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. Changed in v2: - Dropped virtio-console patch which already merged in 2.7 Daniel P. Berrange (4): impi: check return of qemu_chr_fe_write() for errors sclpconsolelm: 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 | 21 +++++++++++++++++++++ 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, 125 insertions(+), 50 deletions(-) -- 2.7.4
