netdev - Re: [PATCH v3 net-next 3/5] dsa: add DSA switch driver for Microchip KSZ9477

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Message-ID: <20170522143134.GC29447@lunn.ch>
Date:   Mon, 22 May 2017 16:31:34 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Woojung.Huh@...rochip.com
Cc:     f.fainelli@...il.com, vivien.didelot@...oirfairelinux.com,
        sergei.shtylyov@...entembedded.com, netdev@...r.kernel.org,
        davem@...emloft.net, UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH v3 net-next 3/5] dsa: add DSA switch driver for Microchip
 KSZ9477

On Fri, May 19, 2017 at 10:57:12PM +0000, Woojung.Huh@...rochip.com wrote:

> +static struct {
> +	int index;
> +	char string[ETH_GSTRING_LEN];

Hi Woojung

Since you need to respin for the skb_put_padto(), please make this
const.

> +static int get_vlan_table(struct dsa_switch *ds, u16 vid, u32 *vlan_table)
> +{
> +	struct ksz_device *dev = ds->priv;
> +	u8 data;
> +	int timeout = 1000;
> +
> +	ksz_write16(dev, REG_SW_VLAN_ENTRY_INDEX__2, vid & VLAN_INDEX_M);
> +	ksz_write8(dev, REG_SW_VLAN_CTRL, VLAN_READ | VLAN_START);
> +
> +	/* wait to be cleared */
> +	data = 0;
> +	do {
> +		ksz_read8(dev, REG_SW_VLAN_CTRL, &data);
> +		if (!(data & VLAN_START))
> +			break;
> +		usleep_range(1, 10);
> +	} while (timeout-- > 0);
> +
> +	if (!timeout)
> +		return -ETIMEDOUT;
> +
> +	ksz_read32(dev, REG_SW_VLAN_ENTRY__4, &vlan_table[0]);
> +	ksz_read32(dev, REG_SW_VLAN_ENTRY_UNTAG__4, &vlan_table[1]);
> +	ksz_read32(dev, REG_SW_VLAN_ENTRY_PORTS__4, &vlan_table[2]);
> +
> +	ksz_write8(dev, REG_SW_VLAN_CTRL, 0);
> +
> +	return 0;
> +}
> +
> +static int set_vlan_table(struct dsa_switch *ds, u16 vid, u32 *vlan_table)
> +{
> +	struct ksz_device *dev = ds->priv;
> +	u8 data;
> +	int timeout = 1000;
> +
> +	ksz_write32(dev, REG_SW_VLAN_ENTRY__4, vlan_table[0]);
> +	ksz_write32(dev, REG_SW_VLAN_ENTRY_UNTAG__4, vlan_table[1]);
> +	ksz_write32(dev, REG_SW_VLAN_ENTRY_PORTS__4, vlan_table[2]);
> +
> +	ksz_write16(dev, REG_SW_VLAN_ENTRY_INDEX__2, vid & VLAN_INDEX_M);
> +	ksz_write8(dev, REG_SW_VLAN_CTRL, VLAN_START | VLAN_WRITE);
> +
> +	do {
> +		ksz_read8(dev, REG_SW_VLAN_CTRL, &data);
> +		if (!(data & VLAN_START))
> +			break;
> +		usleep_range(1, 10);
> +	} while (timeout-- > 0);
> +
> +	if (!timeout)
> +		return -ETIMEDOUT;
> +
> +	ksz_write8(dev, REG_SW_VLAN_CTRL, 0);
> +
> +	mutex_lock(&dev->vlancache_mutex);

Humm. I think this is wrong. Shouldn't you hold the mutex while you
change the hardware as well as the cache. Otherwise there is a risk
your cache could be different to the hardware when you get a race
between two threads?

> +
> +	/* update vlan cache table */
> +	dev->vlan_cache[vid].table[0] = vlan_table[0];
> +	dev->vlan_cache[vid].table[1] = vlan_table[1];
> +	dev->vlan_cache[vid].table[2] = vlan_table[2];
> +
> +	mutex_unlock(&dev->vlancache_mutex);
> +
> +	return 0;
> +}

  Andrew