Message-ID: <4A6D59B6.3040400@cs.helsinki.fi>
Date: Mon, 27 Jul 2009 10:39:34 +0300
From: Pekka Enberg <penberg@cs.helsinki.fi>
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To: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
CC: linux-kernel@vger.kernel.org, npiggin@suse.de
Subject: Re: slqb enables interrupts very early
References: <20090725180321.GA24814@Chamillionaire.breakpoint.cc>
In-Reply-To: <20090725180321.GA24814@Chamillionaire.breakpoint.cc>
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Sebastian Andrzej Siewior wrote:
> I've checkout slab-2.6/linux-next and noticed that the interrupts are
> enabled very early by accident. Please look at the following call stack:
> 
>     start_kernel()
>     kmem_cache_init()
>     kmem_cache_open()
>     down_write(&slqb_lock);
>     __down_write()
>     __down_write_nested()
> 
> Now, __down_write_nested() protects its internal structure the follwing
> way:
>     spin_lock_irq(&sem->wait_lock);
>     ...
>     spin_unlock_irq(&sem->wait_lock);
> 
> so once we return, we return with interrupts on.

Indeed. Nick, do we need to take ->slqb_lock in kmem_cache_open()? A 
quick read on the code suggests that we could just drop it.

			Pekka
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