cpumask: use work_on_cpu in acpi-cpufreq.c for drv_read and drv_write

Impact: use new cpumask API to reduce stack usage

Replace the saving of current->cpus_allowed and set_cpus_allowed_ptr() with
a work_on_cpu function for drv_read() and drv_write().

Basically converts do_drv_{read,write} into "work_on_cpu" functions that
are now called by drv_read and drv_write.

Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 13 insertions, 12 deletions

diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
index fb594170dc53..4e4f2b04dac2 100644
--- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
+++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
@@ -150,8 +150,9 @@ struct drv_cmd {
         u32 val;
 };
 
-static void do_drv_read(struct drv_cmd *cmd)
+static long do_drv_read(void *_cmd)
 {
+        struct drv_cmd *cmd = _cmd;
         u32 h;
 
         switch (cmd->type) {
@@ -166,10 +167,12 @@ static void do_drv_read(struct drv_cmd *cmd)
         default:
                 break;
         }
+        return 0;
 }
 
-static void do_drv_write(struct drv_cmd *cmd)
+static long do_drv_write(void *_cmd)
 {
+        struct drv_cmd *cmd = _cmd;
         u32 lo, hi;
 
         switch (cmd->type) {
@@ -186,30 +189,23 @@ static void do_drv_write(struct drv_cmd *cmd)
         default:
                 break;
         }
+        return 0;
 }
 
 static void drv_read(struct drv_cmd *cmd)
 {
-        cpumask_t saved_mask = current->cpus_allowed;
         cmd->val = 0;
 
-        set_cpus_allowed_ptr(current, cmd->mask);
-        do_drv_read(cmd);
-        set_cpus_allowed_ptr(current, &saved_mask);
+        work_on_cpu(cpumask_any(cmd->mask), do_drv_read, cmd);
 }
 
 static void drv_write(struct drv_cmd *cmd)
 {
-        cpumask_t saved_mask = current->cpus_allowed;
         unsigned int i;
 
         for_each_cpu(i, cmd->mask) {
-                set_cpus_allowed_ptr(current, cpumask_of(i));
-                do_drv_write(cmd);
+                work_on_cpu(i, do_drv_write, cmd);
         }
-
-        set_cpus_allowed_ptr(current, &saved_mask);
-        return;
 }
 
 static u32 get_cur_val(const struct cpumask *mask)
@@ -235,10 +231,15 @@ static u32 get_cur_val(const struct cpumask *mask)
                 return 0;
         }
 
+        if (unlikely(!alloc_cpumask_var(&cmd.mask, GFP_KERNEL)))
+                return 0;
+
         cpumask_copy(cmd.mask, mask);
 
         drv_read(&cmd);
 
+        free_cpumask_var(cmd.mask);
+
         dprintk("get_cur_val = %u\n", cmd.val);
 
         return cmd.val;