[PATCH 5.4 296/320] net: axienet: fix number of TX ring slots for available check

Greg Kroah-Hartman
2022-01-24T19:41:36Z

From: Robert Hancock <robert.hancock@calian.com>

commit aba57a823d2985a2cc8c74a2535f3a88e68d9424 upstream.

The check for the number of available TX ring slots was off by 1 since a
slot is required for the skb header as well as each fragment. This could
result in overwriting a TX ring slot that was still in use.

Fixes: 8a3b7a252dca9 ("drivers/net/ethernet/xilinx: added Xilinx AXI Ethernet driver")
Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -636,7 +636,7 @@ axienet_start_xmit(struct sk_buff *skb,
num_frag = skb_shinfo(skb)->nr_frags;
cur_p = &lp->tx_bd_v[lp->tx_bd_tail];

- if (axienet_check_tx_bd_space(lp, num_frag)) {
+ if (axienet_check_tx_bd_space(lp, num_frag + 1)) {
if (netif_queue_stopped(ndev))
return NETDEV_TX_BUSY;

@@ -646,7 +646,7 @@ axienet_start_xmit(struct sk_buff *skb,
smp_mb();

/* Space might have just been freed - check again */
- if (axienet_check_tx_bd_space(lp, num_frag))
+ if (axienet_check_tx_bd_space(lp, num_frag + 1))
return NETDEV_TX_BUSY;

netif_wake_queue(ndev);