From 89f19f04dc72363d912fd007a399cb10310eff6e Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Sat, 19 Sep 2009 11:55:44 -0700 Subject: sched: Fix raciness in runqueue_is_locked() runqueue_is_locked() is unavoidably racy due to a poor interface design. It does cpu = get_cpu() ret = some_perpcu_thing(cpu); put_cpu(cpu); return ret; Its return value is unreliable. Fix. Signed-off-by: Andrew Morton Acked-by: Steven Rostedt Cc: Peter Zijlstra LKML-Reference: <200909191855.n8JItiko022148@imap1.linux-foundation.org> Signed-off-by: Ingo Molnar --- include/linux/sched.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/sched.h b/include/linux/sched.h index 8af3d249170e..cc37a3fa5065 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -257,7 +257,7 @@ extern asmlinkage void schedule_tail(struct task_struct *prev); extern void init_idle(struct task_struct *idle, int cpu); extern void init_idle_bootup_task(struct task_struct *idle); -extern int runqueue_is_locked(void); +extern int runqueue_is_locked(int cpu); extern void task_rq_unlock_wait(struct task_struct *p); extern cpumask_var_t nohz_cpu_mask; -- cgit v1.2.3-59-g8ed1b From 0d721ceadbeaa24d7f9dd41b3e5e29912327a7e1 Mon Sep 17 00:00:00 2001 From: Peter Williams Date: Mon, 21 Sep 2009 01:31:53 +0000 Subject: sched: Simplify sys_sched_rr_get_interval() system call By removing the need for it to know details of scheduling classes. This allows PlugSched to define orthogonal scheduling classes. Signed-off-by: Peter Williams Acked-by: Peter Zijlstra Cc: Mike Galbraith LKML-Reference: <06d1b89ee15a0eef82d7.1253496713@mudlark.pw.nest> Signed-off-by: Ingo Molnar --- include/linux/sched.h | 2 ++ kernel/sched.c | 17 +---------------- kernel/sched_fair.c | 21 +++++++++++++++++++++ kernel/sched_idletask.c | 7 +++++++ kernel/sched_rt.c | 13 +++++++++++++ 5 files changed, 44 insertions(+), 16 deletions(-) (limited to 'include') diff --git a/include/linux/sched.h b/include/linux/sched.h index cc37a3fa5065..239c8e0dba9f 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1075,6 +1075,8 @@ struct sched_class { void (*prio_changed) (struct rq *this_rq, struct task_struct *task, int oldprio, int running); + unsigned int (*get_rr_interval) (struct task_struct *task); + #ifdef CONFIG_FAIR_GROUP_SCHED void (*moved_group) (struct task_struct *p); #endif diff --git a/kernel/sched.c b/kernel/sched.c index 1b900fb1c6e1..830967e18285 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6819,23 +6819,8 @@ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, if (retval) goto out_unlock; - /* - * Time slice is 0 for SCHED_FIFO tasks and for SCHED_OTHER - * tasks that are on an otherwise idle runqueue: - */ - time_slice = 0; - if (p->policy == SCHED_RR) { - time_slice = DEF_TIMESLICE; - } else if (p->policy != SCHED_FIFO) { - struct sched_entity *se = &p->se; - unsigned long flags; - struct rq *rq; + time_slice = p->sched_class->get_rr_interval(p); - rq = task_rq_lock(p, &flags); - if (rq->cfs.load.weight) - time_slice = NS_TO_JIFFIES(sched_slice(&rq->cfs, se)); - task_rq_unlock(rq, &flags); - } read_unlock(&tasklist_lock); jiffies_to_timespec(time_slice, &t); retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 566e3bb78ed9..cd73738f0d5f 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1938,6 +1938,25 @@ static void moved_group_fair(struct task_struct *p) } #endif +unsigned int get_rr_interval_fair(struct task_struct *task) +{ + struct sched_entity *se = &task->se; + unsigned long flags; + struct rq *rq; + unsigned int rr_interval = 0; + + /* + * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise + * idle runqueue: + */ + rq = task_rq_lock(task, &flags); + if (rq->cfs.load.weight) + rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se)); + task_rq_unlock(rq, &flags); + + return rr_interval; +} + /* * All the scheduling class methods: */ @@ -1966,6 +1985,8 @@ static const struct sched_class fair_sched_class = { .prio_changed = prio_changed_fair, .switched_to = switched_to_fair, + .get_rr_interval = get_rr_interval_fair, + #ifdef CONFIG_FAIR_GROUP_SCHED .moved_group = moved_group_fair, #endif diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c index a8b448af004b..b133a28fcde3 100644 --- a/kernel/sched_idletask.c +++ b/kernel/sched_idletask.c @@ -97,6 +97,11 @@ static void prio_changed_idle(struct rq *rq, struct task_struct *p, check_preempt_curr(rq, p, 0); } +unsigned int get_rr_interval_idle(struct task_struct *task) +{ + return 0; +} + /* * Simple, special scheduling class for the per-CPU idle tasks: */ @@ -122,6 +127,8 @@ static const struct sched_class idle_sched_class = { .set_curr_task = set_curr_task_idle, .task_tick = task_tick_idle, + .get_rr_interval = get_rr_interval_idle, + .prio_changed = prio_changed_idle, .switched_to = switched_to_idle, diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c index 13de7126a6ab..a4d790cddb19 100644 --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -1734,6 +1734,17 @@ static void set_curr_task_rt(struct rq *rq) dequeue_pushable_task(rq, p); } +unsigned int get_rr_interval_rt(struct task_struct *task) +{ + /* + * Time slice is 0 for SCHED_FIFO tasks + */ + if (task->policy == SCHED_RR) + return DEF_TIMESLICE; + else + return 0; +} + static const struct sched_class rt_sched_class = { .next = &fair_sched_class, .enqueue_task = enqueue_task_rt, @@ -1762,6 +1773,8 @@ static const struct sched_class rt_sched_class = { .set_curr_task = set_curr_task_rt, .task_tick = task_tick_rt, + .get_rr_interval = get_rr_interval_rt, + .prio_changed = prio_changed_rt, .switched_to = switched_to_rt, }; -- cgit v1.2.3-59-g8ed1b