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Date:   Mon, 14 Mar 2022 18:27:16 +0200
From:   Vladimir Oltean <olteanv@gmail.com>
To:     Tobias Waldekranz <tobias@waldekranz.com>
Cc:     davem@davemloft.net, kuba@kernel.org, Andrew Lunn <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Jiri Pirko <jiri@resnulli.us>,
        Ivan Vecera <ivecera@redhat.com>,
        Roopa Prabhu <roopa@nvidia.com>,
        Nikolay Aleksandrov <razor@blackwall.org>,
        Russell King <linux@armlinux.org.uk>,
        Ido Schimmel <idosch@nvidia.com>,
        Petr Machata <petrm@nvidia.com>,
        Cooper Lees <me@cooperlees.com>,
        Matt Johnston <matt@codeconstruct.com.au>,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        bridge@lists.linux-foundation.org
Subject: Re: [PATCH v3 net-next 14/14] net: dsa: mv88e6xxx: MST Offloading
Message-ID: <20220314162716.fm4tpkdi4b4ak3th@skbuf>
References: <20220314095231.3486931-1-tobias@waldekranz.com>
 <20220314095231.3486931-15-tobias@waldekranz.com>
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On Mon, Mar 14, 2022 at 10:52:31AM +0100, Tobias Waldekranz wrote:
> Allocate a SID in the STU for each MSTID in use by a bridge and handle
> the mapping of MSTIDs to VLANs using the SID field of each VTU entry.
> 
> Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
> ---
>  drivers/net/dsa/mv88e6xxx/chip.c | 251 ++++++++++++++++++++++++++++++-
>  drivers/net/dsa/mv88e6xxx/chip.h |  13 ++
>  2 files changed, 257 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
> index c14a62aa6a6c..c23dbf37aeec 100644
> --- a/drivers/net/dsa/mv88e6xxx/chip.c
> +++ b/drivers/net/dsa/mv88e6xxx/chip.c
> @@ -1667,24 +1667,32 @@ static int mv88e6xxx_pvt_setup(struct mv88e6xxx_chip *chip)
>  	return 0;
>  }
>  
> -static void mv88e6xxx_port_fast_age(struct dsa_switch *ds, int port)
> +static void mv88e6xxx_port_fast_age_fid(struct mv88e6xxx_chip *chip, int port,
> +					u16 fid)
>  {
> -	struct mv88e6xxx_chip *chip = ds->priv;
>  	int err;
>  
> -	if (dsa_to_port(ds, port)->lag)
> +	if (dsa_to_port(chip->ds, port)->lag)
>  		/* Hardware is incapable of fast-aging a LAG through a
>  		 * regular ATU move operation. Until we have something
>  		 * more fancy in place this is a no-op.
>  		 */
>  		return;
>  
> -	mv88e6xxx_reg_lock(chip);
> -	err = mv88e6xxx_g1_atu_remove(chip, 0, port, false);
> -	mv88e6xxx_reg_unlock(chip);
> +	err = mv88e6xxx_g1_atu_remove(chip, fid, port, false);
>  
>  	if (err)
> -		dev_err(ds->dev, "p%d: failed to flush ATU\n", port);
> +		dev_err(chip->ds->dev, "p%d: failed to flush ATU (FID %u)\n",
> +			port, fid);
> +}
> +
> +static void mv88e6xxx_port_fast_age(struct dsa_switch *ds, int port)
> +{
> +	struct mv88e6xxx_chip *chip = ds->priv;
> +
> +	mv88e6xxx_reg_lock(chip);
> +	mv88e6xxx_port_fast_age_fid(chip, port, 0);
> +	mv88e6xxx_reg_unlock(chip);
>  }
>  
>  static int mv88e6xxx_vtu_setup(struct mv88e6xxx_chip *chip)
> @@ -1818,6 +1826,159 @@ static int mv88e6xxx_stu_setup(struct mv88e6xxx_chip *chip)
>  	return mv88e6xxx_stu_loadpurge(chip, &stu);
>  }
>  
> +static int mv88e6xxx_sid_get(struct mv88e6xxx_chip *chip, u8 *sid)
> +{
> +	DECLARE_BITMAP(busy, MV88E6XXX_N_SID) = { 0 };
> +	struct mv88e6xxx_mst *mst;
> +
> +	set_bit(0, busy);

__set_bit

> +
> +	list_for_each_entry(mst, &chip->msts, node) {
> +		set_bit(mst->stu.sid, busy);
> +	}

Up to you, but parentheses are generally not used for single-line blocks.

> +
> +	*sid = find_first_zero_bit(busy, MV88E6XXX_N_SID);
> +
> +	return (*sid >= mv88e6xxx_max_sid(chip)) ? -ENOSPC : 0;
> +}
> +
> +static int mv88e6xxx_mst_put(struct mv88e6xxx_chip *chip, u8 sid)
> +{
> +	struct mv88e6xxx_mst *mst, *tmp;
> +	int err;
> +
> +	if (!sid)
> +		return 0;

Very minor nitpick: since mv88e6xxx_mst_put already checks this, could
you drop the "!sid" check from callers?

> +
> +	list_for_each_entry_safe(mst, tmp, &chip->msts, node) {
> +		if (mst->stu.sid != sid)
> +			continue;
> +
> +		if (!refcount_dec_and_test(&mst->refcnt))
> +			return 0;
> +
> +		mst->stu.valid = false;
> +		err = mv88e6xxx_stu_loadpurge(chip, &mst->stu);
> +		if (err)

Should we bother with a refcount_set(&mst->refcount, 1) on error?

> +			return err;
> +
> +		list_del(&mst->node);
> +		kfree(mst);
> +		return 0;
> +	}
> +
> +	return -ENOENT;
> +}
> +
> +static int mv88e6xxx_mst_get(struct mv88e6xxx_chip *chip, struct net_device *br,
> +			     u16 msti, u8 *sid)
> +{
> +	struct mv88e6xxx_mst *mst;
> +	int err, i;
> +
> +	if (!mv88e6xxx_has_stu(chip)) {
> +		err = -EOPNOTSUPP;
> +		goto err;
> +	}
> +
> +	if (!msti) {
> +		*sid = 0;
> +		return 0;
> +	}
> +
> +	list_for_each_entry(mst, &chip->msts, node) {
> +		if (mst->br == br && mst->msti == msti) {
> +			refcount_inc(&mst->refcnt);
> +			*sid = mst->stu.sid;
> +			return 0;
> +		}
> +	}
> +
> +	err = mv88e6xxx_sid_get(chip, sid);
> +	if (err)
> +		goto err;
> +
> +	mst = kzalloc(sizeof(*mst), GFP_KERNEL);
> +	if (!mst) {
> +		err = -ENOMEM;
> +		goto err;
> +	}
> +
> +	INIT_LIST_HEAD(&mst->node);
> +	refcount_set(&mst->refcnt, 1);
> +	mst->br = br;
> +	mst->msti = msti;
> +	mst->stu.valid = true;
> +	mst->stu.sid = *sid;
> +
> +	/* The bridge starts out all ports in the disabled state. But
> +	 * a STU state of disabled means to go by the port-global
> +	 * state. So we set all user port's initial state to blocking,
> +	 * to match the bridge's behavior.
> +	 */
> +	for (i = 0; i < mv88e6xxx_num_ports(chip); i++)
> +		mst->stu.state[i] = dsa_is_user_port(chip->ds, i) ?
> +			MV88E6XXX_PORT_CTL0_STATE_BLOCKING :
> +			MV88E6XXX_PORT_CTL0_STATE_DISABLED;
> +
> +	err = mv88e6xxx_stu_loadpurge(chip, &mst->stu);
> +	if (err)
> +		goto err_free;
> +
> +	list_add_tail(&mst->node, &chip->msts);
> +	return 0;
> +
> +err_free:
> +	kfree(mst);
> +err:
> +	return err;
> +}
> +
> +static int mv88e6xxx_port_mst_state_set(struct dsa_switch *ds, int port,
> +					const struct switchdev_mst_state *st)
> +{
> +	struct dsa_port *dp = dsa_to_port(ds, port);
> +	struct mv88e6xxx_chip *chip = ds->priv;
> +	struct mv88e6xxx_mst *mst;
> +	u8 state;
> +	int err;
> +
> +	if (!mv88e6xxx_has_stu(chip))
> +		return -EOPNOTSUPP;
> +
> +	switch (st->state) {
> +	case BR_STATE_DISABLED:
> +	case BR_STATE_BLOCKING:
> +	case BR_STATE_LISTENING:
> +		state = MV88E6XXX_PORT_CTL0_STATE_BLOCKING;
> +		break;
> +	case BR_STATE_LEARNING:
> +		state = MV88E6XXX_PORT_CTL0_STATE_LEARNING;
> +		break;
> +	case BR_STATE_FORWARDING:
> +		state = MV88E6XXX_PORT_CTL0_STATE_FORWARDING;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	list_for_each_entry(mst, &chip->msts, node) {
> +		if (mst->br == dsa_port_bridge_dev_get(dp) &&
> +		    mst->msti == st->msti) {
> +			if (mst->stu.state[port] == state)
> +				return 0;
> +
> +			mst->stu.state[port] = state;
> +			mv88e6xxx_reg_lock(chip);
> +			err = mv88e6xxx_stu_loadpurge(chip, &mst->stu);
> +			mv88e6xxx_reg_unlock(chip);
> +			return err;
> +		}
> +	}
> +
> +	return -ENOENT;
> +}
> +
>  static int mv88e6xxx_port_check_hw_vlan(struct dsa_switch *ds, int port,
>  					u16 vid)
>  {
> @@ -2437,6 +2598,12 @@ static int mv88e6xxx_port_vlan_leave(struct mv88e6xxx_chip *chip,
>  	if (err)
>  		return err;
>  
> +	if (!vlan.valid && vlan.sid) {
> +		err = mv88e6xxx_mst_put(chip, vlan.sid);
> +		if (err)
> +			return err;
> +	}
> +
>  	return mv88e6xxx_g1_atu_remove(chip, vlan.fid, port, false);
>  }
>  
> @@ -2482,6 +2649,72 @@ static int mv88e6xxx_port_vlan_del(struct dsa_switch *ds, int port,
>  	return err;
>  }
>  
> +static void mv88e6xxx_port_vlan_fast_age(struct dsa_switch *ds, int port, u16 vid)
> +{
> +	struct mv88e6xxx_chip *chip = ds->priv;
> +	struct mv88e6xxx_vtu_entry vlan;
> +	int err;
> +
> +	mv88e6xxx_reg_lock(chip);
> +
> +	err = mv88e6xxx_vtu_get(chip, vid, &vlan);
> +	if (err)
> +		goto unlock;
> +
> +	mv88e6xxx_port_fast_age_fid(chip, port, vlan.fid);
> +
> +unlock:
> +	mv88e6xxx_reg_unlock(chip);
> +
> +	if (err)
> +		dev_err(ds->dev, "p%d: failed to flush ATU in VID %u\n",
> +			port, vid);

This error message actually corresponds to an mv88e6xxx_vtu_get() error,
so the message is kind of incorrect. mv88e6xxx_port_fast_age_fid(),
whose error code isn't propagated here, has its own "failed to flush ATU"
error message.

> +}

Otherwise this looks pretty good.