On Tue, 14 Nov 2023 17:16:57 +0800 Baoquan He <b...@redhat.com> wrote:
> This function, being a variant of walk_system_ram_res() introduced in
> commit 8c86e70acead ("resource: provide new functions to walk through
> resources"), walks through a list of all the resources of System RAM
> in reversed order, i.e., from higher to lower.
>
> It will be used in kexec_file code to load kernel, initrd etc when
> preparing kexec reboot.
>
> ...
>
> +/*
> + * This function, being a variant of walk_system_ram_res(), calls the @func
> + * callback against all memory ranges of type System RAM which are marked as
> + * IORESOURCE_SYSTEM_RAM and IORESOUCE_BUSY in reversed order, i.e., from
> + * higher to lower.
> + */
> +int walk_system_ram_res_rev(u64 start, u64 end, void *arg,
> + int (*func)(struct resource *, void *))
> +{
> + struct resource res, *rams;
> + int rams_size = 16, i;
> + unsigned long flags;
> + int ret = -1;
> +
> + /* create a list */
> + rams = kvcalloc(rams_size, sizeof(struct resource), GFP_KERNEL);
> + if (!rams)
> + return ret;
> +
> + flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> + i = 0;
> + while ((start < end) &&
> + (!find_next_iomem_res(start, end, flags, IORES_DESC_NONE,
> &res))) {
> + if (i >= rams_size) {
> + /* re-alloc */
> + struct resource *rams_new;
> + int rams_new_size;
> +
> + rams_new_size = rams_size + 16;
> + rams_new = kvcalloc(rams_new_size, sizeof(struct
> resource),
> + GFP_KERNEL);
kvrealloc()?
> + if (!rams_new)
> + goto out;
> +
> + memcpy(rams_new, rams,
> + sizeof(struct resource) * rams_size);
> + kvfree(rams);
> + rams = rams_new;
> + rams_size = rams_new_size;
> + }
> +
> + rams[i].start = res.start;
> + rams[i++].end = res.end;
> +
> + start = res.end + 1;
> + }
> +
> + /* go reverse */
> + for (i--; i >= 0; i--) {
> + ret = (*func)(&rams[i], arg);
> + if (ret)
> + break;
> + }
> +
> +out:
> + kvfree(rams);
> + return ret;
> +}
> +
> /*
> * This function calls the @func callback against all memory ranges, which
> * are ranges marked as IORESOURCE_MEM and IORESOUCE_BUSY.
> --
> 2.41.0
