在 2017/11/14 19:40, Marc-André Lureau 写道:
> Hi
>
> On Tue, Nov 14, 2017 at 8:09 AM, fangying <fangyi...@huawei.com> wrote:
>> Hi all,
>>
>> We have a vm running migration with vhost-user as network backend, we notice
>> that qemu will abort when openvswitch is restarted
>> when MEMORY_LISTENER_CALL_GLOBAL(log_global_start, Forward) is called. The
>> reasion is clear that vhost_dev_set_log returns -1 because
>> the network connection is temporarily lost due to the restart of openvswitch
>> service.
>>
>> Below is the trace of the call stack.
>>
>> #0 0x00007f868ed971d7 in raise() from /usr/lib64/libc.so.6
>> #1 0x00007f868ed988c8 in abort() from /usr/lib64/libc.so.6
>> #2 0x00000000004d0d35 in vhost_log_global_start (listener=<optimized out>)
>> at /usr/src/debug/qemu-kvm-2.8.1/hw/virtio/vhost.c:794
>> #2 0x0000000000486bd2 in memory_global_dirty_log_start at
>> /usr/src/debug/qemu-kvm-2.8.1/memory.c:2304
>> #3 0x0000000000486dcd in ram_save_init_globals at
>> /usr/src/debug/qemu-kvm-2.8.1/migration/ram.c:2072
>> #4 0x000000000048c185 in ram_save_setup (f=0x25e6ac0, opaque=<optimized
>> out>) at /usr/src/debug/qemu-kvm-2.8.1/migration/ram.c:2093
>> #5 0x00000000004fbee2 in qemu_savevm_state_begin at
>> /usr/src/debug/qemu-kvm-2.8.1/migration/savevm.c:956
>> #6 0x000000000083d8f8 in migration_thread at migration/migration.c:2198
>>
>> static void vhost_log_global_start(MemoryListener *listener)
>> {
>> int r;
>>
>> r = vhost_migration_log(listener, true);
>> if (r < 0) {
>> abort(); /* branch taken */
>> }
>> }
>>
>> What confuse me is that
>> 1. do we really need to abort here ?
>
> Not if we have a sane way to handle the situation. It make sense
> though to not want to support that use case (restarting the vhost-user
> process during migration).
>
>> 2. all member of callbacks in MemoryListener returned with type void, we
>> cannot judge in any upper function on the call stack.
>> Can we just cancel migration here instead of calling abort ? like:
>
> That would be acceptable to me, but there should be a better way than
> calling qmp_migrate_cancel() (we need to give a reason for cancelling,
> and report it to user). Juan should be able to help.
I agree with you, we'd better give more details here instead of passing NULL in
qmp_migrate_cancel.
>
>>
>> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
>> index ddc42f0..27ae4a2 100644
>> --- a/hw/virtio/vhost.c
>> +++ b/hw/virtio/vhost.c
>> @@ -27,6 +27,7 @@
>> #include "hw/virtio/virtio-access.h"
>> #include "migration/blocker.h"
>> #include "sysemu/dma.h"
>> +#include "qmp-commands.h"
>>
>> /* enabled until disconnected backend stabilizes */
>> #define _VHOST_DEBUG 1
>> @@ -885,7 +886,7 @@ static void vhost_log_global_start(MemoryListener
>> *listener)
>>
>> r = vhost_migration_log(listener, true);
>> if (r < 0) {
>> - abort();
>> + qmp_migrate_cancel(NULL);
>> }
>> }
>>
>> @@ -895,7 +896,7 @@ static void vhost_log_global_stop(MemoryListener
>> *listener)
>>
>> r = vhost_migration_log(listener, false);
>> if (r < 0) {
>> - abort();
>> + qmp_migrate_cancel(NULL);
>> }
>> }
>>
>>
>>
>>
>
>
>
