On Sun, Dec 09, 2018 at 01:01:27PM -0500, Demi M. Obenour wrote:
> This can happen via `xl destroy`, for example. When this happens,
> libvirt is stuck in an inconsistent state: libvirt believes the domain
> is still running, but attempts to use libvirt’s APIs to shutdown the
> domain fail. The only way out of this situation is to restart libvirt.
>
> To prevent this from happening, process LIBXL_EVENT_TYPE_DOMAIN_DEATH as
> well as LIBXL_EVENT_TYPE_DOMAIN_SHUTDOWN, but only if libvirt has not
> already begun to destroy the domain.
>
> Signed-off-by: Demi Obenour <demiobenour@xxxxxxxxx>
> ---
> src/conf/domain_conf.h | 4 ++++
> src/libxl/libxl_domain.c | 24 +++++++++++++++++++-----
> 2 files changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index b24e6ec3de..d3520bde15 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -2620,6 +2620,10 @@ struct _virDomainObj {
> unsigned int updated : 1;
> unsigned int removing : 1;
>
> + /* Only used by the Xen backend */
> + unsigned int being_destroyed_by_libvirt : 1;
> + unsigned int already_destroyed : 1;
This ought to go in the _libxlDomainObjPrivate struct instead
> diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c
> index 5fe3f44fbe..680e5f209f 100644
> --- a/src/libxl/libxl_domain.c
> +++ b/src/libxl/libxl_domain.c
> @@ -482,9 +482,21 @@ libxlDomainShutdownThread(void *opaque)
> goto cleanup;
> }
>
> + VIR_INFO("Domain %d died", event->domid);
> +
> if (libxlDomainObjBeginJob(driver, vm, LIBXL_JOB_MODIFY) < 0)
> goto cleanup;
>
> + if (LIBXL_EVENT_TYPE_DOMAIN_DEATH == ev->type) {
Normal style is to have variable name first, constant second
> + if (vm->being_destroyed_by_libvirt) {
> + VIR_INFO("VM %d already being destroyed by libvirt",
> event->domid);
The patch got mangled by your mail client i'm afraid.
> + goto cleanup;
> + }
> +
> + VIR_INFO("Marking VM %d as already destroyed", event->domid);
> + vm->already_destroyed = true;
Using 'true' for an "unsigned int :1' bitfield is not valid.
You would nede to declare the variable as a bool, or use an
integer value here.
> + }
> +
> if (xl_reason == LIBXL_SHUTDOWN_REASON_POWEROFF) {
> virDomainObjSetState(vm, VIR_DOMAIN_SHUTOFF,
> VIR_DOMAIN_SHUTOFF_SHUTDOWN);
> @@ -620,7 +632,8 @@ libxlDomainEventHandler(void *data,
> VIR_LIBXL_EVENT_CONST libxl_event *event)
> virThread thread;
> libxlDriverConfigPtr cfg;
>
> - if (event->type != LIBXL_EVENT_TYPE_DOMAIN_SHUTDOWN) {
> + if (LIBXL_EVENT_TYPE_DOMAIN_DEATH != event->type &&
> + LIBXL_EVENT_TYPE_DOMAIN_SHUTDOWN != event->type) {
Again, this is contrary to normal libvirt style, so please put it
back to variable name first.
> VIR_INFO("Unhandled event type %d", event->type);
> goto error;
> }
> @@ -629,18 +642,16 @@ libxlDomainEventHandler(void *data,
> VIR_LIBXL_EVENT_CONST libxl_event *event)
> * Start a thread to handle shutdown. We don't want to be tying up
> * libxl's event machinery by doing a potentially lengthy shutdown.
> */
> - if (VIR_ALLOC(shutdown_info) < 0)
> - goto error;
> + while (VIR_ALLOC(shutdown_info) < 0) {}
Huh ? This is busy-waiting when getting OOM which is definitely
not what we want.
>
> shutdown_info->driver = driver;
> shutdown_info->event = (libxl_event *)event;
> - if (virThreadCreate(&thread, false, libxlDomainShutdownThread,
> + while (virThreadCreate(&thread, false, libxlDomainShutdownThread,
> shutdown_info) < 0) {
Again, busy-waiting when failin to spawn threads.
> /*
> * Not much we can do on error here except log it.
> */
> VIR_ERROR(_("Failed to create thread to handle domain shutdown"));
> - goto error;
> }
>
> /*
> @@ -752,6 +763,9 @@ libxlDomainDestroyInternal(libxlDriverPrivatePtr driver,
> {
> libxlDriverConfigPtr cfg = libxlDriverConfigGet(driver);
> int ret = -1;
> + if (vm->already_destroyed)
> + return -1;
> + vm->being_destroyed_by_libvirt = true;
Again, using a bool "true" with an unsigned int bitfied.
>
> /* Unlock virDomainObj during destroy, which can take considerable
> * time on large memory domains.
Regards,
Daniel
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