[libvirt] [PATCH v3 1/2] libvirtd: fix crash on termination

[John Ferlan]

On 10/24/2017 06:47 AM, Nikolay Shirokovskiy wrote:
> The problem is incorrect order of qemu driver shutdown and shutdown
> of netserver threads that serve client requests (thru qemu driver
> particularly).
> 
> Net server threads are shutdowned upon dispose which is triggered
> by last daemon object unref at the end of main function. At the same
> time qemu driver is shutdowned earlier in virStateCleanup. As a result
> netserver threads see invalid driver object in the middle of request
> processing.
> 
> Let's move shutting down netserver threads earlier to virNetDaemonClose.
> 
> Note: order of last daemon unref and virStateCleanup
> is introduced in 85c3a182 for a valid reason.
> ---
> 
> One can use next patch to trigger crash on termination. Call domstats function 
> and then send TERM to libvirtd.
> 
> Patch to trigger crash
> #   diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> #   index cf5e4ad..39a57aa 100644
> #   --- a/src/qemu/qemu_driver.c
> #   +++ b/src/qemu/qemu_driver.c
> #   @@ -20144,6 +20144,8 @@ qemuConnectGetAllDomainStats(virConnectPtr conn,
> #        domflags = 0;
> #        vm = vms[i];
> #
> #   +    sleep(5);
> #   +
> #        virObjectLock(vm);
> #
> #        if (HAVE_JOB(privflags) &&
> 
>  src/rpc/virnetdaemon.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/src/rpc/virnetdaemon.c b/src/rpc/virnetdaemon.c
> index e3b9390..495bc4b 100644
> --- a/src/rpc/virnetdaemon.c
> +++ b/src/rpc/virnetdaemon.c
> @@ -880,6 +880,8 @@ virNetDaemonClose(virNetDaemonPtr dmn)
>      virObjectLock(dmn);
>  
>      virHashForEach(dmn->servers, daemonServerClose, NULL);
> +    virHashFree(dmn->servers);

Should this be virHashRemoveAll?

Or I wonder if the virHashFree in virNetDaemonDispose.

John

(I'm at KVM Forum this week so responses will be delayed)

> +    dmn->servers = NULL;
>  
>      virObjectUnlock(dmn);
>  }
>