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

1 files changed, 15 insertions, 16 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 395c8906f502..50db9496c99d 100644
--- 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
@@ -666,8 +666,7 @@ 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
@@ -1532,7 +1531,7 @@ static inline pid_t task_pgrp_nr(struct task_struct *tsk)
 
 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);
@@ -1840,10 +1839,10 @@ static __always_inline void scheduler_ipi(void)
 	 */
 	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;
 }