[tip: sched/urgent] sched/core: Report correct state for TASK_IDLE | TASK_FREEZABLE

[tip-bot2 for NeilBrown]

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

Commit-ID:     0d6b35283bcf1a379cf20066544af8e6a6b16b46
Gitweb:        https://git.kernel.org/tip/0d6b35283bcf1a379cf20066544af8e6a6b16b46
Author:        NeilBrown <neilb@xxxxxxx>
AuthorDate:    Wed, 30 Aug 2023 09:04:19 +10:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Wed, 30 Aug 2023 10:08:38 +02:00

sched/core: Report correct state for TASK_IDLE | TASK_FREEZABLE

task_state_index() ignores uninteresting state flags (such as
TASK_FREEZABLE) for most states, but for TASK_IDLE and TASK_RTLOCK_WAIT
it does not.

So if a task is waiting TASK_IDLE|TASK_FREEZABLE it gets incorrectly
reported as TASK_UNINTERRUPTIBLE or "D".  (it is planned for nfsd to
change to use this state).

Fix this by only testing the interesting bits and not the irrelevant
bits in __task_state_index()

Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/169335025927.5133.4781141800413736103@xxxxxxxxxxxxxxxxxxxxx
---
 include/linux/sched.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index ae6fd76..77f01ac 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1671,7 +1671,7 @@ static inline unsigned int __task_state_index(unsigned int tsk_state,
 
 	BUILD_BUG_ON_NOT_POWER_OF_2(TASK_REPORT_MAX);
 
-	if (tsk_state == TASK_IDLE)
+	if ((tsk_state & TASK_IDLE) == TASK_IDLE)
 		state = TASK_REPORT_IDLE;
 
 	/*
@@ -1679,7 +1679,7 @@ static inline unsigned int __task_state_index(unsigned int tsk_state,
 	 * to userspace, we can make this appear as if the task has gone through
 	 * a regular rt_mutex_lock() call.
 	 */
-	if (tsk_state == TASK_RTLOCK_WAIT)
+	if (tsk_state & TASK_RTLOCK_WAIT)
 		state = TASK_UNINTERRUPTIBLE;
 
 	return fls(state);