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Message-ID: <20090305225921.GE918@n2100.arm.linux.org.uk>
Date: Thu, 5 Mar 2009 22:59:21 +0000
From: Russell King - ARM Linux <linux@....linux.org.uk>
To: Minchan Kim <minchan.kim@...il.com>
Cc: Nicolas Pitre <nico@....org>, lkml <linux-kernel@...r.kernel.org>,
linux-mm@...ck.org
Subject: Re: [RFC] atomic highmem kmap page pinning
On Fri, Mar 06, 2009 at 07:23:44AM +0900, Minchan Kim wrote:
> > +#ifdef ARCH_NEEDS_KMAP_HIGH_GET
> > +/**
> > + * kmap_high_get - pin a highmem page into memory
> > + * @page: &struct page to pin
> > + *
> > + * Returns the page's current virtual memory address, or NULL if no mapping
> > + * exists. When and only when a non null address is returned then a
> > + * matching call to kunmap_high() is necessary.
> > + *
> > + * This can be called from any context.
> > + */
> > +void *kmap_high_get(struct page *page)
> > +{
> > + unsigned long vaddr, flags;
> > +
> > + spin_lock_kmap_any(flags);
> > + vaddr = (unsigned long)page_address(page);
> > + if (vaddr) {
> > + BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1);
> > + pkmap_count[PKMAP_NR(vaddr)]++;
> > + }
> > + spin_unlock_kmap_any(flags);
> > + return (void*) vaddr;
> > +}
> > +#endif
>
> Let's add empty function for architecture of no ARCH_NEEDS_KMAP_HIGH_GET,
The reasoning being?
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