linux-kernel - Re: [patch 0/2] semaphores: add down_interruptible

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Message-ID: <20070227021803.38c8591f@lxorguk.ukuu.org.uk>
Date:	Tue, 27 Feb 2007 02:18:03 +0000
From:	Alan <alan@...rguk.ukuu.org.uk>
To:	Inaky Perez-Gonzalez <inaky@...ux.intel.com>
Cc:	Christoph Hellwig <hch@...radead.org>,
	Arjan van de Ven <arjan@...radead.org>, mingo@...hat.com,
	akpm@...l.org, linux-kernel@...r.kernel.org
Subject: Re: [patch 0/2] semaphores: add down_interruptible_timeout() and
 asm-generic/semaphore.h

> Yeah, I need semaphore. This is a hw register that says when the hw
> is ready to accept a new command. Code that wants to send commands has
> to down the semaphore and then send it. When hw is ready to get a new
> command, it sends and IRQ and the IRQ up()s the semaphore. 

So you need a mutex not a semaphore
> 
> Now, we don't want to hang on that down() forever if the hw spaces out.
> If we get a timeout, we can try recovery actions (like resetting it,
> for sake of being polite). 

Makes sense but you can also do that with mutexes, and its
mutex_interruptible_timeout() you need I suspect ?

Alan
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