linux-kernel - Re: [PATCH] n_hdlc fix read and write locking

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Message-ID: <4CC5F478.40109@microgate.com>
Date:	Mon, 25 Oct 2010 15:19:52 -0600
From:	Paul Fulghum <paulkf@...rogate.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Greg KH <greg@...ah.com>, Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH] n_hdlc fix read and write locking

On 10/25/2010 2:05 PM, Andrew Morton wrote:
> And a signed-off-by:, please.

OK

> It's not a bug afaict, but beware that a copy_to_user() will
> unconditionally flip this task back into TASK_RUNNING state if it takes
> a pagefault.  This means that the below schedule() will fall straight
> through.  It looks like the code will handle this correctly?  If so,
> it's just a little suboptimal.

copy_to_user is only called when data is available to
complete the read and break terminates the loop without
calling schedule().

>> +	set_current_state(TASK_RUNNING);
> 
> We normally use __set_current_state() here - it saves a few cycles.

I'll change it to __set_current_state() and resubmit.

-- 
Paul Fulghum
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