linux-kernel - [PATCH] mm,x86: fix kmap_atomic_push vs ioremap

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Date:	Wed, 27 Oct 2010 12:33:58 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Chris Wilson <chris@...is-wilson.co.uk>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linux-arch@...r.kernel.org, Christoph Hellwig <hch@...radead.org>
Subject: [PATCH] mm,x86: fix kmap_atomic_push vs ioremap_32.c

On Wed, 2010-10-27 at 11:27 +0100, Chris Wilson wrote:
> On Sat, 18 Sep 2010 17:53:26 +0200, Peter Zijlstra <a.p.zijlstra@...llo.nl> wrote:
> > Next version of the kmap_atomic rework using Andrew's fancy CPP trickery to
> > avoid having to convert the whole tree at once.
> > 
> > This is compile tested for i386-allmodconfig, frv, mips-sb1250-swarm,
> > powerpc-ppc6xx_defconfig, sparc32_defconfig, arm-omap3 (all with
> > HIGHEM=y).
> 
> This break on x86, HIGHMEM=n:
> 
> arch/x86/mm/iomap_32.c: In function ‘kmap_atomic_prot_pfn’:
> arch/x86/mm/iomap_32.c:64: error: implicit declaration of function
> ‘kmap_atomic_idx_push’
> arch/x86/mm/iomap_32.c: In function ‘iounmap_atomic’:
> arch/x86/mm/iomap_32.c:101: error: implicit declaration of function
> ‘kmap_atomic_idx_pop’

Christoph just complained about the same on IRC, the below seems to cure
things for i386-defconfig with CONFIG_HIGHMEM=n

---
Subject: mm,x86: fix kmap_atomic_push vs ioremap_32.c

It appears i386 uses kmap_atomic infrastructure regardless of
CONFIG_HIGHMEM which results in a compile error when highmem is
disabled.

Cure this by providing the needed few bits for both CONFIG_HIGHMEM and
CONFIG_X86_32.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
---
 include/linux/highmem.h |   46 +++++++++++++++++++++++++---------------------
 mm/highmem.c            |    6 +++++-
 2 files changed, 30 insertions(+), 22 deletions(-)

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 8a85ec1..102f76b 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -37,27 +37,6 @@ extern unsigned long totalhigh_pages;
 
 void kmap_flush_unused(void);
 
-DECLARE_PER_CPU(int, __kmap_atomic_idx);
-
-static inline int kmap_atomic_idx_push(void)
-{
-	int idx = __get_cpu_var(__kmap_atomic_idx)++;
-#ifdef CONFIG_DEBUG_HIGHMEM
-	WARN_ON_ONCE(in_irq() && !irqs_disabled());
-	BUG_ON(idx > KM_TYPE_NR);
-#endif
-	return idx;
-}
-
-static inline int kmap_atomic_idx_pop(void)
-{
-	int idx = --__get_cpu_var(__kmap_atomic_idx);
-#ifdef CONFIG_DEBUG_HIGHMEM
-	BUG_ON(idx < 0);
-#endif
-	return idx;
-}
-
 #else /* CONFIG_HIGHMEM */
 
 static inline unsigned int nr_free_highpages(void) { return 0; }
@@ -95,6 +74,31 @@ static inline void __kunmap_atomic(void *addr)
 
 #endif /* CONFIG_HIGHMEM */
 
+#if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
+
+DECLARE_PER_CPU(int, __kmap_atomic_idx);
+
+static inline int kmap_atomic_idx_push(void)
+{
+	int idx = __get_cpu_var(__kmap_atomic_idx)++;
+#ifdef CONFIG_DEBUG_HIGHMEM
+	WARN_ON_ONCE(in_irq() && !irqs_disabled());
+	BUG_ON(idx > KM_TYPE_NR);
+#endif
+	return idx;
+}
+
+static inline int kmap_atomic_idx_pop(void)
+{
+	int idx = --__get_cpu_var(__kmap_atomic_idx);
+#ifdef CONFIG_DEBUG_HIGHMEM
+	BUG_ON(idx < 0);
+#endif
+	return idx;
+}
+
+#endif
+
 /*
  * Make both: kmap_atomic(page, idx) and kmap_atomic(page) work.
  */
diff --git a/mm/highmem.c b/mm/highmem.c
index 781e754..693394d 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -29,6 +29,11 @@
 #include <linux/kgdb.h>
 #include <asm/tlbflush.h>
 
+
+#if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
+DEFINE_PER_CPU(int, __kmap_atomic_idx);
+#endif
+
 /*
  * Virtual_count is not a pure "count".
  *  0 means that it is not mapped, and has not been mapped
@@ -43,7 +48,6 @@ unsigned long totalhigh_pages __read_mostly;
 EXPORT_SYMBOL(totalhigh_pages);
 
 
-DEFINE_PER_CPU(int, __kmap_atomic_idx);
 EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx);
 
 unsigned int nr_free_highpages (void)


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