Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752616AbaJPUYV (ORCPT ); Thu, 16 Oct 2014 16:24:21 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:54031 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751369AbaJPUYU (ORCPT ); Thu, 16 Oct 2014 16:24:20 -0400 Date: Thu, 16 Oct 2014 22:24:10 +0200 From: Peter Zijlstra To: Patrick Palka Cc: "Paul E. McKenney" , x86@kernel.org, Thomas Gleixner , Ingo Molnar , Pranith Kumar , "H. Peter Anvin" , Hans-Christian Egtvedt , linux-kernel@vger.kernel.org Subject: Re: [PATCH] Fix the x86 specializations of atomic_[set|clear]_mask Message-ID: <20141016202410.GL7369@worktop.fdxtended.com> References: <1413405481-28818-1-git-send-email-patrick@parcs.ath.cx> <20141016080209.GE7369@worktop.fdxtended.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 16, 2014 at 12:49:43PM -0400, Patrick Palka wrote: > On Oct 16, 2014 4:02 AM, "Peter Zijlstra" wrote: > > > > On Wed, Oct 15, 2014 at 04:38:01PM -0400, Patrick Palka wrote: > > > This patch fixes a number of issues with these specializations: > > > > > > 1. The memory operand inside the asm specification is erroneously > > > declared read-only instead of read-write. > > > > > > 2. There is no reason to require the 1st operand of andl/orl to be > > > inside a register; the 1st operand could also be an immediate operand. > > > So change its specification from "r" to "ir". > > > > > > 3. Since addr is supposed to be an atomic_t *, the memory operand > > > should be addr->counter and not *addr. > > > > > > 4. These specializations should be inline functions instead of macros. > > > > > > 5. Finally, the "memory" clobbers are unnecessary, so they should be > > > removed. (This is in line with the other atomic functions such as > > > atomic_add and atomic_sub, the likes of which do not have a "memory" > > > clobber.) > > > > No real problem with this, but I'm going to kill off these functions > > when I get a little time :) > > Hmm why's that? because they're odd (inconsistent with the rest of the atomic interfaces) and not implemented by all archs. See: https://lkml.org/lkml/2014/2/6/196 3.18 will include up to 4/5 of that series and when I get a spare moment I need cleanup/post the next arch sweep that will get us that 5/5 thing. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/