Commit 1f382215 authored by Pingfan Liu's avatar Pingfan Liu Committed by Tejun Heo
Browse files

cgroup/cpuset: Introduce cpuset_cpus_allowed_locked() 



cpuset_cpus_allowed() uses a reader lock that is sleepable under RT,
which means it cannot be called inside raw_spin_lock_t context.

Introduce a new cpuset_cpus_allowed_locked() helper that performs the
same function as cpuset_cpus_allowed() except that the caller must have
acquired the cpuset_mutex so that no further locking will be needed.

Suggested-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarPingfan Liu <piliu@redhat.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: linux-kernel@vger.kernel.org
To: cgroups@vger.kernel.org
Reviewed-by: default avatarChen Ridong <chenridong@huawei.com>
Reviewed-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent a0131c39

include/linux/cpuset.h

+8 −1
Original line number Diff line number Diff line
@@ -74,6 +74,7 @@ extern void inc_dl_tasks_cs(struct task_struct *task); 
extern void dec_dl_tasks_cs(struct task_struct *task);

extern void cpuset_lock(void);

extern void cpuset_unlock(void);

extern void cpuset_cpus_allowed_locked(struct task_struct *p, struct cpumask *mask);

extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);

extern bool cpuset_cpus_allowed_fallback(struct task_struct *p);

extern bool cpuset_cpu_is_isolated(int cpu);
@@ -195,12 +196,18 @@ static inline void dec_dl_tasks_cs(struct task_struct *task) { } 
static inline void cpuset_lock(void) { }

static inline void cpuset_unlock(void) { }



static inline void cpuset_cpus_allowed(struct task_struct *p,

static inline void cpuset_cpus_allowed_locked(struct task_struct *p,

					struct cpumask *mask)

{

	cpumask_copy(mask, task_cpu_possible_mask(p));

}



static inline void cpuset_cpus_allowed(struct task_struct *p,

				       struct cpumask *mask)

{

	cpuset_cpus_allowed_locked(p, mask);

}



static inline bool cpuset_cpus_allowed_fallback(struct task_struct *p)

{

	return false;

kernel/cgroup/cpuset.c

+36 −15
Original line number Diff line number Diff line
@@ -4160,24 +4160,13 @@ void __init cpuset_init_smp(void) 
	BUG_ON(!cpuset_migrate_mm_wq);

}



/**

 * 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 struct cpumask variable to receive cpus_allowed set.

 *

 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset

 * attached to the specified @tsk.  Guaranteed to return some non-empty

 * subset of cpu_active_mask, even if this means going outside the

 * tasks cpuset, except when the task is in the top cpuset.

 **/



void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)

/*

 * Return cpus_allowed mask from a task's cpuset.

 */

static void __cpuset_cpus_allowed_locked(struct task_struct *tsk, struct cpumask *pmask)

{

	unsigned long flags;

	struct cpuset *cs;



	spin_lock_irqsave(&callback_lock, flags);



	cs = task_cs(tsk);

	if (cs != &top_cpuset)

		guarantee_active_cpus(tsk, pmask);
@@ -4197,7 +4186,39 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) 
		if (!cpumask_intersects(pmask, cpu_active_mask))

			cpumask_copy(pmask, possible_mask);

	}

}



/**

 * cpuset_cpus_allowed_locked - return cpus_allowed mask from a task's cpuset.

 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.

 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.

 *

 * Similir to cpuset_cpus_allowed() except that the caller must have acquired

 * cpuset_mutex.

 */

void cpuset_cpus_allowed_locked(struct task_struct *tsk, struct cpumask *pmask)

{

	lockdep_assert_held(&cpuset_mutex);

	__cpuset_cpus_allowed_locked(tsk, pmask);

}



/**

 * cpuset_cpus_allowed - return cpus_allowed mask from a task's cpuset.

 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.

 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.

 *

 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset

 * attached to the specified @tsk.  Guaranteed to return some non-empty

 * subset of cpu_active_mask, even if this means going outside the

 * tasks cpuset, except when the task is in the top cpuset.

 **/



void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)

{

	unsigned long flags;



	spin_lock_irqsave(&callback_lock, flags);

	__cpuset_cpus_allowed_locked(tsk, pmask);

	spin_unlock_irqrestore(&callback_lock, flags);

}