[PATCH 4/6] sched: Add get_current_state()

Peter Zijlstra
2021-06-02T13:33:40Z

Remove yet another few p->state accesses.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
block/blk-mq.c | 2 +-
include/linux/sched.h | 2 ++
kernel/freezer.c | 2 +-
kernel/sched/core.c | 6 +++---
4 files changed, 7 insertions(+), 5 deletions(-)

--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3891,7 +3891,7 @@ int blk_poll(struct request_queue *q, bl

hctx->poll_considered++;

- state = current->state;
+ state = get_current_state();
do {
int ret;

--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -212,6 +212,8 @@ struct task_group;

#endif

+#define get_current_state() READ_ONCE(current->state)
+
/* Task command name length: */
#define TASK_COMM_LEN 16

--- a/kernel/freezer.c
+++ b/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);

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8273,15 +8273,15 @@ static inline int preempt_count_equals(i

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);