From dba091b9e3522b9d32fc9975e48d3b69633b45f0 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 9 Dec 2009 09:32:03 +0100 Subject: sched: Protect sched_rr_get_param() access to task->sched_class sched_rr_get_param calls task->sched_class->get_rr_interval(task) without protection against a concurrent sched_setscheduler() call which modifies task->sched_class. Serialize the access with task_rq_lock(task) and hand the rq pointer into get_rr_interval() as it's needed at least in the sched_fair implementation. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra LKML-Reference: Signed-off-by: Ingo Molnar --- kernel/sched.c | 6 +++++- kernel/sched_fair.c | 6 +----- kernel/sched_idletask.c | 2 +- kernel/sched_rt.c | 2 +- 4 files changed, 8 insertions(+), 8 deletions(-) (limited to 'kernel') diff --git a/kernel/sched.c b/kernel/sched.c index c4635f74540c..68db5a2e6545 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6887,6 +6887,8 @@ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, { struct task_struct *p; unsigned int time_slice; + unsigned long flags; + struct rq *rq; int retval; struct timespec t; @@ -6903,7 +6905,9 @@ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, if (retval) goto out_unlock; - time_slice = p->sched_class->get_rr_interval(p); + rq = task_rq_lock(p, &flags); + time_slice = p->sched_class->get_rr_interval(rq, p); + task_rq_unlock(rq, &flags); read_unlock(&tasklist_lock); jiffies_to_timespec(time_slice, &t); diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index f61837ad336d..613c1c749677 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -2014,21 +2014,17 @@ static void moved_group_fair(struct task_struct *p) } #endif -unsigned int get_rr_interval_fair(struct task_struct *task) +unsigned int get_rr_interval_fair(struct rq *rq, 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; } diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c index b133a28fcde3..33d5384a73a8 100644 --- a/kernel/sched_idletask.c +++ b/kernel/sched_idletask.c @@ -97,7 +97,7 @@ 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) +unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task) { return 0; } diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c index 5c5fef378415..aecbd9c6b20c 100644 --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -1721,7 +1721,7 @@ static void set_curr_task_rt(struct rq *rq) dequeue_pushable_task(rq, p); } -unsigned int get_rr_interval_rt(struct task_struct *task) +unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task) { /* * Time slice is 0 for SCHED_FIFO tasks -- cgit v1.2.3-59-g8ed1b