On 11/14/23 at 03:17pm, Andrew Morton wrote:
> 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()?
Exactly. Will udpate. Thanks for the great suggestion.
>
> > + 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
>
