Commit 7acf164b authored by Baoquan He's avatar Baoquan He Committed by Andrew Morton
Browse files

resource: add walk_system_ram_res_rev() 

This function, being a variant of walk_system_ram_res() introduced in
commit 8c86e70a ("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.

Link: https://lkml.kernel.org/r/ZVTA6z/06cLnWKUz@MiWiFi-R3L-srv


Signed-off-by: default avatarAKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: default avatarBaoquan He <bhe@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent bfc4372b

include/linux/ioport.h

+3 −0
Original line number Diff line number Diff line
@@ -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 *));

kernel/resource.c

+57 −0
Original line number Diff line number Diff line
@@ -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.