Re: 2.6.24-git: kmap_atomic() WARN_ON()

Ingo Molnar
2008-02-26T20:50:22Z

* 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.

Ingo