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Date: Tue, 14 Aug 2012 12:48:49 -0300
From: Luiz Capitulino <lcapitulino@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] block-migration: deprecate block migration
 for the 1.2 release
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To: Kevin Wolf <kwolf@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

On Tue, 14 Aug 2012 17:02:26 +0200
Kevin Wolf <kwolf@redhat.com> wrote:

> Am 14.08.2012 16:52, schrieb Luiz Capitulino:
> > On Tue, 14 Aug 2012 15:48:37 +0200
> > Kevin Wolf <kwolf@redhat.com> wrote:
> > 
> >> Am 14.08.2012 15:32, schrieb Anthony Liguori:
> >>> To be replaced with live block copy.
> >>>
> >>> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
> >>
> >> Might be worth adding a deprecation note in qapi-schema.json.
> >>
> >>> ---
> >>>  migration.c |    9 +++++++++
> >>>  1 files changed, 9 insertions(+), 0 deletions(-)
> >>>
> >>> diff --git a/migration.c b/migration.c
> >>> index 653a3c1..babccf4 100644
> >>> --- a/migration.c
> >>> +++ b/migration.c
> >>> @@ -482,10 +482,19 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
> >>>      MigrationParams params;
> >>>      const char *p;
> >>>      int ret;
> >>> +    static bool suppress_deprecation_message;
> >>>  
> >>>      params.blk = blk;
> >>>      params.shared = inc;
> >>>  
> >>> +    if (blk && !suppress_deprecation_message) {
> >>
> >> Hm, it's consistent with when we start block migration, but has_blk is
> >> completely ignored for that and blk seems to be uninitialised if
> >> !has_blk. I think this needs to be fixed. (Why does qmp-marshal.c even
> >> compile when it can use blk uninitialised...?)
> > 
> > Are you referring to qmp_marshal_input_migrate()? Where does it use
> > blk uninitialized?
> 
> Yes, I am. Maybe I'm missing the obvious thing, but:
> 
> bool blk;
> ...
> if (has_blk) {
>     visit_type_bool(v, &blk, "blk", errp);
> }
> ...
> qmp_migrate(uri, has_blk, blk, has_inc, inc, has_detach, detach, errp);
> 
> If has_blk is false, blk is never assigned a value before the
> qmp_migrate() call, which uses it.

Yes, qmp_migrate() should only use blk if has_blk is true. The point you
made above about this patch is correct. I thought you were talking about
other usages.