On Thu, May 16, 2024 at 06:41:08PM +0200, Michal Kubiak wrote:
> The commit 6533e558c650 ("i40e: Fix reset path while removing
> the driver") introduced a new PF state "__I40E_IN_REMOVE" to block
> modifying the XDP program while the driver is being removed.
> Unfortunately, such a change is useful only if the ".ndo_bpf()"
> callback was called out of the rmmod context because unloading the
> existing XDP program is also a part of driver removing procedure.
> In other words, from the rmmod context the driver is expected to
> unload the XDP program without reporting any errors. Otherwise,
> the kernel warning with callstack is printed out to dmesg.
>
> Example failing scenario:
> 1. Load the i40e driver.
> 2. Load the XDP program.
> 3. Unload the i40e driver (using "rmmod" command).
>
> Fix this by improving checks in ".ndo_bpf()" to determine if that
> callback was called from the removing context and if the kernel
> wants to unload the XDP program. Allow for unloading the XDP program
> in such a case.
>
> Fixes: 6533e558c650 ("i40e: Fix reset path while removing the driver")
> Reviewed-by: Wojciech Drewek <[email protected]>
> Signed-off-by: Michal Kubiak <[email protected]>
Acked-by: Maciej Fijalkowski <[email protected]>
> ---
> drivers/net/ethernet/intel/i40e/i40e_main.c | 19 ++++++++++++++-----
> 1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c
> b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index ffb9f9f15c52..19fc043e351f 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -13264,6 +13264,20 @@ static int i40e_xdp_setup(struct i40e_vsi *vsi,
> struct bpf_prog *prog,
> bool need_reset;
> int i;
>
> + /* Called from netdev unregister context. Unload the XDP program. */
> + if (vsi->netdev->reg_state == NETREG_UNREGISTERING) {
> + xdp_features_clear_redirect_target(vsi->netdev);
> + old_prog = xchg(&vsi->xdp_prog, NULL);
> + if (old_prog)
> + bpf_prog_put(old_prog);
> +
> + return 0;
> + }
> +
> + /* VSI shall be deleted in a moment, just return EINVAL */
> + if (test_bit(__I40E_IN_REMOVE, pf->state))
> + return -EINVAL;
> +
> /* Don't allow frames that span over multiple buffers */
> if (vsi->netdev->mtu > frame_size - I40E_PACKET_HDR_PAD) {
> NL_SET_ERR_MSG_MOD(extack, "MTU too large for linear frames and
> XDP prog does not support frags");
> @@ -13272,14 +13286,9 @@ static int i40e_xdp_setup(struct i40e_vsi *vsi,
> struct bpf_prog *prog,
>
> /* When turning XDP on->off/off->on we reset and rebuild the rings. */
> need_reset = (i40e_enabled_xdp_vsi(vsi) != !!prog);
> -
> if (need_reset)
> i40e_prep_for_reset(pf);
>
> - /* VSI shall be deleted in a moment, just return EINVAL */
> - if (test_bit(__I40E_IN_REMOVE, pf->state))
> - return -EINVAL;
> -
> old_prog = xchg(&vsi->xdp_prog, prog);
>
> if (need_reset) {
> --
> 2.33.1
>
