[libvirt] [PATCH v2] qemu: agent: Avoid agentError when closing the QEMU agent

[wang.yechao255 at zte.com.cn]

> On 9/28/18 5:36 AM, Wang Yechao wrote:
> > After calling qemuAgentClose(), it is still possible for
> > the QEMU Agent I/O event callback to get invoked. This
> > will trigger an agent error because mon->fd has been set
> > to -1 at this point.  Then vm->privateData->agentError is
> > always 'true' except that restart libvirtd or restart
> > qemu-guest-agent process in guest.
> >
> > Silently ignore the case where mon->fd is -1, likewise for
> > mon->watch being zero.
> >
> > Signed-off-by: Wang Yechao <wang.yechao255 at zte.com.cn>
> > ---
> > v1 patch:
> > https://www.redhat.com/archives/libvir-list/2018-September/msg01382.html
> >
> > Changes in v2:
> >  - do not set agentError, let agent state as disconnected instead of error.
> > ---
> >  src/qemu/qemu_agent.c | 13 ++++++++++++-
> >  1 file changed, 12 insertions(+), 1 deletion(-)
> >
>
> Since the v1 review referenced commit 89563efc which it seems you
> applied or liberally copied here, I think it would be a "good idea" to
> reference that commit in your commit message.  Imitation is a form of
> flattery and so as is attribution.
>
> John

Thanks for your advice, I should reference commit 89563efc in my
commit message.

> > diff --git a/src/qemu/qemu_agent.c b/src/qemu/qemu_agent.c
> > index 97ad0e7..d842b0e 100644
> > --- a/src/qemu/qemu_agent.c
> > +++ b/src/qemu/qemu_agent.c
> > @@ -530,6 +530,9 @@ static void qemuAgentUpdateWatch(qemuAgentPtr mon)
> >          VIR_EVENT_HANDLE_HANGUP |
> >          VIR_EVENT_HANDLE_ERROR;
> >
> > +    if (!mon->watch)
> > +        return;
> > +
> >      if (mon->lastError.code == VIR_ERR_OK) {
> >          events |= VIR_EVENT_HANDLE_READABLE;
> >
> > @@ -555,6 +558,12 @@ qemuAgentIO(int watch, int fd, int events, void *opaque)
> >      VIR_DEBUG("Agent %p I/O on watch %d fd %d events %d", mon, watch, fd, events);
> >  #endif
> >
> > +    if (mon->fd == -1 || mon->watch == 0) {
> > +        virObjectUnlock(mon);
> > +        virObjectUnref(mon);
> > +        return;
> > +    }
> > +
> >      if (mon->fd != fd || mon->watch != watch) {
> >          if (events & (VIR_EVENT_HANDLE_HANGUP | VIR_EVENT_HANDLE_ERROR))
> >              eof = true;
> > @@ -788,8 +797,10 @@ void qemuAgentClose(qemuAgentPtr mon)
> >      virObjectLock(mon);
> >
> >      if (mon->fd >= 0) {
> > -        if (mon->watch)
> > +        if (mon->watch) {
> >              virEventRemoveHandle(mon->watch);
> > +            mon->watch = 0;
> > +        }
> >          VIR_FORCE_CLOSE(mon->fd);
> >      }
> >
>
---
Best wishes
Wang Yechao