linux-kernel - Re: [DOC PATCH] semaphore documentation

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Date:	Tue, 15 Apr 2008 09:24:29 +0100
From:	David Woodhouse <dwmw2@...radead.org>
To:	Matthew Wilcox <matthew@....cx>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Randy Dunlap <randy.dunlap@...cle.com>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Harvey Harrison <harvey.harrison@...il.com>
Subject: Re: [DOC PATCH] semaphore documentation

On Sat, 2008-04-12 at 08:12 -0600, Matthew Wilcox wrote:
> As I wrote in one of the comments, we have places in the kernel which
> know that even though they're in a non-sleeping context, there is at
> least one more token left in the semaphore.  One place this bit me was
> in start_kernel().  We disable interrupts and then call lock_kernel()
> which calls down().  Since we're in start_kernel(), we know there's
> nothing else running and this is perfectly safe.  But a might_sleep()
> would warn bogusly.

I would have thought they'd use down_trylock() in that case.

-- 
dwmw2

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