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Commit 5a16f3d3 authored by Rusty Russell's avatar Rusty Russell Committed by Ingo Molnar
Browse files

sched: convert struct (sys_)sched_setaffinity() to cpumask_var_t. 



Impact: stack usage reduction

Dynamically allocating cpumasks (when CONFIG_CPUMASK_OFFSTACK) saves
space on the stack.  cpumask_var_t is just a struct cpumask for
!CONFIG_CPUMASK_OFFSTACK.

Note the removal of the initializer of new_mask: since the first thing
we did was "cpus_and(new_mask, new_mask, cpus_allowed)" I just changed
that to "cpumask_and(new_mask, in_mask, cpus_allowed);".

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e76bd8d9

kernel/sched.c

+27 −13
Original line number Diff line number Diff line
@@ -5378,8 +5378,7 @@ asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param) 


long sched_setaffinity(pid_t pid, const cpumask_t *in_mask)

{

	cpumask_t cpus_allowed;

	cpumask_t new_mask = *in_mask;

	cpumask_var_t cpus_allowed, new_mask;

	struct task_struct *p;

	int retval;
@@ -5401,6 +5400,14 @@ long sched_setaffinity(pid_t pid, const cpumask_t *in_mask) 
	get_task_struct(p);

	read_unlock(&tasklist_lock);



	if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {

		retval = -ENOMEM;

		goto out_put_task;

	}

	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {

		retval = -ENOMEM;

		goto out_free_cpus_allowed;

	}

	retval = -EPERM;

	if ((current->euid != p->euid) && (current->euid != p->uid) &&

			!capable(CAP_SYS_NICE))
@@ -5410,24 +5417,28 @@ long sched_setaffinity(pid_t pid, const cpumask_t *in_mask) 
	if (retval)

		goto out_unlock;



	cpuset_cpus_allowed(p, &cpus_allowed);

	cpus_and(new_mask, new_mask, cpus_allowed);

	cpuset_cpus_allowed(p, cpus_allowed);

	cpumask_and(new_mask, in_mask, cpus_allowed);

 again:

	retval = set_cpus_allowed_ptr(p, &new_mask);

	retval = set_cpus_allowed_ptr(p, new_mask);



	if (!retval) {

		cpuset_cpus_allowed(p, &cpus_allowed);

		if (!cpus_subset(new_mask, cpus_allowed)) {

		cpuset_cpus_allowed(p, cpus_allowed);

		if (!cpumask_subset(new_mask, cpus_allowed)) {

			/*

			 * We must have raced with a concurrent cpuset

			 * update. Just reset the cpus_allowed to the

			 * cpuset's cpus_allowed

			 */

			new_mask = cpus_allowed;

			cpumask_copy(new_mask, cpus_allowed);

			goto again;

		}

	}

out_unlock:

	free_cpumask_var(new_mask);

out_free_cpus_allowed:

	free_cpumask_var(cpus_allowed);

out_put_task:

	put_task_struct(p);

	put_online_cpus();

	return retval;
@@ -5453,14 +5464,17 @@ static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, 
asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,

				      unsigned long __user *user_mask_ptr)

{

	cpumask_t new_mask;

	cpumask_var_t new_mask;

	int retval;



	retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);

	if (retval)

		return retval;

	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))

		return -ENOMEM;



	return sched_setaffinity(pid, &new_mask);

	retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);

	if (retval == 0)

		retval = sched_setaffinity(pid, new_mask);

	free_cpumask_var(new_mask);

	return retval;

}



long sched_getaffinity(pid_t pid, cpumask_t *mask)