Date: Fri, 26 Dec 2008 11:27:16 +0100
From: Sam Ravnborg <sam@ravnborg.org>
To: Yinghai Lu <yinghai@kernel.org>, David Howells <dhowells@redhat.com>
Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>, mingo@elte.hu,
       Andrew Morton <akpm@linux-foundation.org>,
       Stephen Rothwell <sfr@canb.auug.org.au>, linux-next@vger.kernel.org,
       LKML <linux-kernel@vger.kernel.org>, mel@csn.ul.ie
Subject: Re: [BUG] next-20081216 - WARNING: at kernel/smp.c:333	smp_call_function_mask
Message-ID: <20081226102716.GA31450@uranus.ravnborg.org>
References: <20081219105441.GA19750@linux.vnet.ibm.com> <86802c440812190351q3118516aif664dd5869c21b2a@mail.gmail.com> <20081219134636.GA11772@linux.vnet.ibm.com> <494C0BF0.3080109@kernel.org> <20081223132127.GA5450@linux.vnet.ibm.com> <495153A4.5060201@kernel.org> <20081224163400.GA11562@linux.vnet.ibm.com> <49529CE1.4040005@kernel.org> <20081226091217.GA5100@linux.vnet.ibm.com> <4954AC7B.3020603@kernel.org>
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On Fri, Dec 26, 2008 at 02:05:47AM -0800, Yinghai Lu wrote:
> Kamalesh Babulal wrote:
> > * Yinghai Lu <yinghai@kernel.org> [2008-12-24 12:34:41]:
> > 
> >> --
> > 
> > After the applying the patch, the kernel panic's with the same backtrace. The
> > box is running Fedora 5 on it.
> > 
> 
> please try...
> Ingo, do we need to switch to use #idef and inline function instead?

I recall David Howells had a similar issue with the bootparamter patch set.
The workaround he used was to add a barrier(); call in the weak function
to avoid the inline.

[full context kept as I added David to to: list].
	Sam

> 
> YH
> 
> 
> [PATCH] sparseirq: add printk to workaround compiler optimizing
> 
> Impact: fix panic on null pointer with sparseirq
> 
> some compiler seems to inline the weak global function.
> try to workaround it
> 
> also remove duplicated arch_early_irq_init()
> already have one weak copy in init/main.c
> 
> Signed-off-by: Yinghai <yinghai@kernel.org>
> 
> ---
>  init/main.c         |    2 ++
>  kernel/irq/handle.c |    7 ++-----
>  2 files changed, 4 insertions(+), 5 deletions(-)
> 
> Index: linux-2.6/init/main.c
> ===================================================================
> --- linux-2.6.orig/init/main.c
> +++ linux-2.6/init/main.c
> @@ -544,10 +544,12 @@ void __init __weak thread_info_cache_ini
>  
>  void __init __weak arch_early_irq_init(void)
>  {
> +	printk(KERN_DEBUG "calling __weak arch_early_irq_init\n");
>  }
>  
>  void __init __weak early_irq_init(void)
>  {
> +	printk(KERN_DEBUG "calling __weak early_irq_init\n");
>  	arch_early_irq_init();
>  }
>  
> Index: linux-2.6/kernel/irq/handle.c
> ===================================================================
> --- linux-2.6.orig/kernel/irq/handle.c
> +++ linux-2.6/kernel/irq/handle.c
> @@ -56,10 +56,6 @@ void handle_bad_irq(unsigned int irq, st
>  int nr_irqs = NR_IRQS;
>  EXPORT_SYMBOL_GPL(nr_irqs);
>  
> -void __init __attribute__((weak)) arch_early_irq_init(void)
> -{
> -}
> -
>  #ifdef CONFIG_SPARSE_IRQ
>  static struct irq_desc irq_desc_init = {
>  	.irq	    = -1,
> @@ -90,8 +86,9 @@ void init_kstat_irqs(struct irq_desc *de
>  		desc->kstat_irqs = (unsigned int *)ptr;
>  }
>  
> -void __attribute__((weak)) arch_init_chip_data(struct irq_desc *desc, int cpu)
> +void __weak arch_init_chip_data(struct irq_desc *desc, int cpu)
>  {
> +	printk(KERN_DEBUG "calling __weak arch_init_chip_data\n");
>  }
>  
>  static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
> --
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