Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753011AbcDVJnP (ORCPT ); Fri, 22 Apr 2016 05:43:15 -0400 Received: from merlin.infradead.org ([205.233.59.134]:40741 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752788AbcDVJnM (ORCPT ); Fri, 22 Apr 2016 05:43:12 -0400 Message-Id: <20160422093923.156825130@infradead.org> User-Agent: quilt/0.61-1 Date: Fri, 22 Apr 2016 11:04:15 +0200 From: Peter Zijlstra To: torvalds@linux-foundation.org, mingo@kernel.org, tglx@linutronix.de, will.deacon@arm.com, paulmck@linux.vnet.ibm.com, boqun.feng@gmail.com, waiman.long@hpe.com, fweisbec@gmail.com Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, rth@twiddle.net, vgupta@synopsys.com, linux@arm.linux.org.uk, egtvedt@samfundet.no, realmz6@gmail.com, ysato@users.sourceforge.jp, rkuo@codeaurora.org, tony.luck@intel.com, geert@linux-m68k.org, james.hogan@imgtec.com, ralf@linux-mips.org, dhowells@redhat.com, jejb@parisc-linux.org, mpe@ellerman.id.au, schwidefsky@de.ibm.com, dalias@libc.org, davem@davemloft.net, cmetcalf@mellanox.com, jcmvbkbc@gmail.com, arnd@arndb.de, peterz@infradead.org, dbueso@suse.de, fengguang.wu@intel.com Subject: [RFC][PATCH 02/31] locking,alpha: Implement atomic{,64}_fetch_{add,sub,and,andnot,or,xor}() References: <20160422090413.393652501@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=peterz-atomic-fetch-alpha.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3117 Lines: 112 Implement FETCH-OP atomic primitives, these are very similar to the existing OP-RETURN primitives we already have, except they return the value of the atomic variable _before_ modification. This is especially useful for irreversible operations -- such as bitops (because it becomes impossible to reconstruct the state prior to modification). Signed-off-by: Peter Zijlstra (Intel) --- arch/alpha/include/asm/atomic.h | 67 ++++++++++++++++++++++++++++++++++------ 1 file changed, 58 insertions(+), 9 deletions(-) --- a/arch/alpha/include/asm/atomic.h +++ b/arch/alpha/include/asm/atomic.h @@ -65,6 +65,26 @@ static inline int atomic_##op##_return(i return result; \ } +#define ATOMIC_FETCH_OP(op, asm_op) \ +static inline int atomic_fetch_##op(int i, atomic_t *v) \ +{ \ + long temp, result; \ + smp_mb(); \ + __asm__ __volatile__( \ + "1: ldl_l %0,%1\n" \ + " mov %0,%2\n" \ + " " #asm_op " %0,%3,%0\n" \ + " stl_c %0,%1\n" \ + " beq %0,2f\n" \ + ".subsection 2\n" \ + "2: br 1b\n" \ + ".previous" \ + :"=&r" (temp), "=m" (v->counter), "=&r" (result) \ + :"Ir" (i), "m" (v->counter) : "memory"); \ + smp_mb(); \ + return result; \ +} + #define ATOMIC64_OP(op, asm_op) \ static __inline__ void atomic64_##op(long i, atomic64_t * v) \ { \ @@ -101,11 +121,33 @@ static __inline__ long atomic64_##op##_r return result; \ } +#define ATOMIC64_FETCH_OP(op, asm_op) \ +static __inline__ long atomic64_fetch_##op(long i, atomic64_t * v) \ +{ \ + long temp, result; \ + smp_mb(); \ + __asm__ __volatile__( \ + "1: ldq_l %0,%1\n" \ + " mov %0,%2\n" \ + " " #asm_op " %0,%3,%0\n" \ + " stq_c %0,%1\n" \ + " beq %0,2f\n" \ + ".subsection 2\n" \ + "2: br 1b\n" \ + ".previous" \ + :"=&r" (temp), "=m" (v->counter), "=&r" (result) \ + :"Ir" (i), "m" (v->counter) : "memory"); \ + smp_mb(); \ + return result; \ +} + #define ATOMIC_OPS(op) \ ATOMIC_OP(op, op##l) \ ATOMIC_OP_RETURN(op, op##l) \ + ATOMIC_FETCH_OP(op, op##l) \ ATOMIC64_OP(op, op##q) \ - ATOMIC64_OP_RETURN(op, op##q) + ATOMIC64_OP_RETURN(op, op##q) \ + ATOMIC64_FETCH_OP(op, op##q) ATOMIC_OPS(add) ATOMIC_OPS(sub) @@ -113,18 +155,25 @@ ATOMIC_OPS(sub) #define atomic_andnot atomic_andnot #define atomic64_andnot atomic64_andnot -ATOMIC_OP(and, and) -ATOMIC_OP(andnot, bic) -ATOMIC_OP(or, bis) -ATOMIC_OP(xor, xor) -ATOMIC64_OP(and, and) -ATOMIC64_OP(andnot, bic) -ATOMIC64_OP(or, bis) -ATOMIC64_OP(xor, xor) +#define atomic_fetch_or atomic_fetch_or + +#undef ATOMIC_OPS +#define ATOMIC_OPS(op, asm) \ + ATOMIC_OP(op, asm) \ + ATOMIC_FETCH_OP(op, asm) \ + ATOMIC64_OP(op, asm) \ + ATOMIC64_FETCH_OP(op, asm) + +ATOMIC_OPS(and, and) +ATOMIC_OPS(andnot, bic) +ATOMIC_OPS(or, bis) +ATOMIC_OPS(xor, xor) #undef ATOMIC_OPS +#undef ATOMIC64_FETCH_OP #undef ATOMIC64_OP_RETURN #undef ATOMIC64_OP +#undef ATOMIC_FETCH_OP #undef ATOMIC_OP_RETURN #undef ATOMIC_OP