From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751550AbdFGQVe (ORCPT ); Wed, 7 Jun 2017 12:21:34 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:41901 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750940AbdFGQVb (ORCPT ); Wed, 7 Jun 2017 12:21:31 -0400 Message-Id: <20170607162013.905320602@infradead.org> User-Agent: quilt/0.63-1 Date: Wed, 07 Jun 2017 18:15:06 +0200 From: Peter Zijlstra To: torvalds@linux-foundation.org, will.deacon@arm.com, oleg@redhat.com, paulmck@linux.vnet.ibm.com, benh@kernel.crashing.org, mpe@ellerman.id.au, npiggin@gmail.com Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, stern@rowland.harvard.edu, peterz@infradead.org Subject: [RFC][PATCH 5/5] powerpc: Remove SYNC from _switch References: <20170607161501.819948352@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=peterz-powerpc-switch-to.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Now that the scheduler's rq->lock is RCsc and thus provides full transitivity between scheduling actions. And since we cannot migrate current, a task needs a switch-out and a switch-in in order to migrate, in which case the RCsc provides all the ordering we need. Signed-off-by: Peter Zijlstra (Intel) --- arch/powerpc/kernel/entry_64.S | 8 -------- 1 file changed, 8 deletions(-) --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -488,14 +488,6 @@ _GLOBAL(_switch) std r23,_CCR(r1) std r1,KSP(r3) /* Set old stack pointer */ -#ifdef CONFIG_SMP - /* We need a sync somewhere here to make sure that if the - * previous task gets rescheduled on another CPU, it sees all - * stores it has performed on this one. - */ - sync -#endif /* CONFIG_SMP */ - /* * If we optimise away the clear of the reservation in system * calls because we know the CPU tracks the address of the