Avoid zero size allocation in cache_k8_northbridges()

kmalloc for flush_words resulted in zero size allocation when no
k8_northbridges existed.  Short circuit the code path for this case.

Also remove uneeded zeroing of num_k8_northbridges just after checking if
it is zero.

Signed-off-by: Ben Collins <bcollins@ubuntu.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/arch/x86_64/kernel/k8.c b/arch/x86_64/kernel/k8.c
index bc11b32e8b4d..7377ccb21335 100644
--- a/arch/x86_64/kernel/k8.c
+++ b/arch/x86_64/kernel/k8.c
@@ -39,10 +39,10 @@ int cache_k8_northbridges(void)
 {
         int i;
         struct pci_dev *dev;
+
         if (num_k8_northbridges)
                 return 0;
 
-        num_k8_northbridges = 0;
         dev = NULL;
         while ((dev = next_k8_northbridge(dev)) != NULL)
                 num_k8_northbridges++;
@@ -52,6 +52,11 @@ int cache_k8_northbridges(void)
         if (!k8_northbridges)
                 return -ENOMEM;
 
+        if (!num_k8_northbridges) {
+                k8_northbridges[0] = NULL;
+                return 0;
+        }
+
         flush_words = kmalloc(num_k8_northbridges * sizeof(u32), GFP_KERNEL);
         if (!flush_words) {
                 kfree(k8_northbridges);