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

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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: Jeff Moyer <jmoyer@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jeff Moyer 2006-06-23 02:05:07 -07:00 committed by Linus Torvalds
parent 24bbb1faf3
commit c330dda908
3 changed files with 23 additions and 3 deletions
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1
include/linux/kexec.h
View File

@ -106,6 +106,7 @@ extern struct page *kimage_alloc_control_pages(struct kimage *image,
extern void crash_kexec(struct pt_regs *); extern void crash_kexec(struct pt_regs *);
int kexec_should_crash(struct task_struct *); int kexec_should_crash(struct task_struct *);
extern struct kimage *kexec_image; extern struct kimage *kexec_image;
extern struct kimage *kexec_crash_image;
#define KEXEC_ON_CRASH 0x00000001 #define KEXEC_ON_CRASH 0x00000001
#define KEXEC_ARCH_MASK 0xffff0000 #define KEXEC_ARCH_MASK 0xffff0000

6
kernel/kexec.c
View File

@ -902,14 +902,14 @@ static int kimage_load_segment(struct kimage *image,
* kexec does not sync, or unmount filesystems so if you need * kexec does not sync, or unmount filesystems so if you need
* that to happen you need to do that yourself. * that to happen you need to do that yourself.
*/ */
struct kimage *kexec_image = NULL; struct kimage *kexec_image;
static struct kimage *kexec_crash_image = NULL; struct kimage *kexec_crash_image;
/* /*
* A home grown binary mutex. * A home grown binary mutex.
* Nothing can wait so this mutex is safe to use * Nothing can wait so this mutex is safe to use
* in interrupt context :) * in interrupt context :)
*/ */
static int kexec_lock = 0; static int kexec_lock;
asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments, asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments,
struct kexec_segment __user *segments, struct kexec_segment __user *segments,

19
kernel/ksysfs.c
View File

@ -14,6 +14,7 @@
#include <linux/sysfs.h> #include <linux/sysfs.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/init.h> #include <linux/init.h>
#include <linux/kexec.h>
#define KERNEL_ATTR_RO(_name) \ #define KERNEL_ATTR_RO(_name) \
static struct subsys_attribute _name##_attr = __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); KERNEL_ATTR_RW(uevent_helper);
#endif #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); decl_subsys(kernel, NULL, NULL);
EXPORT_SYMBOL_GPL(kernel_subsys); EXPORT_SYMBOL_GPL(kernel_subsys);
@ -55,6 +70,10 @@ static struct attribute * kernel_attrs[] = {
#if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET) #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
&uevent_seqnum_attr.attr, &uevent_seqnum_attr.attr,
&uevent_helper_attr.attr, &uevent_helper_attr.attr,
#endif
#ifdef CONFIG_KEXEC
&kexec_loaded_attr.attr,
&kexec_crash_loaded_attr.attr,
#endif #endif
NULL NULL
}; };