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sched: Introduce dl_task_check_affinity() to check proposed affinity 

In preparation for restricting the affinity of a task during execve()
on arm64, introduce a new dl_task_check_affinity() helper function to
give an indication as to whether the restricted mask is admissible for
a deadline task.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Link: https://lore.kernel.org/r/20210730112443.23245-10-will@kernel.org
This commit is contained in:
Will Deacon 2021-07-30 12:24:36 +01:00 committed by Peter Zijlstra
parent 07ec77a1d4
commit 234b8ab647
2 changed files with 35 additions and 17 deletions
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6
include/linux/sched.h
View File

@ -1709,6 +1709,7 @@ extern void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new
extern int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask);
extern int dup_user_cpus_ptr(struct task_struct *dst, struct task_struct *src, int node);
extern void release_user_cpus_ptr(struct task_struct *p);
extern int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask);
extern void force_compatible_cpus_allowed_ptr(struct task_struct *p);
extern void relax_compatible_cpus_allowed_ptr(struct task_struct *p);
#else
@ -1731,6 +1732,11 @@ static inline void release_user_cpus_ptr(struct task_struct *p)
{
WARN_ON(p->user_cpus_ptr);
}
static inline int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask)
{
return 0;
}
#endif
extern int yield_to(struct task_struct *p, bool preempt);

46
kernel/sched/core.c
View File

@ -7756,6 +7756,32 @@ out_unlock:
return retval;
}
#ifdef CONFIG_SMP
int dl_task_check_affinity(struct task_struct *p, const struct cpumask *mask)
{
int ret = 0;
/*
* If the task isn't a deadline task or admission control is
* disabled then we don't care about affinity changes.
*/
if (!task_has_dl_policy(p) || !dl_bandwidth_enabled())
return 0;
/*
* Since bandwidth control happens on root_domain basis,
* if admission test is enabled, we only admit -deadline
* tasks allowed to run on all the CPUs in the task's
* root_domain.
*/
rcu_read_lock();
if (!cpumask_subset(task_rq(p)->rd->span, mask))
ret = -EBUSY;
rcu_read_unlock();
return ret;
}
#endif
static int
__sched_setaffinity(struct task_struct *p, const struct cpumask *mask)
{
@ -7773,23 +7799,9 @@ __sched_setaffinity(struct task_struct *p, const struct cpumask *mask)
cpuset_cpus_allowed(p, cpus_allowed);
cpumask_and(new_mask, mask, cpus_allowed);
/*
* Since bandwidth control happens on root_domain basis,
* if admission test is enabled, we only admit -deadline
* tasks allowed to run on all the CPUs in the task's
* root_domain.
*/
#ifdef CONFIG_SMP
if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
rcu_read_lock();
if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
retval = -EBUSY;
rcu_read_unlock();
goto out_free_new_mask;
}
rcu_read_unlock();
}
#endif
retval = dl_task_check_affinity(p, new_mask);
if (retval)
goto out_free_new_mask;
again:
retval = __set_cpus_allowed_ptr(p, new_mask, SCA_CHECK | SCA_USER);
if (retval)