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: 018423e90bee ("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>

diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
index 4f913658eea465a84e28d38b910573803d66563e..24122ccda614cc46fab36f59b208977fbc8b62b7 100644 (file)
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
@@ -413,85 +413,63 @@ 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),
+               skb = napi_alloc_skb(napi, AQ_CFG_RX_HDR_SIZE);
+               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);
+
+               hdr_len = buff->len;
+               if (hdr_len > AQ_CFG_RX_HDR_SIZE)
+                       hdr_len = eth_get_headlen(skb->dev,
+                                                 aq_buf_vaddr(&buff->rxdata),
+                                                 AQ_CFG_RX_HDR_SIZE);
+
+               memcpy(__skb_put(skb, hdr_len), aq_buf_vaddr(&buff->rxdata),
+                      ALIGN(hdr_len, sizeof(long)));
+
+               if (buff->len - hdr_len > 0) {
+                       skb_add_rx_frag(skb, 0, buff->rxdata.page,
+                                       buff->rxdata.pg_off + hdr_len,
+                                       buff->len - hdr_len,
                                        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);
-                               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);
-
-                       hdr_len = buff->len;
-                       if (hdr_len > AQ_CFG_RX_HDR_SIZE)
-                               hdr_len = eth_get_headlen(skb->dev,
-                                                         aq_buf_vaddr(&buff->rxdata),
-                                                         AQ_CFG_RX_HDR_SIZE);
-
-                       memcpy(__skb_put(skb, hdr_len), aq_buf_vaddr(&buff->rxdata),
-                              ALIGN(hdr_len, sizeof(long)));
-
-                       if (buff->len - hdr_len > 0) {
-                               skb_add_rx_frag(skb, 0, buff->rxdata.page,
-                                               buff->rxdata.pg_off + hdr_len,
-                                               buff->len - hdr_len,
-                                               AQ_CFG_RX_FRAME_MAX);
-                               page_ref_inc(buff->rxdata.page);
-                       }
+               }
 
-                       if (!buff->is_eop) {
-                               buff_ = buff;
-                               i = 1U;
-                               do {
-                                       next_ = buff_->next,
-                                       buff_ = &self->buff_ring[next_];
+               if (!buff->is_eop) {
+                       buff_ = buff;
+                       i = 1U;
+                       do {
+                               next_ = buff_->next;
+                               buff_ = &self->buff_ring[next_];
 
-                                       dma_sync_single_range_for_cpu(
-                                                       aq_nic_get_dev(self->aq_nic),
-                                                       buff_->rxdata.daddr,
-                                                       buff_->rxdata.pg_off,
-                                                       buff_->len,
-                                                       DMA_FROM_DEVICE);
-                                       skb_add_rx_frag(skb, i++,
-                                                       buff_->rxdata.page,
-                                                       buff_->rxdata.pg_off,
-                                                       buff_->len,
-                                                       AQ_CFG_RX_FRAME_MAX);
-                                       page_ref_inc(buff_->rxdata.page);
-                                       buff_->is_cleaned = 1;
-
-                                       buff->is_ip_cso &= buff_->is_ip_cso;
-                                       buff->is_udp_cso &= buff_->is_udp_cso;
-                                       buff->is_tcp_cso &= buff_->is_tcp_cso;
-                                       buff->is_cso_err |= buff_->is_cso_err;
+                               dma_sync_single_range_for_cpu(aq_nic_get_dev(self->aq_nic),
+                                                             buff_->rxdata.daddr,
+                                                             buff_->rxdata.pg_off,
+                                                             buff_->len,
+                                                             DMA_FROM_DEVICE);
+                               skb_add_rx_frag(skb, i++,
+                                               buff_->rxdata.page,
+                                               buff_->rxdata.pg_off,
+                                               buff_->len,
+                                               AQ_CFG_RX_FRAME_MAX);
+                               page_ref_inc(buff_->rxdata.page);
+                               buff_->is_cleaned = 1;
 
-                               } while (!buff_->is_eop);
-                       }
+                               buff->is_ip_cso &= buff_->is_ip_cso;
+                               buff->is_udp_cso &= buff_->is_udp_cso;
+                               buff->is_tcp_cso &= buff_->is_tcp_cso;
+                               buff->is_cso_err |= buff_->is_cso_err;
+
+                       } while (!buff_->is_eop);
                }
 
                if (buff->is_vlan)