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Date: Sun, 3 Nov 2002 16:15:46 -0800 (PST)
From: Davide Libenzi <davidel@xmailserver.org>
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To: William Lee Irwin III <wli@holomorphy.com>
cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, <hch@lst.de>,
       Benjamin LaHaise <bcrl@redhat.com>
Subject: Re: interrupt checks for spinlocks
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On Sun, 3 Nov 2002, William Lee Irwin III wrote:

> I recently thought about interrupt disablement and locking again, or
> at least such as has gone about in various places, and I got scared.
>
> Hence, a wee addition to CONFIG_DEBUG_SPINLOCK:
>
> (1) check that spinlocks are not taken in interrupt context without
> 	interrupts disabled
> (2) taint spinlocks taken in interrupt context
> (3) check for tainted spinlocks taken without interrupts disabled
> (4) check for spinlocking calls unconditionally disabling (and
> 	hence later re-enabling) interrupts with interrupts disabled
>
> The only action taken is printk() and dump_stack(). No arch code has
> been futzed with to provide irq tainting yet. Looks like a good way
> to shake out lurking bugs to me (somewhat like may_sleep() etc.).

Wouldn't it be interesting to keep a ( per task ) list of acquired
spinlocks to be able to diagnose cross locks in case of stall ?
( obviously under CONFIG_DEBUG_SPINLOCK )



- Davide


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