Re: [libvirt] [PATCH v2] virnetdevmacvlan.c: Introduce mutex for macvlan creation

On Fri, Mar 01, 2013 at 11:36:24AM +0100, Michal Privoznik wrote: > Currently, after we removed the qemu driver lock, it may happen > that two or more threads will start up a machine with macvlan and > race over virNetDevMacVLanCreateWithVPortProfile(). However, > there's a racy section in which we are generating a sequence of > possible device names and detecting if they exits. If we found > one which doesn't we try to create a device with that name. > However, the other thread is doing just the same. Assume it will > succeed and we must therefore fail. If this happens more than 5 > times (which in massive parallel startup surely will) we return > -1 without any error reported. This patch is a simple hack to > both of these problems. It introduces a mutex, so only one thread > will enter the section, and if it runs out of possibilities, > error is reported. Moreover, the number of retries is raised to 20. > --- > > diff to v1: > -don't increase @retries > -move error reporting to virNetDevMacVLanCreateMutexOnceInit > > src/util/virnetdevmacvlan.c | 37 ++++++++++++++++++++++++++++++++----- > 1 file changed, 32 insertions(+), 5 deletions(-) >

ACK Daniel