Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753994Ab1FTMrY (ORCPT ); Mon, 20 Jun 2011 08:47:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54307 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752248Ab1FTMrX (ORCPT ); Mon, 20 Jun 2011 08:47:23 -0400 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20110619235147.GQ11521@ZenIV.linux.org.uk> References: <20110619235147.GQ11521@ZenIV.linux.org.uk> To: Al Viro Cc: dhowells@redhat.com, linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds Subject: Re: [RFC] get_write_access()/deny_write_access() without inode->i_lock Date: Mon, 20 Jun 2011 13:47:17 +0100 Message-ID: <21839.1308574037@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 633 Lines: 18 Al Viro wrote: > + for (v = atomic_read(&inode->i_writecount); v >= 0; v = v1) { > + v1 = atomic_cmpxchg(&inode->i_writecount, v, v + 1); > + if (likely(v1 == v)) > + return 0; > + } You don't need to reissue the atomic_read(). atomic_cmpxchg() returns the current value of the memory location. Just set v to v1 before going round the loop again. David -- 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/