From 154f1e30c09d261b12937c385632c05474989b02 Mon Sep 17 00:00:00 2001 From: Bo Yang Date: Wed, 29 Aug 2012 19:26:11 +0800 Subject: [PATCH] eepro100: Fix network hang when rx buffers run out This is reported by QA. When installing os with pxe, after the initial kernel and initrd are loaded, the procedure tries to copy files from install server to local harddisk, the network becomes stall because of running out of receive descriptor. [Whitespace fixes and removed qemu_notify_event() because Paolo's earlier net patches have moved it into qemu_flush_queued_packets(). Additional info: I can reproduce the network hang with a tap device doing a iPXE HTTP boot as follows: $ qemu -enable-kvm -m 1024 \ -netdev tap,id=netdev0,script=no,downscript=no \ -device i82559er,netdev=netdev0,romfile=80861209.rom \ -drive if=virtio,cache=none,file=test.img iPXE> ifopen net0 iPXE> config # set static network configuration iPXE> kernel http://mirror.bytemark.co.uk/fedora/linux/releases/17/Fedora/x86_64/os/images/pxeboot/vmlinuz I needed a vanilla iPXE ROM to get to the iPXE prompt. I think the boot prompt has been disabled in the ROMs that ship with QEMU to reduce boot time. During the vmlinuz HTTP download there is a network hang. hw/eepro100.c has reached the end of the rx descriptor list. When the iPXE driver replenishes the rx descriptor list we don't kick the QEMU net subsystem and event loop, thereby leaving the tap netdev without its file descriptor in select(2). Stefan Hajnoczi ] Signed-off-by: Bo Yang Signed-off-by: Stefan Hajnoczi (cherry picked from commit 1069985fb132cd4324fc02d371f1e61492a1823f) Signed-off-by: Michael Roth --- hw/eepro100.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/hw/eepro100.c b/hw/eepro100.c index 50d117e..5b23116 100644 --- a/hw/eepro100.c +++ b/hw/eepro100.c @@ -1036,6 +1036,7 @@ static void eepro100_ru_command(EEPRO100State * s, uint8_t val) } set_ru_state(s, ru_ready); s->ru_offset = e100_read_reg4(s, SCBPointer); + qemu_flush_queued_packets(&s->nic->nc); TRACE(OTHER, logout("val=0x%02x (rx start)\n", val)); break; case RX_RESUME: @@ -1770,7 +1771,8 @@ static ssize_t nic_receive(NetClientState *nc, const uint8_t * buf, size_t size) if (rfd_command & COMMAND_EL) { /* EL bit is set, so this was the last frame. */ logout("receive: Running out of frames\n"); - set_ru_state(s, ru_suspended); + set_ru_state(s, ru_no_resources); + eepro100_rnr_interrupt(s); } if (rfd_command & COMMAND_S) { /* S bit is set. */