Subject: Re: interruptible_sleep_on, interrupts and device drivers
From: Arjan van de Ven <arjan@infradead.org>
To: Gabriele Brugnoni <news@dveprojects.com>
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <200510151229.37124.news@dveprojects.com>
References: <200510151229.37124.news@dveprojects.com>
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Date: Sat, 15 Oct 2005 12:36:29 +0200
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On Sat, 2005-10-15 at 12:29 +0200, Gabriele Brugnoni wrote:
> Arjan van de Ven wrote:
> 
> > 
> > don't.
> > 
> > interruptible_sleep_on() is a broken interface (see the comments in the
> > header) and should not be used in any new code (where "new" is "since
> > the year 2000" :)
> > 
> > Just use the wait_event() interfaces .... or just a simple semaphore
> > even if what you want to do is simple and performance isn't too
> > critical.
> > 
> 
> OK, i'll not use, but the kernel has a lot of device drivers using it, that 
> may present the problem explained in my message.
> 
> In my code i've try the following:
> 
> 		save_flags(flags); cli();

this is broken code; cli() cannot and should not be used. (and isn't
even available on SMP kernels anymore)

> 		if( !rs.txdone ) {
> 			if( arg < 0 ) arg = rs.ttimeout;
> 			if( arg > 0 )
> 				interruptible_sleep_on_timeout ( &rs.txwait, arg );
> 			else
> 				interruptible_sleep_on ( &rs.txwait );
> 		}
> 		restore_flags(flags);

and this is missing a sti()

> 		return rs.txdone;


your code is just wrong. Yes I know many really old drivers do this, but
those are getting extinct fast..

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