linux-kernel - [PATCH 15/24] sched,freezer: Mark TASK

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Message-Id: <20240727105029.998329901@infradead.org>
Date: Sat, 27 Jul 2024 12:27:47 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: mingo@...hat.com,
 peterz@...radead.org,
 juri.lelli@...hat.com,
 vincent.guittot@...aro.org,
 dietmar.eggemann@....com,
 rostedt@...dmis.org,
 bsegall@...gle.com,
 mgorman@...e.de,
 vschneid@...hat.com,
 linux-kernel@...r.kernel.org
Cc: kprateek.nayak@....com,
 wuyun.abel@...edance.com,
 youssefesmat@...omium.org,
 tglx@...utronix.de,
 efault@....de
Subject: [PATCH 15/24] 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@...radead.org>
---
 include/linux/sched.h |    5 +++--
 kernel/freezer.c      |    2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -147,8 +147,9 @@ 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)				\
--- 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);