[GIT PULL] scheduler fixes

From: Ingo Molnar
Date: Mon Sep 21 2009 - 09:06:09 EST

Linus,

Please pull the latest sched-fixes-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git sched-fixes-for-linus

( There's one non-fix commit included as well: "sched: Simplify
sys_sched_rr_get_interval() system call" is a cleanup. )

Thanks,

Ingo

------------------>
Andrew Morton (1):
sched: Fix raciness in runqueue_is_locked()

Mike Galbraith (2):
sched: Remove unneeded indentation in sched_fair.c::place_entity()
sched: Re-add lost cpu_allowed check to sched_fair.c::select_task_rq_fair()

Peter Williams (1):
sched: Simplify sys_sched_rr_get_interval() system call

Yong Zhang (1):
sched: Fix potential NULL derference of doms_cur


include/linux/sched.h | 4 ++-
kernel/sched.c | 29 +++------------------
kernel/sched_fair.c | 65 ++++++++++++++++++++++++++++++----------------
kernel/sched_idletask.c | 7 +++++
kernel/sched_rt.c | 13 +++++++++
kernel/trace/trace.c | 8 +++++-
6 files changed, 76 insertions(+), 50 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8af3d24..239c8e0 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;
@@ -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 faf4d46..830967e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -681,15 +681,9 @@ inline void update_rq_clock(struct rq *rq)
* This interface allows printk to be called with the runqueue lock
* held and know whether or not it is OK to wake up the klogd.
*/
-int runqueue_is_locked(void)
+int runqueue_is_locked(int cpu)
{
- int cpu = get_cpu();
- struct rq *rq = cpu_rq(cpu);
- int ret;
-
- ret = spin_is_locked(&rq->lock);
- put_cpu();
- return ret;
+ return spin_is_locked(&cpu_rq(cpu)->lock);
}

/*
@@ -6825,23 +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;
@@ -9171,6 +9150,7 @@ void __init sched_init_smp(void)
cpumask_var_t non_isolated_cpus;

alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
+ alloc_cpumask_var(&fallback_doms, GFP_KERNEL);

#if defined(CONFIG_NUMA)
sched_group_nodes_bycpu = kzalloc(nr_cpu_ids * sizeof(void **),
@@ -9202,7 +9182,6 @@ void __init sched_init_smp(void)
sched_init_granularity();
free_cpumask_var(non_isolated_cpus);

- alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
init_sched_rt_class();
}
#else
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 10d218a..cd73738 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -709,31 +709,28 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
if (initial && sched_feat(START_DEBIT))
vruntime += sched_vslice(cfs_rq, se);

- if (!initial) {
- /* sleeps upto a single latency don't count. */
- if (sched_feat(FAIR_SLEEPERS)) {
- unsigned long thresh = sysctl_sched_latency;
+ /* sleeps up to a single latency don't count. */
+ if (!initial && sched_feat(FAIR_SLEEPERS)) {
+ unsigned long thresh = sysctl_sched_latency;

- /*
- * Convert the sleeper threshold into virtual time.
- * SCHED_IDLE is a special sub-class. We care about
- * fairness only relative to other SCHED_IDLE tasks,
- * all of which have the same weight.
- */
- if (sched_feat(NORMALIZED_SLEEPER) &&
- (!entity_is_task(se) ||
- task_of(se)->policy != SCHED_IDLE))
- thresh = calc_delta_fair(thresh, se);
+ /*
+ * Convert the sleeper threshold into virtual time.
+ * SCHED_IDLE is a special sub-class. We care about
+ * fairness only relative to other SCHED_IDLE tasks,
+ * all of which have the same weight.
+ */
+ if (sched_feat(NORMALIZED_SLEEPER) && (!entity_is_task(se) ||
+ task_of(se)->policy != SCHED_IDLE))
+ thresh = calc_delta_fair(thresh, se);

- /*
- * Halve their sleep time's effect, to allow
- * for a gentler effect of sleepers:
- */
- if (sched_feat(GENTLE_FAIR_SLEEPERS))
- thresh >>= 1;
+ /*
+ * Halve their sleep time's effect, to allow
+ * for a gentler effect of sleepers:
+ */
+ if (sched_feat(GENTLE_FAIR_SLEEPERS))
+ thresh >>= 1;

- vruntime -= thresh;
- }
+ vruntime -= thresh;
}

/* ensure we never gain time by being placed backwards. */
@@ -1342,7 +1339,8 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag
int sync = wake_flags & WF_SYNC;

if (sd_flag & SD_BALANCE_WAKE) {
- if (sched_feat(AFFINE_WAKEUPS))
+ if (sched_feat(AFFINE_WAKEUPS) &&
+ cpumask_test_cpu(cpu, &p->cpus_allowed))
want_affine = 1;
new_cpu = prev_cpu;
}
@@ -1940,6 +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:
*/
@@ -1968,6 +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 a8b448a..b133a28 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 13de712..a4d790c 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,
};
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index fd52a19..420232a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -275,12 +275,18 @@ static DEFINE_SPINLOCK(tracing_start_lock);
*/
void trace_wake_up(void)
{
+ int cpu;
+
+ if (trace_flags & TRACE_ITER_BLOCK)
+ return;
/*
* The runqueue_is_locked() can fail, but this is the best we
* have for now:
*/
- if (!(trace_flags & TRACE_ITER_BLOCK) && !runqueue_is_locked())
+ cpu = get_cpu();
+ if (!runqueue_is_locked(cpu))
wake_up(&trace_wait);
+ put_cpu();
}

static int __init set_buf_size(char *str)
--
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