[tip: sched/core] sched,freezer: Mark TASK_FROZEN special

[tip-bot2 for Peter Zijlstra]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     a1c446611e31ca5363d4db51e398271da1dce0af
Gitweb:        https://git.kernel.org/tip/a1c446611e31ca5363d4db51e398271da1dce0af
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Mon, 01 Jul 2024 21:30:09 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Sat, 17 Aug 2024 11:06:44 +02:00

sched,freezer: Mark TASK_FROZEN special

The special task states are those that do not suffer spurious wakeups,
TASK_FROZEN is very much one of those, mark it as such.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Valentin Schneider <vschneid@xxxxxxxxxx>
Tested-by: Valentin Schneider <vschneid@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20240727105029.998329901@xxxxxxxxxxxxx
---
 include/linux/sched.h | 5 +++--
 kernel/freezer.c      | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index f4a648e..8a3a389 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -149,8 +149,9 @@ struct user_event_mm;
  * Special states are those that do not use the normal wait-loop pattern. See
  * the comment with set_special_state().
  */
-#define is_special_task_state(state)				\
-	((state) & (__TASK_STOPPED | __TASK_TRACED | TASK_PARKED | TASK_DEAD))
+#define is_special_task_state(state)					\
+	((state) & (__TASK_STOPPED | __TASK_TRACED | TASK_PARKED |	\
+		    TASK_DEAD | TASK_FROZEN))
 
 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
 # define debug_normal_state_change(state_value)				\
diff --git a/kernel/freezer.c b/kernel/freezer.c
index f57aaf9..44bbd7d 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -72,7 +72,7 @@ bool __refrigerator(bool check_kthr_stop)
 		bool freeze;
 
 		raw_spin_lock_irq(&current->pi_lock);
-		set_current_state(TASK_FROZEN);
+		WRITE_ONCE(current->__state, TASK_FROZEN);
 		/* unstale saved_state so that __thaw_task() will wake us up */
 		current->saved_state = TASK_RUNNING;
 		raw_spin_unlock_irq(&current->pi_lock);