This is a note to let you know that I've just added the patch titled net: axienet: fix RX ring refill allocation failure handling to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-axienet-fix-rx-ring-refill-allocation-failure-ha.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 004f33a40f8961a6941b713e85f959fe72c3cc95 Author: Robert Hancock <robert.hancock@xxxxxxxxxx> Date: Fri Mar 4 20:24:37 2022 -0600 net: axienet: fix RX ring refill allocation failure handling [ Upstream commit 7a7d340ba4d9351e4c8847b898a2b996727a922a ] If a memory allocation error occurred during an attempt to refill a slot in the RX ring after the packet was received, the hardware tail pointer would still have been updated to point to or past the slot which remained marked as previously completed. This would likely result in the DMA engine raising an error when it eventually tried to use that slot again. If a slot cannot be refilled, then just stop processing and do not move the tail pointer past it. On the next attempt, we should skip receiving the packet from the empty slot and just try to refill it again. This failure mode has not actually been observed, but was found as part of other driver updates. Fixes: 8a3b7a252dca ("drivers/net/ethernet/xilinx: added Xilinx AXI Ethernet driver") Signed-off-by: Robert Hancock <robert.hancock@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c index 2169417210c2..80637ffcca93 100644 --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c @@ -857,46 +857,53 @@ static void axienet_recv(struct net_device *ndev) while ((cur_p->status & XAXIDMA_BD_STS_COMPLETE_MASK)) { dma_addr_t phys; - tail_p = lp->rx_bd_p + sizeof(*lp->rx_bd_v) * lp->rx_bd_ci; - /* Ensure we see complete descriptor update */ dma_rmb(); - phys = desc_get_phys_addr(lp, cur_p); - dma_unmap_single(ndev->dev.parent, phys, lp->max_frm_size, - DMA_FROM_DEVICE); skb = cur_p->skb; cur_p->skb = NULL; - length = cur_p->app4 & 0x0000FFFF; - - skb_put(skb, length); - skb->protocol = eth_type_trans(skb, ndev); - /*skb_checksum_none_assert(skb);*/ - skb->ip_summed = CHECKSUM_NONE; - - /* if we're doing Rx csum offload, set it up */ - if (lp->features & XAE_FEATURE_FULL_RX_CSUM) { - csumstatus = (cur_p->app2 & - XAE_FULL_CSUM_STATUS_MASK) >> 3; - if ((csumstatus == XAE_IP_TCP_CSUM_VALIDATED) || - (csumstatus == XAE_IP_UDP_CSUM_VALIDATED)) { - skb->ip_summed = CHECKSUM_UNNECESSARY; + + /* skb could be NULL if a previous pass already received the + * packet for this slot in the ring, but failed to refill it + * with a newly allocated buffer. In this case, don't try to + * receive it again. + */ + if (likely(skb)) { + length = cur_p->app4 & 0x0000FFFF; + + phys = desc_get_phys_addr(lp, cur_p); + dma_unmap_single(ndev->dev.parent, phys, lp->max_frm_size, + DMA_FROM_DEVICE); + + skb_put(skb, length); + skb->protocol = eth_type_trans(skb, ndev); + /*skb_checksum_none_assert(skb);*/ + skb->ip_summed = CHECKSUM_NONE; + + /* if we're doing Rx csum offload, set it up */ + if (lp->features & XAE_FEATURE_FULL_RX_CSUM) { + csumstatus = (cur_p->app2 & + XAE_FULL_CSUM_STATUS_MASK) >> 3; + if (csumstatus == XAE_IP_TCP_CSUM_VALIDATED || + csumstatus == XAE_IP_UDP_CSUM_VALIDATED) { + skb->ip_summed = CHECKSUM_UNNECESSARY; + } + } else if ((lp->features & XAE_FEATURE_PARTIAL_RX_CSUM) != 0 && + skb->protocol == htons(ETH_P_IP) && + skb->len > 64) { + skb->csum = be32_to_cpu(cur_p->app3 & 0xFFFF); + skb->ip_summed = CHECKSUM_COMPLETE; } - } else if ((lp->features & XAE_FEATURE_PARTIAL_RX_CSUM) != 0 && - skb->protocol == htons(ETH_P_IP) && - skb->len > 64) { - skb->csum = be32_to_cpu(cur_p->app3 & 0xFFFF); - skb->ip_summed = CHECKSUM_COMPLETE; - } - netif_rx(skb); + netif_rx(skb); - size += length; - packets++; + size += length; + packets++; + } new_skb = netdev_alloc_skb_ip_align(ndev, lp->max_frm_size); if (!new_skb) - return; + break; phys = dma_map_single(ndev->dev.parent, new_skb->data, lp->max_frm_size, @@ -905,7 +912,7 @@ static void axienet_recv(struct net_device *ndev) if (net_ratelimit()) netdev_err(ndev, "RX DMA mapping error\n"); dev_kfree_skb(new_skb); - return; + break; } desc_set_phys_addr(lp, phys, cur_p); @@ -913,6 +920,11 @@ static void axienet_recv(struct net_device *ndev) cur_p->status = 0; cur_p->skb = new_skb; + /* Only update tail_p to mark this slot as usable after it has + * been successfully refilled. + */ + tail_p = lp->rx_bd_p + sizeof(*lp->rx_bd_v) * lp->rx_bd_ci; + if (++lp->rx_bd_ci >= lp->rx_bd_num) lp->rx_bd_ci = 0; cur_p = &lp->rx_bd_v[lp->rx_bd_ci];