[Qemu-devel] [PATCH v8 0/7] char: non-blocking writes, virtio-console flow control

[Amit Shah]

Hello,

This refreshed series adds support for non-blocking chardev writes if
the caller asks for it.

This series does away with the special qemu_chr_write_nb() call that
did nonblocking writes.  Instead, now the writes are nonblocking if
the caller registers a callback function with the chardev that
indicates a driver became writable.

Individual drivers too have to be modified a bit to update their fd
handlers for nonblocking writes to work.

This series has non-blocking support for the unix and tcp drivers.
The virtio-console code is tweaked to use this facility.

This helps a fast guest slow down in case of a slow host reader.  The
worst-case condition was a guest writing data to a chardev that wasn't
being read from resulting in the guest getting unresponsive.

Amit Shah (7):
  virtio-console: Factor out common init between console and generic
    ports
  char: Add a QemuChrHandlers struct to initialise chardev handlers
  char: Introduce char_set/remove_fd_handlers()
  char: Add framework for a 'write unblocked' callback
  char: Update send_all() to handle nonblocking chardev write requests
  char: Equip the unix/tcp backend to handle nonblocking writes
  virtio-console: Enable port throttling when chardev is slow to
    consume data

 gdbstub.c            |    9 ++-
 hw/debugcon.c        |    2 +-
 hw/escc.c            |    9 ++-
 hw/etraxfs_ser.c     |   13 +++-
 hw/ivshmem.c         |   28 ++++++--
 hw/mcf_uart.c        |    9 ++-
 hw/pl011.c           |    9 ++-
 hw/pxa2xx.c          |   13 +++-
 hw/serial.c          |    9 ++-
 hw/sh_serial.c       |   12 +++-
 hw/syborg_serial.c   |    9 ++-
 hw/usb-serial.c      |    9 ++-
 hw/virtio-console.c  |   53 +++++++++-----
 hw/xen_console.c     |   16 +++--
 hw/xilinx_uartlite.c |   11 +++-
 monitor.c            |   19 ++++-
 net/slirp.c          |    8 ++-
 net/socket.c         |    4 +-
 qemu-char.c          |  190 ++++++++++++++++++++++++++++++++++++++++----------
 qemu-char.h          |   17 ++++-
 qemu_socket.h        |    2 +-
 21 files changed, 343 insertions(+), 108 deletions(-)

-- 
1.7.3.2