[libvirt] [PATCH] libvirt: add daemon itself as shutdown reason
John Ferlan
jferlan at redhat.com
Tue Oct 16 12:48:52 UTC 2018
On 10/8/18 7:21 AM, Nikolay Shirokovskiy wrote:
> Let's introduce shutdown reason "daemon" which means we have to
> kill running domain ourselves as the best action we can take at
> that moment. Failure to pick up domain on daemon restart is
> one example of such case. Using reason "crashed" is a bit misleading
> as it is used when qemu is actually crashed or qemu destroyed on
> guest panic as result of user choice that is the problem was
> in qemu/guest itself. So I propose to use "crashed" only for
> qemu side issues and introduce "daemon" when we have to kill the qemu
> for good.
How about (although reading below may shed some more context):
This patch introduces a new shutdown reason "daemon" in order
to indicate that the daemon needed to force shutdown the domain
as the best course of action to take at the moment.
This action would occur during Reconnect processing when it's
determined that either the QEMU monitor no longer exists for
some unknown reason or creation of a thread to reconnect the
domain failed.
>
> There is another example where "daemon" will be useful. If we can
> not reboot domain we kill it and got "crashed" reason now. Looks
> like good candidate for "daemon" reason.
If you feel this way, then a followup patch could/should be posted;
otherwise, this'll be lost to commit message heaven where all good ideas
go to die ;-).
>
> Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy at virtuozzo.com>
> ---
> include/libvirt/libvirt-domain.h | 1 +
> src/conf/domain_conf.c | 3 ++-
> src/qemu/qemu_process.c | 11 ++++-------
> tools/virsh-domain-monitor.c | 3 ++-
> 4 files changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
> index fdd2d6b..11fdab5 100644
> --- a/include/libvirt/libvirt-domain.h
> +++ b/include/libvirt/libvirt-domain.h
> @@ -145,6 +145,7 @@ typedef enum {
> VIR_DOMAIN_SHUTOFF_FAILED = 6, /* domain failed to start */
> VIR_DOMAIN_SHUTOFF_FROM_SNAPSHOT = 7, /* restored from a snapshot which was
> * taken while domain was shutoff */
> + VIR_DOMAIN_SHUTOFF_DAEMON = 8, /* daemon have to kill domain */
s/have to/decides to/
> # ifdef VIR_ENUM_SENTINELS
> VIR_DOMAIN_SHUTOFF_LAST
> # endif
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 9911d56..e441723 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -779,7 +779,8 @@ VIR_ENUM_IMPL(virDomainShutoffReason, VIR_DOMAIN_SHUTOFF_LAST,
> "migrated",
> "saved",
> "failed",
> - "from snapshot")
> + "from snapshot",
> + "daemon")
>
> VIR_ENUM_IMPL(virDomainCrashedReason, VIR_DOMAIN_CRASHED_LAST,
> "unknown",
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index e9c7618..c4bc9ca 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -7988,15 +7988,12 @@ qemuProcessReconnect(void *opaque)
> /* We can't get the monitor back, so must kill the VM
> * to remove danger of it ending up running twice if
> * user tries to start it again later
Since we're changing anyway, let's put the stop there, e.g.
"s/later/later./"
> - * If we couldn't get the monitor since QEMU supports
> - * no-shutdown, we can safely say that the domain
> - * crashed ... */
> - state = VIR_DOMAIN_SHUTOFF_CRASHED;
> - /* If BeginJob failed, we jumped here without a job, let's hope another
> + * If BeginJob failed, we jumped here without a job, let's hope another
> * thread didn't have a chance to start playing with the domain yet
> * (it's all we can do anyway).
> */
> - qemuProcessStop(driver, obj, state, QEMU_ASYNC_JOB_NONE, stopFlags);
> + qemuProcessStop(driver, obj, VIR_DOMAIN_SHUTOFF_DAEMON,
> + QEMU_ASYNC_JOB_NONE, stopFlags);
> }
> goto cleanup;
> }
> @@ -8035,7 +8032,7 @@ qemuProcessReconnectHelper(virDomainObjPtr obj,
> * is no thread that could be doing anything else with the same domain
> * object.
> */
> - qemuProcessStop(src->driver, obj, VIR_DOMAIN_SHUTOFF_FAILED,
> + qemuProcessStop(src->driver, obj, VIR_DOMAIN_SHUTOFF_DAEMON,
> QEMU_ASYNC_JOB_NONE, 0);
> qemuDomainRemoveInactiveJobLocked(src->driver, obj);
>
When qemuProcessReconnectHelper was introduced (commit d38897a5d)
reconnection failure used VIR_DOMAIN_SHUTOFF_FAILED; however, that was
changed in commit bda2f17d to either VIR_DOMAIN_SHUTOFF_CRASHED or
VIR_DOMAIN_SHUTOFF_UNKNOWN. When QEMU_CAPS_NO_SHUTDOWN checking was
removed in commit fe35b1ad6 the conditional state was just left at
VIR_DOMAIN_SHUTOFF_CRASHED.
Still I agree w/ Martin's thoughts, which unfortunately wasn't commented
on in the code leading to the latter revert commit losing that unknown
reason. The reason for the "-no-shutdown" *did* change and that probably
should have been reflected in the qemuProcessReconnect logic.
So I think perhaps we should have an initial patch which references or
uses that first paragraph in order to change the code to:
/* We cannot get the monitor back, so kill the VM to
* remove possibility of it ending up running twice if
* user tries to start it again later.
*
* If we cannot get to the monitor when the QEMU command
* line used -no-shutdown, then we can safely say that the
* domain crashed; otherwise we don't really know. */
if (priv->monJSON && priv->allowReboot == VIR_TRISTATE_BOOL_YES)
state = VIR_DOMAIN_SHUTOFF_CRASHED;
else
state = VIR_DOMAIN_SHUTOFF_UNKNOWN;
and uses the short commit msg of "qemu: Restore lost shutdown reason".
Then this followup would change the "UNKNOWN" to "DAEMON" keeping the
CRASHED otherwise.
John
> diff --git a/tools/virsh-domain-monitor.c b/tools/virsh-domain-monitor.c
> index 3a26363..f0ad558 100644
> --- a/tools/virsh-domain-monitor.c
> +++ b/tools/virsh-domain-monitor.c
> @@ -212,7 +212,8 @@ VIR_ENUM_IMPL(virshDomainShutoffReason,
> N_("migrated"),
> N_("saved"),
> N_("failed"),
> - N_("from snapshot"))
> + N_("from snapshot"),
> + N_("daemon"))
>
> VIR_ENUM_DECL(virshDomainCrashedReason)
> VIR_ENUM_IMPL(virshDomainCrashedReason,
>
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