linux-kernel - Re: [PATCH 3/3] x86/iommu: use __GFP

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Date:	Thu, 25 Sep 2008 12:42:12 +0200
From:	Joerg Roedel <joerg.roedel@....com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	mingo@...hat.com, tglx@...utronix.de, hpa@...or.com,
	linux-kernel@...r.kernel.org, fujita.tomonori@....ntt.co.jp
Subject: Re: [PATCH 3/3] x86/iommu: use __GFP_ZERO instead of memset for GART

On Thu, Sep 25, 2008 at 12:20:12PM +0200, Ingo Molnar wrote:
> 
> * Joerg Roedel <joerg.roedel@....com> wrote:
> 
> >  #ifdef CONFIG_IOMMU_LEAK
> >  	if (leak_trace) {
> > -		iommu_leak_tab = (void *)__get_free_pages(GFP_KERNEL,
> > +		iommu_leak_tab = (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO,
> >  				  get_order(iommu_pages*sizeof(void *)));
> > -		if (iommu_leak_tab)
> > -			memset(iommu_leak_tab, 0, iommu_pages * 8);
> >  		else
> >  			printk(KERN_DEBUG
> >  			       "PCI-DMA: Cannot allocate leak trace area\n");
> 
> hm, that looks broken.

Argh, yes. Please try this one:

=
>From c402fd7f5fe930d45a02ef863bf3fb61851e6ad0 Mon Sep 17 00:00:00 2001
From: Joerg Roedel <joerg.roedel@....com>
Date: Thu, 25 Sep 2008 12:39:06 +0200
Subject: [PATCH] x86/iommu: use __GFP_ZERO instead of memset for GART

Signed-off-by: Joerg Roedel <joerg.roedel@....com>
---
 arch/x86/kernel/pci-gart_64.c |   13 +++++--------
 1 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
index aecea06..d077116 100644
--- a/arch/x86/kernel/pci-gart_64.c
+++ b/arch/x86/kernel/pci-gart_64.c
@@ -674,13 +674,13 @@ static __init int init_k8_gatt(struct agp_kern_info *info)
 	info->aper_size = aper_size >> 20;
 
 	gatt_size = (aper_size >> PAGE_SHIFT) * sizeof(u32);
-	gatt = (void *)__get_free_pages(GFP_KERNEL, get_order(gatt_size));
+	gatt = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+					get_order(gatt_size));
 	if (!gatt)
 		panic("Cannot allocate GATT table");
 	if (set_memory_uc((unsigned long)gatt, gatt_size >> PAGE_SHIFT))
 		panic("Could not set GART PTEs to uncacheable pages");
 
-	memset(gatt, 0, gatt_size);
 	agp_gatt_table = gatt;
 
 	enable_gart_translations();
@@ -788,19 +788,16 @@ void __init gart_iommu_init(void)
 	iommu_size = check_iommu_size(info.aper_base, aper_size);
 	iommu_pages = iommu_size >> PAGE_SHIFT;
 
-	iommu_gart_bitmap = (void *) __get_free_pages(GFP_KERNEL,
+	iommu_gart_bitmap = (void *) __get_free_pages(GFP_KERNEL | __GFP_ZERO,
 						      get_order(iommu_pages/8));
 	if (!iommu_gart_bitmap)
 		panic("Cannot allocate iommu bitmap\n");
-	memset(iommu_gart_bitmap, 0, iommu_pages/8);
 
 #ifdef CONFIG_IOMMU_LEAK
 	if (leak_trace) {
-		iommu_leak_tab = (void *)__get_free_pages(GFP_KERNEL,
+		iommu_leak_tab = (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO,
 				  get_order(iommu_pages*sizeof(void *)));
-		if (iommu_leak_tab)
-			memset(iommu_leak_tab, 0, iommu_pages * 8);
-		else
+		if (!iommu_leak_tab)
 			printk(KERN_DEBUG
 			       "PCI-DMA: Cannot allocate leak trace area\n");
 	}
-- 
1.5.6.4


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