linux-kernel - [patch] x86, cacheinfo: dereferences before check

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Date:	Tue, 1 Jun 2010 09:11:27 +0200
From:	Dan Carpenter <error27@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>,
	x86@...nel.org, Borislav Petkov <borislav.petkov@....com>,
	Dave Jones <davej@...hat.com>, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [patch] x86, cacheinfo: dereferences before check

This moves a couple dereferences after the checks in
show_cache_disable() and store_cache_disable().  These were introduced
fairly recently in 9350f982e4: "x86, cacheinfo: Reorganize AMD L3 cache
structure"

Signed-off-by: Dan Carpenter <error27@...il.com>

diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
index 33eae20..1725a0e 100644
--- a/arch/x86/kernel/cpu/intel_cacheinfo.c
+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
@@ -399,12 +399,13 @@ amd_check_l3_disable(int index, struct _cpuid4_info_regs *this_leaf)
 static ssize_t show_cache_disable(struct _cpuid4_info *this_leaf, char *buf,
 				  unsigned int slot)
 {
-	struct pci_dev *dev = this_leaf->l3->dev;
+	struct pci_dev *dev;
 	unsigned int reg = 0;
 
 	if (!this_leaf->l3 || !this_leaf->l3->can_disable)
 		return -EINVAL;
 
+	dev = this_leaf->l3->dev;
 	if (!dev)
 		return -EINVAL;
 
@@ -456,7 +457,7 @@ static ssize_t store_cache_disable(struct _cpuid4_info *this_leaf,
 				   const char *buf, size_t count,
 				   unsigned int slot)
 {
-	struct pci_dev *dev = this_leaf->l3->dev;
+	struct pci_dev *dev;
 	int cpu = cpumask_first(to_cpumask(this_leaf->shared_cpu_map));
 	unsigned long val = 0;
 
@@ -469,6 +470,7 @@ static ssize_t store_cache_disable(struct _cpuid4_info *this_leaf,
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
+	dev = this_leaf->l3->dev;
 	if (!dev)
 		return -EINVAL;
 
--
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