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From: Andrew Morton <akpm@osdl.org>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Ingo Molnar <mingo@redhat.com>,
	Greg Kroah-Hartman <gregkh@suse.de>,
	Christoph Hellwig <hch@infradead.org>,
	linux-kernel@vger.kernel.org, ltt-dev@shafik.org,
	"Martin J. Bligh" <mbligh@mbligh.org>,
	Douglas Niehaus <niehaus@eecs.ku.edu>,
	systemtap@sources.redhat.com,
	Thomas Gleixner <tglx@linutronix.de>,
	Richard J Moore <richardj_moore@uk.ibm.com>
Subject: Re: [PATCH 2/2] lockdep reentrancy
Date: Tue, 23 Jan 2007 20:29:09 -0800	[thread overview]
Message-ID: <20070123202909.6b7dcd17.akpm@osdl.org> (raw)
In-Reply-To: <20070116175631.GB16084@Krystal>

On Tue, 16 Jan 2007 12:56:31 -0500
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> 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 <mathieu.desnoyers@polymtl.ca>
> 
> 
> @@ -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?

>  	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()?

  reply	other threads:[~2007-01-24  4:30 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-12-20 23:52 [PATCH 0/4] Linux Kernel Markers Mathieu Desnoyers
2006-12-20 23:57 ` [PATCH 1/4] Linux Kernel Markers : Architecture agnostic code Mathieu Desnoyers
2006-12-20 23:59 ` [PATCH 2/4] Linux Kernel Markers : kconfig menus Mathieu Desnoyers
2006-12-21  0:00 ` [PATCH 3/4] Linux Kernel Markers : i386 optimisation Mathieu Desnoyers
2006-12-21  0:01 ` [PATCH 4/4] Linux Kernel Markers : powerpc optimisation Mathieu Desnoyers
2007-01-13  1:33 ` [PATCH 0/4] Linux Kernel Markers Richard J Moore
2007-01-13  5:45   ` Mathieu Desnoyers
2007-01-16 17:41     ` [PATCH 0/4 update] Linux Kernel Markers - i386 : pIII erratum 49 : XMC Mathieu Desnoyers
2007-01-16 18:35       ` Frank Ch. Eigler
2007-01-16 21:27       ` [PATCH 0/4 update] kprobes and traps Mathieu Desnoyers
2007-01-17 12:25         ` S. P. Prasanna
2007-01-16 17:56   ` [PATCH 1/2] lockdep missing barrier() Mathieu Desnoyers
2007-01-24  4:26     ` Andrew Morton
2007-01-24 16:51       ` Mathieu Desnoyers
2007-01-24 17:24         ` [PATCH] order of lockdep off/on in vprintk() should be changed Mathieu Desnoyers
2007-01-24 17:55           ` [PATCH] minimize lockdep_on/off side-effect Mathieu Desnoyers
2007-01-16 17:56   ` [PATCH 2/2] lockdep reentrancy Mathieu Desnoyers
2007-01-24  4:29     ` Andrew Morton [this message]
2007-01-24 16:55       ` Mathieu Desnoyers

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