[v2,1/2] resource: add walk_system_ram_res_rev()

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.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Baoquan He <bhe@redhat.com>
---
v1->v2:
- Use kvrealloc() to reallocate memory instead of kvcalloc(), this
  simplifies code. Suggested by Andrew.

 include/linux/ioport.h |  3 +++
 kernel/resource.c      | 57 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+)

Hi Andrew,

On 11/15/23 at 09:00pm, Baoquan He 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.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> v1->v2:
> - Use kvrealloc() to reallocate memory instead of kvcalloc(), this
>   simplifies code. Suggested by Andrew.
> 
>  include/linux/ioport.h |  3 +++
>  kernel/resource.c      | 57 ++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 60 insertions(+)

Gentle ping.

Could you pick this patchset into next tree so that it can be run on
testing robots?

Thanks
Baoquan

> 
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index 14f5cfabbbc8..db7fe25f3370 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -331,6 +331,9 @@ extern int
>  walk_system_ram_res(u64 start, u64 end, void *arg,
>  		    int (*func)(struct resource *, void *));
>  extern int
> +walk_system_ram_res_rev(u64 start, u64 end, void *arg,
> +			int (*func)(struct resource *, void *));
> +extern int
>  walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start, u64 end,
>  		    void *arg, int (*func)(struct resource *, void *));
>  
> diff --git a/kernel/resource.c b/kernel/resource.c
> index 866ef3663a0b..e8a244300e5b 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -27,6 +27,8 @@
>  #include <linux/mount.h>
>  #include <linux/resource_ext.h>
>  #include <uapi/linux/magic.h>
> +#include <linux/string.h>
> +#include <linux/vmalloc.h>
>  #include <asm/io.h>
>  
>  
> @@ -429,6 +431,61 @@ int walk_system_ram_res(u64 start, u64 end, void *arg,
>  				     func);
>  }
>  
> +/*
> + * 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;
> +
> +			rams_new = kvrealloc(rams, rams_size * sizeof(struct resource),
> +					     (rams_size + 16) * sizeof(struct resource),
> +					     GFP_KERNEL);
> +			if (!rams_new)
> +				goto out;
> +
> +			rams = rams_new;
> +			rams_size += 16;
> +		}
> +
> +		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
>

Hello:

This patch was applied to riscv/linux.git (fixes)
by Andrew Morton <akpm@linux-foundation.org>:

On Wed, 15 Nov 2023 21:00:27 +0800 you 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.
> 
> [...]

Here is the summary with links:
  - [v2,1/2] resource: add walk_system_ram_res_rev()
    https://git.kernel.org/riscv/c/7acf164b259d

You are awesome, thank you!