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[Qemu-devel] [PATCH 0/5] Global fix / workaround usage of qemu_chr_fe_wr
From: |
Daniel P. Berrange |
Subject: |
[Qemu-devel] [PATCH 0/5] Global fix / workaround usage of qemu_chr_fe_write |
Date: |
Wed, 3 Aug 2016 17:22:35 +0100 |
This series does a global fix and/or workaround for bad usage of
qemu_chr_fe_write(). Essentially only about 4/5 places in the code
got the usage correct, by handling errors. Everything else would
silently loose data if used with a chardev backend that can return
EAGAIN. One specific instance of that bug was highlighted when I
fixed the socket backend, such that in connect mode, it would be
non-blocking. https://bugs.launchpad.net/qemu/+bug/1586756
The "correct" fix is to check for short writes, or EAGAIN and
then schedule an event callback to re-try the write later. A
couple of places do that correctly (for example hw/char/serial.c
and hw/char/virtioconsole.c). Changing existing serial port
impls todo this though is a fair amount of amount, so as a
temporary fix, this series changes all the broken code to simply
use qemu_chr_fe_write_all() instead. Thus we at least stop
silently loosing data, albeit at the cost of blocking the guest
execution while we wait. So we still need to do a proper fix
in all these devices models at some point, hence I've left
comments in the code as a reminder.
This series also includes a patch to virtio-console I sent
previously, but with a fixed commit message that more accurately
describes what is going on.
Daniel P. Berrange (5):
virtio-console: set frontend open permanently for console devs
impi: check return of qemu_chr_fe_write() for errors
sclpconsole: remove bogus check for -EAGAIN
hw: replace most use of qemu_chr_fe_write with qemu_chr_fe_write_all
char: convert qemu_chr_fe_write to qemu_chr_fe_write_all
backends/rng-egd.c | 4 +++-
gdbstub.c | 4 +++-
hw/arm/omap2.c | 8 +++++---
hw/arm/pxa2xx.c | 4 +++-
hw/arm/strongarm.c | 4 +++-
hw/char/bcm2835_aux.c | 4 +++-
hw/char/debugcon.c | 4 +++-
hw/char/digic-uart.c | 2 ++
hw/char/escc.c | 4 +++-
hw/char/etraxfs_ser.c | 4 +++-
hw/char/exynos4210_uart.c | 4 +++-
hw/char/grlib_apbuart.c | 4 +++-
hw/char/imx_serial.c | 4 +++-
hw/char/ipoctal232.c | 4 +++-
hw/char/lm32_juart.c | 2 ++
hw/char/lm32_uart.c | 2 ++
hw/char/mcf_uart.c | 4 +++-
hw/char/parallel.c | 4 +++-
hw/char/pl011.c | 4 +++-
hw/char/sclpconsole-lm.c | 22 ++++++----------------
hw/char/sclpconsole.c | 2 ++
hw/char/sh_serial.c | 4 +++-
hw/char/spapr_vty.c | 5 +++--
hw/char/stm32f2xx_usart.c | 2 ++
hw/char/virtio-console.c | 46 +++++++++++++++++++++++++++++++++++++++++----
hw/char/xilinx_uartlite.c | 4 +++-
hw/ipmi/ipmi_bmc_extern.c | 8 ++++++--
hw/usb/ccid-card-passthru.c | 7 +++++--
hw/usb/dev-serial.c | 4 +++-
qemu-char.c | 18 ++++++++++++------
slirp/slirp.c | 4 +++-
31 files changed, 146 insertions(+), 54 deletions(-)
--
2.7.4
- [Qemu-devel] [PATCH 0/5] Global fix / workaround usage of qemu_chr_fe_write,
Daniel P. Berrange <=
- [Qemu-devel] [PATCH 4/5] hw: replace most use of qemu_chr_fe_write with qemu_chr_fe_write_all, Daniel P. Berrange, 2016/08/03
- [Qemu-devel] [PATCH 1/5] virtio-console: set frontend open permanently for console devs, Daniel P. Berrange, 2016/08/03
- [Qemu-devel] [PATCH 2/5] impi: check return of qemu_chr_fe_write() for errors, Daniel P. Berrange, 2016/08/03
- [Qemu-devel] [PATCH 3/5] sclpconsole: remove bogus check for -EAGAIN, Daniel P. Berrange, 2016/08/03
- [Qemu-devel] [PATCH 5/5] char: convert qemu_chr_fe_write to qemu_chr_fe_write_all, Daniel P. Berrange, 2016/08/03