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 this lock in noop in this case. Fix this by using netif_xdp_propagate instead of dev_xdp_propagate to avoid recursive locking in this path.

This issue has not observed so far because net_shaper_ops was unset, making the lock path effectively a no-op. To prevent recursive locking and avoid this deadlock, replace dev_xdp_propagate() with netif_xdp_propagate(), which does not acquire the lock again.

Also, clean up the unregistration path by removing 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 --- drivers/net/hyperv/netvsc_bpf.c | 2 +- drivers/net/hyperv/netvsc_drv.c | 2 -- net/core/dev.c | 1 + 3 files changed, 2 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 d8b169ac0343..ee3aaf9c10e6 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); diff --git a/net/core/dev.c b/net/core/dev.c index fccf2167b235..8c6c9d7fba26 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -9953,6 +9953,7 @@ 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) {