Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 20 Sep 2002 07:38:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 20 Sep 2002 07:38:47 -0400 Received: from angband.namesys.com ([212.16.7.85]:8353 "HELO angband.namesys.com") by vger.kernel.org with SMTP id ; Fri, 20 Sep 2002 07:38:46 -0400 Date: Fri, 20 Sep 2002 15:43:47 +0400 From: Oleg Drokin To: Ingo Molnar Cc: Linus Torvalds , William Lee Irwin III , linux-kernel@vger.kernel.org Subject: Re: [patch] generic-pidhash-2.5.36-D4, BK-curr Message-ID: <20020920154347.A12399@namesys.com> References: <20020920122716.A2297@namesys.com> Mime-Version: 1.0 Content-Type: text/plain; charset=koi8-r Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.22.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1036 Lines: 25 Hello! On Fri, Sep 20, 2002 at 11:40:16AM +0200, Ingo Molnar wrote: > > > + if (cmpxchg(&map->page, NULL, page)) > > > + free_page(page); > > Note that this piece breaks compilation for every arch that does not > > have cmpxchg implementation. > > This is the case with x86 (with CONFIG_X86_CMPXCHG undefined, e.g. i386), > > ARM, CRIS, m68k, MIPS, MIPS64, PARISC, s390, SH, sparc32, UML (for x86). > we need a cmpxchg() function in the generic library, using a spinlock. But this is not safe for arches that provides SMP but does not provide cmpxchg in hadware, right? I mean it is only safe to use such spinlock-based function if all other places read and write this value via special functions that are also taking this spinlock. Do you think we can count on this? Bye, Oleg - 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/