370076d932
I got the following oops during interface ifup. Unfortunately its not easily reproducable so I cant say for sure that my fix fixes this problem, but I am confident and I think its correct anyway: <2>kernel BUG at /space/kvm/drivers/virtio/virtio_ring.c:234! <4>illegal operation: 0001 [#1] PREEMPT SMP <4>Modules linked in: <4>CPU: 0 Not tainted 2.6.24zlive-guest-07293-gf1ca151-dirty #91 <4>Process swapper (pid: 0, task: 0000000000800938, ksp: 000000000084ddb8) <4>Krnl PSW : 0404300180000000 0000000000466374 (vring_disable_cb+0x30/0x34) <4> R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:0 CC:3 PM:0 EA:3 <4>Krnl GPRS: 0000000000000001 0000000000000001 0000000010003800 0000000000466344 <4> 000000000e980900 00000000008848b0 000000000084e748 0000000000000000 <4> 000000000087b300 0000000000001237 0000000000001237 000000000f85bdd8 <4> 000000000e980920 00000000001137c0 0000000000464754 000000000f85bdd8 <4>Krnl Code: 0000000000466368: e3b0b0700004 lg %r11,112(%r11) <4> 000000000046636e: 07fe bcr 15,%r14 <4> 0000000000466370: a7f40001 brc 15,466372 <4> >0000000000466374: a7f4fff6 brc 15,466360 <4> 0000000000466378: eb7ff0500024 stmg %r7,%r15,80(%r15) <4> 000000000046637e: a7f13e00 tmll %r15,15872 <4> 0000000000466382: b90400ef lgr %r14,%r15 <4> 0000000000466386: a7840001 brc 8,466388 <4>Call Trace: <4>([<000201500f85c000>] 0x201500f85c000) <4> [<0000000000466556>] vring_interrupt+0x72/0x88 <4> [<00000000004801a0>] kvm_extint_handler+0x34/0x44 <4> [<000000000010d22c>] do_extint+0xbc/0xf8 <4> [<0000000000113f98>] ext_no_vtime+0x16/0x1a <4> [<000000000010a182>] cpu_idle+0x216/0x238 <4>([<000000000010a162>] cpu_idle+0x1f6/0x238) <4> [<0000000000568656>] rest_init+0xaa/0xb8 <4> [<000000000084ee2c>] start_kernel+0x3fc/0x490 <4> [<0000000000100020>] _stext+0x20/0x80 <4> <4> <0>Kernel panic - not syncing: Fatal exception in interrupt <4> After looking at the code and the dump I think the following scenario happened: Ifup was running on cpu2 and the interrupt arrived on cpu0. Now virtnet_open on cpu 2 managed to execute napi_enable and disable_cb but did not execute rx_schedule. Meanwhile on cpu 0 skb_recv_done was called by vring_interrupt, executed netif_rx_schedule_prep, which succeeded and therefore called disable_cb. This triggered the BUG_ON, as interrupts were already disabled by cpu 2. I think the proper solution is to make the call to disable_cb depend on the atomic update of NAPI_STATE_SCHED by using netif_rx_schedule_prep in the same way as skb_recv_done. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Jeff Garzik <jeff@garzik.org>
464 lines
12 KiB
C
464 lines
12 KiB
C
/* A simple network driver using virtio.
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*
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* Copyright 2007 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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//#define DEBUG
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#include <linux/netdevice.h>
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#include <linux/etherdevice.h>
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#include <linux/module.h>
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#include <linux/virtio.h>
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#include <linux/virtio_net.h>
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#include <linux/scatterlist.h>
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static int napi_weight = 128;
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module_param(napi_weight, int, 0444);
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static int csum = 1, gso = 1;
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module_param(csum, bool, 0444);
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module_param(gso, bool, 0444);
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/* FIXME: MTU in config. */
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#define MAX_PACKET_LEN (ETH_HLEN+ETH_DATA_LEN)
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struct virtnet_info
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{
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struct virtio_device *vdev;
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struct virtqueue *rvq, *svq;
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struct net_device *dev;
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struct napi_struct napi;
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/* Number of input buffers, and max we've ever had. */
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unsigned int num, max;
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/* Receive & send queues. */
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struct sk_buff_head recv;
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struct sk_buff_head send;
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};
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static inline struct virtio_net_hdr *skb_vnet_hdr(struct sk_buff *skb)
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{
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return (struct virtio_net_hdr *)skb->cb;
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}
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static inline void vnet_hdr_to_sg(struct scatterlist *sg, struct sk_buff *skb)
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{
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sg_init_one(sg, skb_vnet_hdr(skb), sizeof(struct virtio_net_hdr));
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}
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static void skb_xmit_done(struct virtqueue *svq)
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{
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struct virtnet_info *vi = svq->vdev->priv;
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/* Suppress further interrupts. */
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svq->vq_ops->disable_cb(svq);
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/* We were waiting for more output buffers. */
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netif_wake_queue(vi->dev);
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}
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static void receive_skb(struct net_device *dev, struct sk_buff *skb,
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unsigned len)
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{
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struct virtio_net_hdr *hdr = skb_vnet_hdr(skb);
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if (unlikely(len < sizeof(struct virtio_net_hdr) + ETH_HLEN)) {
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pr_debug("%s: short packet %i\n", dev->name, len);
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dev->stats.rx_length_errors++;
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goto drop;
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}
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len -= sizeof(struct virtio_net_hdr);
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BUG_ON(len > MAX_PACKET_LEN);
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skb_trim(skb, len);
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skb->protocol = eth_type_trans(skb, dev);
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pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
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ntohs(skb->protocol), skb->len, skb->pkt_type);
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dev->stats.rx_bytes += skb->len;
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dev->stats.rx_packets++;
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if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
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pr_debug("Needs csum!\n");
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if (!skb_partial_csum_set(skb,hdr->csum_start,hdr->csum_offset))
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goto frame_err;
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}
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if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
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pr_debug("GSO!\n");
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switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
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case VIRTIO_NET_HDR_GSO_TCPV4:
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skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
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break;
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case VIRTIO_NET_HDR_GSO_UDP:
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skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
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break;
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case VIRTIO_NET_HDR_GSO_TCPV6:
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skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
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break;
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default:
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if (net_ratelimit())
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printk(KERN_WARNING "%s: bad gso type %u.\n",
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dev->name, hdr->gso_type);
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goto frame_err;
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}
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if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
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skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
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skb_shinfo(skb)->gso_size = hdr->gso_size;
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if (skb_shinfo(skb)->gso_size == 0) {
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if (net_ratelimit())
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printk(KERN_WARNING "%s: zero gso size.\n",
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dev->name);
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goto frame_err;
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}
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/* Header must be checked, and gso_segs computed. */
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skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
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skb_shinfo(skb)->gso_segs = 0;
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}
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netif_receive_skb(skb);
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return;
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frame_err:
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dev->stats.rx_frame_errors++;
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drop:
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dev_kfree_skb(skb);
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}
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static void try_fill_recv(struct virtnet_info *vi)
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{
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struct sk_buff *skb;
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struct scatterlist sg[1+MAX_SKB_FRAGS];
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int num, err;
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sg_init_table(sg, 1+MAX_SKB_FRAGS);
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for (;;) {
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skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN);
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if (unlikely(!skb))
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break;
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skb_put(skb, MAX_PACKET_LEN);
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vnet_hdr_to_sg(sg, skb);
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num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
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skb_queue_head(&vi->recv, skb);
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err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, num, skb);
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if (err) {
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skb_unlink(skb, &vi->recv);
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kfree_skb(skb);
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break;
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}
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vi->num++;
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}
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if (unlikely(vi->num > vi->max))
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vi->max = vi->num;
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vi->rvq->vq_ops->kick(vi->rvq);
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}
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static void skb_recv_done(struct virtqueue *rvq)
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{
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struct virtnet_info *vi = rvq->vdev->priv;
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/* Schedule NAPI, Suppress further interrupts if successful. */
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if (netif_rx_schedule_prep(vi->dev, &vi->napi)) {
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rvq->vq_ops->disable_cb(rvq);
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__netif_rx_schedule(vi->dev, &vi->napi);
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}
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}
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static int virtnet_poll(struct napi_struct *napi, int budget)
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{
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struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
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struct sk_buff *skb = NULL;
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unsigned int len, received = 0;
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again:
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while (received < budget &&
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(skb = vi->rvq->vq_ops->get_buf(vi->rvq, &len)) != NULL) {
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__skb_unlink(skb, &vi->recv);
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receive_skb(vi->dev, skb, len);
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vi->num--;
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received++;
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}
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/* FIXME: If we oom and completely run out of inbufs, we need
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* to start a timer trying to fill more. */
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if (vi->num < vi->max / 2)
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try_fill_recv(vi);
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/* Out of packets? */
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if (received < budget) {
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netif_rx_complete(vi->dev, napi);
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if (unlikely(!vi->rvq->vq_ops->enable_cb(vi->rvq))
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&& netif_rx_reschedule(vi->dev, napi))
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goto again;
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}
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return received;
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}
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static void free_old_xmit_skbs(struct virtnet_info *vi)
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{
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struct sk_buff *skb;
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unsigned int len;
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while ((skb = vi->svq->vq_ops->get_buf(vi->svq, &len)) != NULL) {
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pr_debug("Sent skb %p\n", skb);
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__skb_unlink(skb, &vi->send);
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vi->dev->stats.tx_bytes += len;
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vi->dev->stats.tx_packets++;
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kfree_skb(skb);
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}
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}
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static int start_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct virtnet_info *vi = netdev_priv(dev);
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int num, err;
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struct scatterlist sg[1+MAX_SKB_FRAGS];
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struct virtio_net_hdr *hdr;
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const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
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DECLARE_MAC_BUF(mac);
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sg_init_table(sg, 1+MAX_SKB_FRAGS);
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pr_debug("%s: xmit %p %s\n", dev->name, skb, print_mac(mac, dest));
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/* Encode metadata header at front. */
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hdr = skb_vnet_hdr(skb);
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if (skb->ip_summed == CHECKSUM_PARTIAL) {
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hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
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hdr->csum_start = skb->csum_start - skb_headroom(skb);
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hdr->csum_offset = skb->csum_offset;
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} else {
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hdr->flags = 0;
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hdr->csum_offset = hdr->csum_start = 0;
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}
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if (skb_is_gso(skb)) {
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hdr->hdr_len = skb_transport_header(skb) - skb->data;
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hdr->gso_size = skb_shinfo(skb)->gso_size;
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if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
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hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
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else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
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hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
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else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
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hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
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else
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BUG();
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if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
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hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
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} else {
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hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
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hdr->gso_size = hdr->hdr_len = 0;
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}
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vnet_hdr_to_sg(sg, skb);
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num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
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__skb_queue_head(&vi->send, skb);
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again:
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/* Free up any pending old buffers before queueing new ones. */
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free_old_xmit_skbs(vi);
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err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
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if (err) {
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pr_debug("%s: virtio not prepared to send\n", dev->name);
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netif_stop_queue(dev);
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/* Activate callback for using skbs: if this fails it
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* means some were used in the meantime. */
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if (unlikely(!vi->svq->vq_ops->enable_cb(vi->svq))) {
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printk("Unlikely: restart svq failed\n");
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netif_start_queue(dev);
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goto again;
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}
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__skb_unlink(skb, &vi->send);
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return NETDEV_TX_BUSY;
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}
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vi->svq->vq_ops->kick(vi->svq);
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return 0;
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}
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static int virtnet_open(struct net_device *dev)
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{
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struct virtnet_info *vi = netdev_priv(dev);
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napi_enable(&vi->napi);
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/* If all buffers were filled by other side before we napi_enabled, we
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* won't get another interrupt, so process any outstanding packets
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* now. virtnet_poll wants re-enable the queue, so we disable here.
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* We synchronize against interrupts via NAPI_STATE_SCHED */
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if (netif_rx_schedule_prep(dev, &vi->napi)) {
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vi->rvq->vq_ops->disable_cb(vi->rvq);
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__netif_rx_schedule(dev, &vi->napi);
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}
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return 0;
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}
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static int virtnet_close(struct net_device *dev)
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{
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struct virtnet_info *vi = netdev_priv(dev);
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napi_disable(&vi->napi);
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return 0;
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}
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static int virtnet_probe(struct virtio_device *vdev)
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{
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int err;
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struct net_device *dev;
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struct virtnet_info *vi;
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/* Allocate ourselves a network device with room for our info */
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dev = alloc_etherdev(sizeof(struct virtnet_info));
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if (!dev)
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return -ENOMEM;
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/* Set up network device as normal. */
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dev->open = virtnet_open;
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dev->stop = virtnet_close;
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dev->hard_start_xmit = start_xmit;
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dev->features = NETIF_F_HIGHDMA;
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SET_NETDEV_DEV(dev, &vdev->dev);
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/* Do we support "hardware" checksums? */
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if (csum && vdev->config->feature(vdev, VIRTIO_NET_F_CSUM)) {
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/* This opens up the world of extra features. */
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dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
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if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_GSO)) {
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dev->features |= NETIF_F_TSO | NETIF_F_UFO
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| NETIF_F_TSO_ECN | NETIF_F_TSO6;
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}
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}
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/* Configuration may specify what MAC to use. Otherwise random. */
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if (vdev->config->feature(vdev, VIRTIO_NET_F_MAC)) {
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vdev->config->get(vdev,
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offsetof(struct virtio_net_config, mac),
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dev->dev_addr, dev->addr_len);
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} else
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random_ether_addr(dev->dev_addr);
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/* Set up our device-specific information */
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vi = netdev_priv(dev);
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netif_napi_add(dev, &vi->napi, virtnet_poll, napi_weight);
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vi->dev = dev;
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vi->vdev = vdev;
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/* We expect two virtqueues, receive then send. */
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vi->rvq = vdev->config->find_vq(vdev, 0, skb_recv_done);
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if (IS_ERR(vi->rvq)) {
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err = PTR_ERR(vi->rvq);
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goto free;
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}
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vi->svq = vdev->config->find_vq(vdev, 1, skb_xmit_done);
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if (IS_ERR(vi->svq)) {
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err = PTR_ERR(vi->svq);
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goto free_recv;
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}
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/* Initialize our empty receive and send queues. */
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skb_queue_head_init(&vi->recv);
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skb_queue_head_init(&vi->send);
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err = register_netdev(dev);
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if (err) {
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pr_debug("virtio_net: registering device failed\n");
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goto free_send;
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}
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/* Last of all, set up some receive buffers. */
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try_fill_recv(vi);
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/* If we didn't even get one input buffer, we're useless. */
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if (vi->num == 0) {
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err = -ENOMEM;
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goto unregister;
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}
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pr_debug("virtnet: registered device %s\n", dev->name);
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vdev->priv = vi;
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return 0;
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unregister:
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unregister_netdev(dev);
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free_send:
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vdev->config->del_vq(vi->svq);
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free_recv:
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vdev->config->del_vq(vi->rvq);
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free:
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free_netdev(dev);
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return err;
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}
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static void virtnet_remove(struct virtio_device *vdev)
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{
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struct virtnet_info *vi = vdev->priv;
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struct sk_buff *skb;
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/* Stop all the virtqueues. */
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vdev->config->reset(vdev);
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/* Free our skbs in send and recv queues, if any. */
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while ((skb = __skb_dequeue(&vi->recv)) != NULL) {
|
|
kfree_skb(skb);
|
|
vi->num--;
|
|
}
|
|
while ((skb = __skb_dequeue(&vi->send)) != NULL)
|
|
kfree_skb(skb);
|
|
|
|
BUG_ON(vi->num != 0);
|
|
|
|
vdev->config->del_vq(vi->svq);
|
|
vdev->config->del_vq(vi->rvq);
|
|
unregister_netdev(vi->dev);
|
|
free_netdev(vi->dev);
|
|
}
|
|
|
|
static struct virtio_device_id id_table[] = {
|
|
{ VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
|
|
{ 0 },
|
|
};
|
|
|
|
static struct virtio_driver virtio_net = {
|
|
.driver.name = KBUILD_MODNAME,
|
|
.driver.owner = THIS_MODULE,
|
|
.id_table = id_table,
|
|
.probe = virtnet_probe,
|
|
.remove = __devexit_p(virtnet_remove),
|
|
};
|
|
|
|
static int __init init(void)
|
|
{
|
|
return register_virtio_driver(&virtio_net);
|
|
}
|
|
|
|
static void __exit fini(void)
|
|
{
|
|
unregister_virtio_driver(&virtio_net);
|
|
}
|
|
module_init(init);
|
|
module_exit(fini);
|
|
|
|
MODULE_DEVICE_TABLE(virtio, id_table);
|
|
MODULE_DESCRIPTION("Virtio network driver");
|
|
MODULE_LICENSE("GPL");
|