netdev - Re: [patch net-next 3/6] mlxsw: spectrum_router: Use FIB notifications instead of switchdev calls

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Message-ID: <20160922065102.GA13287@splinter>
Date:   Thu, 22 Sep 2016 09:51:02 +0300
From:   Ido Schimmel <idosch@...sch.org>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, idosch@...lanox.com,
        eladr@...lanox.com, yotamg@...lanox.com, nogahf@...lanox.com,
        ogerlitz@...lanox.com, roopa@...ulusnetworks.com,
        nikolay@...ulusnetworks.com, linville@...driver.com,
        andy@...yhouse.net, f.fainelli@...il.com, dsa@...ulusnetworks.com,
        jhs@...atatu.com, vivien.didelot@...oirfairelinux.com,
        andrew@...n.ch, ivecera@...hat.com, kaber@...sh.net,
        john@...ozen.org
Subject: Re: [patch net-next 3/6] mlxsw: spectrum_router: Use FIB
 notifications instead of switchdev calls

On Wed, Sep 21, 2016 at 01:53:11PM +0200, Jiri Pirko wrote:
> From: Jiri Pirko <jiri@...lanox.com>
> 
> Until now, in order to offload a FIB entry to HW we use switchdev op.
> However that has limits. Mainly in case we need to make the HW aware of
> all route prefixes configured in kernel. HW needs to know those in order
> to properly trap appropriate packets and pass the to kernel to do
> the forwarding. Abort mechanism is now handled within the mlxsw driver.

FWIW, I think it's smart to move abort into the driver instead of
flushing all the routes from the namespace as before.

> 
> Signed-off-by: Jiri Pirko <jiri@...lanox.com>

[...]

> +static void mlxsw_sp_router_fib4_abort(struct mlxsw_sp *mlxsw_sp)
> +{
> +	char ralue_pl[MLXSW_REG_RALUE_LEN];
> +	struct mlxsw_resources *resources;
> +	struct mlxsw_sp_fib_entry *fib_entry;
> +	struct mlxsw_sp_fib_entry *tmp;
> +	struct mlxsw_sp_vr *vr;
> +	int i;
> +	int err;
> +
> +	resources = mlxsw_core_resources_get(mlxsw_sp->core);
> +	for (i = 0; i < resources->max_virtual_routers; i++) {
> +		vr = &mlxsw_sp->router.vrs[i];
> +		if (!vr->used)
> +			continue;
> +
> +		list_for_each_entry_safe(fib_entry, tmp,
> +					 &vr->fib->entry_list, list) {
> +			fib_info_offload_dec(fib_entry->fi);
> +			mlxsw_sp_fib_entry_del(mlxsw_sp, fib_entry);
> +			mlxsw_sp_fib_entry_remove(fib_entry->vr->fib,
> +						  fib_entry);
> +			mlxsw_sp_fib_entry_put_all(mlxsw_sp, fib_entry);

If we now do the routing in slow path, then maybe it makes sense to also
flush all the neighbour entries and prevent new neighbours from being
programmed into the device?

> +		}
> +	}
> +	mlxsw_sp->router.aborted = true;
> +
> +	mlxsw_reg_ralue_pack4(ralue_pl, MLXSW_SP_L3_PROTO_IPV4,
> +			      MLXSW_REG_RALUE_OP_WRITE_WRITE, 0, 0, 0);

I'm not sure about that, but the loop above removed all the tables from
the device and now you are using table 0 again. Will this work w/o
binding some tree to it (0?)?

> +	mlxsw_reg_ralue_act_ip2me_pack(ralue_pl);
> +	err = mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(ralue), ralue_pl);
> +	if (err)
> +		dev_warn(mlxsw_sp->bus_info->dev, "Failed to set abort trap.\n");
> +}

Thanks