This is a note to let you know that I've just added the patch titled net: axienet: add missing memory barriers to the 5.16-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-add-missing-memory-barriers.patch and it can be found in the queue-5.16 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 95978df6fa328df619c15312e65ece469c2be2d2 Mon Sep 17 00:00:00 2001 From: Robert Hancock <robert.hancock@xxxxxxxxxx> Date: Tue, 18 Jan 2022 15:41:27 -0600 Subject: net: axienet: add missing memory barriers From: Robert Hancock <robert.hancock@xxxxxxxxxx> commit 95978df6fa328df619c15312e65ece469c2be2d2 upstream. This driver was missing some required memory barriers: Use dma_rmb to ensure we see all updates to the descriptor after we see that an entry has been completed. Use wmb and rmb to avoid stale descriptor status between the TX path and TX complete IRQ path. Fixes: 8a3b7a252dca9 ("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: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) --- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c @@ -632,6 +632,8 @@ static int axienet_free_tx_chain(struct if (nr_bds == -1 && !(status & XAXIDMA_BD_STS_COMPLETE_MASK)) break; + /* Ensure we see complete descriptor update */ + dma_rmb(); phys = desc_get_phys_addr(lp, cur_p); dma_unmap_single(ndev->dev.parent, phys, (cur_p->cntrl & XAXIDMA_BD_CTRL_LENGTH_MASK), @@ -645,8 +647,10 @@ static int axienet_free_tx_chain(struct cur_p->app1 = 0; cur_p->app2 = 0; cur_p->app4 = 0; - cur_p->status = 0; cur_p->skb = NULL; + /* ensure our transmit path and device don't prematurely see status cleared */ + wmb(); + cur_p->status = 0; if (sizep) *sizep += status & XAXIDMA_BD_STS_ACTUAL_LEN_MASK; @@ -704,6 +708,9 @@ static inline int axienet_check_tx_bd_sp int num_frag) { struct axidma_bd *cur_p; + + /* Ensure we see all descriptor updates from device or TX IRQ path */ + rmb(); cur_p = &lp->tx_bd_v[(lp->tx_bd_tail + num_frag) % lp->tx_bd_num]; if (cur_p->status & XAXIDMA_BD_STS_ALL_MASK) return NETDEV_TX_BUSY; @@ -843,6 +850,8 @@ static void axienet_recv(struct net_devi 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); Patches currently in stable-queue which might be from robert.hancock@xxxxxxxxxx are queue-5.16/net-axienet-wait-for-phyrstcmplt-after-core-reset.patch queue-5.16/net-axienet-add-missing-memory-barriers.patch queue-5.16/clk-si5341-fix-clock-hw-provider-cleanup.patch queue-5.16/net-axienet-increase-default-tx-ring-size-to-128.patch queue-5.16/net-axienet-fix-tx-ring-slot-available-check.patch queue-5.16/net-axienet-fix-for-tx-busy-handling.patch queue-5.16/net-axienet-limit-minimum-tx-ring-size.patch queue-5.16/net-axienet-reset-core-on-initialization-prior-to-mdio-access.patch queue-5.16/net-axienet-fix-number-of-tx-ring-slots-for-available-check.patch queue-5.16/net-axienet-increase-reset-timeout.patch