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Commit f17c8607 authored by Rusty Russell's avatar Rusty Russell Committed by Ingo Molnar
Browse files

sched: convert sys_sched_getaffinity() to cpumask_var_t. 



Impact: stack usage reduction

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

Some jiggling here to make sure we always exit at the bottom (so we hit
the free_cpumask_var there).

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent a0e90245

kernel/sched.c

+13 −8
Original line number Diff line number Diff line
@@ -5499,19 +5499,24 @@ asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len, 
				      unsigned long __user *user_mask_ptr)

{

	int ret;

	cpumask_t mask;

	cpumask_var_t mask;



	if (len < sizeof(cpumask_t))

	if (len < cpumask_size())

		return -EINVAL;



	ret = sched_getaffinity(pid, &mask);

	if (ret < 0)

		return ret;

	if (!alloc_cpumask_var(&mask, GFP_KERNEL))

		return -ENOMEM;



	if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))

		return -EFAULT;

	ret = sched_getaffinity(pid, mask);

	if (ret == 0) {

		if (copy_to_user(user_mask_ptr, mask, cpumask_size()))

			ret = -EFAULT;

		else

			ret = cpumask_size();

	}

	free_cpumask_var(mask);



	return sizeof(cpumask_t);

	return ret;

}



/**