linux/drivers/net/virtio_net.c
Christian Borntraeger 370076d932 virtio net: fix oops on interface-up
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>
2008-02-06 06:42:30 -05:00

464 lines
12 KiB
C

/* A simple network driver using virtio.
*
* Copyright 2007 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
//#define DEBUG
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/module.h>
#include <linux/virtio.h>
#include <linux/virtio_net.h>
#include <linux/scatterlist.h>
static int napi_weight = 128;
module_param(napi_weight, int, 0444);
static int csum = 1, gso = 1;
module_param(csum, bool, 0444);
module_param(gso, bool, 0444);
/* FIXME: MTU in config. */
#define MAX_PACKET_LEN (ETH_HLEN+ETH_DATA_LEN)
struct virtnet_info
{
struct virtio_device *vdev;
struct virtqueue *rvq, *svq;
struct net_device *dev;
struct napi_struct napi;
/* Number of input buffers, and max we've ever had. */
unsigned int num, max;
/* Receive & send queues. */
struct sk_buff_head recv;
struct sk_buff_head send;
};
static inline struct virtio_net_hdr *skb_vnet_hdr(struct sk_buff *skb)
{
return (struct virtio_net_hdr *)skb->cb;
}
static inline void vnet_hdr_to_sg(struct scatterlist *sg, struct sk_buff *skb)
{
sg_init_one(sg, skb_vnet_hdr(skb), sizeof(struct virtio_net_hdr));
}
static void skb_xmit_done(struct virtqueue *svq)
{
struct virtnet_info *vi = svq->vdev->priv;
/* Suppress further interrupts. */
svq->vq_ops->disable_cb(svq);
/* We were waiting for more output buffers. */
netif_wake_queue(vi->dev);
}
static void receive_skb(struct net_device *dev, struct sk_buff *skb,
unsigned len)
{
struct virtio_net_hdr *hdr = skb_vnet_hdr(skb);
if (unlikely(len < sizeof(struct virtio_net_hdr) + ETH_HLEN)) {
pr_debug("%s: short packet %i\n", dev->name, len);
dev->stats.rx_length_errors++;
goto drop;
}
len -= sizeof(struct virtio_net_hdr);
BUG_ON(len > MAX_PACKET_LEN);
skb_trim(skb, len);
skb->protocol = eth_type_trans(skb, dev);
pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
ntohs(skb->protocol), skb->len, skb->pkt_type);
dev->stats.rx_bytes += skb->len;
dev->stats.rx_packets++;
if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
pr_debug("Needs csum!\n");
if (!skb_partial_csum_set(skb,hdr->csum_start,hdr->csum_offset))
goto frame_err;
}
if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
pr_debug("GSO!\n");
switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
case VIRTIO_NET_HDR_GSO_TCPV4:
skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
break;
case VIRTIO_NET_HDR_GSO_UDP:
skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
break;
case VIRTIO_NET_HDR_GSO_TCPV6:
skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
break;
default:
if (net_ratelimit())
printk(KERN_WARNING "%s: bad gso type %u.\n",
dev->name, hdr->gso_type);
goto frame_err;
}
if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
skb_shinfo(skb)->gso_size = hdr->gso_size;
if (skb_shinfo(skb)->gso_size == 0) {
if (net_ratelimit())
printk(KERN_WARNING "%s: zero gso size.\n",
dev->name);
goto frame_err;
}
/* Header must be checked, and gso_segs computed. */
skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
skb_shinfo(skb)->gso_segs = 0;
}
netif_receive_skb(skb);
return;
frame_err:
dev->stats.rx_frame_errors++;
drop:
dev_kfree_skb(skb);
}
static void try_fill_recv(struct virtnet_info *vi)
{
struct sk_buff *skb;
struct scatterlist sg[1+MAX_SKB_FRAGS];
int num, err;
sg_init_table(sg, 1+MAX_SKB_FRAGS);
for (;;) {
skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN);
if (unlikely(!skb))
break;
skb_put(skb, MAX_PACKET_LEN);
vnet_hdr_to_sg(sg, skb);
num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
skb_queue_head(&vi->recv, skb);
err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, num, skb);
if (err) {
skb_unlink(skb, &vi->recv);
kfree_skb(skb);
break;
}
vi->num++;
}
if (unlikely(vi->num > vi->max))
vi->max = vi->num;
vi->rvq->vq_ops->kick(vi->rvq);
}
static void skb_recv_done(struct virtqueue *rvq)
{
struct virtnet_info *vi = rvq->vdev->priv;
/* Schedule NAPI, Suppress further interrupts if successful. */
if (netif_rx_schedule_prep(vi->dev, &vi->napi)) {
rvq->vq_ops->disable_cb(rvq);
__netif_rx_schedule(vi->dev, &vi->napi);
}
}
static int virtnet_poll(struct napi_struct *napi, int budget)
{
struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
struct sk_buff *skb = NULL;
unsigned int len, received = 0;
again:
while (received < budget &&
(skb = vi->rvq->vq_ops->get_buf(vi->rvq, &len)) != NULL) {
__skb_unlink(skb, &vi->recv);
receive_skb(vi->dev, skb, len);
vi->num--;
received++;
}
/* FIXME: If we oom and completely run out of inbufs, we need
* to start a timer trying to fill more. */
if (vi->num < vi->max / 2)
try_fill_recv(vi);
/* Out of packets? */
if (received < budget) {
netif_rx_complete(vi->dev, napi);
if (unlikely(!vi->rvq->vq_ops->enable_cb(vi->rvq))
&& netif_rx_reschedule(vi->dev, napi))
goto again;
}
return received;
}
static void free_old_xmit_skbs(struct virtnet_info *vi)
{
struct sk_buff *skb;
unsigned int len;
while ((skb = vi->svq->vq_ops->get_buf(vi->svq, &len)) != NULL) {
pr_debug("Sent skb %p\n", skb);
__skb_unlink(skb, &vi->send);
vi->dev->stats.tx_bytes += len;
vi->dev->stats.tx_packets++;
kfree_skb(skb);
}
}
static int start_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct virtnet_info *vi = netdev_priv(dev);
int num, err;
struct scatterlist sg[1+MAX_SKB_FRAGS];
struct virtio_net_hdr *hdr;
const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
DECLARE_MAC_BUF(mac);
sg_init_table(sg, 1+MAX_SKB_FRAGS);
pr_debug("%s: xmit %p %s\n", dev->name, skb, print_mac(mac, dest));
/* Encode metadata header at front. */
hdr = skb_vnet_hdr(skb);
if (skb->ip_summed == CHECKSUM_PARTIAL) {
hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
hdr->csum_start = skb->csum_start - skb_headroom(skb);
hdr->csum_offset = skb->csum_offset;
} else {
hdr->flags = 0;
hdr->csum_offset = hdr->csum_start = 0;
}
if (skb_is_gso(skb)) {
hdr->hdr_len = skb_transport_header(skb) - skb->data;
hdr->gso_size = skb_shinfo(skb)->gso_size;
if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
else
BUG();
if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
} else {
hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
hdr->gso_size = hdr->hdr_len = 0;
}
vnet_hdr_to_sg(sg, skb);
num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
__skb_queue_head(&vi->send, skb);
again:
/* Free up any pending old buffers before queueing new ones. */
free_old_xmit_skbs(vi);
err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);
if (err) {
pr_debug("%s: virtio not prepared to send\n", dev->name);
netif_stop_queue(dev);
/* Activate callback for using skbs: if this fails it
* means some were used in the meantime. */
if (unlikely(!vi->svq->vq_ops->enable_cb(vi->svq))) {
printk("Unlikely: restart svq failed\n");
netif_start_queue(dev);
goto again;
}
__skb_unlink(skb, &vi->send);
return NETDEV_TX_BUSY;
}
vi->svq->vq_ops->kick(vi->svq);
return 0;
}
static int virtnet_open(struct net_device *dev)
{
struct virtnet_info *vi = netdev_priv(dev);
napi_enable(&vi->napi);
/* If all buffers were filled by other side before we napi_enabled, we
* won't get another interrupt, so process any outstanding packets
* now. virtnet_poll wants re-enable the queue, so we disable here.
* We synchronize against interrupts via NAPI_STATE_SCHED */
if (netif_rx_schedule_prep(dev, &vi->napi)) {
vi->rvq->vq_ops->disable_cb(vi->rvq);
__netif_rx_schedule(dev, &vi->napi);
}
return 0;
}
static int virtnet_close(struct net_device *dev)
{
struct virtnet_info *vi = netdev_priv(dev);
napi_disable(&vi->napi);
return 0;
}
static int virtnet_probe(struct virtio_device *vdev)
{
int err;
struct net_device *dev;
struct virtnet_info *vi;
/* Allocate ourselves a network device with room for our info */
dev = alloc_etherdev(sizeof(struct virtnet_info));
if (!dev)
return -ENOMEM;
/* Set up network device as normal. */
dev->open = virtnet_open;
dev->stop = virtnet_close;
dev->hard_start_xmit = start_xmit;
dev->features = NETIF_F_HIGHDMA;
SET_NETDEV_DEV(dev, &vdev->dev);
/* Do we support "hardware" checksums? */
if (csum && vdev->config->feature(vdev, VIRTIO_NET_F_CSUM)) {
/* This opens up the world of extra features. */
dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_GSO)) {
dev->features |= NETIF_F_TSO | NETIF_F_UFO
| NETIF_F_TSO_ECN | NETIF_F_TSO6;
}
}
/* Configuration may specify what MAC to use. Otherwise random. */
if (vdev->config->feature(vdev, VIRTIO_NET_F_MAC)) {
vdev->config->get(vdev,
offsetof(struct virtio_net_config, mac),
dev->dev_addr, dev->addr_len);
} else
random_ether_addr(dev->dev_addr);
/* Set up our device-specific information */
vi = netdev_priv(dev);
netif_napi_add(dev, &vi->napi, virtnet_poll, napi_weight);
vi->dev = dev;
vi->vdev = vdev;
/* We expect two virtqueues, receive then send. */
vi->rvq = vdev->config->find_vq(vdev, 0, skb_recv_done);
if (IS_ERR(vi->rvq)) {
err = PTR_ERR(vi->rvq);
goto free;
}
vi->svq = vdev->config->find_vq(vdev, 1, skb_xmit_done);
if (IS_ERR(vi->svq)) {
err = PTR_ERR(vi->svq);
goto free_recv;
}
/* Initialize our empty receive and send queues. */
skb_queue_head_init(&vi->recv);
skb_queue_head_init(&vi->send);
err = register_netdev(dev);
if (err) {
pr_debug("virtio_net: registering device failed\n");
goto free_send;
}
/* Last of all, set up some receive buffers. */
try_fill_recv(vi);
/* If we didn't even get one input buffer, we're useless. */
if (vi->num == 0) {
err = -ENOMEM;
goto unregister;
}
pr_debug("virtnet: registered device %s\n", dev->name);
vdev->priv = vi;
return 0;
unregister:
unregister_netdev(dev);
free_send:
vdev->config->del_vq(vi->svq);
free_recv:
vdev->config->del_vq(vi->rvq);
free:
free_netdev(dev);
return err;
}
static void virtnet_remove(struct virtio_device *vdev)
{
struct virtnet_info *vi = vdev->priv;
struct sk_buff *skb;
/* Stop all the virtqueues. */
vdev->config->reset(vdev);
/* Free our skbs in send and recv queues, if any. */
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");