Use atomic_try_cmpxchg_acquire(*ptr, &old, new) instead of
atomic_cmpxchg_acquire(*ptr, old, new) == old in kexec_trylock().
x86 CMPXCHG instruction returns success in ZF flag, so
this change saves a compare after cmpxchg.
Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
---
kernel/kexec_internal.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index 2595defe8c0d..d35d9792402d 100644
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -23,7 +23,8 @@ int kimage_is_destination_range(struct kimage *image,
extern atomic_t __kexec_lock;
static inline bool kexec_trylock(void)
{
- return atomic_cmpxchg_acquire(&__kexec_lock, 0, 1) == 0;
+ int old = 0;
+ return atomic_try_cmpxchg_acquire(&__kexec_lock, &old, 1);
}
static inline void kexec_unlock(void)
{
--
2.42.0
_______________________________________________
kexec mailing list
kexec@xxxxxxxxxxxxxxxxxxx
http://lists.infradead.org/mailman/listinfo/kexec
