Commit a5be2d0d authored by Tejun Heo's avatar Tejun Heo
Browse files

freezer: rename thaw_process() to __thaw_task() and simplify the implementation 



thaw_process() now has only internal users - system and cgroup
freezers.  Remove the unnecessary return value, rename, unexport and
collapse __thaw_process() into it.  This will help further updates to
the freezer code.

-v3: oom_kill grew a use of thaw_process() while this patch was
     pending.  Convert it to use __thaw_task() for now.  In the longer
     term, this should be handled by allowing tasks to die if killed
     even if it's frozen.

-v2: minor style update as suggested by Matt.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Paul Menage <menage@google.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
parent 8a32c441

include/linux/freezer.h

+1 −2
Original line number Diff line number Diff line
@@ -45,7 +45,7 @@ static inline bool should_send_signal(struct task_struct *p) 
}



/* Takes and releases task alloc lock using task_lock() */

extern int thaw_process(struct task_struct *p);

extern void __thaw_task(struct task_struct *t);



extern bool __refrigerator(bool check_kthr_stop);

extern int freeze_processes(void);
@@ -178,7 +178,6 @@ static inline int frozen(struct task_struct *p) { return 0; } 
static inline int freezing(struct task_struct *p) { return 0; }

static inline void set_freeze_flag(struct task_struct *p) {}

static inline void clear_freeze_flag(struct task_struct *p) {}

static inline int thaw_process(struct task_struct *p) { return 1; }



static inline bool __refrigerator(bool check_kthr_stop) { return false; }

static inline int freeze_processes(void) { return -ENOSYS; }

kernel/cgroup_freezer.c

+3 −4
Original line number Diff line number Diff line
@@ -130,7 +130,7 @@ struct cgroup_subsys freezer_subsys; 
 *   write_lock css_set_lock (cgroup iterator start)

 *    task->alloc_lock

 *   read_lock css_set_lock (cgroup iterator start)

 *    task->alloc_lock (inside thaw_process(), prevents race with refrigerator())

 *    task->alloc_lock (inside __thaw_task(), prevents race with refrigerator())

 *     sighand->siglock

 */

static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss,
@@ -300,9 +300,8 @@ static void unfreeze_cgroup(struct cgroup *cgroup, struct freezer *freezer) 
	struct task_struct *task;



	cgroup_iter_start(cgroup, &it);

	while ((task = cgroup_iter_next(cgroup, &it))) {

		thaw_process(task);

	}

	while ((task = cgroup_iter_next(cgroup, &it)))

		__thaw_task(task);

	cgroup_iter_end(cgroup, &it);



	freezer->state = CGROUP_THAWED;

kernel/freezer.c

+12 −19
Original line number Diff line number Diff line
@@ -145,18 +145,8 @@ void cancel_freezing(struct task_struct *p) 
	}

}



static int __thaw_process(struct task_struct *p)

{

	if (frozen(p)) {

		p->flags &= ~PF_FROZEN;

		return 1;

	}

	clear_freeze_flag(p);

	return 0;

}



/*

 * Wake up a frozen process

 * Wake up a frozen task

 *

 * task_lock() is needed to prevent the race with refrigerator() which may

 * occur if the freezing of tasks fails.  Namely, without the lock, if the
@@ -164,15 +154,18 @@ static int __thaw_process(struct task_struct *p) 
 * refrigerator() could call frozen_process(), in which case the task would be

 * frozen and no one would thaw it.

 */

int thaw_process(struct task_struct *p)

void __thaw_task(struct task_struct *p)

{

	bool was_frozen;



	task_lock(p);

	if (__thaw_process(p) == 1) {

	was_frozen = frozen(p);

	if (was_frozen)

		p->flags &= ~PF_FROZEN;

	else

		clear_freeze_flag(p);

	task_unlock(p);



	if (was_frozen)

		wake_up_process(p);

		return 1;

	}

	task_unlock(p);

	return 0;

}
 
EXPORT_SYMBOL(thaw_process);

kernel/power/process.c

+1 −1
Original line number Diff line number Diff line
@@ -186,7 +186,7 @@ static void thaw_tasks(bool nosig_only) 
		if (cgroup_freezing_or_frozen(p))

			continue;



		thaw_process(p);

		__thaw_task(p);

	} while_each_thread(g, p);

	read_unlock(&tasklist_lock);

}

mm/oom_kill.c

+1 −1
Original line number Diff line number Diff line
@@ -328,7 +328,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, 
		 */

		if (test_tsk_thread_flag(p, TIF_MEMDIE)) {

			if (unlikely(frozen(p)))

				thaw_process(p);

				__thaw_task(p);

			return ERR_PTR(-1UL);

		}

		if (!p->mm)

CRA Git | Maintained and supported by SUSTech CRA and CCSE