skb

问题 in r8169 driver from realtek it does rx_buf = page_address(tp->Rx_databuff[entry]); dma_sync_single_for_cpu(d, addr, pkt_size, DMA_FROM_DEVICE); prefetch(rx_buf); skb_copy_to_linear_data(skb, rx_buf, pkt_size);<----//Do I get packet at this???? skb->tail += pkt_size; skb->len = pkt_size; dma_sync_single_for_device(d, addr, pkt_size, DMA_FROM_DEVICE); //csum... skb->protocol = eth_type_trans(skb, dev); napi_gro_receive(&tp->napi, skb); this is inside rtl_rx function called from poll of driver.

问题 in r8169 driver from realtek it does rx_buf = page_address(tp->Rx_databuff[entry]); dma_sync_single_for_cpu(d, addr, pkt_size, DMA_FROM_DEVICE); prefetch(rx_buf); skb_copy_to_linear_data(skb, rx_buf, pkt_size);<----//Do I get packet at this???? skb->tail += pkt_size; skb->len = pkt_size; dma_sync_single_for_device(d, addr, pkt_size, DMA_FROM_DEVICE); //csum... skb->protocol = eth_type_trans(skb, dev); napi_gro_receive(&tp->napi, skb); this is inside rtl_rx function called from poll of driver.

问题 I'm currently trying to debug an ATM encapsulation layer that runs on-top of Ethernet. Basically the ATM cells are stored in order after the ethernet header. However I suspect the drivers naive approach to the sk_buffs is broken. The driver blindly assumes that skb->data can be iterated through but looking at the kernel code for virtio_net.c:page_to_skb I see the following behaviour: memcpy(hdr, p, hdr_len); len -= hdr_len; p += offset; copy = len; if (copy > skb_tailroom(skb)) copy = skb