From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932718AbcFBL5t (ORCPT ); Thu, 2 Jun 2016 07:57:49 -0400 Received: from merlin.infradead.org ([205.233.59.134]:50823 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932678AbcFBL5r (ORCPT ); Thu, 2 Jun 2016 07:57:47 -0400 Message-Id: <20160602115438.964652080@infradead.org> User-Agent: quilt/0.61-1 Date: Thu, 02 Jun 2016 13:52:00 +0200 From: Peter Zijlstra To: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, manfred@colorfullife.com, dave@stgolabs.net, paulmck@linux.vnet.ibm.com, will.deacon@arm.com Cc: boqun.feng@gmail.com, Waiman.Long@hpe.com, tj@kernel.org, pablo@netfilter.org, kaber@trash.net, davem@davemloft.net, oleg@redhat.com, netfilter-devel@vger.kernel.org, sasha.levin@oracle.com, hofrat@osadl.org, peterz@infradead.org Subject: [PATCH -v4 3/7] locking: Move smp_cond_load_acquire() to asm-generic/barrier.h References: <20160602115157.249037373@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=peterz-locking-move-asm-generic.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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) --- include/asm-generic/barrier.h | 39 +++++++++++++++++++++++++++++++++++++++ include/linux/compiler.h | 37 ------------------------------------- 2 files changed, 39 insertions(+), 37 deletions(-) --- a/include/asm-generic/barrier.h +++ b/include/asm-generic/barrier.h @@ -207,5 +207,44 @@ do { \ #define virt_store_release(p, v) __smp_store_release(p, v) #define virt_load_acquire(p) __smp_load_acquire(p) +/** + * 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(). + */ +#ifndef smp_acquire__after_ctrl_dep +#define smp_acquire__after_ctrl_dep() smp_rmb() +#endif + +/** + * 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 /* !__ASSEMBLY__ */ #endif /* __ASM_GENERIC_BARRIER_H */ --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -304,43 +304,6 @@ static __always_inline void __write_once __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__ */