Re: [Qemu-block] [PATCH RFC 1/1] vmstate: draft fix for failed iotests case 68 and 91

[Kevin Wolf]

Am 07.03.2017 um 03:53 hat QingFeng Hao geschrieben:
> I am not very clear about the logic in vmstate.c, but from its context in
> vmstate_save_state, it seems size should not be 0, otherwise the followed
> for loop will keep working on the same element. So I just add a simple
> check to pass that case, not sure if it's right but it can pass iotest
> case 68 and 91 now.
> 
> The iotest's failed output is:
> 068 1s ... - output mismatch (see 068.out.bad)
> --- 
> /home/haoqf/KVMonz/gitcheck/work/qemu-master/tree/qemu/tests/qemu-iotests/068.out
>    2017-03-06 05:52:24.817328899 +0100
> +++ 068.out.bad 2017-03-07 03:28:44.426714519 +0100
> @@ -3,9 +3,13 @@
>  === Saving and reloading a VM state to/from a qcow2 image ===
> 
>  Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072
> +qemu-system-s390x: migration/vmstate.c:336: vmstate_save_state: Assertion 
> `first_elem || !n_elems' failed.
> +./common.config: line 109: 52497 Aborted                 ( if [ -n 
> "${QEMU_NEED_PID}" ]; then
> +    echo $BASHPID > "${QEMU_TEST_DIR}/qemu-${_QEMU_HANDLE}.pid";
> +fi; exec "$QEMU_PROG" $QEMU_OPTIONS "$@" )
>  QEMU X.Y.Z monitor - type 'help' for more information
>  (qemu) savevm 0
> -(qemu) quit
> +qemu-system-s390x: Device 'virtio0' does not have the requested snapshot '0'
>  QEMU X.Y.Z monitor - type 'help' for more information
>  (qemu) quit
>  *** done
> 
> 091 1s ... [failed, exit status 1] - output mismatch (see 091.out.bad)
>     --- tests/qemu-iotests/091.out    2016-08-30 12:35:04.207683276 +0200
>     +++ 091.out.bad   2017-03-06 13:08:03.717135426 +0100
>     @@ -11,18 +11,23 @@
>      
>      vm1: qemu-io disk write complete
>      vm1: live migration started
>     -vm1: live migration completed
>     -
>     -=== VM 2: Post-migration, write to disk, verify running ===
>     -
>     -vm2: qemu-io disk write complete
>     -vm2: qemu process running successfully
>     -vm2: flush io, and quit
>     -Check image pattern
>     -read 4194304/4194304 bytes at offset 0
>     -4 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>     -Running 'qemu-img check -r all $TEST_IMG'
>     -No errors were found on the image.
>     -80/16384 = 0.49% allocated, 0.00% fragmented, 0.00% compressed clusters
>     -Image end offset: 5570560
>     -*** done
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +./common.qemu: line 110: write error: Broken pipe
>     +Timeout waiting for completed on handle 0
> 
> Signed-off-by: QingFeng Hao <address@hidden>
> ---
>  migration/vmstate.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/migration/vmstate.c b/migration/vmstate.c
> index 78b3cd4..ff28dde 100644
> --- a/migration/vmstate.c
> +++ b/migration/vmstate.c
> @@ -106,6 +106,10 @@ int vmstate_load_state(QEMUFile *f, const 
> VMStateDescription *vmsd,
>              int i, n_elems = vmstate_n_elems(opaque, field);
>              int size = vmstate_size(opaque, field);
>  
> +            if (size == 0) {
> +                field++;
> +                continue;
> +            }
>              vmstate_handle_alloc(first_elem, field, opaque);
>              if (field->flags & VMS_POINTER) {
>                  first_elem = *(void **)first_elem;
> @@ -322,6 +326,10 @@ void vmstate_save_state(QEMUFile *f, const 
> VMStateDescription *vmsd,
>              int64_t old_offset, written_bytes;
>              QJSON *vmdesc_loop = vmdesc;
>  
> +            if (size == 0) {
> +                field++;
> +                continue;
> +            }
>              trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems);
>              if (field->flags & VMS_POINTER) {
>                  first_elem = *(void **)first_elem;

This is really a live migration fix, so I'm adding Juan and Dave to CC.

I suspect the real question is why a field with size 0 was even stored
in the vmstate to begin with.

Kevin