net: axienet: Fix TX ring slot available check

commit 996defd7f8b5dafc1d480b7585c7c62437f80c3c upstream.

The check for whether a TX ring slot was available was incorrect,
since a slot which had been loaded with transmit data but the device had
not started transmitting would be treated as available, potentially
causing non-transmitted slots to be overwritten. The control field in
the descriptor should be checked, rather than the status field (which may
only be updated when the device completes the entry).

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>

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index acfd7d545fef55391ffeb9305e963e98d1599562..94e39750932c7a0bc4ce9e631dc0185b7bd8c9eb 100644 (file)
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -643,7 +643,6 @@ static int axienet_free_tx_chain(struct net_device *ndev, u32 first_bd,
                if (cur_p->skb && (status & XAXIDMA_BD_STS_COMPLETE_MASK))
                        dev_consume_skb_irq(cur_p->skb);
 
-               cur_p->cntrl = 0;
                cur_p->app0 = 0;
                cur_p->app1 = 0;
                cur_p->app2 = 0;
@@ -651,6 +650,7 @@ static int axienet_free_tx_chain(struct net_device *ndev, u32 first_bd,
                cur_p->skb = NULL;
                /* ensure our transmit path and device don't prematurely see status cleared */
                wmb();
+               cur_p->cntrl = 0;
                cur_p->status = 0;
 
                if (sizep)
@@ -713,7 +713,7 @@ static inline int axienet_check_tx_bd_space(struct axienet_local *lp,
        /* 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)
+       if (cur_p->cntrl)
                return NETDEV_TX_BUSY;
        return 0;
 }