sched: Extend enqueue_task to allow head queueing

commit ea87bb7853168434f4a82426dd1ea8421f9e604d upstream

The ability of enqueueing a task to the head of a SCHED_FIFO priority
list is required to fix some violations of POSIX scheduling policy.

Extend the related functions with a "head" argument.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Carsten Emde <cbe@osadl.org>
Tested-by: Mathias Weber <mathias.weber.mw1@roche.com>
LKML-Reference: <20100120171629.734886007@linutronix.de>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/sched.h b/include/linux/sched.h
index f6da930a8dacfb238d2f82c42c1ca5ac6d39cb57..5f317d65db6afd53d66d8a64d65d2b0d15e95bc6 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1071,7 +1071,8 @@ struct sched_domain;
 struct sched_class {
        const struct sched_class *next;
 
-       void (*enqueue_task) (struct rq *rq, struct task_struct *p, int wakeup);
+       void (*enqueue_task) (struct rq *rq, struct task_struct *p, int wakeup,
+                             bool head);
        void (*dequeue_task) (struct rq *rq, struct task_struct *p, int sleep);
        void (*yield_task) (struct rq *rq);
 

diff --git a/kernel/sched.c b/kernel/sched.c
index f7145edf0ac8ac6951423636629c062db6d7cf09..23863b6a5df607939592c6c3be4acebce25e788b 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1903,13 +1903,14 @@ static void update_avg(u64 *avg, u64 sample)
        *avg += diff >> 3;
 }
 
-static void enqueue_task(struct rq *rq, struct task_struct *p, int wakeup)
+static void
+enqueue_task(struct rq *rq, struct task_struct *p, int wakeup, bool head)
 {
        if (wakeup)
                p->se.start_runtime = p->se.sum_exec_runtime;
 
        sched_info_queued(p);
-       p->sched_class->enqueue_task(rq, p, wakeup);
+       p->sched_class->enqueue_task(rq, p, wakeup, head);
        p->se.on_rq = 1;
 }
 
@@ -1985,7 +1986,7 @@ static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
        if (task_contributes_to_load(p))
                rq->nr_uninterruptible--;
 
-       enqueue_task(rq, p, wakeup);
+       enqueue_task(rq, p, wakeup, false);
        inc_nr_running(rq);
 }
 
@@ -6183,7 +6184,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
        if (running)
                p->sched_class->set_curr_task(rq);
        if (on_rq) {
-               enqueue_task(rq, p, 0);
+               enqueue_task(rq, p, 0, false);
 
                check_class_changed(rq, p, prev_class, oldprio, running);
        }
@@ -6227,7 +6228,7 @@ void set_user_nice(struct task_struct *p, long nice)
        delta = p->prio - old_prio;
 
        if (on_rq) {
-               enqueue_task(rq, p, 0);
+               enqueue_task(rq, p, 0, false);
                /*
                 * If the task increased its priority or is running and
                 * lowered its priority, then reschedule its CPU:
@@ -10180,7 +10181,7 @@ void sched_move_task(struct task_struct *tsk)
        if (unlikely(running))
                tsk->sched_class->set_curr_task(rq);
        if (on_rq)
-               enqueue_task(rq, tsk, 0);
+               enqueue_task(rq, tsk, 0, false);
 
        task_rq_unlock(rq, &flags);
 }

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 08f4d543942448fdba5fcc499fca81339f94198c..04ec8b82ce532022b027e00b87d53d5f34777e1e 100644 (file)
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1031,7 +1031,8 @@ static inline void hrtick_update(struct rq *rq)
  * increased. Here we update the fair scheduling stats and
  * then put the task into the rbtree:
  */
-static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup)
+static void
+enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup, bool head)
 {
        struct cfs_rq *cfs_rq;
        struct sched_entity *se = &p->se;

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index b2edb89d021a7f1cb1202eb8fa7bde36da5aaa43..4ce9f7e6be1687a9866b019fd3e9a5097cda108b 100644 (file)
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -878,7 +878,8 @@ static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
 /*
  * Adding/removing a task to/from a priority array:
  */
-static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
+static void
+enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup, bool head)
 {
        struct sched_rt_entity *rt_se = &p->rt;