sched: Change task_struct::state
Change the type and name of task_struct::state. Drop the volatile and
shrink it to an 'unsigned int'. Rename it in order to find all uses
such that we can use READ_ONCE/WRITE_ONCE as appropriate.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20210611082838.550736351@infradead.org
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 45ebb3c..309745a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2638,7 +2638,7 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
return -EINVAL;
}
- if (task_running(rq, p) || p->state == TASK_WAKING) {
+ if (task_running(rq, p) || READ_ONCE(p->__state) == TASK_WAKING) {
/*
* MIGRATE_ENABLE gets here because 'p == current', but for
* anything else we cannot do is_migration_disabled(), punt
@@ -2781,19 +2781,20 @@ EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
{
#ifdef CONFIG_SCHED_DEBUG
+ unsigned int state = READ_ONCE(p->__state);
+
/*
* We should never call set_task_cpu() on a blocked task,
* ttwu() will sort out the placement.
*/
- WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
- !p->on_rq);
+ WARN_ON_ONCE(state != TASK_RUNNING && state != TASK_WAKING && !p->on_rq);
/*
* Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
* because schedstat_wait_{start,end} rebase migrating task's wait_start
* time relying on p->on_rq.
*/
- WARN_ON_ONCE(p->state == TASK_RUNNING &&
+ WARN_ON_ONCE(state == TASK_RUNNING &&
p->sched_class == &fair_sched_class &&
(p->on_rq && !task_on_rq_migrating(p)));
@@ -2965,7 +2966,7 @@ int migrate_swap(struct task_struct *cur, struct task_struct *p,
* smp_call_function() if an IPI is sent by the same process we are
* waiting to become inactive.
*/
-unsigned long wait_task_inactive(struct task_struct *p, long match_state)
+unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state)
{
int running, queued;
struct rq_flags rf;
@@ -2993,7 +2994,7 @@ unsigned long wait_task_inactive(struct task_struct *p, long match_state)
* is actually now running somewhere else!
*/
while (task_running(rq, p)) {
- if (match_state && unlikely(p->state != match_state))
+ if (match_state && unlikely(READ_ONCE(p->__state) != match_state))
return 0;
cpu_relax();
}
@@ -3008,7 +3009,7 @@ unsigned long wait_task_inactive(struct task_struct *p, long match_state)
running = task_running(rq, p);
queued = task_on_rq_queued(p);
ncsw = 0;
- if (!match_state || p->state == match_state)
+ if (!match_state || READ_ONCE(p->__state) == match_state)
ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
task_rq_unlock(rq, p, &rf);
@@ -3317,7 +3318,7 @@ static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags,
struct rq_flags *rf)
{
check_preempt_curr(rq, p, wake_flags);
- p->state = TASK_RUNNING;
+ WRITE_ONCE(p->__state, TASK_RUNNING);
trace_sched_wakeup(p);
#ifdef CONFIG_SMP
@@ -3709,12 +3710,12 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
* - we're serialized against set_special_state() by virtue of
* it disabling IRQs (this allows not taking ->pi_lock).
*/
- if (!(p->state & state))
+ if (!(READ_ONCE(p->__state) & state))
goto out;
success = 1;
trace_sched_waking(p);
- p->state = TASK_RUNNING;
+ WRITE_ONCE(p->__state, TASK_RUNNING);
trace_sched_wakeup(p);
goto out;
}
@@ -3727,7 +3728,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
*/
raw_spin_lock_irqsave(&p->pi_lock, flags);
smp_mb__after_spinlock();
- if (!(p->state & state))
+ if (!(READ_ONCE(p->__state) & state))
goto unlock;
trace_sched_waking(p);
@@ -3793,7 +3794,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
* TASK_WAKING such that we can unlock p->pi_lock before doing the
* enqueue, such as ttwu_queue_wakelist().
*/
- p->state = TASK_WAKING;
+ WRITE_ONCE(p->__state, TASK_WAKING);
/*
* If the owning (remote) CPU is still in the middle of schedule() with
@@ -3886,7 +3887,7 @@ bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct t
ret = func(p, arg);
rq_unlock(rq, &rf);
} else {
- switch (p->state) {
+ switch (READ_ONCE(p->__state)) {
case TASK_RUNNING:
case TASK_WAKING:
break;
@@ -4086,7 +4087,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
* nobody will actually run it, and a signal or other external
* event cannot wake it up and insert it on the runqueue either.
*/
- p->state = TASK_NEW;
+ p->__state = TASK_NEW;
/*
* Make sure we do not leak PI boosting priority to the child.
@@ -4192,7 +4193,7 @@ void wake_up_new_task(struct task_struct *p)
struct rq *rq;
raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
- p->state = TASK_RUNNING;
+ WRITE_ONCE(p->__state, TASK_RUNNING);
#ifdef CONFIG_SMP
/*
* Fork balancing, do it here and not earlier because:
@@ -4554,7 +4555,7 @@ static struct rq *finish_task_switch(struct task_struct *prev)
* running on another CPU and we could rave with its RUNNING -> DEAD
* transition, resulting in a double drop.
*/
- prev_state = prev->state;
+ prev_state = READ_ONCE(prev->__state);
vtime_task_switch(prev);
perf_event_task_sched_in(prev, current);
finish_task(prev);
@@ -5248,7 +5249,7 @@ static inline void schedule_debug(struct task_struct *prev, bool preempt)
#endif
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
- if (!preempt && prev->state && prev->non_block_count) {
+ if (!preempt && READ_ONCE(prev->__state) && prev->non_block_count) {
printk(KERN_ERR "BUG: scheduling in a non-blocking section: %s/%d/%i\n",
prev->comm, prev->pid, prev->non_block_count);
dump_stack();
@@ -5874,10 +5875,10 @@ static void __sched notrace __schedule(bool preempt)
* - we form a control dependency vs deactivate_task() below.
* - ptrace_{,un}freeze_traced() can change ->state underneath us.
*/
- prev_state = prev->state;
+ prev_state = READ_ONCE(prev->__state);
if (!preempt && prev_state) {
if (signal_pending_state(prev_state, prev)) {
- prev->state = TASK_RUNNING;
+ WRITE_ONCE(prev->__state, TASK_RUNNING);
} else {
prev->sched_contributes_to_load =
(prev_state & TASK_UNINTERRUPTIBLE) &&
@@ -6049,7 +6050,7 @@ void __sched schedule_idle(void)
* current task can be in any other state. Note, idle is always in the
* TASK_RUNNING state.
*/
- WARN_ON_ONCE(current->state);
+ WARN_ON_ONCE(current->__state);
do {
__schedule(false);
} while (need_resched());
@@ -8176,26 +8177,28 @@ EXPORT_SYMBOL_GPL(sched_show_task);
static inline bool
state_filter_match(unsigned long state_filter, struct task_struct *p)
{
+ unsigned int state = READ_ONCE(p->__state);
+
/* no filter, everything matches */
if (!state_filter)
return true;
/* filter, but doesn't match */
- if (!(p->state & state_filter))
+ if (!(state & state_filter))
return false;
/*
* When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows
* TASK_KILLABLE).
*/
- if (state_filter == TASK_UNINTERRUPTIBLE && p->state == TASK_IDLE)
+ if (state_filter == TASK_UNINTERRUPTIBLE && state == TASK_IDLE)
return false;
return true;
}
-void show_state_filter(unsigned long state_filter)
+void show_state_filter(unsigned int state_filter)
{
struct task_struct *g, *p;
@@ -8252,7 +8255,7 @@ void __init init_idle(struct task_struct *idle, int cpu)
raw_spin_lock_irqsave(&idle->pi_lock, flags);
raw_spin_rq_lock(rq);
- idle->state = TASK_RUNNING;
+ idle->__state = TASK_RUNNING;
idle->se.exec_start = sched_clock();
/*
* PF_KTHREAD should already be set at this point; regardless, make it
@@ -9567,7 +9570,7 @@ static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
* has happened. This would lead to problems with PELT, due to
* move wanting to detach+attach while we're not attached yet.
*/
- if (task->state == TASK_NEW)
+ if (READ_ONCE(task->__state) == TASK_NEW)
ret = -EINVAL;
raw_spin_unlock_irq(&task->pi_lock);