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| author | Peter Zijlstra <peterz@infradead.org> | 2016-06-01 19:23:54 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-06-14 11:55:14 +0200 |
| commit | 7cb45c0fe9858f92cc264f6bf9d2f6a0e7d3b249 (patch) | |
| tree | f429581d6b993e303a297a461d06cd0dad58ea68 /include/linux/compiler.h | |
| parent | 33ac279677dcc2441cb93d8cb9cf7a74df62814d (diff) | |
| download | lwn-7cb45c0fe9858f92cc264f6bf9d2f6a0e7d3b249.tar.gz lwn-7cb45c0fe9858f92cc264f6bf9d2f6a0e7d3b249.zip | |
locking/barriers: Move smp_cond_load_acquire() to asm-generic/barrier.h
Since all asm/barrier.h should/must include asm-generic/barrier.h the
latter is a good place for generic infrastructure like this.
This also allows archs to override the new smp_acquire__after_ctrl_dep().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/compiler.h')
| -rw-r--r-- | include/linux/compiler.h | 37 |
1 files changed, 0 insertions, 37 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 59a7004fc7dd..2e853b679a5d 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -304,43 +304,6 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s __u.__val; \ }) -/** - * smp_acquire__after_ctrl_dep() - Provide ACQUIRE ordering after a control dependency - * - * A control dependency provides a LOAD->STORE order, the additional RMB - * provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order, - * aka. (load)-ACQUIRE. - * - * Architectures that do not do load speculation can have this be barrier(). - */ -#define smp_acquire__after_ctrl_dep() smp_rmb() - -/** - * smp_cond_load_acquire() - (Spin) wait for cond with ACQUIRE ordering - * @ptr: pointer to the variable to wait on - * @cond: boolean expression to wait for - * - * Equivalent to using smp_load_acquire() on the condition variable but employs - * the control dependency of the wait to reduce the barrier on many platforms. - * - * Due to C lacking lambda expressions we load the value of *ptr into a - * pre-named variable @VAL to be used in @cond. - */ -#ifndef smp_cond_load_acquire -#define smp_cond_load_acquire(ptr, cond_expr) ({ \ - typeof(ptr) __PTR = (ptr); \ - typeof(*ptr) VAL; \ - for (;;) { \ - VAL = READ_ONCE(*__PTR); \ - if (cond_expr) \ - break; \ - cpu_relax(); \ - } \ - smp_acquire__after_ctrl_dep(); \ - VAL; \ -}) -#endif - #endif /* __KERNEL__ */ #endif /* __ASSEMBLY__ */ |