[tip: sched/urgent] sched: Fix preemption string of preempt_dynamic_none

[tip-bot2 for Thomas Weißschuh]

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

Commit-ID:     3ebb1b6522392f64902b4e96954e35927354aa27
Gitweb:        https://git.kernel.org/tip/3ebb1b6522392f64902b4e96954e35927354aa27
Author:        Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
AuthorDate:    Thu, 26 Jun 2025 11:23:44 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Tue, 01 Jul 2025 15:02:02 +02:00

sched: Fix preemption string of preempt_dynamic_none

Zero is a valid value for "preempt_dynamic_mode", namely
"preempt_dynamic_none".

Fix the off-by-one in preempt_model_str(), so that "preempty_dynamic_none"
is correctly formatted as PREEMPT(none) instead of PREEMPT(undef).

Fixes: 8bdc5daaa01e ("sched: Add a generic function to return the preemption string")
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Tested-by: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20250626-preempt-str-none-v2-1-526213b70a89@xxxxxxxxxxxxx
---
 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 8988d38..cd80b66 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7663,7 +7663,7 @@ const char *preempt_model_str(void)
 
 		if (IS_ENABLED(CONFIG_PREEMPT_DYNAMIC)) {
 			seq_buf_printf(&s, "(%s)%s",
-				       preempt_dynamic_mode > 0 ?
+				       preempt_dynamic_mode >= 0 ?
 				       preempt_modes[preempt_dynamic_mode] : "undef",
 				       brace ? "}" : "");
 			return seq_buf_str(&s);