Re: [PATCH] libxl_set_memory_target: retain the same maxmem offset on top of the current target

[Don Slutz <dslutz@verizon.com>]

On 11/25/14 12:54, Stefano Stabellini wrote:
> In libxl_set_memory_target when setting the new maxmem, retain the same
> offset on top of the current target. The offset includes memory
> allocated by QEMU for rom files.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
>
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index de23fec..8381c3e 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -4767,10 +4767,12 @@ retry_transaction:
>                   "%s/memory/videoram", dompath));
>       videoram = videoram_s ? atoi(videoram_s) : 0;
>   
> -    if (enforce) {
> -        memorykb = new_target_memkb;
> -        rc = xc_domain_setmaxmem(ctx->xch, domid, memorykb +
> -                LIBXL_MAXMEM_CONSTANT);
> +    libxl_dominfo_init(&ptr);
> +    xcinfo2xlinfo(ctx, &info, &ptr);

This fills ptr with uninitialized data.  You need to call

xc_domain_getinfolist()

before this.  However calling xc_domain_getinfolist() here and retry
of the xenstore transaction, you will adjust this more then one time.

So I think that xc_domain_getinfolist() needs to be called before
the label retry_transaction.  However rc is a mess in this routine.

rc = 1 is the normal return (since rc = xc_domain_getinfolist() is
the last setting of rc).  So all the rest of "rc =" needs to be adjusted
someway.

    -Don Slutz


> +
> +    if (enforce && new_target_memkb > 0) {
> +        memorykb = ptr.max_memkb - current_target_memkb + new_target_memkb;
> +        rc = xc_domain_setmaxmem(ctx->xch, domid, memorykb);
>           if (rc != 0) {
>               LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR,
>                       "xc_domain_setmaxmem domid=%d memkb=%d failed "
> @@ -4800,8 +4802,6 @@ retry_transaction:
>           goto out;
>       }
>   
> -    libxl_dominfo_init(&ptr);
> -    xcinfo2xlinfo(ctx, &info, &ptr);
>       uuid = libxl__uuid2string(gc, ptr.uuid);
>       libxl__xs_write(gc, t, libxl__sprintf(gc, "/vm/%s/memory", uuid),
>               "%"PRIu32, new_target_memkb / 1024);
>
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