From acf02be3c72f12c31f916d3465c4c716b4729538 Mon Sep 17 00:00:00 2001 From: Uros Bizjak Date: Fri, 19 Jul 2024 12:38:52 +0200 Subject: [PATCH] kexec: use atomic_try_cmpxchg_acquire() in kexec_trylock() 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. Link: https://lkml.kernel.org/r/20240719103937.53742-1-ubizjak@gmail.com Signed-off-by: Uros Bizjak Acked-by: Baoquan He Cc: Eric Biederman Signed-off-by: Andrew Morton --- 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) {