Message-ID: <55804408.2090507@free.fr>
Date: Tue, 16 Jun 2015 17:43:04 +0200
From: Mason <slash.tmp@free.fr>
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To: Thomas Gleixner <tglx@linutronix.de>
CC: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [Semaphore API] down_interruptible_timeout
References: <557E9030.6080901@free.fr> <alpine.DEB.2.11.1506151855160.4120@nanos>
In-Reply-To: <alpine.DEB.2.11.1506151855160.4120@nanos>
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On 15/06/2015 18:56, Thomas Gleixner wrote:

> On Mon, 15 Jun 2015, Mason wrote:
> 
>> A) process-context kernel thread fills a FIFO and calls down(&fifo_empty);
>> B) ISR handles the FIFO-empty interrupt with up(&fifo_empty);
>>
>> However, in case something goes wrong and the interrupt never fires,
>> I don't want the process to be stuck in an uninterruptible sleep.
>>
>> Perhaps I can set a tiny timeout (e.g. 10 ?s) and not worry about
>> the interruptible part for such a small duration? (Hmm, __down_common
>> calls schedule_timeout, which is jiffies-based. I don't think there
>> is a hrtimers flavor. So ?s timeouts would be off the table?)
>>
>> Or I could use the interruptible version, and let the user kill the
>> operation if necessary.
> 
> Use a completion.

Thanks for the pointer. I will also read the following LKML thread.
http://thread.gmane.org/gmane.linux.kernel/664514

Regards.

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