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net/cadence_gem: Don't rx packets when no rx buffer available

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Return false from can_receive() when no valid buffer descriptor is
available. Ensures against mass packet droppage in some applications.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: cde00ef774e84e2586bf10fd37b542f75bf36cfb.1386136219.git.peter.crosthwaite@xilinx.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Crosthwaite 2013-12-03 22:02:03 -08:00 committed by Peter Maydell
parent 3ae5725f86
commit 8202aa5391
1 changed files with 10 additions and 1 deletions
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11
hw/net/cadence_gem.c
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@ -463,6 +463,15 @@ static int gem_can_receive(NetClientState *nc)
return 0; return 0;
} }
if (rx_desc_get_ownership(s->rx_desc) == 1) {
if (s->can_rx_state != 2) {
s->can_rx_state = 2;
DB_PRINT("can't receive - busy buffer descriptor 0x%x\n",
s->rx_desc_addr);
}
return 0;
}
if (s->can_rx_state != 0) { if (s->can_rx_state != 0) {
s->can_rx_state = 0; s->can_rx_state = 0;
DB_PRINT("can receive 0x%x\n", s->rx_desc_addr); DB_PRINT("can receive 0x%x\n", s->rx_desc_addr);
@ -1142,7 +1151,7 @@ static void gem_write(void *opaque, hwaddr offset, uint64_t val,
/* Reset to start of Q when transmit disabled. */ /* Reset to start of Q when transmit disabled. */
s->tx_desc_addr = s->regs[GEM_TXQBASE]; s->tx_desc_addr = s->regs[GEM_TXQBASE];
} }
if (val & GEM_NWCTRL_RXENA) { if (gem_can_receive(qemu_get_queue(s->nic))) {
qemu_flush_queued_packets(qemu_get_queue(s->nic)); qemu_flush_queued_packets(qemu_get_queue(s->nic));
} }
break; break;