linux-kernel - Re: [PATCH] bootmem.c: Avoid c90 declaration warning

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Date:	Thu, 18 Jun 2009 23:57:45 +0200
From:	Johannes Weiner <hannes@...xchg.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Joe Perches <joe@...ches.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Pekka Enberg <penberg@...helsinki.fi>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Tejun Heo <tj@...nel.org>, Yinghai Lu <yinghai@...nel.org>
Subject: Re: [PATCH] bootmem.c: Avoid c90 declaration warning

On Thu, Jun 18, 2009 at 01:24:10PM -0700, Andrew Morton wrote:
> On Thu, 18 Jun 2009 13:07:13 -0700
> Joe Perches <joe@...ches.com> wrote:
> 
> > Signed-off-by: Joe Perches <joe@...ches.com>
> > 
> > diff --git a/mm/bootmem.c b/mm/bootmem.c
> > index 282df0a..09d9c98 100644
> > --- a/mm/bootmem.c
> > +++ b/mm/bootmem.c
> > @@ -536,11 +536,13 @@ static void * __init alloc_arch_preferred_bootmem(bootmem_data_t *bdata,
> >  		return kzalloc(size, GFP_NOWAIT);
> >  
> >  #ifdef CONFIG_HAVE_ARCH_BOOTMEM
> > +	{
> >  	bootmem_data_t *p_bdata;
> >  
> >  	p_bdata = bootmem_arch_preferred_node(bdata, size, align, goal, limit);
> >  	if (p_bdata)
> >  		return alloc_bootmem_core(p_bdata, size, align, goal, limit);
> > +	}
> >  #endif
> >  	return NULL;
> >  }
> 
> Well yes.
> 
> We'll be needing some tabs there.
> 
> Unrelatedly, I'm struggling a bit with bootmem_arch_preferred_node(). 
> It's only defined if CONFIG_X86_32=y && CONFIG_NEED_MULTIPLE_NODES=y,
> but it gets called if CONFIG_HAVE_ARCH_BOOTMEM=y.
> 
> Is this correct, logical and as simple as we can make it??

x86_32 numa is the only setter of HAVE_ARCH_BOOTMEM.  I don't know why
this arch has a strict preference/requirement(?) for bootmem on node
0.

I found this mail from Yinghai

  http://marc.info/?l=linux-kernel&m=123614990906256&w=2

where he says that it expects all bootmem on node zero but with the
current code and alloc_arch_preferred_bootmem() failing, we could fall
back to another node.  Won't this break?  Yinghai?

Otherwise, could we perhaps use something as simple as this?

diff --git a/arch/x86/include/asm/mmzone_32.h b/arch/x86/include/asm/mmzone_32.h
index ede6998..b68a672 100644
--- a/arch/x86/include/asm/mmzone_32.h
+++ b/arch/x86/include/asm/mmzone_32.h
@@ -92,8 +92,7 @@ static inline int pfn_valid(int pfn)
 
 #ifdef CONFIG_NEED_MULTIPLE_NODES
 /* always use node 0 for bootmem on this numa platform */
-#define bootmem_arch_preferred_node(__bdata, size, align, goal, limit)	\
-	(NODE_DATA(0)->bdata)
+#define bootmem_arch_preferred_node (NODE(0)->bdata)
 #endif /* CONFIG_NEED_MULTIPLE_NODES */
 
 #endif /* _ASM_X86_MMZONE_32_H */
diff --git a/mm/bootmem.c b/mm/bootmem.c
index 282df0a..0097fa2 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -528,23 +528,6 @@ find_block:
 	return NULL;
 }
 
-static void * __init alloc_arch_preferred_bootmem(bootmem_data_t *bdata,
-					unsigned long size, unsigned long align,
-					unsigned long goal, unsigned long limit)
-{
-	if (WARN_ON_ONCE(slab_is_available()))
-		return kzalloc(size, GFP_NOWAIT);
-
-#ifdef CONFIG_HAVE_ARCH_BOOTMEM
-	bootmem_data_t *p_bdata;
-
-	p_bdata = bootmem_arch_preferred_node(bdata, size, align, goal, limit);
-	if (p_bdata)
-		return alloc_bootmem_core(p_bdata, size, align, goal, limit);
-#endif
-	return NULL;
-}
-
 static void * __init ___alloc_bootmem_nopanic(unsigned long size,
 					unsigned long align,
 					unsigned long goal,
@@ -553,11 +536,15 @@ static void * __init ___alloc_bootmem_nopanic(unsigned long size,
 	bootmem_data_t *bdata;
 	void *region;
 
+	if (WARN_ON_ONCE(slab_is_available()))
+		return kzalloc(size, GFP_NOWAIT);
 restart:
-	region = alloc_arch_preferred_bootmem(NULL, size, align, goal, limit);
+#ifdef bootmem_arch_preferred_node
+	region = alloc_bootmem_core(bootmem_arch_preferred_node,
+				size, align, goal, limit);
 	if (region)
 		return region;
-
+#endif
 	list_for_each_entry(bdata, &bdata_list, list) {
 		if (goal && bdata->node_low_pfn <= PFN_DOWN(goal))
 			continue;
@@ -636,13 +623,11 @@ static void * __init ___alloc_bootmem_node(bootmem_data_t *bdata,
 {
 	void *ptr;
 
-	ptr = alloc_arch_preferred_bootmem(bdata, size, align, goal, limit);
-	if (ptr)
-		return ptr;
-
+#ifndef bootmem_arch_preferred_node
 	ptr = alloc_bootmem_core(bdata, size, align, goal, limit);
 	if (ptr)
 		return ptr;
+#endif
 
 	return ___alloc_bootmem(size, align, goal, limit);
 }
--
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