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kexec: use atomic_try_cmpxchg_acquire() in kexec_trylock()

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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 <ubizjak@gmail.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Uros Bizjak 2024-07-19 12:38:52 +02:00 committed by Andrew Morton
parent e24f4de8a7
commit acf02be3c7
1 changed files with 2 additions and 1 deletions
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3
kernel/kexec_internal.h
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@ -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)
{