| Message ID | 1581026465-36161-1-git-send-email-haiyangz@microsoft.com |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net] hv_netvsc: Fix XDP refcnt for synthetic and VF NICs | expand |
From: Haiyang Zhang <haiyangz@microsoft.com> Date: Thu, 6 Feb 2020 14:01:05 -0800 > The caller of XDP_SETUP_PROG has already incremented refcnt in > __bpf_prog_get(), so drivers should only increment refcnt by > num_queues - 1. > > To fix the issue, update netvsc_xdp_set() to add the correct number > to refcnt. > > Hold a refcnt in netvsc_xdp_set()’s other caller, netvsc_attach(). > > And, do the same in netvsc_vf_setxdp(). Otherwise, every time when VF is > removed and added from the host side, the refcnt will be decreased by one, > which may cause page fault when unloading xdp program. > > Fixes: 351e1581395f ("hv_netvsc: Add XDP support") > Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com> Applied, thank you.
diff --git a/drivers/net/hyperv/netvsc_bpf.c b/drivers/net/hyperv/netvsc_bpf.c index 20adfe5..b866110 100644 --- a/drivers/net/hyperv/netvsc_bpf.c +++ b/drivers/net/hyperv/netvsc_bpf.c @@ -120,7 +120,7 @@ int netvsc_xdp_set(struct net_device *dev, struct bpf_prog *prog, } if (prog) - bpf_prog_add(prog, nvdev->num_chn); + bpf_prog_add(prog, nvdev->num_chn - 1); for (i = 0; i < nvdev->num_chn; i++) rcu_assign_pointer(nvdev->chan_table[i].bpf_prog, prog); @@ -136,6 +136,7 @@ int netvsc_vf_setxdp(struct net_device *vf_netdev, struct bpf_prog *prog) { struct netdev_bpf xdp; bpf_op_t ndo_bpf; + int ret; ASSERT_RTNL(); @@ -148,10 +149,18 @@ int netvsc_vf_setxdp(struct net_device *vf_netdev, struct bpf_prog *prog) memset(&xdp, 0, sizeof(xdp)); + if (prog) + bpf_prog_inc(prog); + xdp.command = XDP_SETUP_PROG; xdp.prog = prog; - return ndo_bpf(vf_netdev, &xdp); + ret = ndo_bpf(vf_netdev, &xdp); + + if (ret && prog) + bpf_prog_put(prog); + + return ret; } static u32 netvsc_xdp_query(struct netvsc_device *nvdev) diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 8fc71bd..65e12cb 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -1059,9 +1059,12 @@ static int netvsc_attach(struct net_device *ndev, prog = dev_info->bprog; if (prog) { + bpf_prog_inc(prog); ret = netvsc_xdp_set(ndev, prog, NULL, nvdev); - if (ret) + if (ret) { + bpf_prog_put(prog); goto err1; + } } /* In any case device is now ready */
The caller of XDP_SETUP_PROG has already incremented refcnt in __bpf_prog_get(), so drivers should only increment refcnt by num_queues - 1. To fix the issue, update netvsc_xdp_set() to add the correct number to refcnt. Hold a refcnt in netvsc_xdp_set()’s other caller, netvsc_attach(). And, do the same in netvsc_vf_setxdp(). Otherwise, every time when VF is removed and added from the host side, the refcnt will be decreased by one, which may cause page fault when unloading xdp program. Fixes: 351e1581395f ("hv_netvsc: Add XDP support") Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com> --- drivers/net/hyperv/netvsc_bpf.c | 13 +++++++++++-- drivers/net/hyperv/netvsc_drv.c | 5 ++++- 2 files changed, 15 insertions(+), 3 deletions(-)