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Commit c330dda9 authored by Jeff Moyer's avatar Jeff Moyer Committed by Linus Torvalds
Browse files

[PATCH] Add a sysfs file to determine if a kexec kernel is loaded 



Create two files in /sys/kernel, kexec_loaded and kexec_crash_loaded.  Each
file contains a simple boolean value indicating whether the relevant kernel
has been loaded into memory.  The motivation for this is geared around
support.

Signed-off-by: default avatarJeff Moyer <jmoyer@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 24bbb1fa

include/linux/kexec.h

+1 −0
Original line number Diff line number Diff line
@@ -106,6 +106,7 @@ extern struct page *kimage_alloc_control_pages(struct kimage *image, 
extern void crash_kexec(struct pt_regs *);

int kexec_should_crash(struct task_struct *);

extern struct kimage *kexec_image;

extern struct kimage *kexec_crash_image;



#define KEXEC_ON_CRASH  0x00000001

#define KEXEC_ARCH_MASK 0xffff0000

kernel/kexec.c

+3 −3
Original line number Diff line number Diff line
@@ -902,14 +902,14 @@ static int kimage_load_segment(struct kimage *image, 
 * kexec does not sync, or unmount filesystems so if you need

 * that to happen you need to do that yourself.

 */

struct kimage *kexec_image = NULL;

static struct kimage *kexec_crash_image = NULL;

struct kimage *kexec_image;

struct kimage *kexec_crash_image;

/*

 * A home grown binary mutex.

 * Nothing can wait so this mutex is safe to use

 * in interrupt context :)

 */

static int kexec_lock = 0;

static int kexec_lock;



asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments,

				struct kexec_segment __user *segments,

kernel/ksysfs.c

+19 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/sysfs.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/kexec.h>



#define KERNEL_ATTR_RO(_name) \

static struct subsys_attribute _name##_attr = __ATTR_RO(_name)
@@ -48,6 +49,20 @@ static ssize_t uevent_helper_store(struct subsystem *subsys, const char *page, s 
KERNEL_ATTR_RW(uevent_helper);

#endif



#ifdef CONFIG_KEXEC

static ssize_t kexec_loaded_show(struct subsystem *subsys, char *page)

{

	return sprintf(page, "%d\n", !!kexec_image);

}

KERNEL_ATTR_RO(kexec_loaded);



static ssize_t kexec_crash_loaded_show(struct subsystem *subsys, char *page)

{

	return sprintf(page, "%d\n", !!kexec_crash_image);

}

KERNEL_ATTR_RO(kexec_crash_loaded);

#endif /* CONFIG_KEXEC */



decl_subsys(kernel, NULL, NULL);

EXPORT_SYMBOL_GPL(kernel_subsys);
@@ -55,6 +70,10 @@ static struct attribute * kernel_attrs[] = { 
#if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)

	&uevent_seqnum_attr.attr,

	&uevent_helper_attr.attr,

#endif

#ifdef CONFIG_KEXEC

	&kexec_loaded_attr.attr,

	&kexec_crash_loaded_attr.attr,

#endif

	NULL

};