Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752024AbXAXQzH (ORCPT ); Wed, 24 Jan 2007 11:55:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752027AbXAXQzG (ORCPT ); Wed, 24 Jan 2007 11:55:06 -0500 Received: from tomts20-srv.bellnexxia.net ([209.226.175.74]:53799 "EHLO tomts20-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752016AbXAXQzF (ORCPT ); Wed, 24 Jan 2007 11:55:05 -0500 Date: Wed, 24 Jan 2007 11:55:00 -0500 From: Mathieu Desnoyers To: Andrew Morton Cc: Ingo Molnar , Greg Kroah-Hartman , Christoph Hellwig , linux-kernel@vger.kernel.org, ltt-dev@shafik.org, "Martin J. Bligh" , Douglas Niehaus , systemtap@sources.redhat.com, Thomas Gleixner , Richard J Moore Subject: Re: [PATCH 2/2] lockdep reentrancy Message-ID: <20070124165500.GD4979@Krystal> References: <20061220235216.GA28643@Krystal> <20070116175631.GB16084@Krystal> <20070123202909.6b7dcd17.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <20070123202909.6b7dcd17.akpm@osdl.org> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.4.32-grsec (i686) X-Uptime: 11:52:20 up 154 days, 13:59, 4 users, load average: 1.39, 0.76, 0.62 User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3580 Lines: 126 Hi Andrew, * Andrew Morton (akpm@osdl.org) wrote: > On Tue, 16 Jan 2007 12:56:31 -0500 > Mathieu Desnoyers wrote: > > > Here is a patch to lockdep.c so it behaves correctly when a kprobe breakpoint is > > put on a marker within hardirq tracing functions as long as the marker is within > > the lockdep_recursion incremented boundaries. It should apply on > > 2.6.20-rc4-git3. > > > > Mathieu > > > > Signed-off-by: Mathieu Desnoyers > > > > > > @@ -1841,33 +1843,36 @@ void trace_hardirqs_on(void) > > You lost the patch headers. > > > struct task_struct *curr = current; > > unsigned long ip; > > > > if (unlikely(!debug_locks || current->lockdep_recursion)) > > return; > > > > + current->lockdep_recursion++; > > + barrier(); > > Why can't we use lockdep_off() here? > Because I thought that changing lockdep_off() for the whole system might be a little different than adding a lockdep recursion protection. See my other email for the lockdep_on/off() discussion. And please drop this patch : It sometimes make lockdep trigger false positives under heavy IRQ load because of a dropped lockdep event. Mathieu > > if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled))) > > - return; > > + goto end; > > > > if (unlikely(curr->hardirqs_enabled)) { > > debug_atomic_inc(&redundant_hardirqs_on); > > - return; > > + goto end; > > } > > /* we'll do an OFF -> ON transition: */ > > curr->hardirqs_enabled = 1; > > ip = (unsigned long) __builtin_return_address(0); > > > > if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) > > - return; > > + goto end; > > if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) > > - return; > > + goto end; > > /* > > * We are going to turn hardirqs on, so set the > > * usage bit for all held locks: > > */ > > if (!mark_held_locks(curr, 1, ip)) > > - return; > > + goto end; > > /* > > * If we have softirqs enabled, then set the usage > > * bit for all held locks. (disabled hardirqs prevented > > @@ -1875,11 +1880,14 @@ void trace_hardirqs_on(void) > > */ > > if (curr->softirqs_enabled) > > if (!mark_held_locks(curr, 0, ip)) > > - return; > > + goto end; > > > > curr->hardirq_enable_ip = ip; > > curr->hardirq_enable_event = ++curr->irq_events; > > debug_atomic_inc(&hardirqs_on_events); > > +end: > > + barrier(); > > + current->lockdep_recursion--; > > lockdep_on()? > > > } > > > > EXPORT_SYMBOL(trace_hardirqs_on); > > @@ -1888,14 +1896,17 @@ void trace_hardirqs_off(void) > > { > > struct task_struct *curr = current; > > > > if (unlikely(!debug_locks || current->lockdep_recursion)) > > return; > > > > + current->lockdep_recursion++; > > + barrier(); > > lockdep_off()? > > > if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) > > - return; > > + goto end; > > > > if (curr->hardirqs_enabled) { > > /* > > @@ -1910,6 +1921,9 @@ void trace_hardirqs_off(void) > > debug_atomic_inc(&hardirqs_off_events); > > } else > > debug_atomic_inc(&redundant_hardirqs_off); > > +end: > > + barrier(); > > + current->lockdep_recursion--; > > lockdep_on()? -- OpenPGP public key: http://krystal.dyndns.org:8080/key/compudj.gpg Key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - 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/