linux-kernel - Re: [patch 04/15] cleanup clocksource selection

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Message-ID: <20090817093439.60521924@skybase>
Date:	Mon, 17 Aug 2009 09:34:39 +0200
From:	Martin Schwidefsky <schwidefsky@...ibm.com>
To:	john stultz <johnstul@...ibm.com>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Daniel Walker <dwalker@...o99.com>
Subject: Re: [patch 04/15] cleanup clocksource selection

On Fri, 14 Aug 2009 18:42:20 -0700
john stultz <johnstul@...ibm.com> wrote:

> Here when you return count, count may have been decremented in the code
> above, which causes the writer to get back fewer bytes then what they
> passed in, causing the last char to be repeatedly sent. This is what
> causes the immediate switch back to the default clocksource (override
> gets set to null), and the hang of the command writing to the sysfs
> file.
> 
> The fix is simply keeping the initial "size_t ret = count;" and the
> final "return ret;"
> 
> 
> Index: linux-2.6-tip/kernel/time/clocksource.c
> ===================================================================
> --- linux-2.6-tip.orig/kernel/time/clocksource.c	2009-08-14 17:29:50.000000000 -0400
> +++ linux-2.6-tip/kernel/time/clocksource.c	2009-08-14 17:30:36.000000000 -0400
> @@ -478,6 +478,8 @@
>  					  struct sysdev_attribute *attr,
>  					  const char *buf, size_t count)
>  {
> +	size_t ret = count;
> +
>  	/* strings from sysfs write are not 0 terminated! */
>  	if (count >= sizeof(override_name))
>  		return -EINVAL;
> @@ -495,7 +497,7 @@
> 
>  	spin_unlock_irq(&clocksource_lock);
> 
> -	return count;
> +	return ret;
>  }
> 
>  /**

Opps :-(
Thanks for bisecting & fixing.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.

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