linux-kernel - Re: slqb enables interrupts very early

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Message-ID: <4A6D59B6.3040400@cs.helsinki.fi>
Date:	Mon, 27 Jul 2009 10:39:34 +0300
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Sebastian Andrzej Siewior <sebastian@...akpoint.cc>
CC:	linux-kernel@...r.kernel.org, npiggin@...e.de
Subject: Re: slqb enables interrupts very early

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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