The MANA driver's probe registers netdevice via the following call chain:

mana_probe() register_netdev() register_netdevice()

register_netdevice() calls notifier callback for netvsc driver, holding the netdev mutex via netdev_lock_ops().

Further this netvsc notifier callback end up attempting to acquire the same lock again in dev_xdp_propagate() leading to deadlock.

netvsc_netdev_event() netvsc_vf_setxdp() dev_xdp_propagate()

This deadlock was not observed so far because net_shaper_ops was never set, and thus the lock was effectively a no-op in this case. Fix this by using netif_xdp_propagate() instead of dev_xdp_propagate() to avoid recursive locking in this path.

And, since no deadlock is observed on the other path which is via netvsc_probe, add the lock exclusivly for that path.

Also, clean up the unregistration path by removing the unnecessary call to netvsc_vf_setxdp(), since unregister_netdevice_many_notify() already performs this cleanup via dev_xdp_uninstall().

Fixes: 97246d6d21c2 ("net: hold netdev instance lock during ndo_bpf") Cc: stable@vger.kernel.org Signed-off-by: Saurabh Sengar ssengar@linux.microsoft.com Tested-by: Erni Sri Satya Vennela ernis@linux.microsoft.com Reviewed-by: Haiyang Zhang haiyangz@microsoft.com Reviewed-by: Subbaraya Sundeep sbhatta@marvell.com --- [V3] - Add the lock for netvsc probe path

[V2] - Modified commit message

drivers/net/hyperv/netvsc_bpf.c | 2 +- drivers/net/hyperv/netvsc_drv.c | 4 ++-- net/core/dev.c | 1 + 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/hyperv/netvsc_bpf.c b/drivers/net/hyperv/netvsc_bpf.c index e01c5997a551..1dd3755d9e6d 100644 --- a/drivers/net/hyperv/netvsc_bpf.c +++ b/drivers/net/hyperv/netvsc_bpf.c @@ -183,7 +183,7 @@ int netvsc_vf_setxdp(struct net_device *vf_netdev, struct bpf_prog *prog) xdp.command = XDP_SETUP_PROG; xdp.prog = prog;

- ret = dev_xdp_propagate(vf_netdev, &xdp); + ret = netif_xdp_propagate(vf_netdev, &xdp);

if (ret && prog) bpf_prog_put(prog); diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 14a0d04e21ae..c41a025c66f0 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -2462,8 +2462,6 @@ static int netvsc_unregister_vf(struct net_device *vf_netdev)

netdev_info(ndev, "VF unregistering: %s\n", vf_netdev->name);

- netvsc_vf_setxdp(vf_netdev, NULL); - reinit_completion(&net_device_ctx->vf_add); netdev_rx_handler_unregister(vf_netdev); netdev_upper_dev_unlink(vf_netdev, ndev); @@ -2631,7 +2629,9 @@ static int netvsc_probe(struct hv_device *dev, continue;

netvsc_prepare_bonding(vf_netdev); + netdev_lock_ops(vf_netdev); netvsc_register_vf(vf_netdev, VF_REG_IN_PROBE); + netdev_unlock_ops(vf_netdev); __netvsc_vf_setup(net, vf_netdev); break; } diff --git a/net/core/dev.c b/net/core/dev.c index 2b514d95c528..a388f459a366 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -9968,6 +9968,7 @@ int netif_xdp_propagate(struct net_device *dev, struct netdev_bpf *bpf)

return dev->netdev_ops->ndo_bpf(dev, bpf); } +EXPORT_SYMBOL_GPL(netif_xdp_propagate);

u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode) {