Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760624AbYFWRTb (ORCPT ); Mon, 23 Jun 2008 13:19:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752921AbYFWRTY (ORCPT ); Mon, 23 Jun 2008 13:19:24 -0400 Received: from styx.suse.cz ([82.119.242.94]:52108 "EHLO mail.suse.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754722AbYFWRTX (ORCPT ); Mon, 23 Jun 2008 13:19:23 -0400 Subject: Re: Spinlocks: Factor our GENERIC_LOCKBREAK in order to avoid spin with irqs disable From: Petr Tesarik To: Christoph Lameter Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Peter Zijlstra In-Reply-To: References: <20080507073017.GJ32195@elte.hu> Content-Type: text/plain Organization: SUSE LINUX Date: Mon, 23 Jun 2008 19:19:21 +0200 Message-Id: <1214241561.19392.21.camel@elijah.suse.cz> Mime-Version: 1.0 X-Mailer: Evolution 2.6.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2048 Lines: 48 On Wed, 2008-05-07 at 11:49 -0700, Christoph Lameter wrote: > Subject: Spinlocks: Factor our GENERIC_LOCKBREAK in order to avoid spin with irqs disabled > > The nice spinlock functions that enable interrupts while spinning are only > usable if GENERIC_LOCKBREAK is set (and we do not debug locks but lock > debugging would not be used for a production configuration). > > Factor out the dependencies on the ->lock_break field from the nice functions > into a set of BREAKLOCK macros (cannot be functions since the type of the lock > variable varies). > > The nice spinlock function can then also be used if !GENERIC_LOCKBREAK > > Signed-off-by: Christoph Lameter > > --- > kernel/spinlock.c | 40 ++++++++++++++++++++++++++++++---------- > 1 file changed, 30 insertions(+), 10 deletions(-) > > Index: linux-2.6/kernel/spinlock.c > =================================================================== > --- linux-2.6.orig/kernel/spinlock.c 2008-05-07 11:19:31.000000000 -0700 > +++ linux-2.6/kernel/spinlock.c 2008-05-07 11:40:56.000000000 -0700 > @@ -65,7 +65,7 @@ EXPORT_SYMBOL(_write_trylock); > * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are > * not re-enabled during lock-acquire (which the preempt-spin-ops do): > */ > -#if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC) > +#ifdef CONFIG_DEBUG_LOCK_ALLOC Maybe I'm just blind, but doesn't this change effectively disable any arch-specific optimized code for _raw_*_lock? If CONFIG_DEBUG_LOCK_ALLOC is set, then CONFIG_DEBUG_SPINLOCK must also be set, so in that case the debugging versions of _raw_*_lock are used. But if CONFIG_DEBUG_LOCK_ALLOC is _not_ set, then the locks are built with _trylock and _can_lock primitives. What am I missing here? Petr Tesarik -- 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/