提交 fb7b26e4 编写于 作者: L Linus Torvalds

Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Thomas Gleixner:
 "This updates contains the following changes:

   - Fix a signal handling regression in the bit wait functions.

   - Avoid false positive warnings in the wakeup path.

   - Initialize the scheduler root domain properly.

   - Handle gtime calculations in proc/$PID/stat proper.

   - Add more documentation for the barriers in try_to_wake_up().

   - Fix a subtle race in try_to_wake_up() which might cause a task to
     be scheduled on two cpus

   - Compile static helper function only when it is used"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Fix an SMP ordering race in try_to_wake_up() vs. schedule()
  sched/core: Better document the try_to_wake_up() barriers
  sched/cputime: Fix invalid gtime in proc
  sched/core: Clear the root_domain cpumasks in init_rootdomain()
  sched/core: Remove false-positive warning from wake_up_process()
  sched/wait: Fix signal handling in bit wait helpers
  sched/rt: Hide the push_irq_work_func() declaration
......@@ -1946,6 +1946,25 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
goto stat;
#ifdef CONFIG_SMP
/*
* Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
* possible to, falsely, observe p->on_cpu == 0.
*
* One must be running (->on_cpu == 1) in order to remove oneself
* from the runqueue.
*
* [S] ->on_cpu = 1; [L] ->on_rq
* UNLOCK rq->lock
* RMB
* LOCK rq->lock
* [S] ->on_rq = 0; [L] ->on_cpu
*
* Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock
* from the consecutive calls to schedule(); the first switching to our
* task, the second putting it to sleep.
*/
smp_rmb();
/*
* If the owning (remote) cpu is still in the middle of schedule() with
* this task as prev, wait until its done referencing the task.
......@@ -1953,7 +1972,13 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
while (p->on_cpu)
cpu_relax();
/*
* Pairs with the smp_wmb() in finish_lock_switch().
* Combined with the control dependency above, we have an effective
* smp_load_acquire() without the need for full barriers.
*
* Pairs with the smp_store_release() in finish_lock_switch().
*
* This ensures that tasks getting woken will be fully ordered against
* their previous state and preserve Program Order.
*/
smp_rmb();
......@@ -2039,7 +2064,6 @@ static void try_to_wake_up_local(struct task_struct *p)
*/
int wake_up_process(struct task_struct *p)
{
WARN_ON(task_is_stopped_or_traced(p));
return try_to_wake_up(p, TASK_NORMAL, 0);
}
EXPORT_SYMBOL(wake_up_process);
......@@ -5847,13 +5871,13 @@ static int init_rootdomain(struct root_domain *rd)
{
memset(rd, 0, sizeof(*rd));
if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
goto out;
if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
goto free_span;
if (!alloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
goto free_online;
if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
goto free_dlo_mask;
init_dl_bw(&rd->dl_bw);
......
......@@ -788,6 +788,9 @@ cputime_t task_gtime(struct task_struct *t)
unsigned int seq;
cputime_t gtime;
if (!context_tracking_is_enabled())
return t->gtime;
do {
seq = read_seqbegin(&t->vtime_seqlock);
......
......@@ -64,7 +64,7 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
raw_spin_unlock(&rt_b->rt_runtime_lock);
}
#ifdef CONFIG_SMP
#if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI)
static void push_irq_work_func(struct irq_work *work);
#endif
......
......@@ -1073,6 +1073,9 @@ static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
* We must ensure this doesn't happen until the switch is completely
* finished.
*
* In particular, the load of prev->state in finish_task_switch() must
* happen before this.
*
* Pairs with the control dependency and rmb in try_to_wake_up().
*/
smp_store_release(&prev->on_cpu, 0);
......
......@@ -583,18 +583,18 @@ EXPORT_SYMBOL(wake_up_atomic_t);
__sched int bit_wait(struct wait_bit_key *word)
{
if (signal_pending_state(current->state, current))
return 1;
schedule();
if (signal_pending(current))
return -EINTR;
return 0;
}
EXPORT_SYMBOL(bit_wait);
__sched int bit_wait_io(struct wait_bit_key *word)
{
if (signal_pending_state(current->state, current))
return 1;
io_schedule();
if (signal_pending(current))
return -EINTR;
return 0;
}
EXPORT_SYMBOL(bit_wait_io);
......@@ -602,11 +602,11 @@ EXPORT_SYMBOL(bit_wait_io);
__sched int bit_wait_timeout(struct wait_bit_key *word)
{
unsigned long now = READ_ONCE(jiffies);
if (signal_pending_state(current->state, current))
return 1;
if (time_after_eq(now, word->timeout))
return -EAGAIN;
schedule_timeout(word->timeout - now);
if (signal_pending(current))
return -EINTR;
return 0;
}
EXPORT_SYMBOL_GPL(bit_wait_timeout);
......@@ -614,11 +614,11 @@ EXPORT_SYMBOL_GPL(bit_wait_timeout);
__sched int bit_wait_io_timeout(struct wait_bit_key *word)
{
unsigned long now = READ_ONCE(jiffies);
if (signal_pending_state(current->state, current))
return 1;
if (time_after_eq(now, word->timeout))
return -EAGAIN;
io_schedule_timeout(word->timeout - now);
if (signal_pending(current))
return -EINTR;
return 0;
}
EXPORT_SYMBOL_GPL(bit_wait_io_timeout);
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