[tip: locking/core] sched: Avoid signed comparison of preempt_count() in __cant_migrate()

[tip-bot2 for Boqun Feng]

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

Commit-ID:     31f35d04a29a7554bb3b9ad827dd37c2942e31d4
Gitweb:        https://git.kernel.org/tip/31f35d04a29a7554bb3b9ad827dd37c2942e31d4
Author:        Boqun Feng <boqun@xxxxxxxxxx>
AuthorDate:    Tue, 04 Aug 2026 09:14:31 -07:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Sat, 08 Aug 2026 22:44:08 +02:00

sched: Avoid signed comparison of preempt_count() in __cant_migrate()

Currently preempt_count() is always a non-negative int on all archs
(PREEMPT_NEED_RESCHED archs will mask out the MSB when returning
preempt_count()), hence the checking in __cant_migrate() is in fact just
checking whether preempt_count() is 0 or not. In a future change, we are
going to use all the 32 bits of preempt_count(), which would make
negative int values possible from preempt_count(). Therefore convert the
"> 0" comparison into a zero check to prepare for the future change.
No functional changes are intended.

Signed-off-by: Boqun Feng <boqun@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://patch.msgid.link/20260804161447.84806-10-boqun@xxxxxxxxxx
---
 kernel/sched/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index aa116da..9b3f176 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9241,7 +9241,7 @@ void __cant_migrate(const char *file, int line)
 	if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
 		return;
 
-	if (preempt_count() > 0)
+	if (preempt_count())
 		return;
 
 	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)