Re: [PATCH bpf-next v2 2/8] bpf: XDP metadata RX kfuncs

Martin KaFai Lau
2022-11-23T06:34:13Z

On 11/21/22 10:25 AM, Stanislav Fomichev wrote:
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -2576,6 +2576,7 @@ static void bpf_prog_free_deferred(struct work_struct *work)
> } else {
> bpf_jit_free(aux->prog);
> }
> + dev_put(aux->xdp_netdev);

I think dev_put needs to be done during unregister_netdevice event also.
Otherwise, a loaded bpf prog may hold the dev for a long time. May be there is
ideas in offload.c.

[ ... ]

> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 35972afb6850..ece7f9234b2d 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2491,7 +2491,8 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
> BPF_F_TEST_STATE_FREQ |
> BPF_F_SLEEPABLE |
> BPF_F_TEST_RND_HI32 |
> - BPF_F_XDP_HAS_FRAGS))
> + BPF_F_XDP_HAS_FRAGS |
> + BPF_F_XDP_HAS_METADATA))
> return -EINVAL;
>
> if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) &&
> @@ -2579,6 +2580,20 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
> prog->aux->sleepable = attr->prog_flags & BPF_F_SLEEPABLE;
> prog->aux->xdp_has_frags = attr->prog_flags & BPF_F_XDP_HAS_FRAGS;
>
> + if (attr->prog_flags & BPF_F_XDP_HAS_METADATA) {
> + /* Reuse prog_ifindex to bind to the device
> + * for XDP metadata kfuncs.
> + */
> + prog->aux->offload_requested = false;
> +
> + prog->aux->xdp_netdev = dev_get_by_index(current->nsproxy->net_ns,
> + attr->prog_ifindex);
> + if (!prog->aux->xdp_netdev) {
> + err = -EINVAL;
> + goto free_prog;
> + }
> + }