > > > + if (mem->type != MEM_TYPE_PAGE_POOL) { > > > + __xdp_return(xdpf->data, &xdpf->mem, false); > > > + return; > > > + } > > > + > > > + rcu_read_lock(); > > > + > > > + xa = bq->xa; > > > + if (unlikely(!xa || mem->id != xa->mem.id)) { > > > > Why is this marked as unlikely? The driver passes it as NULL. Should unlikely be > > checked on both xa and the comparison? > > xa is NULL only for the first xdp_frame in the burst while it is set for > subsequent ones. Do you think it is better to remove it? Ah correct, missed the general context of the driver this runs in. > > > > > > + nxa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params); > > > > Is there a chance nxa can be NULL? > > I do not think so since the page_pool is not destroyed while there are > in-flight pages, right? I think so but I am not 100% sure. I'll apply the patch and have a closer look Cheers /Ilias
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