[PATCH] tick/nohz: fix inverted return value in check_tick_dependency() fast path
From: Josh Snyder
Date: Thu Apr 02 2026 - 19:23:56 EST
Commit 56534673cea7f ("tick/nohz: Optimize check_tick_dependency() with
early return") added a fast path that returns !val when the tick_stop
tracepoint is disabled. This is inverted: the slow path returns true
when a dependency IS found (val != 0), but !val returns true when val
is zero (no dependency). The result is that can_stop_full_tick() sees
"dependency found" when there are none, and the tick never stops on
nohz_full CPUs.
Fix by returning val instead of !val, matching the slow-path semantics.
Fixes: 56534673cea7f ("tick/nohz: Optimize check_tick_dependency() with early return")
Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Josh Snyder <josh@xxxxxxxxxxx>
---
kernel/time/tick-sched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index f7907fadd63f2..4324f3838ab0d 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -345,7 +345,7 @@ static bool check_tick_dependency(atomic_t *dep)
int val = atomic_read(dep);
if (likely(!tracepoint_enabled(tick_stop)))
- return !val;
+ return val;
if (val & TICK_DEP_MASK_POSIX_TIMER) {
trace_tick_stop(0, TICK_DEP_MASK_POSIX_TIMER);
---
base-commit: 4f59dbcc2a99c8dd9b438c4e9ccb0e4870ef92f6
change-id: 20260402-fix-idle-tick2-50a4f96df527
Best regards,
--
Josh