[PATCH 6/6] sched: Change task_struct::state

From: Peter Zijlstra
Date: Wed Jun 02 2021 - 09:32:03 EST

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@xxxxxxxxxxxxx>
---
block/blk-mq.c | 2 -
drivers/md/dm.c | 6 ++--
fs/binfmt_elf.c | 8 +++---
fs/userfaultfd.c | 4 +--
include/linux/sched.h | 31 +++++++++++------------
include/linux/sched/debug.h | 2 -
include/linux/sched/signal.h | 2 -
init/init_task.c | 2 -
kernel/cgroup/cgroup-v1.c | 2 -
kernel/debug/kdb/kdb_support.c | 18 +++++++------
kernel/fork.c | 4 +--
kernel/hung_task.c | 2 -
kernel/kthread.c | 4 +--
kernel/locking/mutex.c | 6 ++--
kernel/locking/rtmutex.c | 4 +--
kernel/locking/rwsem.c | 2 -
kernel/ptrace.c | 12 ++++-----
kernel/rcu/rcutorture.c | 4 +--
kernel/rcu/tree_stall.h | 12 ++++-----
kernel/sched/core.c | 53 +++++++++++++++++++++--------------------
kernel/sched/deadline.c | 10 +++----
kernel/sched/fair.c | 11 +++++---
lib/syscall.c | 4 +--
net/core/dev.c | 2 -
24 files changed, 108 insertions(+), 99 deletions(-)

--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3886,7 +3886,7 @@ static bool blk_mq_poll_hybrid(struct re
int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
{
struct blk_mq_hw_ctx *hctx;
- long state;
+ unsigned int state;

if (!blk_qc_t_valid(cookie) ||
!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2328,7 +2328,7 @@ static bool md_in_flight_bios(struct map
return sum != 0;
}

-static int dm_wait_for_bios_completion(struct mapped_device *md, long task_state)
+static int dm_wait_for_bios_completion(struct mapped_device *md, unsigned int task_state)
{
int r = 0;
DEFINE_WAIT(wait);
@@ -2351,7 +2351,7 @@ static int dm_wait_for_bios_completion(s
return r;
}

-static int dm_wait_for_completion(struct mapped_device *md, long task_state)
+static int dm_wait_for_completion(struct mapped_device *md, unsigned int task_state)
{
int r = 0;

@@ -2478,7 +2478,7 @@ static void unlock_fs(struct mapped_devi
* are being added to md->deferred list.
*/
static int __dm_suspend(struct mapped_device *md, struct dm_table *map,
- unsigned suspend_flags, long task_state,
+ unsigned suspend_flags, unsigned int task_state,
int dmf_suspended_flag)
{
bool do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG;
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1537,7 +1537,8 @@ static int fill_psinfo(struct elf_prpsin
{
const struct cred *cred;
unsigned int i, len;
-
+ unsigned int state;
+
/* first copy the parameters from user space */
memset(psinfo, 0, sizeof(struct elf_prpsinfo));

@@ -1559,7 +1560,8 @@ static int fill_psinfo(struct elf_prpsin
psinfo->pr_pgrp = task_pgrp_vnr(p);
psinfo->pr_sid = task_session_vnr(p);

- i = p->state ? ffz(~p->state) + 1 : 0;
+ state = READ_ONCE(p->__state);
+ i = state ? ffz(~state) + 1 : 0;
psinfo->pr_state = i;
psinfo->pr_sname = (i > 5) ? '.' : "RSDTZW"[i];
psinfo->pr_zomb = psinfo->pr_sname == 'Z';
@@ -1571,7 +1573,7 @@ static int fill_psinfo(struct elf_prpsin
SET_GID(psinfo->pr_gid, from_kgid_munged(cred->user_ns, cred->gid));
rcu_read_unlock();
strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname));
-
+
return 0;
}

--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -337,7 +337,7 @@ static inline bool userfaultfd_must_wait
return ret;
}

-static inline long userfaultfd_get_blocking_state(unsigned int flags)
+static inline unsigned int userfaultfd_get_blocking_state(unsigned int flags)
{
if (flags & FAULT_FLAG_INTERRUPTIBLE)
return TASK_INTERRUPTIBLE;
@@ -370,7 +370,7 @@ vm_fault_t handle_userfault(struct vm_fa
struct userfaultfd_wait_queue uwq;
vm_fault_t ret = VM_FAULT_SIGBUS;
bool must_wait;
- long blocking_state;
+ unsigned int blocking_state;

/*
* We don't do userfault handling for the final child pid update.
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -113,13 +113,13 @@ struct task_group;
__TASK_TRACED | EXIT_DEAD | EXIT_ZOMBIE | \
TASK_PARKED)

-#define task_is_running(task) (READ_ONCE((task)->state) == TASK_RUNNING)
+#define task_is_running(task) (READ_ONCE((task)->__state) == TASK_RUNNING)

-#define task_is_traced(task) ((task->state & __TASK_TRACED) != 0)
+#define task_is_traced(task) ((READ_ONCE(task->__state) & __TASK_TRACED) != 0)

-#define task_is_stopped(task) ((task->state & __TASK_STOPPED) != 0)
+#define task_is_stopped(task) ((READ_ONCE(task->__state) & __TASK_STOPPED) != 0)

-#define task_is_stopped_or_traced(task) ((task->state & (__TASK_STOPPED | __TASK_TRACED)) != 0)
+#define task_is_stopped_or_traced(task) ((READ_ONCE(task->__state) & (__TASK_STOPPED | __TASK_TRACED)) != 0)

#ifdef CONFIG_DEBUG_ATOMIC_SLEEP

@@ -134,14 +134,14 @@ struct task_group;
do { \
WARN_ON_ONCE(is_special_task_state(state_value));\
current->task_state_change = _THIS_IP_; \
- current->state = (state_value); \
+ WRITE_ONCE(current->__state, (state_value)); \
} while (0)

#define set_current_state(state_value) \
do { \
WARN_ON_ONCE(is_special_task_state(state_value));\
current->task_state_change = _THIS_IP_; \
- smp_store_mb(current->state, (state_value)); \
+ smp_store_mb(current->__state, (state_value)); \
} while (0)

#define set_special_state(state_value) \
@@ -150,7 +150,7 @@ struct task_group;
WARN_ON_ONCE(!is_special_task_state(state_value)); \
raw_spin_lock_irqsave(&current->pi_lock, flags); \
current->task_state_change = _THIS_IP_; \
- current->state = (state_value); \
+ WRITE_ONCE(current->__state, (state_value)); \
raw_spin_unlock_irqrestore(&current->pi_lock, flags); \
} while (0)
#else
@@ -192,10 +192,10 @@ struct task_group;
* Also see the comments of try_to_wake_up().
*/
#define __set_current_state(state_value) \
- current->state = (state_value)
+ WRITE_ONCE(current->__state, (state_value))

#define set_current_state(state_value) \
- smp_store_mb(current->state, (state_value))
+ smp_store_mb(current->__state, (state_value))

/*
* set_special_state() should be used for those states when the blocking task
@@ -207,13 +207,13 @@ struct task_group;
do { \
unsigned long flags; /* may shadow */ \
raw_spin_lock_irqsave(&current->pi_lock, flags); \
- current->state = (state_value); \
+ WRITE_ONCE(current->__state, (state_value)); \
raw_spin_unlock_irqrestore(&current->pi_lock, flags); \
} while (0)

#endif

-#define get_current_state() READ_ONCE(current->state)
+#define get_current_state() READ_ONCE(current->__state)

/* Task command name length: */
#define TASK_COMM_LEN 16
@@ -658,8 +658,7 @@ struct task_struct {
*/
struct thread_info thread_info;
#endif
- /* -1 unrunnable, 0 runnable, >0 stopped: */
- volatile long state;
+ unsigned int __state;

/*
* This begins the randomizable portion of task_struct. Only
@@ -1524,7 +1523,7 @@ static inline pid_t task_pgrp_nr(struct

static inline unsigned int task_state_index(struct task_struct *tsk)
{
- unsigned int tsk_state = READ_ONCE(tsk->state);
+ unsigned int tsk_state = READ_ONCE(tsk->__state);
unsigned int state = (tsk_state | tsk->exit_state) & TASK_REPORT;

BUILD_BUG_ON_NOT_POWER_OF_2(TASK_REPORT_MAX);
@@ -1832,10 +1831,10 @@ static __always_inline void scheduler_ip
*/
preempt_fold_need_resched();
}
-extern unsigned long wait_task_inactive(struct task_struct *, long match_state);
+extern unsigned long wait_task_inactive(struct task_struct *, unsigned int match_state);
#else
static inline void scheduler_ipi(void) { }
-static inline unsigned long wait_task_inactive(struct task_struct *p, long match_state)
+static inline unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state)
{
return 1;
}
--- a/include/linux/sched/debug.h
+++ b/include/linux/sched/debug.h
@@ -14,7 +14,7 @@ extern void dump_cpu_task(int cpu);
/*
* Only dump TASK_* tasks. (0 for all tasks)
*/
-extern void show_state_filter(unsigned long state_filter);
+extern void show_state_filter(unsigned int state_filter);

static inline void show_state(void)
{
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -382,7 +382,7 @@ static inline int fatal_signal_pending(s
return task_sigpending(p) && __fatal_signal_pending(p);
}

-static inline int signal_pending_state(long state, struct task_struct *p)
+static inline int signal_pending_state(unsigned int state, struct task_struct *p)
{
if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
return 0;
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -71,7 +71,7 @@ struct task_struct init_task
.thread_info = INIT_THREAD_INFO(init_task),
.stack_refcount = REFCOUNT_INIT(1),
#endif
- .state = 0,
+ .__state = 0,
.stack = init_stack,
.usage = REFCOUNT_INIT(2),
.flags = PF_KTHREAD,
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -713,7 +713,7 @@ int cgroupstats_build(struct cgroupstats

css_task_iter_start(&cgrp->self, 0, &it);
while ((tsk = css_task_iter_next(&it))) {
- switch (tsk->state) {
+ switch (READ_ONCE(tsk->__state)) {
case TASK_RUNNING:
stats->nr_running++;
break;
--- a/kernel/debug/kdb/kdb_support.c
+++ b/kernel/debug/kdb/kdb_support.c
@@ -609,23 +609,25 @@ unsigned long kdb_task_state_string(cons
*/
char kdb_task_state_char (const struct task_struct *p)
{
- int cpu;
- char state;
+ unsigned int p_state;
unsigned long tmp;
+ char state;
+ int cpu;

if (!p ||
copy_from_kernel_nofault(&tmp, (char *)p, sizeof(unsigned long)))
return 'E';

cpu = kdb_process_cpu(p);
- state = (p->state == 0) ? 'R' :
- (p->state < 0) ? 'U' :
- (p->state & TASK_UNINTERRUPTIBLE) ? 'D' :
- (p->state & TASK_STOPPED) ? 'T' :
- (p->state & TASK_TRACED) ? 'C' :
+ p_state = READ_ONCE(p->__state);
+ state = (p_state == 0) ? 'R' :
+ (p_state < 0) ? 'U' :
+ (p_state & TASK_UNINTERRUPTIBLE) ? 'D' :
+ (p_state & TASK_STOPPED) ? 'T' :
+ (p_state & TASK_TRACED) ? 'C' :
(p->exit_state & EXIT_ZOMBIE) ? 'Z' :
(p->exit_state & EXIT_DEAD) ? 'E' :
- (p->state & TASK_INTERRUPTIBLE) ? 'S' : '?';
+ (p_state & TASK_INTERRUPTIBLE) ? 'S' : '?';
if (is_idle_task(p)) {
/* Idle task. Is it really idle, apart from the kdb
* interrupt? */
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -425,7 +425,7 @@ static int memcg_charge_kernel_stack(str

static void release_task_stack(struct task_struct *tsk)
{
- if (WARN_ON(tsk->state != TASK_DEAD))
+ if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
return; /* Better to leak the stack than to free prematurely */

account_kernel_stack(tsk, -1);
@@ -2392,7 +2392,7 @@ static __latent_entropy struct task_stru
atomic_dec(&p->cred->user->processes);
exit_creds(p);
bad_fork_free:
- p->state = TASK_DEAD;
+ WRITE_ONCE(p->__state, TASK_DEAD);
put_task_stack(p);
delayed_free_task(p);
fork_out:
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -196,7 +196,7 @@ static void check_hung_uninterruptible_t
last_break = jiffies;
}
/* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
- if (t->state == TASK_UNINTERRUPTIBLE)
+ if (READ_ONCE(t->__state) == TASK_UNINTERRUPTIBLE)
check_hung_task(t, timeout);
}
unlock:
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -457,7 +457,7 @@ struct task_struct *kthread_create_on_no
}
EXPORT_SYMBOL(kthread_create_on_node);

-static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state)
+static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, unsigned int state)
{
unsigned long flags;

@@ -473,7 +473,7 @@ static void __kthread_bind_mask(struct t
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
}

-static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state)
+static void __kthread_bind(struct task_struct *p, unsigned int cpu, unsigned int state)
{
__kthread_bind_mask(p, cpumask_of(cpu), state);
}
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -923,7 +923,7 @@ __ww_mutex_add_waiter(struct mutex_waite
* Lock a mutex (possibly interruptible), slowpath:
*/
static __always_inline int __sched
-__mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
+__mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclass,
struct lockdep_map *nest_lock, unsigned long ip,
struct ww_acquire_ctx *ww_ctx, const bool use_ww_ctx)
{
@@ -1098,14 +1098,14 @@ __mutex_lock_common(struct mutex *lock,
}

static int __sched
-__mutex_lock(struct mutex *lock, long state, unsigned int subclass,
+__mutex_lock(struct mutex *lock, unsigned int state, unsigned int subclass,
struct lockdep_map *nest_lock, unsigned long ip)
{
return __mutex_lock_common(lock, state, subclass, nest_lock, ip, NULL, false);
}

static int __sched
-__ww_mutex_lock(struct mutex *lock, long state, unsigned int subclass,
+__ww_mutex_lock(struct mutex *lock, unsigned int state, unsigned int subclass,
struct lockdep_map *nest_lock, unsigned long ip,
struct ww_acquire_ctx *ww_ctx)
{
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1135,7 +1135,7 @@ void __sched rt_mutex_init_waiter(struct
*
* Must be called with lock->wait_lock held and interrupts disabled
*/
-static int __sched __rt_mutex_slowlock(struct rt_mutex *lock, int state,
+static int __sched __rt_mutex_slowlock(struct rt_mutex *lock, unsigned int state,
struct hrtimer_sleeper *timeout,
struct rt_mutex_waiter *waiter)
{
@@ -1190,7 +1190,7 @@ static void __sched rt_mutex_handle_dead
/*
* Slow path lock function:
*/
-static int __sched rt_mutex_slowlock(struct rt_mutex *lock, int state,
+static int __sched rt_mutex_slowlock(struct rt_mutex *lock, unsigned int state,
struct hrtimer_sleeper *timeout,
enum rtmutex_chainwalk chwalk)
{
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -889,7 +889,7 @@ rwsem_spin_on_owner(struct rw_semaphore
* Wait for the read lock to be granted
*/
static struct rw_semaphore __sched *
-rwsem_down_read_slowpath(struct rw_semaphore *sem, long count, int state)
+rwsem_down_read_slowpath(struct rw_semaphore *sem, long count, unsigned int state)
{
long adjustment = -RWSEM_READER_BIAS;
long rcnt = (count >> RWSEM_READER_SHIFT);
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -197,7 +197,7 @@ static bool ptrace_freeze_traced(struct
spin_lock_irq(&task->sighand->siglock);
if (task_is_traced(task) && !looks_like_a_spurious_pid(task) &&
!__fatal_signal_pending(task)) {
- task->state = __TASK_TRACED;
+ WRITE_ONCE(task->__state, __TASK_TRACED);
ret = true;
}
spin_unlock_irq(&task->sighand->siglock);
@@ -207,7 +207,7 @@ static bool ptrace_freeze_traced(struct

static void ptrace_unfreeze_traced(struct task_struct *task)
{
- if (task->state != __TASK_TRACED)
+ if (READ_ONCE(task->__state) != __TASK_TRACED)
return;

WARN_ON(!task->ptrace || task->parent != current);
@@ -217,11 +217,11 @@ static void ptrace_unfreeze_traced(struc
* Recheck state under the lock to close this race.
*/
spin_lock_irq(&task->sighand->siglock);
- if (task->state == __TASK_TRACED) {
+ if (READ_ONCE(task->__state) == __TASK_TRACED) {
if (__fatal_signal_pending(task))
wake_up_state(task, __TASK_TRACED);
else
- task->state = TASK_TRACED;
+ WRITE_ONCE(task->__state, TASK_TRACED);
}
spin_unlock_irq(&task->sighand->siglock);
}
@@ -256,7 +256,7 @@ static int ptrace_check_attach(struct ta
*/
read_lock(&tasklist_lock);
if (child->ptrace && child->parent == current) {
- WARN_ON(child->state == __TASK_TRACED);
+ WARN_ON(READ_ONCE(child->__state) == __TASK_TRACED);
/*
* child->sighand can't be NULL, release_task()
* does ptrace_unlink() before __exit_signal().
@@ -273,7 +273,7 @@ static int ptrace_check_attach(struct ta
* ptrace_stop() changes ->state back to TASK_RUNNING,
* so we should not worry about leaking __TASK_TRACED.
*/
- WARN_ON(child->state == __TASK_TRACED);
+ WARN_ON(READ_ONCE(child->__state) == __TASK_TRACED);
ret = -ESRCH;
}
}
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1831,10 +1831,10 @@ rcu_torture_stats_print(void)
srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
&flags, &gp_seq);
wtp = READ_ONCE(writer_task);
- pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
+ pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#x cpu %d\n",
rcu_torture_writer_state_getname(),
rcu_torture_writer_state, gp_seq, flags,
- wtp == NULL ? ~0UL : wtp->state,
+ wtp == NULL ? ~0U : wtp->__state,
wtp == NULL ? -1 : (int)task_cpu(wtp));
if (!splatted && wtp) {
sched_show_task(wtp);
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -460,12 +460,12 @@ static void rcu_check_gp_kthread_starvat

if (rcu_is_gp_kthread_starving(&j)) {
cpu = gpk ? task_cpu(gpk) : -1;
- pr_err("%s kthread starved for %ld jiffies! g%ld f%#x %s(%d) ->state=%#lx ->cpu=%d\n",
+ pr_err("%s kthread starved for %ld jiffies! g%ld f%#x %s(%d) ->state=%#x ->cpu=%d\n",
rcu_state.name, j,
(long)rcu_seq_current(&rcu_state.gp_seq),
data_race(rcu_state.gp_flags),
gp_state_getname(rcu_state.gp_state), rcu_state.gp_state,
- gpk ? gpk->state : ~0, cpu);
+ gpk ? gpk->__state : ~0, cpu);
if (gpk) {
pr_err("\tUnless %s kthread gets sufficient CPU time, OOM is now expected behavior.\n", rcu_state.name);
pr_err("RCU grace-period kthread stack dump:\n");
@@ -503,12 +503,12 @@ static void rcu_check_gp_kthread_expired
time_after(jiffies, jiffies_fqs + RCU_STALL_MIGHT_MIN) &&
gpk && !READ_ONCE(gpk->on_rq)) {
cpu = task_cpu(gpk);
- pr_err("%s kthread timer wakeup didn't happen for %ld jiffies! g%ld f%#x %s(%d) ->state=%#lx\n",
+ pr_err("%s kthread timer wakeup didn't happen for %ld jiffies! g%ld f%#x %s(%d) ->state=%#x\n",
rcu_state.name, (jiffies - jiffies_fqs),
(long)rcu_seq_current(&rcu_state.gp_seq),
data_race(rcu_state.gp_flags),
gp_state_getname(RCU_GP_WAIT_FQS), RCU_GP_WAIT_FQS,
- gpk->state);
+ gpk->__state);
pr_err("\tPossible timer handling issue on cpu=%d timer-softirq=%u\n",
cpu, kstat_softirqs_cpu(TIMER_SOFTIRQ, cpu));
}
@@ -735,9 +735,9 @@ void show_rcu_gp_kthreads(void)
ja = j - data_race(rcu_state.gp_activity);
jr = j - data_race(rcu_state.gp_req_activity);
jw = j - data_race(rcu_state.gp_wake_time);
- pr_info("%s: wait state: %s(%d) ->state: %#lx delta ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_flags %#x\n",
+ pr_info("%s: wait state: %s(%d) ->state: %#x delta ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_flags %#x\n",
rcu_state.name, gp_state_getname(rcu_state.gp_state),
- rcu_state.gp_state, t ? t->state : 0x1ffffL,
+ rcu_state.gp_state, t ? t->__state : 0x1ffff,
ja, jr, jw, (long)data_race(rcu_state.gp_wake_seq),
(long)data_race(rcu_state.gp_seq),
(long)data_race(rcu_get_root()->gp_seq_needed),
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2643,7 +2643,7 @@ static int affine_move_task(struct rq *r
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
@@ -2786,19 +2786,20 @@ 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)));

@@ -2970,7 +2971,7 @@ int migrate_swap(struct task_struct *cur
* 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;
@@ -2998,7 +2999,7 @@ unsigned long wait_task_inactive(struct
* 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();
}
@@ -3013,7 +3014,7 @@ unsigned long wait_task_inactive(struct
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);

@@ -3322,7 +3323,7 @@ static void ttwu_do_wakeup(struct rq *rq
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
@@ -3711,12 +3712,12 @@ try_to_wake_up(struct task_struct *p, un
* - 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;
}
@@ -3729,7 +3730,7 @@ try_to_wake_up(struct task_struct *p, un
*/
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);
@@ -3795,7 +3796,7 @@ try_to_wake_up(struct task_struct *p, un
* 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
@@ -3888,7 +3889,7 @@ bool try_invoke_on_locked_down_task(stru
ret = func(p, arg);
rq_unlock(rq, &rf);
} else {
- switch (p->state) {
+ switch (READ_ONCE(p->__state)) {
case TASK_RUNNING:
case TASK_WAKING:
break;
@@ -4101,7 +4102,7 @@ int sched_fork(unsigned long clone_flags
* 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.
@@ -4207,7 +4208,7 @@ void wake_up_new_task(struct task_struct
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:
@@ -4569,7 +4570,7 @@ static struct rq *finish_task_switch(str
* 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);
@@ -5263,7 +5264,7 @@ static inline void schedule_debug(struct
#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();
@@ -5889,10 +5890,10 @@ static void __sched notrace __schedule(b
* - 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) &&
@@ -6064,7 +6065,7 @@ 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());
@@ -8191,26 +8192,28 @@ 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;

@@ -8267,7 +8270,7 @@ void __init init_idle(struct task_struct
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
@@ -9582,7 +9585,7 @@ static int cpu_cgroup_can_attach(struct
* 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);

--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -348,10 +348,10 @@ static void task_non_contending(struct t
if ((zerolag_time < 0) || hrtimer_active(&dl_se->inactive_timer)) {
if (dl_task(p))
sub_running_bw(dl_se, dl_rq);
- if (!dl_task(p) || p->state == TASK_DEAD) {
+ if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
struct dl_bw *dl_b = dl_bw_of(task_cpu(p));

- if (p->state == TASK_DEAD)
+ if (READ_ONCE(p->__state) == TASK_DEAD)
sub_rq_bw(&p->dl, &rq->dl);
raw_spin_lock(&dl_b->lock);
__dl_sub(dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
@@ -1355,10 +1355,10 @@ static enum hrtimer_restart inactive_tas
sched_clock_tick();
update_rq_clock(rq);

- if (!dl_task(p) || p->state == TASK_DEAD) {
+ if (!dl_task(p) || READ_ONCE(p->__state) == TASK_DEAD) {
struct dl_bw *dl_b = dl_bw_of(task_cpu(p));

- if (p->state == TASK_DEAD && dl_se->dl_non_contending) {
+ if (READ_ONCE(p->__state) == TASK_DEAD && dl_se->dl_non_contending) {
sub_running_bw(&p->dl, dl_rq_of_se(&p->dl));
sub_rq_bw(&p->dl, dl_rq_of_se(&p->dl));
dl_se->dl_non_contending = 0;
@@ -1722,7 +1722,7 @@ static void migrate_task_rq_dl(struct ta
{
struct rq *rq;

- if (p->state != TASK_WAKING)
+ if (READ_ONCE(p->__state) != TASK_WAKING)
return;

rq = task_rq(p);
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -993,11 +993,14 @@ update_stats_dequeue(struct cfs_rq *cfs_

if ((flags & DEQUEUE_SLEEP) && entity_is_task(se)) {
struct task_struct *tsk = task_of(se);
+ unsigned int state;

- if (tsk->state & TASK_INTERRUPTIBLE)
+ /* XXX racy against TTWU */
+ state = READ_ONCE(tsk->__state);
+ if (state & TASK_INTERRUPTIBLE)
__schedstat_set(se->statistics.sleep_start,
rq_clock(rq_of(cfs_rq)));
- if (tsk->state & TASK_UNINTERRUPTIBLE)
+ if (state & TASK_UNINTERRUPTIBLE)
__schedstat_set(se->statistics.block_start,
rq_clock(rq_of(cfs_rq)));
}
@@ -6830,7 +6833,7 @@ static void migrate_task_rq_fair(struct
* min_vruntime -- the latter is done by enqueue_entity() when placing
* the task on the new runqueue.
*/
- if (p->state == TASK_WAKING) {
+ if (READ_ONCE(p->__state) == TASK_WAKING) {
struct sched_entity *se = &p->se;
struct cfs_rq *cfs_rq = cfs_rq_of(se);
u64 min_vruntime;
@@ -11012,7 +11015,7 @@ static inline bool vruntime_normalized(s
* waiting for actually being woken up by sched_ttwu_pending().
*/
if (!se->sum_exec_runtime ||
- (p->state == TASK_WAKING && p->sched_remote_wakeup))
+ (READ_ONCE(p->__state) == TASK_WAKING && p->sched_remote_wakeup))
return true;

return false;
--- a/lib/syscall.c
+++ b/lib/syscall.c
@@ -68,13 +68,13 @@ static int collect_syscall(struct task_s
*/
int task_current_syscall(struct task_struct *target, struct syscall_info *info)
{
- long state;
unsigned long ncsw;
+ unsigned int state;

if (target == current)
return collect_syscall(target, info);

- state = target->state;
+ state = READ_ONCE(target->__state);
if (unlikely(!state))
return -EAGAIN;

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4363,7 +4363,7 @@ static inline void ____napi_schedule(str
* makes sure to proceed with napi polling
* if the thread is explicitly woken from here.
*/
- if (READ_ONCE(thread->state) != TASK_INTERRUPTIBLE)
+ if (READ_ONCE(thread->__state) != TASK_INTERRUPTIBLE)
set_bit(NAPI_STATE_SCHED_THREADED, &napi->state);
wake_up_process(thread);
return;