On Wed, 27 Mar 2013 10:10:42 +0100 Stefan Hajnoczi <stefa...@redhat.com> wrote:
> 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: Nice series: Applied to the qmp branch, thanks. > > 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 <mpriv...@redhat.com> 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. > > v2: > * Rename socket_set_nonblock() in Patch 1 to avoid code churn [eblake] > * Avoid qemu_set_block(-1) calls that clobber errno [quintela] > > Stefan Hajnoczi (4): > oslib-posix: rename socket_set_nonblock() to qemu_set_nonblock() > net: ensure "socket" backend uses non-blocking fds > qemu-socket: set passed fd non-blocking in socket_connect() > 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 | 13 +++++++++---- > 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, 37 insertions(+), 28 deletions(-) >
