netdev - Re: [PATCH net-next 3/4] net: dsa: mv88e6xxx: check hardware VLAN in use

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Date:	Sat, 13 Feb 2016 14:53:06 -0500
From:	Vivien Didelot <vivien.didelot@...oirfairelinux.com>
To:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	netdev@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, kernel@...oirfairelinux.com,
	"David S. Miller" <davem@...emloft.net>,
	Florian Fainelli <f.fainelli@...il.com>,
	Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH net-next 3/4] net: dsa: mv88e6xxx: check hardware VLAN in use

Hi Sergei,

Sergei Shtylyov <sergei.shtylyov@...entembedded.com> writes:

> Hello.
>
> On 2/12/2016 8:09 PM, Vivien Didelot wrote:
>
>> The DSA drivers now have access to the VLAN prepare phase and the bridge
>> net_device. It is easier to check for overlapping bridges from within
>> the driver. Thus add such check in mv88e6xxx_port_vlan_prepare.
>>
>> Signed-off-by: Vivien Didelot <vivien.didelot@...oirfairelinux.com>
>> ---
>>   drivers/net/dsa/mv88e6xxx.c | 64 +++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 64 insertions(+)
>>
>> diff --git a/drivers/net/dsa/mv88e6xxx.c b/drivers/net/dsa/mv88e6xxx.c
>> index 2e515e8..685dcb0 100644
>> --- a/drivers/net/dsa/mv88e6xxx.c
>> +++ b/drivers/net/dsa/mv88e6xxx.c
>> @@ -1471,14 +1471,78 @@ static int _mv88e6xxx_vlan_init(struct dsa_switch *ds, u16 vid,
>>   	return 0;
>>   }
>>
>> +static int mv88e6xxx_port_check_hw_vlan(struct dsa_switch *ds, int port,
>> +					u16 vid_begin, u16 vid_end)
>> +{
>> +	struct mv88e6xxx_priv_state *ps = ds_to_priv(ds);
>> +	struct mv88e6xxx_vtu_stu_entry vlan;
>> +	int i, err;
>> +
>> +	if (!vid_begin)
>> +		return -EOPNOTSUPP;
>> +
>> +	mutex_lock(&ps->smi_mutex);
>> +
>> +	err = _mv88e6xxx_vtu_vid_write(ds, vid_begin - 1);
>> +	if (err)
>> +		goto unlock;
>> +
>> +	do {
>> +		err = _mv88e6xxx_vtu_getnext(ds, &vlan);
>> +		if (err)
>> +			goto unlock;
>
>     Why are you not using *break*?

I use goto for explicit error handling, and break for expected flow.

>> +
>> +		if (!vlan.valid)
>> +			break;
>> +
>> +		if (vlan.vid > vid_end)
>> +			break;
>> +
>> +		for (i = 0; i < ps->num_ports; ++i) {
>> +			if (dsa_is_dsa_port(ds, i) || dsa_is_cpu_port(ds, i))
>> +				continue;
>> +
>> +			if (vlan.data[i] ==
>> +			    GLOBAL_VTU_DATA_MEMBER_TAG_NON_MEMBER)
>> +				continue;
>> +
>> +			if (ps->ports[i].bridge_dev ==
>> +			    ps->ports[port].bridge_dev)
>> +				break; /* same bridge, check next VLAN */
>> +
>> +			netdev_warn(ds->ports[port],
>> +				    "hardware VLAN %d already used by %s\n",
>> +				    vlan.vid,
>> +				    netdev_name(ps->ports[i].bridge_dev));
>> +			err = -EOPNOTSUPP;
>> +			goto unlock;
>> +		}
>
>     Why not *break*?

Because here it would only break the for loop, and not the while loop.

>
>> +	} while (vlan.vid < vid_end);
>> +
>> +unlock:
>> +	mutex_unlock(&ps->smi_mutex);
>> +
>> +	return err;
>> +}
>> +
> [...]
>
> MBR, Sergei

Thanks,
-v