On Mon, Feb 20, 2017 at 11:50:20AM +0800, Jason Wang wrote:
> We set queues before reset which will cause a crash[1]. This is
> because is_xdp_raw_buffer_queue() depends on the old xdp queue pairs
> number to do the correct detection. So fix this by
>
> - passing xdp queue pairs and current queue pairs to virtnet_reset()
> - change vi->xdp_qp after reset but before refill, to make sure both
> free_unused_bufs() and refill can make correct detection of XDP.
> - remove the duplicated queue pairs setting before virtnet_reset()
> since we will do it inside virtnet_reset()
>
> [1]
>
> [ 74.328168] general protection fault: 0000 [#1] SMP
> [ 74.328625] Modules linked in: nfsd xfs libcrc32c virtio_net virtio_pci
> [ 74.329117] CPU: 0 PID: 2849 Comm: xdp2 Not tainted 4.10.0-rc7+ #499
> [ 74.329577] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.10.1-0-g8891697-prebuilt.qemu-project.org 04/01/2014
> [ 74.330424] task: ffff88007a894000 task.stack: ffffc90004388000
> [ 74.330844] RIP: 0010:skb_release_head_state+0x28/0x80
> [ 74.331298] RSP: 0018:ffffc9000438b8d0 EFLAGS: 00010206
> [ 74.331676] RAX: 0000000000000000 RBX: ffff88007ad96300 RCX:
> 0000000000000000
> [ 74.332217] RDX: ffff88007fc137a8 RSI: ffff88007fc0db28 RDI:
> 0001bf00000001be
> [ 74.332758] RBP: ffffc9000438b8d8 R08: 000000000005008f R09:
> 00000000000005f9
> [ 74.333274] R10: ffff88007d001700 R11: ffffffff820a8a4d R12:
> ffff88007ad96300
> [ 74.333787] R13: 0000000000000002 R14: ffff880036604000 R15:
> 000077ff80000000
> [ 74.334308] FS: 00007fc70d8a7b40(0000) GS:ffff88007fc00000(0000)
> knlGS:0000000000000000
> [ 74.334891] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 74.335314] CR2: 00007fff4144a710 CR3: 000000007ab56000 CR4:
> 00000000003406f0
> [ 74.335830] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [ 74.336373] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
> 0000000000000400
> [ 74.336895] Call Trace:
> [ 74.337086] skb_release_all+0xd/0x30
> [ 74.337356] consume_skb+0x2c/0x90
> [ 74.337607] free_unused_bufs+0x1ff/0x270 [virtio_net]
> [ 74.337988] ? vp_synchronize_vectors+0x3b/0x60 [virtio_pci]
> [ 74.338398] virtnet_xdp+0x21e/0x440 [virtio_net]
> [ 74.338741] dev_change_xdp_fd+0x101/0x140
> [ 74.339048] do_setlink+0xcf4/0xd20
> [ 74.339304] ? symcmp+0xf/0x20
> [ 74.339529] ? mls_level_isvalid+0x52/0x60
> [ 74.339828] ? mls_range_isvalid+0x43/0x50
> [ 74.340135] ? nla_parse+0xa0/0x100
> [ 74.340400] rtnl_setlink+0xd4/0x120
> [ 74.340664] ? cpumask_next_and+0x30/0x50
> [ 74.340966] rtnetlink_rcv_msg+0x7f/0x1f0
> [ 74.341259] ? sock_has_perm+0x59/0x60
> [ 74.341586] ? napi_consume_skb+0xe2/0x100
> [ 74.342010] ? rtnl_newlink+0x890/0x890
> [ 74.342435] netlink_rcv_skb+0x92/0xb0
> [ 74.342846] rtnetlink_rcv+0x23/0x30
> [ 74.343277] netlink_unicast+0x162/0x210
> [ 74.343677] netlink_sendmsg+0x2db/0x390
> [ 74.343968] sock_sendmsg+0x33/0x40
> [ 74.344233] SYSC_sendto+0xee/0x160
> [ 74.344482] ? SYSC_bind+0xb0/0xe0
> [ 74.344806] ? sock_alloc_file+0x92/0x110
> [ 74.345106] ? fd_install+0x20/0x30
> [ 74.345360] ? sock_map_fd+0x3f/0x60
> [ 74.345586] SyS_sendto+0x9/0x10
> [ 74.345790] entry_SYSCALL_64_fastpath+0x1a/0xa9
> [ 74.346086] RIP: 0033:0x7fc70d1b8f6d
> [ 74.346312] RSP: 002b:00007fff4144a708 EFLAGS: 00000246 ORIG_RAX:
> 000000000000002c
> [ 74.346785] RAX: ffffffffffffffda RBX: 00000000ffffffff RCX:
> 00007fc70d1b8f6d
> [ 74.347244] RDX: 000000000000002c RSI: 00007fff4144a720 RDI:
> 0000000000000003
> [ 74.347683] RBP: 0000000000000003 R08: 0000000000000000 R09:
> 0000000000000000
> [ 74.348544] R10: 0000000000000000 R11: 0000000000000246 R12:
> 00007fff4144bd90
> [ 74.349082] R13: 0000000000000002 R14: 0000000000000002 R15:
> 00007fff4144cda0
> [ 74.349607] Code: 00 00 00 55 48 89 e5 53 48 89 fb 48 8b 7f 58 48 85 ff 74
> 0e 40 f6 c7 01 74 3d 48 c7 43 58 00 00 00 00 48 8b 7b 68 48 85 ff 74 05 <f0>
> ff 0f 74 20 48 8b 43 60 48 85 c0 74 14 65 8b 15 f3 ab 8d 7e
> [ 74.351008] RIP: skb_release_head_state+0x28/0x80 RSP: ffffc9000438b8d0
> [ 74.351625] ---[ end trace fe6e19fd11cfc80b ]---
>
> Fixes: 2de2f7f40ef9 ("virtio_net: XDP support for adjust_head")
> Cc: John Fastabend <john.fastab...@gmail.com>
> Signed-off-by: Jason Wang <jasow...@redhat.com>
Acked-by: Michael S. Tsirkin <m...@redhat.com>
I think this makes sense in stable as well.
> ---
> Changes from V1:
> - passing xdp_qp and curr_qp to virtnet_reset() to refill correctly
> - remove the duplicated queue pair setting after virtnet_reset()
> ---
> drivers/net/virtio_net.c | 28 ++++++++--------------------
> 1 file changed, 8 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 11e2853..d12e5d6 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1737,7 +1737,7 @@ static int virtnet_restore_up(struct virtio_device
> *vdev)
> return err;
> }
>
> -static int virtnet_reset(struct virtnet_info *vi)
> +static int virtnet_reset(struct virtnet_info *vi, int curr_qp, int xdp_qp)
> {
> struct virtio_device *dev = vi->vdev;
> int ret;
> @@ -1755,10 +1755,11 @@ static int virtnet_reset(struct virtnet_info *vi)
> if (ret)
> goto err;
>
> + vi->xdp_queue_pairs = xdp_qp;
> ret = virtnet_restore_up(dev);
> if (ret)
> goto err;
> - ret = _virtnet_set_queues(vi, vi->curr_queue_pairs);
> + ret = _virtnet_set_queues(vi, curr_qp);
> if (ret)
> goto err;
>
> @@ -1775,7 +1776,7 @@ static int virtnet_xdp_set(struct net_device *dev,
> struct bpf_prog *prog)
> unsigned long int max_sz = PAGE_SIZE - sizeof(struct padded_vnet_hdr);
> struct virtnet_info *vi = netdev_priv(dev);
> struct bpf_prog *old_prog;
> - u16 oxdp_qp, xdp_qp = 0, curr_qp;
> + u16 xdp_qp = 0, curr_qp;
> int i, err;
>
> if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
> @@ -1813,24 +1814,17 @@ static int virtnet_xdp_set(struct net_device *dev,
> struct bpf_prog *prog)
> return PTR_ERR(prog);
> }
>
> - err = _virtnet_set_queues(vi, curr_qp + xdp_qp);
> - if (err) {
> - dev_warn(&dev->dev, "XDP Device queue allocation failure.\n");
> - goto virtio_queue_err;
> - }
> -
> - oxdp_qp = vi->xdp_queue_pairs;
> -
> /* Changing the headroom in buffers is a disruptive operation because
> * existing buffers must be flushed and reallocated. This will happen
> * when a xdp program is initially added or xdp is disabled by removing
> * the xdp program resulting in number of XDP queues changing.
> */
> if (vi->xdp_queue_pairs != xdp_qp) {
> - vi->xdp_queue_pairs = xdp_qp;
> - err = virtnet_reset(vi);
> - if (err)
> + err = virtnet_reset(vi, curr_qp + xdp_qp, xdp_qp);
> + if (err) {
> + dev_warn(&dev->dev, "XDP reset failure.\n");
> goto virtio_reset_err;
> + }
> }
>
> netif_set_real_num_rx_queues(dev, curr_qp + xdp_qp);
> @@ -1849,12 +1843,6 @@ static int virtnet_xdp_set(struct net_device *dev,
> struct bpf_prog *prog)
> * error up to user space for resolution. The underlying reset hung on
> * us so not much we can do here.
> */
> - dev_warn(&dev->dev, "XDP reset failure and queues unstable\n");
> - vi->xdp_queue_pairs = oxdp_qp;
> -virtio_queue_err:
> - /* On queue set error we can unwind bpf ref count and user space can
> - * retry this is most likely an allocation failure.
> - */
> if (prog)
> bpf_prog_sub(prog, vi->max_queue_pairs - 1);
> return err;
> --
> 2.7.4
