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

tip-bot2 for Peter Zijlstra
2024-08-18T06:23:11Z

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@infradead.org>
AuthorDate: Mon, 01 Jul 2024 21:30:09 +02:00
Committer: Peter Zijlstra <peterz@infradead.org>
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@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lkml.kernel.org/r/20240727105029.998329901@infradead.org
---
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);