[PATCH] x86 microcode driver vs hotplug CPUs.

This driver loops over 'num_online_cpus', but it doesn't account for holes
in the online map created by offlined cpus, and assumes that the cpu
numbers stay linear.

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 9 insertions, 6 deletions

diff --git a/arch/i386/kernel/microcode.c b/arch/i386/kernel/microcode.c
index d3fdf0057d82..5390b521aca0 100644
--- a/arch/i386/kernel/microcode.c
+++ b/arch/i386/kernel/microcode.c
@@ -74,6 +74,7 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/sched.h>
+#include <linux/cpumask.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
@@ -250,8 +251,8 @@ static int find_matching_ucodes (void)
                         error = -EINVAL;
                         goto out;
                 }
-                
-                for (cpu_num = 0; cpu_num < num_online_cpus(); cpu_num++) {
+
+                for_each_online_cpu(cpu_num) {
                         struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;
                         if (uci->err != MC_NOTFOUND) /* already found a match or not an online cpu*/
                                 continue;
@@ -293,7 +294,7 @@ static int find_matching_ucodes (void)
                                         error = -EFAULT;
                                         goto out;
                                 }
-                                for (cpu_num = 0; cpu_num < num_online_cpus(); cpu_num++) {
+                                for_each_online_cpu(cpu_num) {
                                         struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;
                                         if (uci->err != MC_NOTFOUND) /* already found a match or not an online cpu*/
                                                 continue;
@@ -304,7 +305,9 @@ static int find_matching_ucodes (void)
                         }
                 }
                 /* now check if any cpu has matched */
-                for (cpu_num = 0, allocated_flag = 0, sum = 0; cpu_num < num_online_cpus(); cpu_num++) {
+                allocated_flag = 0;
+                sum = 0;
+                for_each_online_cpu(cpu_num) {
                         if (ucode_cpu_info[cpu_num].err == MC_MARKED) { 
                                 struct ucode_cpu_info *uci = ucode_cpu_info + cpu_num;
                                 if (!allocated_flag) {
@@ -415,12 +418,12 @@ static int do_microcode_update (void)
         }
 
 out_free:
-        for (i = 0; i < num_online_cpus(); i++) {
+        for_each_online_cpu(i) {
                 if (ucode_cpu_info[i].mc) {
                         int j;
                         void *tmp = ucode_cpu_info[i].mc;
                         vfree(tmp);
-                        for (j = i; j < num_online_cpus(); j++) {
+                        for_each_online_cpu(j) {
                                 if (ucode_cpu_info[j].mc == tmp)
                                         ucode_cpu_info[j].mc = NULL;
                         }