Re: [PATCH v8 3/4] libs/guest: allocate various migration arrays just once

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Sat, Jul 11, 2026 at 10:21:27PM +0100, Frediano Ziglio wrote:
> diff --git a/tools/libs/guest/xg_sr_save.c b/tools/libs/guest/xg_sr_save.c
> index e7c22e6500..34e41cf410 100644
> --- a/tools/libs/guest/xg_sr_save.c
> +++ b/tools/libs/guest/xg_sr_save.c
> @@ -115,24 +115,18 @@ static int write_batch(struct xc_sr_context *ctx)
>      assert(ctx->save.buffers);
>  
>      /* Mfns of the batch pfns. */
> -    mfns = malloc(nr_pfns * sizeof(*mfns));
> +    mfns = ctx->save.buffers->mfns;

You could have done the same thing you did in the previous patch, and
use const pointer ;-)

>      /* Types of the batch pfns. */
> -    types = malloc(nr_pfns * sizeof(*types));
> +    types = ctx->save.buffers->types;
>      /* Errors from attempting to map the gfns. */
> -    errors = malloc(nr_pfns * sizeof(*errors));
> +    errors = ctx->save.buffers->errors;
>      /* Pointers to locally allocated pages.  Need freeing. */
> -    local_pages = calloc(nr_pfns, sizeof(*local_pages));
> +    local_pages = ctx->save.buffers->local_pages;
> +    memset(local_pages, 0, sizeof(*local_pages) * nr_pfns);

This memset() looks unnecessary, the buffer is allocated with calloc()
so the page is already cleared. And write_batch() clear the array a
second time at the end. Did I miss something?

Thanks,


--
Anthony Perard | Vates XCP-ng Developer

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