[pxe] Update UNDI transmit count before transmitting packet

It is possible that the UNDI ISR may be triggered before netdev_tx()
returns control to pxenv_undi_transmit().  This means that
pxenv_undi_isr() may see a zero undi_tx_count, and so not check for TX
completions.  This is not a significant problem, since it will check
for TX completions on the next call to pxenv_undi_isr() anyway; it
just means that the NBP will see a spurious IRQ that was apparently
caused by nothing.

Fix by updating the undi_tx_count before calling netdev_tx(), so that
pxenv_undi_isr() can decrement it and report the TX completion.

diff --git a/src/arch/i386/interface/pxe/pxe_undi.c b/src/arch/i386/interface/pxe/pxe_undi.c
index e284c905dd957388a6844109e41026aba2c63e4b..bd387ea552ad0cc8200ce3a030e0e166e7a81b8c 100644 (file)
--- a/src/arch/i386/interface/pxe/pxe_undi.c
+++ b/src/arch/i386/interface/pxe/pxe_undi.c
@@ -316,18 +316,22 @@ PXENV_EXIT_t pxenv_undi_transmit ( struct s_PXENV_UNDI_TRANSMIT
                }
        }
 
+       /* Flag transmission as in-progress.  Do this before starting
+        * to transmit the packet, because the ISR may trigger before
+        * we return from netdev_tx().
+        */
+       undi_tx_count++;
+
        /* Transmit packet */
-       DBG2 ( "\n" ); /* ISR may trigger before we return from netdev_tx() */
+       DBG2 ( "\n" );
        if ( ( rc = netdev_tx ( pxe_netdev, iobuf ) ) != 0 ) {
                DBG2 ( "PXENV_UNDI_TRANSMIT could not transmit: %s\n",
                       strerror ( rc ) );
+               undi_tx_count--;
                undi_transmit->Status = PXENV_STATUS ( rc );
                return PXENV_EXIT_FAILURE;
        }
 
-       /* Flag transmission as in-progress */
-       undi_tx_count++;
-
        undi_transmit->Status = PXENV_STATUS_SUCCESS;
        return PXENV_EXIT_SUCCESS;
 }