Re: [libvirt] [PATCH v2] qemu: agent: Avoid agentError when closing the QEMU agent
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(a)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