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From: Andrew Morton <akpm@linux-foundation.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: "Jeff Garzik" <jgarzik@pobox.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Björn Steinbrink" <B.Steinbrink@gmx.de>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: 2.6.24-git: kmap_atomic() WARN_ON()
Date: Tue, 26 Feb 2008 13:37:15 -0800	[thread overview]
Message-ID: <20080226133715.d9cd32e7.akpm@linux-foundation.org> (raw)
In-Reply-To: <20080226204943.GD14350@elte.hu>

On Tue, 26 Feb 2008 21:49:43 +0100 Ingo Molnar <mingo@elte.hu> wrote:

> 
> * Andrew Morton <akpm@linux-foundation.org> wrote:
> 
> > > This is only being done to satisfy kmap_atomic's requirements, not 
> > > libata's.
> > > 
> > > I could add a "kmap lock" but that just seems silly.
> > > 
> > 
> > It's a bit sad to disable interupts across a memset (how big is it?) 
> > just for the small proportion of cases which are accessing a highmem 
> > page.
> > 
> > What you could do is to add an `unsigned long *flags' arg to 
> > ata_scsi_rbuf_get() and ata_scsi_rbuf_put(), and then, in 
> > ata_scsi_rbuf_get() do
> > 
> > 	if (PageHighmem(page))
> > 		local_irq_disable(*flags);
> 
> it would be much nicer to attach the irq disabling to the object, not to 
> some arbitrary place in the code.
> 
> i.e. to introduce a kmap_atomic_irqsave(...,flags) and 
> kunmap_atomic_irqrestore() API variant. _That_ then could be mapped by 
> -rt to a non-irq disabling thing.
> 

Sure.  But iirc we haven't had a need for this before.  Which is a bit odd.
 

  reply	other threads:[~2008-02-26 21:49 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-06 23:58 Thomas Gleixner
2008-02-13 22:39 ` Rafael J. Wysocki
2008-02-14  1:13   ` Thomas Gleixner
2008-02-25 19:59 ` Björn Steinbrink
2008-02-25 20:08   ` Jeff Garzik
2008-02-25 20:35     ` Björn Steinbrink
2008-02-25 20:40     ` Andrew Morton
2008-02-25 22:01       ` Thomas Gleixner
2008-02-25 22:17         ` Andrew Morton
2008-02-25 23:19         ` Jeff Garzik
2008-02-26  8:39           ` Ingo Molnar
2008-02-26 16:32             ` Jeff Garzik
2008-02-26 18:19               ` Andrew Morton
2008-02-26 20:49                 ` Ingo Molnar
2008-02-26 21:37                   ` Andrew Morton [this message]
2008-02-26 22:59                     ` Jeff Garzik
2008-02-27  0:02                       ` Alan Cox
2008-02-26 23:49                   ` Nick Piggin
2008-02-26  8:50           ` Thomas Gleixner

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