cpumask: Replace cpumask_of_cpu with cpumask_of_cpu_ptr

  * This patch replaces the dangerous lvalue version of cpumask_of_cpu
    with new cpumask_of_cpu_ptr macros.  These are patterned after the
    node_to_cpumask_ptr macros.

    In general terms, if there is a cpumask_of_cpu_map[] then a pointer to
    the cpumask_of_cpu_map[cpu] entry is used.  The cpumask_of_cpu_map
    is provided when there is a large NR_CPUS count, reducing
    greatly the amount of code generated and stack space used for
    cpumask_of_cpu().  The pointer to the cpumask_t value is needed for
    calling set_cpus_allowed_ptr() to reduce the amount of stack space
    needed to pass the cpumask_t value.

    If there isn't a cpumask_of_cpu_map[], then a temporary variable is
    declared and filled in with value from cpumask_of_cpu(cpu) as well as
    a pointer variable pointing to this temporary variable.  Afterwards,
    the pointer is used to reference the cpumask value.  The compiler
    will optimize out the extra dereference through the pointer as well
    as the stack space used for the pointer, resulting in identical code.

    A good example of the orthogonal usages is in net/sunrpc/svc.c:

	case SVC_POOL_PERCPU:
	{
		unsigned int cpu = m->pool_to[pidx];
		cpumask_of_cpu_ptr(cpumask, cpu);

		*oldmask = current->cpus_allowed;
		set_cpus_allowed_ptr(current, cpumask);
		return 1;
	}
	case SVC_POOL_PERNODE:
	{
		unsigned int node = m->pool_to[pidx];
		node_to_cpumask_ptr(nodecpumask, node);

		*oldmask = current->cpus_allowed;
		set_cpus_allowed_ptr(current, nodecpumask);
		return 1;
	}

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 10 insertions, 5 deletions

diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
index c45ca6d4dce1..53c7b6936973 100644
--- a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
+++ b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
@@ -479,11 +479,12 @@ static int core_voltage_post_transition(struct powernow_k8_data *data, u32 reqvi
 static int check_supported_cpu(unsigned int cpu)
 {
         cpumask_t oldmask;
+        cpumask_of_cpu_ptr(cpu_mask, cpu);
         u32 eax, ebx, ecx, edx;
         unsigned int rc = 0;
 
         oldmask = current->cpus_allowed;
-        set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
+        set_cpus_allowed_ptr(current, cpu_mask);
 
         if (smp_processor_id() != cpu) {
                 printk(KERN_ERR PFX "limiting to cpu %u failed\n", cpu);
@@ -1016,6 +1017,7 @@ static int transition_frequency_pstate(struct powernow_k8_data *data, unsigned i
 static int powernowk8_target(struct cpufreq_policy *pol, unsigned targfreq, unsigned relation)
 {
         cpumask_t oldmask;
+        cpumask_of_cpu_ptr(cpu_mask, pol->cpu);
         struct powernow_k8_data *data = per_cpu(powernow_data, pol->cpu);
         u32 checkfid;
         u32 checkvid;
@@ -1030,7 +1032,7 @@ static int powernowk8_target(struct cpufreq_policy *pol, unsigned targfreq, unsi
 
         /* only run on specific CPU from here on */
         oldmask = current->cpus_allowed;
-        set_cpus_allowed_ptr(current, &cpumask_of_cpu(pol->cpu));
+        set_cpus_allowed_ptr(current, cpu_mask);
 
         if (smp_processor_id() != pol->cpu) {
                 printk(KERN_ERR PFX "limiting to cpu %u failed\n", pol->cpu);
@@ -1105,6 +1107,7 @@ static int __cpuinit powernowk8_cpu_init(struct cpufreq_policy *pol)
 {
         struct powernow_k8_data *data;
         cpumask_t oldmask;
+        cpumask_of_cpu_ptr_declare(newmask);
         int rc;
 
         if (!cpu_online(pol->cpu))
@@ -1156,7 +1159,8 @@ static int __cpuinit powernowk8_cpu_init(struct cpufreq_policy *pol)
 
         /* only run on specific CPU from here on */
         oldmask = current->cpus_allowed;
-        set_cpus_allowed_ptr(current, &cpumask_of_cpu(pol->cpu));
+        cpumask_of_cpu_ptr_next(newmask, pol->cpu);
+        set_cpus_allowed_ptr(current, newmask);
 
         if (smp_processor_id() != pol->cpu) {
                 printk(KERN_ERR PFX "limiting to cpu %u failed\n", pol->cpu);
@@ -1178,7 +1182,7 @@ static int __cpuinit powernowk8_cpu_init(struct cpufreq_policy *pol)
         set_cpus_allowed_ptr(current, &oldmask);
 
         if (cpu_family == CPU_HW_PSTATE)
-                pol->cpus = cpumask_of_cpu(pol->cpu);
+                pol->cpus = *newmask;
         else
                 pol->cpus = per_cpu(cpu_core_map, pol->cpu);
         data->available_cores = &(pol->cpus);
@@ -1244,6 +1248,7 @@ static unsigned int powernowk8_get (unsigned int cpu)
 {
         struct powernow_k8_data *data;
         cpumask_t oldmask = current->cpus_allowed;
+        cpumask_of_cpu_ptr(newmask, cpu);
         unsigned int khz = 0;
         unsigned int first;
 
@@ -1253,7 +1258,7 @@ static unsigned int powernowk8_get (unsigned int cpu)
         if (!data)
                 return -EINVAL;
 
-        set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
+        set_cpus_allowed_ptr(current, newmask);
         if (smp_processor_id() != cpu) {
                 printk(KERN_ERR PFX
                         "limiting to CPU %d failed in powernowk8_get\n", cpu);