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From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <1b6a1999-95bb-5eac-70e1-39e6ba5b22fc@redhat.com>
Date: Mon, 5 Feb 2018 16:53:47 +0100
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Subject: Re: [Qemu-devel] [RFC] exec: eliminate ram naming issue as migration
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To: Jianfeng Tan <jianfeng.tan@intel.com>, qemu-devel@nongnu.org
Cc: Jason Wang <jasowang@redhat.com>, "Michael S . Tsirkin" <mst@redhat.com>, Maxime Coquelin <maxime.coquelin@redhat.com>

On 05/02/2018 15:58, Jianfeng Tan wrote:
> Here are some options to fix this:
>=20
> 1. When we do ram name comparison, we truncate the prefix as this patch=
 shows.
> It cannot cover the corner case: the source VM could have two ram block=
s
> with name of "pc.ram" and "/object/pc.ram".

That shouldn't happen ("pc.ram" exists even in the "-numa
node,memdev=3D..." case, but it has no RAM block).

>      RAMBLOCK_FOREACH(block) {
> -        if (!strcmp(name, block->idstr)) {
> +        name2 =3D strdup(block->idstr);
> +	id2 =3D basename(name2);
> +        if (!strcmp(id1, id2)) {
> +            free(name1);
> +	    free(name2);
>              return block;
>          }
> +	free(name2);

Instead of this, perhaps just skip "/object/" in both id1 and
block->idstr?  This also removes the need for strdup/free.

However, note that

  -m xG -numa node,memdev=3Dpc.ram \
  -object memory-backend-file,id=3Dpc.ram,...

works for both vhost-kernel and vhost-user, so I'd rather consider this
a configuration problem and not do anything.

Thanks,

Paolo

>      }
> =20
> +    free(name1);
>      return NULL;
>  }
> =20
>=20