sched: Add get_current_state()

Remove yet another few p->state accesses.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210611082838.347475156@infradead.org

block/blk-mq.c

@@ -3910,7 +3910,7 @@ int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
 
 	hctx->poll_considered++;
 
-	state = current->state;
+	state = get_current_state();
 	do {
 		int ret;
 

include/linux/sched.h

@@ -213,6 +213,8 @@ struct task_group;
 
 #endif
 
+#define get_current_state()	READ_ONCE(current->state)
+
 /* Task command name length: */
 #define TASK_COMM_LEN			16
 

kernel/freezer.c

@@ -58,7 +58,7 @@ bool __refrigerator(bool check_kthr_stop)
 	/* Hmm, should we be allowed to suspend when there are realtime
 	   processes around? */
 	bool was_frozen = false;
-	long save = current->state;
+	unsigned int save = get_current_state();
 
 	pr_debug("%s entered refrigerator\n", current->comm);
 

kernel/sched/core.c

@@ -9098,15 +9098,15 @@ static inline int preempt_count_equals(int preempt_offset)
 
 void __might_sleep(const char *file, int line, int preempt_offset)
 {
+	unsigned int state = get_current_state();
 	/*
 	 * Blocking primitives will set (and therefore destroy) current->state,
 	 * since we will exit with TASK_RUNNING make sure we enter with it,
 	 * otherwise we will destroy state.
 	 */
-	WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
+	WARN_ONCE(state != TASK_RUNNING && current->task_state_change,
 			"do not call blocking ops when !TASK_RUNNING; "
-			"state=%lx set at [<%p>] %pS\n",
-			current->state,
+			"state=%x set at [<%p>] %pS\n", state,
 			(void *)current->task_state_change,
 			(void *)current->task_state_change);