On Mon, Mar 26, 2018 at 03:19:36PM +0200, Ján Tomko wrote: > On Wed, Mar 14, 2018 at 05:33:05PM +0000, Daniel P. Berrangé wrote: > > There is a race condition when spawning QEMU where libvirt has spawned > > QEMU but the monitor socket is not yet open. Libvirt has to repeatedly > > try to connect() to QEMU's monitor until eventually it succeeds, or > > times out. We use kill() to check if QEMU is still alive so we avoid > > waiting a long time if QEMU exited, but having a timeout at all is still > > unpleasant. > > > > With QEMU 2.12 we can pass in a pre-opened FD for UNIX domain or TCP > > sockets. If libvirt has called bind() and listen() on this FD, then we > > have a guarantee that libvirt can immediately call connect() and > > succeed without any race. > > > > Although we only really care about this for the monitor socket and agent > > socket, this patch does FD passing for all UNIX socket based character > > devices since there appears to be no downside to it. > > > > We don't do FD passing for TCP sockets, however, because it is only > > possible to pass a single FD, while some hostnames may require listening > > on multiple FDs to cover IPv4 and IPv6 concurrently. > > > > Signed-off-by: Daniel P. Berrangé <berrange@xxxxxxxxxx> > > --- > > src/qemu/qemu_command.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++-- > > 1 file changed, 56 insertions(+), 2 deletions(-) > > > > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c > > index fa0aa5d5c3..291aad13cf 100644 > > --- a/src/qemu/qemu_command.c > > +++ b/src/qemu/qemu_command.c > > @@ -5010,8 +5010,62 @@ qemuBuildChrChardevStr(virLogManagerPtr logManager, > > break; > > > > case VIR_DOMAIN_CHR_TYPE_UNIX: > > - virBufferAsprintf(&buf, "socket,id=%s,path=", charAlias); > > - virQEMUBuildBufferEscapeComma(&buf, dev->data.nix.path); > > +#ifndef WIN32 > > Why the ifdef? > > Do we even build QEMU driver on WIN32? Good point - this was just habit for any UNIX sockets code. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
