From e9efbcd84ca910b416cb5869a9b92f0e2e73e72c Mon Sep 17 00:00:00 2001 From: Michael Brown Date: Sun, 5 Sep 2010 18:52:57 +0100 Subject: [PATCH] [rtl8139] Check for oversized packets when transmitting An attempt to transmit a packet of 8192 bytes or larger will collide with the status bits in the TX descriptor. This gives the appearance of the network card's transmit data path having just suddenly stopped responding; iPXE is waiting for the card to report a TX completion but, because of the status bit collision, the card thinks that the descriptor has not yet been written. Fix by explicitly checking for oversized packets in rtl_transmit(). Discovered during Fibre Channel over Ethernet testing, and debugged by using gdb to examine the state of the emulated rtl8139 card in qemu. Signed-off-by: Michael Brown --- src/drivers/net/rtl8139.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/src/drivers/net/rtl8139.c b/src/drivers/net/rtl8139.c index dd3f80e5..4ed43c02 100644 --- a/src/drivers/net/rtl8139.c +++ b/src/drivers/net/rtl8139.c @@ -86,6 +86,7 @@ FILE_LICENCE ( GPL_ANY ); #include #define TX_RING_SIZE 4 +#define TX_MAX_LEN 8192 struct rtl8139_tx { unsigned int next; @@ -383,6 +384,13 @@ static int rtl_transmit ( struct net_device *netdev, return -ENOBUFS; } + /* Check for oversized packets */ + if ( iob_len ( iobuf ) >= TX_MAX_LEN ) { + DBGC ( rtl, "rtl8139 %p TX too large (%zd bytes)\n", + rtl, iob_len ( iobuf ) ); + return -ERANGE; + } + /* Pad and align packet */ iob_pad ( iobuf, ETH_ZLEN );