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Thu, 5 Mar 2020 14:35:37 +0000 (UTC) Received: from carbon (ovpn-200-32.brq.redhat.com [10.40.200.32]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3D8AD1001902; Thu, 5 Mar 2020 14:35:29 +0000 (UTC) Date: Thu, 5 Mar 2020 15:35:27 +0100 From: Jesper Dangaard Brouer To: Denis Kirjanov Cc: brouer@redhat.com, netdev@vger.kernel.org, jgross@suse.com, ilias.apalodimas@linaro.org Subject: Re: [PATCH net-next v2] xen-netfront: add basic XDP support Message-ID: <20200305153515.4ce0ecf4@carbon> In-Reply-To: <1583158874-2751-1-git-send-email-kda@linux-powerpc.org> References: <1583158874-2751-1-git-send-email-kda@linux-powerpc.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, 2 Mar 2020 17:21:14 +0300 Denis Kirjanov wrote: > diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c > index 482c6c8..db8a280 100644 > --- a/drivers/net/xen-netfront.c > +++ b/drivers/net/xen-netfront.c [...] > @@ -778,6 +782,40 @@ static int xennet_get_extras(struct netfront_queue *queue, > return err; > } > > +u32 xennet_run_xdp(struct netfront_queue *queue, struct page *pdata, > + struct xen_netif_rx_response *rx, struct bpf_prog *prog, > + struct xdp_buff *xdp) > +{ > + u32 len = rx->status; > + u32 act = XDP_PASS; > + > + xdp->data_hard_start = page_address(pdata); > + xdp->data = xdp->data_hard_start + XDP_PACKET_HEADROOM; > + xdp_set_data_meta_invalid(xdp); > + xdp->data_end = xdp->data + len; > + xdp->handle = 0; > + > + act = bpf_prog_run_xdp(prog, xdp); > + switch (act) { > + case XDP_PASS: > + case XDP_TX: > + case XDP_DROP: > + break; > + > + case XDP_ABORTED: > + trace_xdp_exception(queue->info->netdev, prog, act); > + break; > + > + default: > + bpf_warn_invalid_xdp_action(act); > + } > + > + if (act != XDP_PASS && act != XDP_TX) > + xdp->data_hard_start = NULL; > + > + return act; > +} > + > static int xennet_get_responses(struct netfront_queue *queue, > struct netfront_rx_info *rinfo, RING_IDX rp, > struct sk_buff_head *list) > @@ -792,6 +830,9 @@ static int xennet_get_responses(struct netfront_queue *queue, > int slots = 1; > int err = 0; > unsigned long ret; > + struct bpf_prog *xdp_prog; > + struct xdp_buff xdp; > + u32 verdict; > > if (rx->flags & XEN_NETRXF_extra_info) { > err = xennet_get_extras(queue, extras, rp); > @@ -827,6 +868,22 @@ static int xennet_get_responses(struct netfront_queue *queue, > > gnttab_release_grant_reference(&queue->gref_rx_head, ref); > > + rcu_read_lock(); > + xdp_prog = rcu_dereference(queue->xdp_prog); > + if (xdp_prog) { > + /* currently only a single page contains data */ > + WARN_ON_ONCE(skb_shinfo(skb)->nr_frags != 1); > + verdict = xennet_run_xdp(queue, > + skb_frag_page(&skb_shinfo(skb)->frags[0]), This looks really weird, skb_shinfo(skb)->frags[0], you already have an SKB and you are sending fragment-0 to the xennet_run_xdp() function. XDP meant to run before an SKB is allocated... > + rx, xdp_prog, &xdp); > + > + if (verdict != XDP_PASS && verdict != XDP_TX) { > + err = -EINVAL; > + goto next; > + } > + > + } > + rcu_read_unlock(); > __skb_queue_tail(list, skb); -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer