From fe944a0427202e1074240820711c89eecdad22e7 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Thu, 8 Aug 2013 21:48:24 +0800 Subject: [PATCH] USBNET: support DMA SG This patch introduces support of DMA SG if the USB host controller which usbnet device is attached to is capable of building packet from discontinuous buffers. The patch supports passing the skb fragment buffers to usb stack directly via urb->sg. Cc: Ben Hutchings Cc: Grant Grundler Cc: Freddy Xin Cc: Alan Stern Acked-by: Oliver Neukum Signed-off-by: Ming Lei Reviewed-by: Eric Dumazet Acked-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/usb/usbnet.c | 45 +++++++++++++++++++++++++++++++++++--- include/linux/usb/usbnet.h | 1 + 2 files changed, 43 insertions(+), 3 deletions(-) diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index 06ee82f557d45..27a00b0060332 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -1197,6 +1197,37 @@ EXPORT_SYMBOL_GPL(usbnet_tx_timeout); /*-------------------------------------------------------------------------*/ +static int build_dma_sg(const struct sk_buff *skb, struct urb *urb) +{ + unsigned num_sgs, total_len = 0; + int i, s = 0; + + num_sgs = skb_shinfo(skb)->nr_frags + 1; + if (num_sgs == 1) + return 0; + + urb->sg = kmalloc(num_sgs * sizeof(struct scatterlist), GFP_ATOMIC); + if (!urb->sg) + return -ENOMEM; + + urb->num_sgs = num_sgs; + sg_init_table(urb->sg, urb->num_sgs); + + sg_set_buf(&urb->sg[s++], skb->data, skb_headlen(skb)); + total_len += skb_headlen(skb); + + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { + struct skb_frag_struct *f = &skb_shinfo(skb)->frags[i]; + + total_len += skb_frag_size(f); + sg_set_page(&urb->sg[i + s], f->page.p, f->size, + f->page_offset); + } + urb->transfer_buffer_length = total_len; + + return 1; +} + netdev_tx_t usbnet_start_xmit (struct sk_buff *skb, struct net_device *net) { @@ -1223,7 +1254,6 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb, goto drop; } } - length = skb->len; if (!(urb = usb_alloc_urb (0, GFP_ATOMIC))) { netif_dbg(dev, tx_err, dev->net, "no urb\n"); @@ -1233,10 +1263,14 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb, entry = (struct skb_data *) skb->cb; entry->urb = urb; entry->dev = dev; - entry->length = length; usb_fill_bulk_urb (urb, dev->udev, dev->out, skb->data, skb->len, tx_complete, skb); + if (dev->can_dma_sg) { + if (build_dma_sg(skb, urb) < 0) + goto drop; + } + entry->length = length = urb->transfer_buffer_length; /* don't assume the hardware handles USB_ZERO_PACKET * NOTE: strictly conforming cdc-ether devices should expect @@ -1305,7 +1339,10 @@ drop: not_drop: if (skb) dev_kfree_skb_any (skb); - usb_free_urb (urb); + if (urb) { + kfree(urb->sg); + usb_free_urb(urb); + } } else netif_dbg(dev, tx_queued, dev->net, "> tx, len %d, type 0x%x\n", length, skb->protocol); @@ -1356,6 +1393,7 @@ static void usbnet_bh (unsigned long param) rx_process (dev, skb); continue; case tx_done: + kfree(entry->urb->sg); case rx_cleanup: usb_free_urb (entry->urb); dev_kfree_skb (skb); @@ -1689,6 +1727,7 @@ int usbnet_resume (struct usb_interface *intf) retval = usb_submit_urb(res, GFP_ATOMIC); if (retval < 0) { dev_kfree_skb_any(skb); + kfree(res->sg); usb_free_urb(res); usb_autopm_put_interface_async(dev->intf); } else { diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h index f18d64129f999..2b47e6364e369 100644 --- a/include/linux/usb/usbnet.h +++ b/include/linux/usb/usbnet.h @@ -34,6 +34,7 @@ struct usbnet { struct mutex phy_mutex; unsigned char suspend_count; unsigned char pkt_cnt, pkt_err; + unsigned can_dma_sg:1; /* i/o info: pipes etc */ unsigned in, out; -- 2.39.5