linux-kernel - Re: [PATCH net-next] net: dsa: mv88e6xxx: rework port state setter

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Date:	Tue, 8 Mar 2016 15:36:51 +0100
From:	Andrew Lunn <andrew@...n.ch>
To:	Vivien Didelot <vivien.didelot@...oirfairelinux.com>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel@...oirfairelinux.com,
	"David S. Miller" <davem@...emloft.net>,
	Kevin Smith <kevin.smith@...csyscorp.com>
Subject: Re: [PATCH net-next] net: dsa: mv88e6xxx: rework port state setter

On Mon, Mar 07, 2016 at 06:24:17PM -0500, Vivien Didelot wrote:
> Apply a few non-functional changes on the port state setter:
> 
>   * add a dynamic debug message with state names to track changes
>   * explicit states checking instead of assuming their numeric values
>   * lock mutex only once when changing several port states
>   * use bitmap macros to declare and access port_state_update_mask
> 
> Signed-off-by: Vivien Didelot <vivien.didelot@...oirfairelinux.com>

Tested-by: Andrew Lunn <andrew@...n.ch>

Thanks
	Andrew

> ---
>  drivers/net/dsa/mv88e6xxx.c | 54 +++++++++++++++++++++++++++------------------
>  drivers/net/dsa/mv88e6xxx.h |  2 +-
>  2 files changed, 34 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/net/dsa/mv88e6xxx.c b/drivers/net/dsa/mv88e6xxx.c
> index d11c9d5..3a58a8a 100644
> --- a/drivers/net/dsa/mv88e6xxx.c
> +++ b/drivers/net/dsa/mv88e6xxx.c
> @@ -1051,39 +1051,49 @@ static int _mv88e6xxx_atu_remove(struct dsa_switch *ds, u16 fid, int port,
>  	return _mv88e6xxx_atu_move(ds, fid, port, 0x0f, static_too);
>  }
>  
> -static int mv88e6xxx_set_port_state(struct dsa_switch *ds, int port, u8 state)
> +static const char * const mv88e6xxx_port_state_names[] = {
> +	[PORT_CONTROL_STATE_DISABLED] = "Disabled",
> +	[PORT_CONTROL_STATE_BLOCKING] = "Blocking/Listening",
> +	[PORT_CONTROL_STATE_LEARNING] = "Learning",
> +	[PORT_CONTROL_STATE_FORWARDING] = "Forwarding",
> +};
> +
> +static int _mv88e6xxx_port_state(struct dsa_switch *ds, int port, u8 state)
>  {
> -	struct mv88e6xxx_priv_state *ps = ds_to_priv(ds);
>  	int reg, ret = 0;
>  	u8 oldstate;
>  
> -	mutex_lock(&ps->smi_mutex);
> -
>  	reg = _mv88e6xxx_reg_read(ds, REG_PORT(port), PORT_CONTROL);
> -	if (reg < 0) {
> -		ret = reg;
> -		goto abort;
> -	}
> +	if (reg < 0)
> +		return reg;
>  
>  	oldstate = reg & PORT_CONTROL_STATE_MASK;
> +
>  	if (oldstate != state) {
>  		/* Flush forwarding database if we're moving a port
>  		 * from Learning or Forwarding state to Disabled or
>  		 * Blocking or Listening state.
>  		 */
> -		if (oldstate >= PORT_CONTROL_STATE_LEARNING &&
> -		    state <= PORT_CONTROL_STATE_BLOCKING) {
> +		if ((oldstate == PORT_CONTROL_STATE_LEARNING ||
> +		     oldstate == PORT_CONTROL_STATE_FORWARDING)
> +		    && (state == PORT_CONTROL_STATE_DISABLED ||
> +			state == PORT_CONTROL_STATE_BLOCKING)) {
>  			ret = _mv88e6xxx_atu_remove(ds, 0, port, false);
>  			if (ret)
> -				goto abort;
> +				return ret;
>  		}
> +
>  		reg = (reg & ~PORT_CONTROL_STATE_MASK) | state;
>  		ret = _mv88e6xxx_reg_write(ds, REG_PORT(port), PORT_CONTROL,
>  					   reg);
> +		if (ret)
> +			return ret;
> +
> +		netdev_dbg(ds->ports[port], "PortState %s (was %s)\n",
> +			   mv88e6xxx_port_state_names[state],
> +			   mv88e6xxx_port_state_names[oldstate]);
>  	}
>  
> -abort:
> -	mutex_unlock(&ps->smi_mutex);
>  	return ret;
>  }
>  
> @@ -1146,13 +1156,11 @@ int mv88e6xxx_port_stp_update(struct dsa_switch *ds, int port, u8 state)
>  		break;
>  	}
>  
> -	netdev_dbg(ds->ports[port], "port state %d [%d]\n", state, stp_state);
> -
>  	/* mv88e6xxx_port_stp_update may be called with softirqs disabled,
>  	 * so we can not update the port state directly but need to schedule it.
>  	 */
>  	ps->ports[port].state = stp_state;
> -	set_bit(port, &ps->port_state_update_mask);
> +	set_bit(port, ps->port_state_update_mask);
>  	schedule_work(&ps->bridge_work);
>  
>  	return 0;
> @@ -2228,11 +2236,15 @@ static void mv88e6xxx_bridge_work(struct work_struct *work)
>  	ps = container_of(work, struct mv88e6xxx_priv_state, bridge_work);
>  	ds = ((struct dsa_switch *)ps) - 1;
>  
> -	while (ps->port_state_update_mask) {
> -		port = __ffs(ps->port_state_update_mask);
> -		clear_bit(port, &ps->port_state_update_mask);
> -		mv88e6xxx_set_port_state(ds, port, ps->ports[port].state);
> -	}
> +	mutex_lock(&ps->smi_mutex);
> +
> +	for (port = 0; port < ps->num_ports; ++port)
> +		if (test_and_clear_bit(port, ps->port_state_update_mask) &&
> +		    _mv88e6xxx_port_state(ds, port, ps->ports[port].state))
> +			netdev_warn(ds->ports[port], "failed to update state to %s\n",
> +				    mv88e6xxx_port_state_names[ps->ports[port].state]);
> +
> +	mutex_unlock(&ps->smi_mutex);
>  }
>  
>  static int mv88e6xxx_setup_port(struct dsa_switch *ds, int port)
> diff --git a/drivers/net/dsa/mv88e6xxx.h b/drivers/net/dsa/mv88e6xxx.h
> index d7b088d..3425616 100644
> --- a/drivers/net/dsa/mv88e6xxx.h
> +++ b/drivers/net/dsa/mv88e6xxx.h
> @@ -426,7 +426,7 @@ struct mv88e6xxx_priv_state {
>  
>  	struct mv88e6xxx_priv_port	ports[DSA_MAX_PORTS];
>  
> -	unsigned long port_state_update_mask;
> +	DECLARE_BITMAP(port_state_update_mask, DSA_MAX_PORTS);
>  
>  	struct work_struct bridge_work;
>  };
> -- 
> 2.7.2
>