Re: [PATCH v2 14/15] block: Don't poll in bdrv_replace_child_noperm()

[Paolo Bonzini]

On 11/18/22 18:41, Kevin Wolf wrote:
> In order to make sure that bdrv_replace_child_noperm() doesn't have to
> poll any more, get rid of the bdrv_parent_drained_begin_single() call.
>
> This is possible now because we can require that the parent is already
> drained through the child in question when the function is called and we
> don't call the parent drain callbacks more than once.
>
> The additional drain calls needed in callers cause the test case to run
> its code in the drain handler too early (bdrv_attach_child() drains
> now), so modify it to only enable the code after the test setup has
> completed.
>
> Signed-off-by: Kevin Wolf<kwolf@redhat.com>

I hate to bear bad news, but this breaks the Windows builds on github 
(msys-32bit, msys-64bit) with an obscure but 100% reproducible

51/88 qemu:unit / test-bdrv-drain 
ERROR           1.30s   (exit status 3221225477 or signal 3221225349 
SIGinvalid)

The exit status is 0xC0000005 aka a Windows SIGSEGV.  With some luck it 
could be reproducible with Wine (but no gdb).

Paolo