diff options
| -rw-r--r-- | kernel/freezer.c | 41 | ||||
| -rw-r--r-- | kernel/sched/core.c | 23 |
2 files changed, 33 insertions, 31 deletions
diff --git a/kernel/freezer.c b/kernel/freezer.c index 4fad0e6fca64..c450fa8b8b5e 100644 --- a/kernel/freezer.c +++ b/kernel/freezer.c @@ -71,7 +71,11 @@ bool __refrigerator(bool check_kthr_stop) for (;;) { bool freeze; + raw_spin_lock_irq(¤t->pi_lock); set_current_state(TASK_FROZEN); + /* unstale saved_state so that __thaw_task() will wake us up */ + current->saved_state = TASK_RUNNING; + raw_spin_unlock_irq(¤t->pi_lock); spin_lock_irq(&freezer_lock); freeze = freezing(current) && !(check_kthr_stop && kthread_should_stop()); @@ -129,6 +133,7 @@ static int __set_task_frozen(struct task_struct *p, void *arg) WARN_ON_ONCE(debug_locks && p->lockdep_depth); #endif + p->saved_state = p->__state; WRITE_ONCE(p->__state, TASK_FROZEN); return TASK_FROZEN; } @@ -170,42 +175,34 @@ bool freeze_task(struct task_struct *p) } /* - * The special task states (TASK_STOPPED, TASK_TRACED) keep their canonical - * state in p->jobctl. If either of them got a wakeup that was missed because - * TASK_FROZEN, then their canonical state reflects that and the below will - * refuse to restore the special state and instead issue the wakeup. + * Restore the saved_state before the task entered freezer. For typical task + * in the __refrigerator(), saved_state == TASK_RUNNING so nothing happens + * here. For tasks which were TASK_NORMAL | TASK_FREEZABLE, their initial state + * is restored unless they got an expected wakeup (see ttwu_state_match()). + * Returns 1 if the task state was restored. */ -static int __set_task_special(struct task_struct *p, void *arg) +static int __restore_freezer_state(struct task_struct *p, void *arg) { - unsigned int state = 0; + unsigned int state = p->saved_state; - if (p->jobctl & JOBCTL_TRACED) - state = TASK_TRACED; - - else if (p->jobctl & JOBCTL_STOPPED) - state = TASK_STOPPED; - - if (state) + if (state != TASK_RUNNING) { WRITE_ONCE(p->__state, state); + return 1; + } - return state; + return 0; } void __thaw_task(struct task_struct *p) { - unsigned long flags, flags2; + unsigned long flags; spin_lock_irqsave(&freezer_lock, flags); if (WARN_ON_ONCE(freezing(p))) goto unlock; - if (lock_task_sighand(p, &flags2)) { - /* TASK_FROZEN -> TASK_{STOPPED,TRACED} */ - bool ret = task_call_func(p, __set_task_special, NULL); - unlock_task_sighand(p, &flags2); - if (ret) - goto unlock; - } + if (task_call_func(p, __restore_freezer_state, NULL)) + goto unlock; wake_up_state(p, TASK_FROZEN); unlock: diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 49541e3c1295..5a50c4e41be9 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2242,8 +2242,8 @@ static __always_inline int task_state_match(struct task_struct *p, unsigned int state) { /* - * Serialize against current_save_and_set_rtlock_wait_state() and - * current_restore_rtlock_saved_state(). + * Serialize against current_save_and_set_rtlock_wait_state(), + * current_restore_rtlock_saved_state(), and __refrigerator(). */ guard(raw_spinlock_irq)(&p->pi_lock); return __task_state_match(p, state); @@ -4015,13 +4015,17 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) * The caller holds p::pi_lock if p != current or has preemption * disabled when p == current. * - * The rules of PREEMPT_RT saved_state: + * The rules of saved_state: * * The related locking code always holds p::pi_lock when updating * p::saved_state, which means the code is fully serialized in both cases. * - * The lock wait and lock wakeups happen via TASK_RTLOCK_WAIT. No other - * bits set. This allows to distinguish all wakeup scenarios. + * For PREEMPT_RT, the lock wait and lock wakeups happen via TASK_RTLOCK_WAIT. + * No other bits set. This allows to distinguish all wakeup scenarios. + * + * For FREEZER, the wakeup happens via TASK_FROZEN. No other bits set. This + * allows us to prevent early wakeup of tasks before they can be run on + * asymmetric ISA architectures (eg ARMv9). */ static __always_inline bool ttwu_state_match(struct task_struct *p, unsigned int state, int *success) @@ -4037,10 +4041,11 @@ bool ttwu_state_match(struct task_struct *p, unsigned int state, int *success) /* * Saved state preserves the task state across blocking on - * an RT lock. If the state matches, set p::saved_state to - * TASK_RUNNING, but do not wake the task because it waits - * for a lock wakeup. Also indicate success because from - * the regular waker's point of view this has succeeded. + * an RT lock or TASK_FREEZABLE tasks. If the state matches, + * set p::saved_state to TASK_RUNNING, but do not wake the task + * because it waits for a lock wakeup or __thaw_task(). Also + * indicate success because from the regular waker's point of + * view this has succeeded. * * After acquiring the lock the task will restore p::__state * from p::saved_state which ensures that the regular |