generic: reduce stack pressure in sched_affinity

  * Modify sched_affinity functions to pass cpumask_t variables by reference
    instead of by value.

  * Use new set_cpus_allowed_ptr function.

Depends on:
	[sched-devel]: sched: add new set_cpus_allowed_ptr function

Cc: Paul Jackson <pj@sgi.com>
Cc: Cliff Wickman <cpw@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 6 insertions, 5 deletions

diff --git a/kernel/compat.c b/kernel/compat.c
index 9c48abfcd4a5..e1ef04870c2a 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -445,7 +445,7 @@ asmlinkage long compat_sys_sched_setaffinity(compat_pid_t pid,
         if (retval)
                 return retval;
 
-        return sched_setaffinity(pid, new_mask);
+        return sched_setaffinity(pid, &new_mask);
 }
 
 asmlinkage long compat_sys_sched_getaffinity(compat_pid_t pid, unsigned int len,
diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c
index e9517014b57c..e1cdf196a515 100644
--- a/kernel/rcupreempt.c
+++ b/kernel/rcupreempt.c
@@ -1007,10 +1007,10 @@ void __synchronize_sched(void)
         if (sched_getaffinity(0, &oldmask) < 0)
                 oldmask = cpu_possible_map;
         for_each_online_cpu(cpu) {
-                sched_setaffinity(0, cpumask_of_cpu(cpu));
+                sched_setaffinity(0, &cpumask_of_cpu(cpu));
                 schedule();
         }
-        sched_setaffinity(0, oldmask);
+        sched_setaffinity(0, &oldmask);
 }
 EXPORT_SYMBOL_GPL(__synchronize_sched);
 
diff --git a/kernel/sched.c b/kernel/sched.c
index ccc23a9cd264..1a8252385c4d 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4908,9 +4908,10 @@ out_unlock:
         return retval;
 }
 
-long sched_setaffinity(pid_t pid, cpumask_t new_mask)
+long sched_setaffinity(pid_t pid, const cpumask_t *in_mask)
 {
         cpumask_t cpus_allowed;
+        cpumask_t new_mask = *in_mask;
         struct task_struct *p;
         int retval;
 
@@ -4991,7 +4992,7 @@ asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
         if (retval)
                 return retval;
 
-        return sched_setaffinity(pid, new_mask);
+        return sched_setaffinity(pid, &new_mask);
 }
 
 /*