On Sun, Apr 10, 2005 at 09:27:27PM +0200, Thomas Graf ([email protected]) wrote:
> * jamal <[email protected]> 2005-04-10 10:39
> > Please crosspost on netdev - you should know that by now;->
> >
> > I actually disagreee with Herbert on this. Theres definetely good
> > need to have a more usable messaging system that rides on top of
> > netlink. It is not that netlink cant be extended (I actually think thats
> > a separate topic)
>
> I find it quite easy already but I guess a few macros would improve
> it even more. The routing attribute macros could be made generic to
> so can benefit from the advanages of TLVs.
>
> Evgeniy, Sorry for not having time earlier to give your patch a
> review. I'm not yet through completely and won't comment on the
> overall architecture until I have understood it all.
>
> diff -Nru /tmp/empty/cn_queue.c linux-2.6/drivers/connector/cn_queue.c
> --- /tmp/empty/cn_queue.c 1970-01-01 03:00:00.000000000 +0300
> +++ linux-2.6/drivers/connector/cn_queue.c 2004-09-24 00:01:00.000000000
> +int cn_queue_add_callback(struct cn_queue_dev *dev, struct cn_callback *cb)
> +{
> + struct cn_callback_entry *cbq, *n, *__cbq;
> + int found = 0;
> +
> + cbq = cn_queue_alloc_callback_entry(cb);
> + if (!cbq)
> + return -ENOMEM;
> +
> + atomic_inc(&dev->refcnt);
> + cbq->pdev = dev;
> +
> + spin_lock(&dev->queue_lock);
> + list_for_each_entry_safe(__cbq, n, &dev->queue_list, callback_entry) {
>
> Why _safe? There is no way a entry can be removed here.
No particular reason - it easier to copy-paste it from other line :)
> + if (cn_cb_equal(&__cbq->cb->id, &cb->id)) {
> + found = 1;
> + break;
> + }
> + }
> diff -Nru /tmp/empty/connector.c linux-2.6/drivers/connector/connector.c
> --- /tmp/empty/connector.c 1970-01-01 03:00:00.000000000 +0300
> +++ linux-2.6/drivers/connector/connector.c 2004-09-24 00:01:00.000000000
> +void cn_netlink_send(struct cn_msg *msg, u32 __groups)
> +{
> + struct cn_callback_entry *n, *__cbq;
> + unsigned int size;
> + struct sk_buff *skb;
> + struct nlmsghdr *nlh;
> + struct cn_msg *data;
> + struct cn_dev *dev = &cdev;
> + u32 groups = 0;
> + int found = 0;
> +
> + if (!__groups)
> + {
> + spin_lock(&dev->cbdev->queue_lock);
> + list_for_each_entry_safe(__cbq, n, &dev->cbdev->queue_list, callback_entry) {
>
> Same here
>
> + if (cn_cb_equal(&__cbq->cb->id, &msg->id)) {
> + found = 1;
> + groups = __cbq->group;
> + }
> + }
> + spin_unlock(&dev->cbdev->queue_lock);
> +
> + if (!found) {
> + printk(KERN_ERR "Failed to find multicast netlink group for callback[0x%x.0x%x]. seq=%u\n",
> + msg->id.idx, msg->id.val, msg->seq);
> + return;
> + }
> + }
> + else
> + groups = __groups;
> +
> + size = NLMSG_SPACE(sizeof(*msg) + msg->len);
> +
> + skb = alloc_skb(size, GFP_ATOMIC);
> + if (!skb) {
> + printk(KERN_ERR "Failed to allocate new skb with size=%u.\n", size);
> + return;
> + }
> +
> + nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh));
>
> This is not correct, what happens is:
> size = NLMSG_SPACE(sizeof(*msg) + msg->len);
> --> align(hdr)+align(data)
> size - sizeof(*nlh)
> --> (align(hdr)-hdr)+align(data)
> NLMSG_PUT pads again to get to the end of the data block (NLMSG_LENGTH)
> --> align(hdr)+(align(hdr)-hdr)+align(data)
>
> At the moment align(hdr) == hdr since nlmsghdr is already aligned
> but this might change and your code will break.
As far as I remember, header is always supposed to be aligned properly
"by design", so it even could be nonaligned here.
--
Evgeniy Polyakov ( s0mbre )
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