diff options
| author | Rodrigo Vivi <rodrigo.vivi@intel.com> | 2024-04-02 08:17:13 -0400 |
|---|---|---|
| committer | Rodrigo Vivi <rodrigo.vivi@intel.com> | 2024-04-02 08:17:13 -0400 |
| commit | 5add703f6acad1c63f8a532b6de56e50d548e904 (patch) | |
| tree | be39a82716119cd8b7cf7e2734baf8cd9a80ceb7 /arch/x86/include/asm/local.h | |
| parent | 71cdfa8cad300caa7afcbba09776bbc8dcfa9e39 (diff) | |
| parent | 39cd87c4eb2b893354f3b850f916353f2658ae6f (diff) | |
Merge drm/drm-next into drm-intel-next
Catching up on 6.9-rc2
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Diffstat (limited to 'arch/x86/include/asm/local.h')
| -rw-r--r-- | arch/x86/include/asm/local.h | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/arch/x86/include/asm/local.h b/arch/x86/include/asm/local.h index 73dba8b94443..59aa966dc212 100644 --- a/arch/x86/include/asm/local.h +++ b/arch/x86/include/asm/local.h @@ -131,8 +131,20 @@ static inline bool local_try_cmpxchg(local_t *l, long *old, long new) (typeof(l->a.counter) *) old, new); } -/* Always has a lock prefix */ -#define local_xchg(l, n) (xchg(&((l)->a.counter), (n))) +/* + * Implement local_xchg using CMPXCHG instruction without the LOCK prefix. + * XCHG is expensive due to the implied LOCK prefix. The processor + * cannot prefetch cachelines if XCHG is used. + */ +static __always_inline long +local_xchg(local_t *l, long n) +{ + long c = local_read(l); + + do { } while (!local_try_cmpxchg(l, &c, n)); + + return c; +} /** * local_add_unless - add unless the number is already a given value |