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double-check me?

To: Maillist netdev <netdev@xxxxxxxxxxx>
Subject: double-check me?
From: Jeff Garzik <jgarzik@xxxxxxxxx>
Date: Sun, 17 Aug 2003 13:45:52 -0400
Cc: "David S. Miller" <davem@xxxxxxxxxx>
Organization: none
Sender: netdev-bounce@xxxxxxxxxxx
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2.1) Gecko/20021213 Debian/1.2.1-2.bunk
Maybe you guys can spot something I'm missing here. alloc_netdev is supposed to guarantee that dev->priv is aligned by 32 bytes:

struct net_device *alloc_netdev(int sizeof_priv, const char *mask,
                                       void (*setup)(struct net_device *))
{
        struct net_device *dev;
        int alloc_size;

        /* ensure 32-byte alignment of the private area */
        alloc_size = sizeof (*dev) + sizeof_priv + 31;

        dev = (struct net_device *) kmalloc (alloc_size, GFP_KERNEL);
        if (dev == NULL)
        {
printk(KERN_ERR "alloc_dev: Unable to allocate device memory.\n"
);
                return NULL;
        }

        memset(dev, 0, alloc_size);

        if (sizeof_priv)
                dev->priv = (void *) (((long)(dev + 1) + 31) & ~31);


Now... shouldn't that last line of code be "dev + 1 + sizeof(*dev)" ?

It seems to work 2.[456] for a long time, so I am doubting myself... surely it would have caused memory corruption or something by now if I have really found a bug.

        Jeff




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