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authorAndrew Morton <akpm@linux-foundation.org>2008-08-15 00:40:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-08-15 08:35:43 -0700
commit8c5a1cf0ad3ac5fcdf51314a63b16a440870f6a2 (patch)
tree6b2d9084e05083daf6de69421f323c958b1d46ec /kernel
parent3122c331190e9d1622bf1c8cf6ce3b17cca67c9e (diff)
kexec: use a mutex for locking rather than xchg()
Functionally the same, but more conventional. Cc: Huang Ying <ying.huang@intel.com> Tested-by: Vivek Goyal <vgoyal@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/kexec.c34
1 files changed, 10 insertions, 24 deletions
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 9fc6f7cbd8a8..59f3f0df35d4 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -12,7 +12,7 @@
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/kexec.h>
-#include <linux/spinlock.h>
+#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/highmem.h>
#include <linux/syscalls.h>
@@ -924,19 +924,14 @@ static int kimage_load_segment(struct kimage *image,
*/
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;
+
+static DEFINE_MUTEX(kexec_mutex);
asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments,
struct kexec_segment __user *segments,
unsigned long flags)
{
struct kimage **dest_image, *image;
- int locked;
int result;
/* We only trust the superuser with rebooting the system. */
@@ -972,8 +967,7 @@ asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments,
*
* KISS: always take the mutex.
*/
- locked = xchg(&kexec_lock, 1);
- if (locked)
+ if (!mutex_trylock(&kexec_mutex))
return -EBUSY;
dest_image = &kexec_image;
@@ -1015,8 +1009,7 @@ asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments,
image = xchg(dest_image, image);
out:
- locked = xchg(&kexec_lock, 0); /* Release the mutex */
- BUG_ON(!locked);
+ mutex_unlock(&kexec_mutex);
kimage_free(image);
return result;
@@ -1063,10 +1056,7 @@ asmlinkage long compat_sys_kexec_load(unsigned long entry,
void crash_kexec(struct pt_regs *regs)
{
- int locked;
-
-
- /* Take the kexec_lock here to prevent sys_kexec_load
+ /* Take the kexec_mutex here to prevent sys_kexec_load
* running on one cpu from replacing the crash kernel
* we are using after a panic on a different cpu.
*
@@ -1074,8 +1064,7 @@ void crash_kexec(struct pt_regs *regs)
* of memory the xchg(&kexec_crash_image) would be
* sufficient. But since I reuse the memory...
*/
- locked = xchg(&kexec_lock, 1);
- if (!locked) {
+ if (mutex_trylock(&kexec_mutex)) {
if (kexec_crash_image) {
struct pt_regs fixed_regs;
crash_setup_regs(&fixed_regs, regs);
@@ -1083,8 +1072,7 @@ void crash_kexec(struct pt_regs *regs)
machine_crash_shutdown(&fixed_regs);
machine_kexec(kexec_crash_image);
}
- locked = xchg(&kexec_lock, 0);
- BUG_ON(!locked);
+ mutex_unlock(&kexec_mutex);
}
}
@@ -1434,7 +1422,7 @@ int kernel_kexec(void)
{
int error = 0;
- if (xchg(&kexec_lock, 1))
+ if (!mutex_trylock(&kexec_mutex))
return -EBUSY;
if (!kexec_image) {
error = -EINVAL;
@@ -1498,8 +1486,6 @@ int kernel_kexec(void)
#endif
Unlock:
- if (!xchg(&kexec_lock, 0))
- BUG();
-
+ mutex_unlock(&kexec_mutex);
return error;
}

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