Commit 9bd2702d authored Nov 23, 2020 by Lincoln Ramsay Committed by Jakub Kicinski Nov 24, 2020

aquantia: Remove the build_skb path



When performing IPv6 forwarding, there is an expectation that SKBs
will have some headroom. When forwarding a packet from the aquantia
driver, this does not always happen, triggering a kernel warning.

aq_ring.c has this code (edited slightly for brevity):

if (buff->is_eop && buff->len <= AQ_CFG_RX_FRAME_MAX - AQ_SKB_ALIGN) {
    skb = build_skb(aq_buf_vaddr(&buff->rxdata), AQ_CFG_RX_FRAME_MAX);
} else {
    skb = napi_alloc_skb(napi, AQ_CFG_RX_HDR_SIZE);

There is a significant difference between the SKB produced by these
2 code paths. When napi_alloc_skb creates an SKB, there is a certain
amount of headroom reserved. However, this is not done in the
build_skb codepath.

As the hardware buffer that build_skb is built around does not
handle the presence of the SKB header, this code path is being
removed and the napi_alloc_skb path will always be used. This code
path does have to copy the packet header into the SKB, but it adds
the packet data as a frag.

Fixes: 018423e9 ("net: ethernet: aquantia: Add ring support code")
Signed-off-by: Lincoln Ramsay <lincoln.ramsay@opengear.com>
Link: https://lore.kernel.org/r/MWHPR1001MB23184F3EAFA413E0D1910EC9E8FC0@MWHPR1001MB2318.namprd10.prod.outlook.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent d5496990

drivers/net/ethernet/aquantia/atlantic/aq_ring.c

+52 −74

Original line number	Diff line number	Diff line
		@@ -413,26 +413,6 @@ int aq_ring_rx_clean(struct aq_ring_s *self,
		buff->rxdata.pg_off,
		buff->len, DMA_FROM_DEVICE);

		/* for single fragment packets use build_skb() */
		if (buff->is_eop &&
		buff->len <= AQ_CFG_RX_FRAME_MAX - AQ_SKB_ALIGN) {
		skb = build_skb(aq_buf_vaddr(&buff->rxdata),
		AQ_CFG_RX_FRAME_MAX);
		if (unlikely(!skb)) {
		u64_stats_update_begin(&self->stats.rx.syncp);
		self->stats.rx.skb_alloc_fails++;
		u64_stats_update_end(&self->stats.rx.syncp);
		err = -ENOMEM;
		goto err_exit;
		}
		if (is_ptp_ring)
		buff->len -=
		aq_ptp_extract_ts(self->aq_nic, skb,
		aq_buf_vaddr(&buff->rxdata),
		buff->len);
		skb_put(skb, buff->len);
		page_ref_inc(buff->rxdata.page);
		} else {
		skb = napi_alloc_skb(napi, AQ_CFG_RX_HDR_SIZE);
		if (unlikely(!skb)) {
		u64_stats_update_begin(&self->stats.rx.syncp);
		@@ -468,11 +448,10 @@ int aq_ring_rx_clean(struct aq_ring_s *self,
		buff_ = buff;
		i = 1U;
		do {
		next_ = buff_->next,
		next_ = buff_->next;
		buff_ = &self->buff_ring[next_];

		dma_sync_single_range_for_cpu(
		aq_nic_get_dev(self->aq_nic),
		dma_sync_single_range_for_cpu(aq_nic_get_dev(self->aq_nic),
		buff_->rxdata.daddr,
		buff_->rxdata.pg_off,
		buff_->len,
		@@ -492,7 +471,6 @@ int aq_ring_rx_clean(struct aq_ring_s *self,

		} while (!buff_->is_eop);
		}
		}

		if (buff->is_vlan)
		__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),