linux-kernel - Re: most users of msleep

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Message-ID: <20061011203001.GB3935@ucw.cz>
Date:	Wed, 11 Oct 2006 20:30:02 +0000
From:	Pavel Machek <pavel@...e.cz>
To:	Matthew Wilcox <matthew@....cx>
Cc:	Arjan van de Ven <arjan@...radead.org>,
	Amol Lad <amol@...ismonetworks.com>,
	kernel Janitors <kernel-janitors@...ts.osdl.org>,
	linux kernel <linux-kernel@...r.kernel.org>
Subject: Re: most users of msleep_interruptible are broken

Hi!

> > > +++ linux-2.6.19-rc1/drivers/mmc/mmc.c	2006-10-11 17:57:02.000000000 +0530
> > > @@ -454,7 +454,7 @@ static void mmc_deselect_cards(struct mm
> > >  static inline void mmc_delay(unsigned int ms)
> > >  {
> > >  	if (ms < HZ / 1000) {
> > > -		yield();
> > > +		cond_resched();
> > >  		mdelay(ms);
> > 
> > 
> > this probably wants msleep(), especially with hrtimers comming up; there
> > the sleeps are always exact...
> 
> They clearly don't care about exactness; they msleep_interruptible and
> throw away the return value, so they don't know how long they slept
> before they got a signal.
> 
> __must_check treatment for msleep_interruptible, anyone?  On the one hand,
> that's 136 new warnings.  On the other hand, that's 136 places wheree
> we may as well *delete the call* to msleep_interruptible.  Since it can
> return immediately, the code must be prepared to deal with that ... right?

Well, it must work, but it may busyloop instead of sleeping. This does
not look like must_check to me.
						Pavel

-- 
Thanks for all the (sleeping) penguins.
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