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[Qemu-devel] [PATCH 0/4] monitor: do not rely on O_NONBLOCK for passed f
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH 0/4] monitor: do not rely on O_NONBLOCK for passed file descriptors |
Date: |
Tue, 26 Mar 2013 17:07:48 +0100 |
There are several places where QEMU accidentally relies on the O_NONBLOCK state
of passed file descriptors. Exposing O_NONBLOCK state makes it part of the QMP
API whenever getfd or fdset_add_fd are used!
Whether or not QEMU will use O_NONBLOCK is an implementation detail and should
be hidden from QMP clients.
This patch series addresses this in 3 steps:
1. Fix callers of monitor_handle_fd_param(), monitor_fdset_get_fd(), and
monitor_get_fd() that depend on O_NONBLOCK being set. Luckily there are
only two instances and they are fixed in Patches 1 & 2.
2. Rename socket_set_nonblock() to qemu_set_nonblock() just like
qemu_set_cloexec(). This makes code cleaner when working with arbitrary
file descriptors that may not be sockets. See Patch 3.
3. Clear O_NONBLOCK when a chardev receives file descriptors. From now on QEMU
can assume that passed file descriptors are in blocking mode. Simply use
qemu_set_nonblock(fd) if you want to enable O_NONBLOCK. See Patch 4.
This fixes live migration with recent libvirt. Libvirt checks if QEMU supports
file descriptor passing and, if yes, hands QEMU a socket with O_NONBLOCK set.
The migrate fd:<foo> code assumes the socket is in blocking mode. The result
is a corrupted migration stream. For more info on this bug, see:
https://bugzilla.redhat.com/show_bug.cgi?id=923124
Note that Michal Privoznik <address@hidden> also sent a libvirt patch so
that old QEMUs work with new libvirts:
https://www.redhat.com/archives/libvir-list/2013-March/msg01486.html
My patch series fixes the QMP API and allows old libvirts to work again with
new QEMUs.
Stefan Hajnoczi (4):
net: ensure "socket" backend uses non-blocking fds
qemu-socket: set passed fd non-blocking in socket_connect()
oslib-posix: rename socket_set_nonblock() to qemu_set_nonblock()
chardev: clear O_NONBLOCK on SCM_RIGHTS file descriptors
block/nbd.c | 2 +-
block/sheepdog.c | 2 +-
include/qemu/sockets.h | 4 ++--
migration.c | 2 +-
nbd.c | 8 ++++----
net/socket.c | 8 +++++---
qemu-char.c | 11 +++++++----
savevm.c | 2 +-
slirp/misc.c | 2 +-
slirp/tcp_subr.c | 4 ++--
ui/vnc.c | 2 +-
util/oslib-posix.c | 4 ++--
util/oslib-win32.c | 4 ++--
util/qemu-sockets.c | 5 +++--
14 files changed, 33 insertions(+), 27 deletions(-)
--
1.8.1.4
- [Qemu-devel] [PATCH 0/4] monitor: do not rely on O_NONBLOCK for passed file descriptors,
Stefan Hajnoczi <=