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From: Michael Hanselmann <linux-kernel@hansmi.ch>
To: Andrew Morton <akpm@osdl.org>
Cc: linuxppc-dev@ozlabs.org, johannes@sipsolutions.net,
	aris@valeta.org, linux-kernel@killerfox.forkbomb.ch
Subject: Re: powermac: More powermac backlight fixes
Date: Tue, 25 Jul 2006 20:44:06 +0200	[thread overview]
Message-ID: <20060725184406.GA12226@hansmi.ch> (raw)
In-Reply-To: <20060724200315.d3c80ed0.akpm@osdl.org>

Hello Andrew

On Mon, Jul 24, 2006 at 08:03:15PM -0700, Andrew Morton wrote:
> I see schedule_work()s in there, but no flush_scheduled_work()s or anything
> like that.  Generally, this means there are races against rmmod, close(),
> etc.

I'll check that. Another patch is in the work already.

> > +void pmac_backlight_disable()
> > +{
> > +	atomic_inc(&kernel_backlight_disabled);
> > +}
> > +
> > +void pmac_backlight_enable()
> > +{
> > +	atomic_dec(&kernel_backlight_disabled);
> > +}
> > +

> So if userspace calls ioctl(PMU_IOC_GRAB_BACKLIGHT) eleven times, eleven
> enables are needed?  (Actually, eleven open()/close() sequences, I think).

> Methinks you wanted just

> 	kernel_backlight_disabled = 1;
> ?

Aristeu already asked me that, and no, the disabling is meant to be
recursive. The old code did something like "spin_lock(...); disable++;
spin_unlock(...);". It then checked for "if (disable) return;". My code
basically moves the code from the via-pmu driver and removes the
spinlocks.

Thanks,
Michael

  reply	other threads:[~2006-07-25 18:44 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-07-15 13:09 powermac: More powermac backlight fixes Michael Hanselmann
2006-07-25  3:03 ` Andrew Morton
2006-07-25 18:44   ` Michael Hanselmann [this message]
2006-07-25 20:06     ` Michael Hanselmann
2006-07-25 21:49   ` Benjamin Herrenschmidt

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