Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754559Ab0FXIoa (ORCPT ); Thu, 24 Jun 2010 04:44:30 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:58270 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754486Ab0FXIo1 convert rfc822-to-8bit (ORCPT ); Thu, 24 Jun 2010 04:44:27 -0400 Subject: Re: [patch 24/52] fs: dcache reduce d_parent locking From: Peter Zijlstra To: npiggin@suse.de Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, John Stultz , Frank Mayhar , "Paul E.McKenney" In-Reply-To: <20100624030729.395195069@suse.de> References: <20100624030212.676457061@suse.de> <20100624030729.395195069@suse.de> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Thu, 24 Jun 2010 10:44:22 +0200 Message-ID: <1277369062.1875.928.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 645 Lines: 14 On Thu, 2010-06-24 at 13:02 +1000, npiggin@suse.de wrote: > Use RCU property of dcache to simplify locking in some places where we > take d_parent and d_lock. > > Comment: don't need rcu_deref because we take the spinlock and recheck it. But does the LOCK barrier imply a DATA DEPENDENCY barrier? (It does on x86, and the compiler barrier implied by spin_lock() suffices to replace ACCESS_ONCE()). -- 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/