x86: cpumask: x86 mmio-mod.c use cpumask_var_t for downed_cpus

Impact: cleanup, reduce memory usage for CONFIG_CPUMASK_OFFSTACK=y

Part of the "getting rid of obsolete cpumask_t" patch:

 1) Use cpumask_var_t: this is a pointer if CONFIG_CPUMASK_OFFSTACK=y
 2) Call alloc_cpumask_var() on first entry into enter_uniprocessor()
 3) Use modern cpumask_* functions.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Pekka Paalanen <pq@iki.fi>
LKML-Reference: <200903111633.55952.rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 13 insertions, 6 deletions

diff --git a/arch/x86/mm/mmio-mod.c b/arch/x86/mm/mmio-mod.c
index 2c4baa88f2cb..c9342ed8b402 100644
--- a/arch/x86/mm/mmio-mod.c
+++ b/arch/x86/mm/mmio-mod.c
@@ -378,27 +378,34 @@ static void clear_trace_list(void)
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
-static cpumask_t downed_cpus;
+static cpumask_var_t downed_cpus;
 
 static void enter_uniprocessor(void)
 {
         int cpu;
         int err;
 
+        if (downed_cpus == NULL &&
+            !alloc_cpumask_var(&downed_cpus, GFP_KERNEL)) {
+                pr_notice(NAME "Failed to allocate mask\n");
+                goto out;
+        }
+
         get_online_cpus();
-        downed_cpus = cpu_online_map;
-        cpu_clear(first_cpu(cpu_online_map), downed_cpus);
+        cpumask_copy(downed_cpus, cpu_online_mask);
+        cpumask_clear_cpu(cpumask_first(cpu_online_mask), downed_cpus);
         if (num_online_cpus() > 1)
                 pr_notice(NAME "Disabling non-boot CPUs...\n");
         put_online_cpus();
 
-        for_each_cpu_mask(cpu, downed_cpus) {
+        for_each_cpu(cpu, downed_cpus) {
                 err = cpu_down(cpu);
                 if (!err)
                         pr_info(NAME "CPU%d is down.\n", cpu);
                 else
                         pr_err(NAME "Error taking CPU%d down: %d\n", cpu, err);
         }
+out:
         if (num_online_cpus() > 1)
                 pr_warning(NAME "multiple CPUs still online, "
                                                 "may miss events.\n");
@@ -411,10 +418,10 @@ static void __ref leave_uniprocessor(void)
         int cpu;
         int err;
 
-        if (cpus_weight(downed_cpus) == 0)
+        if (downed_cpus == NULL || cpumask_weight(downed_cpus) == 0)
                 return;
         pr_notice(NAME "Re-enabling CPUs...\n");
-        for_each_cpu_mask(cpu, downed_cpus) {
+        for_each_cpu(cpu, downed_cpus) {
                 err = cpu_up(cpu);
                 if (!err)
                         pr_info(NAME "enabled CPU%d.\n", cpu);