Messages in this thread | | | From | Jesper Dangaard Brouer <> | Date | Wed, 15 Mar 2023 15:55:44 +0100 | Subject | Re: [PATCH bpf-next v3 3/4] xdp: recycle Page Pool backed skbs built from XDP frames |
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On 13/03/2023 22.55, Alexander Lobakin wrote: > __xdp_build_skb_from_frame() state(d): > > /* Until page_pool get SKB return path, release DMA here */ > > Page Pool got skb pages recycling in April 2021, but missed this > function. > > xdp_release_frame() is relevant only for Page Pool backed frames and it > detaches the page from the corresponding page_pool in order to make it > freeable via page_frag_free(). It can instead just mark the output skb > as eligible for recycling if the frame is backed by a pp. No change for > other memory model types (the same condition check as before). > cpumap redirect and veth on Page Pool drivers now become zero-alloc (or > almost). > > Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> > --- > net/core/xdp.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/core/xdp.c b/net/core/xdp.c > index 8c92fc553317..a2237cfca8e9 100644 > --- a/net/core/xdp.c > +++ b/net/core/xdp.c > @@ -658,8 +658,8 @@ struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf, > * - RX ring dev queue index (skb_record_rx_queue) > */ > > - /* Until page_pool get SKB return path, release DMA here */ > - xdp_release_frame(xdpf); > + if (xdpf->mem.type == MEM_TYPE_PAGE_POOL) > + skb_mark_for_recycle(skb);
I hope this is safe ;-) ... Meaning hopefully drivers does the correct thing when XDP_REDIRECT'ing page_pool pages.
Looking for drivers doing weird refcnt tricks and XDP_REDIRECT'ing, I noticed the driver aquantia/atlantic (in aq_get_rxpages_xdp), but I now see this is not using page_pool, so it should be affected by this (but I worry if atlantic driver have a potential race condition for its refcnt scheme).
> > /* Allow SKB to reuse area used by xdp_frame */ > xdp_scrub_frame(xdpf);
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