Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 25 Jul 2001 15:00:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 25 Jul 2001 14:59:51 -0400 Received: from barney.blueskylabs.com ([64.0.135.181]:29797 "EHLO barney.intra.blueskylabs.com") by vger.kernel.org with ESMTP id convert rfc822-to-8bit; Wed, 25 Jul 2001 14:59:30 -0400 Subject: RE: user-mode port 0.44-2.4.7 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT content-class: urn:content-classes:message Date: Wed, 25 Jul 2001 12:03:48 -0700 X-MimeOLE: Produced By Microsoft Exchange V6.0.4417.0 Message-ID: <32B25F556FCD9D418D73C742C9B2E36D096795@barney.intra.blueskylabs.com> Thread-Topic: RE: user-mode port 0.44-2.4.7 Thread-Index: AcEVPIj7FROOn4eFRz+mkOnIC1AIKw== From: "James W. Lake" To: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Original-Recipient: rfc822;linux-kernel-outgoing What about a case when you have a struct struct queue { int head; int tail; ... } myqueue; You update head in an isr and tail in one singular open fop_read() call. Either don't mind getting old values of the one they don't update, want to get the latest version of the variable as often as possible. Should head and tail be volatile in the definition, or should they be accessed with: int head = (volatile)myqueue.head; or with barrier() around the read/write? Jim Lake - 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/