cpuset: modify cpuset_set_cpus_allowed to use cpumask pointer

  * Modify cpuset_cpus_allowed to return the currently allowed cpuset
    via a pointer argument instead of as the function return value.

  * Use new set_cpus_allowed_ptr function.

  * Cleanup CPU_MASK_ALL and NODE_MASK_ALL uses.

Depends on:
	[sched-devel]: sched: add new set_cpus_allowed_ptr function
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/cpuset.h

@@ -20,8 +20,8 @@ extern int number_of_cpusets;	/* How many cpusets are defined in system? */
 extern int cpuset_init_early(void);
 extern int cpuset_init(void);
 extern void cpuset_init_smp(void);
-extern cpumask_t cpuset_cpus_allowed(struct task_struct *p);
-extern cpumask_t cpuset_cpus_allowed_locked(struct task_struct *p);
+extern void cpuset_cpus_allowed(struct task_struct *p, cpumask_t *mask);
+extern void cpuset_cpus_allowed_locked(struct task_struct *p, cpumask_t *mask);
 extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
 #define cpuset_current_mems_allowed (current->mems_allowed)
 void cpuset_init_current_mems_allowed(void);
@@ -84,13 +84,14 @@ static inline int cpuset_init_early(void) { return 0; }
 static inline int cpuset_init(void) { return 0; }
 static inline void cpuset_init_smp(void) {}
 
-static inline cpumask_t cpuset_cpus_allowed(struct task_struct *p)
+static inline void cpuset_cpus_allowed(struct task_struct *p, cpumask_t *mask)
 {
-	return cpu_possible_map;
+	*mask = cpu_possible_map;
 }
-static inline cpumask_t cpuset_cpus_allowed_locked(struct task_struct *p)
+static inline void cpuset_cpus_allowed_locked(struct task_struct *p,
+								cpumask_t *mask)
 {
-	return cpu_possible_map;
+	*mask = cpu_possible_map;
 }
 
 static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)

kernel/cpuset.c

@@ -729,7 +729,7 @@ int cpuset_test_cpumask(struct task_struct *tsk, struct cgroup_scanner *scan)
  */
 void cpuset_change_cpumask(struct task_struct *tsk, struct cgroup_scanner *scan)
 {
-	set_cpus_allowed(tsk, (cgroup_cs(scan->cg))->cpus_allowed);
+	set_cpus_allowed_ptr(tsk, &((cgroup_cs(scan->cg))->cpus_allowed));
 }
 
 /**
@@ -1178,7 +1178,7 @@ static void cpuset_attach(struct cgroup_subsys *ss,
 
 	mutex_lock(&callback_mutex);
 	guarantee_online_cpus(cs, &cpus);
-	set_cpus_allowed(tsk, cpus);
+	set_cpus_allowed_ptr(tsk, &cpus);
 	mutex_unlock(&callback_mutex);
 
 	from = oldcs->mems_allowed;
@@ -1555,8 +1555,8 @@ static struct cgroup_subsys_state *cpuset_create(
 	if (is_spread_slab(parent))
 		set_bit(CS_SPREAD_SLAB, &cs->flags);
 	set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
-	cs->cpus_allowed = CPU_MASK_NONE;
-	cs->mems_allowed = NODE_MASK_NONE;
+	cpus_clear(cs->cpus_allowed);
+	nodes_clear(cs->mems_allowed);
 	cs->mems_generation = cpuset_mems_generation++;
 	fmeter_init(&cs->fmeter);
 
@@ -1625,8 +1625,8 @@ int __init cpuset_init(void)
 {
 	int err = 0;
 
-	top_cpuset.cpus_allowed = CPU_MASK_ALL;
-	top_cpuset.mems_allowed = NODE_MASK_ALL;
+	cpus_setall(top_cpuset.cpus_allowed);
+	nodes_setall(top_cpuset.mems_allowed);
 
 	fmeter_init(&top_cpuset.fmeter);
 	top_cpuset.mems_generation = cpuset_mems_generation++;
@@ -1844,6 +1844,7 @@ void __init cpuset_init_smp(void)
 
  * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
  * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
+ * @pmask: pointer to cpumask_t variable to receive cpus_allowed set.
  *
  * Description: Returns the cpumask_t cpus_allowed of the cpuset
  * attached to the specified @tsk.  Guaranteed to return some non-empty
@@ -1851,35 +1852,27 @@ void __init cpuset_init_smp(void)
  * tasks cpuset.
  **/
 
-cpumask_t cpuset_cpus_allowed(struct task_struct *tsk)
+void cpuset_cpus_allowed(struct task_struct *tsk, cpumask_t *pmask)
 {
-	cpumask_t mask;
-
 	mutex_lock(&callback_mutex);
-	mask = cpuset_cpus_allowed_locked(tsk);
+	cpuset_cpus_allowed_locked(tsk, pmask);
 	mutex_unlock(&callback_mutex);
-
-	return mask;
 }
 
 /**
  * cpuset_cpus_allowed_locked - return cpus_allowed mask from a tasks cpuset.
  * Must be called with callback_mutex held.
  **/
-cpumask_t cpuset_cpus_allowed_locked(struct task_struct *tsk)
+void cpuset_cpus_allowed_locked(struct task_struct *tsk, cpumask_t *pmask)
 {
-	cpumask_t mask;
-
 	task_lock(tsk);
-	guarantee_online_cpus(task_cs(tsk), &mask);
+	guarantee_online_cpus(task_cs(tsk), pmask);
 	task_unlock(tsk);
-
-	return mask;
 }
 
 void cpuset_init_current_mems_allowed(void)
 {
-	current->mems_allowed = NODE_MASK_ALL;
+	nodes_setall(current->mems_allowed);
 }
 
 /**

kernel/sched.c

@@ -4941,13 +4941,13 @@ long sched_setaffinity(pid_t pid, cpumask_t new_mask)
 	if (retval)
 		goto out_unlock;
 
-	cpus_allowed = cpuset_cpus_allowed(p);
+	cpuset_cpus_allowed(p, &cpus_allowed);
 	cpus_and(new_mask, new_mask, cpus_allowed);
  again:
 	retval = set_cpus_allowed(p, new_mask);
 
 	if (!retval) {
-		cpus_allowed = cpuset_cpus_allowed(p);
+		cpuset_cpus_allowed(p, &cpus_allowed);
 		if (!cpus_subset(new_mask, cpus_allowed)) {
 			/*
 			 * We must have raced with a concurrent cpuset
@@ -5661,7 +5661,9 @@ static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
 
 		/* No more Mr. Nice Guy. */
 		if (dest_cpu >= nr_cpu_ids) {
-			cpumask_t cpus_allowed = cpuset_cpus_allowed_locked(p);
+			cpumask_t cpus_allowed;
+
+			cpuset_cpus_allowed_locked(p, &cpus_allowed);
 			/*
 			 * Try to stay on the same cpuset, where the
 			 * current cpuset may be a subset of all cpus.

mm/pdflush.c

@@ -187,8 +187,8 @@ static int pdflush(void *dummy)
 	 * This is needed as pdflush's are dynamically created and destroyed.
 	 * The boottime pdflush's are easily placed w/o these 2 lines.
 	 */
-	cpus_allowed = cpuset_cpus_allowed(current);
-	set_cpus_allowed(current, cpus_allowed);
+	cpuset_cpus_allowed(current, &cpus_allowed);
+	set_cpus_allowed_ptr(current, &cpus_allowed);
 
 	return __pdflush(&my_work);
 }