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-rw-r--r--include/linux/compiler.h17
1 files changed, 12 insertions, 5 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 2bcaedc0f032..59a7004fc7dd 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -305,6 +305,17 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
305}) 305})
306 306
307/** 307/**
308 * smp_acquire__after_ctrl_dep() - Provide ACQUIRE ordering after a control dependency
309 *
310 * A control dependency provides a LOAD->STORE order, the additional RMB
311 * provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order,
312 * aka. (load)-ACQUIRE.
313 *
314 * Architectures that do not do load speculation can have this be barrier().
315 */
316#define smp_acquire__after_ctrl_dep() smp_rmb()
317
318/**
308 * smp_cond_load_acquire() - (Spin) wait for cond with ACQUIRE ordering 319 * smp_cond_load_acquire() - (Spin) wait for cond with ACQUIRE ordering
309 * @ptr: pointer to the variable to wait on 320 * @ptr: pointer to the variable to wait on
310 * @cond: boolean expression to wait for 321 * @cond: boolean expression to wait for
@@ -314,10 +325,6 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
314 * 325 *
315 * Due to C lacking lambda expressions we load the value of *ptr into a 326 * Due to C lacking lambda expressions we load the value of *ptr into a
316 * pre-named variable @VAL to be used in @cond. 327 * pre-named variable @VAL to be used in @cond.
317 *
318 * The control dependency provides a LOAD->STORE order, the additional RMB
319 * provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order,
320 * aka. ACQUIRE.
321 */ 328 */
322#ifndef smp_cond_load_acquire 329#ifndef smp_cond_load_acquire
323#define smp_cond_load_acquire(ptr, cond_expr) ({ \ 330#define smp_cond_load_acquire(ptr, cond_expr) ({ \
@@ -329,7 +336,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
329 break; \ 336 break; \
330 cpu_relax(); \ 337 cpu_relax(); \
331 } \ 338 } \
332 smp_rmb(); /* ctrl + rmb := acquire */ \ 339 smp_acquire__after_ctrl_dep(); \
333 VAL; \ 340 VAL; \
334}) 341})
335#endif 342#endif