Chris Leech <[email protected]> wrote:
>
> Locks down user pages and sets up for DMA in tcp_recvmsg, then calls
> dma_async_try_early_copy in tcp_v4_do_rcv
>
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
+#ifdef CONFIG_NET_DMA
waaay too many ifdefs. There are various tricks we use to minimise them.
> +#ifdef CONFIG_NET_DMA
> + tp->ucopy.dma_chan = NULL;
> + if ((len > sysctl_tcp_dma_copybreak) && !(flags & MSG_PEEK) && !sysctl_tcp_low_latency && __get_cpu_var(softnet_data.net_dma))
> + dma_lock_iovec_pages(msg->msg_iov, len, &tp->ucopy.locked_list);
> +#endif
Please try to fit code into 80 columns.
That's decimal 80 ;)
> @@ -1328,13 +1342,39 @@ do_prequeue:
> }
>
> if (!(flags & MSG_TRUNC)) {
> - err = skb_copy_datagram_iovec(skb, offset,
> - msg->msg_iov, used);
> - if (err) {
> - /* Exception. Bailout! */
> - if (!copied)
> - copied = -EFAULT;
> - break;
> +#ifdef CONFIG_NET_DMA
> + if (!tp->ucopy.dma_chan && tp->ucopy.locked_list)
> + tp->ucopy.dma_chan = get_softnet_dma();
> +
> + if (tp->ucopy.dma_chan) {
> + tp->ucopy.dma_cookie = dma_skb_copy_datagram_iovec(
> + tp->ucopy.dma_chan, skb, offset,
> + msg->msg_iov, used,
> + tp->ucopy.locked_list);
> +
> + if (tp->ucopy.dma_cookie < 0) {
> +
> + printk(KERN_ALERT "dma_cookie < 0\n");
> +
> + /* Exception. Bailout! */
> + if (!copied)
> + copied = -EFAULT;
> + break;
> + }
> + if ((offset + used) == skb->len)
> + copied_early = 1;
> +
Consider trimming some of those blank lines. I don't think they add any
value?
> + } else
> +#endif
> + {
These games with ifdefs and else statements aren't at all pleasant.
Sometimes they're hard to avoid, but you'll probably find that some code
rearrangemnt (in a preceding patch) makes it easier. Like, split this
function into several.
> @@ -1354,15 +1394,33 @@ skip_copy:
>
> if (skb->h.th->fin)
> goto found_fin_ok;
> - if (!(flags & MSG_PEEK))
> - sk_eat_skb(sk, skb);
> + if (!(flags & MSG_PEEK)) {
> + if (!copied_early)
> + sk_eat_skb(sk, skb);
> +#ifdef CONFIG_NET_DMA
> + else {
> + __skb_unlink(skb, &sk->sk_receive_queue);
> + __skb_queue_tail(&sk->sk_async_wait_queue, skb);
> + copied_early = 0;
> + }
> +#endif
> ...
> - sk_eat_skb(sk, skb);
> + if (!(flags & MSG_PEEK)) {
> + if (!copied_early)
> + sk_eat_skb(sk, skb);
> +#ifdef CONFIG_NET_DMA
> + else {
> + __skb_unlink(skb, &sk->sk_receive_queue);
> + __skb_queue_tail(&sk->sk_async_wait_queue, skb);
> + copied_early = 0;
> + }
> +#endif
> + }
etc.
> +#ifdef CONFIG_NET_DMA
> + if (copied_early)
> + __skb_queue_tail(&sk->sk_async_wait_queue, skb);
> + else
> +#endif
> if (eaten)
> __kfree_skb(skb);
> else
etc.
> @@ -4049,6 +4067,52 @@ discard:
> return 0;
> }
>
> +#ifdef CONFIG_NET_DMA
> +int dma_async_try_early_copy(struct sock *sk, struct sk_buff *skb, int hlen)
> +{
> + struct tcp_sock *tp = tcp_sk(sk);
> + int chunk = skb->len - hlen;
> + int dma_cookie;
> + int copied_early = 0;
> +
> + if (tp->ucopy.wakeup)
> + goto out;
In this case a simple
return 0;
would be fine. We haven't done anything yet.
> +#ifdef CONFIG_NET_DMA
> + struct tcp_sock *tp = tcp_sk(sk);
> + if (!tp->ucopy.dma_chan && tp->ucopy.locked_list)
> + tp->ucopy.dma_chan = get_softnet_dma();
> + if (tp->ucopy.dma_chan)
> + ret = tcp_v4_do_rcv(sk, skb);
> + else
> +#endif
> + {
> + if (!tcp_prequeue(sk, skb))
> ret = tcp_v4_do_rcv(sk, skb);
> + }
> } else
etc.
> +#ifdef CONFIG_NET_DMA
> + struct tcp_sock *tp = tcp_sk(sk);
> + if (tp->ucopy.dma_chan)
> + ret = tcp_v6_do_rcv(sk, skb);
> + else
> +#endif
> + {
> + if (!tcp_prequeue(sk, skb))
> + ret = tcp_v6_do_rcv(sk, skb);
> + }
> } else
ow, my eyes!
-
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