[PATCH 8/9] sched: Simplify try_steal_cookie()

From: Peter Zijlstra
Date: Tue Aug 01 2023 - 17:25:33 EST


Use guards to reduce gotos and simplify control flow.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
kernel/sched/core.c | 21 +++++++++------------
1 file changed, 9 insertions(+), 12 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6229,19 +6229,19 @@ static bool try_steal_cookie(int this, i
unsigned long cookie;
bool success = false;

- local_irq_disable();
- double_rq_lock(dst, src);
+ guard(irq)();
+ guard(double_rq_lock)(dst, src);

cookie = dst->core->core_cookie;
if (!cookie)
- goto unlock;
+ return false;

if (dst->curr != dst->idle)
- goto unlock;
+ return false;

p = sched_core_find(src, cookie);
if (!p)
- goto unlock;
+ return false;

do {
if (p == src->core_pick || p == src->curr)
@@ -6253,9 +6253,10 @@ static bool try_steal_cookie(int this, i
if (p->core_occupation > dst->idle->core_occupation)
goto next;
/*
- * sched_core_find() and sched_core_next() will ensure that task @p
- * is not throttled now, we also need to check whether the runqueue
- * of the destination CPU is being throttled.
+ * sched_core_find() and sched_core_next() will ensure
+ * that task @p is not throttled now, we also need to
+ * check whether the runqueue of the destination CPU is
+ * being throttled.
*/
if (sched_task_is_throttled(p, this))
goto next;
@@ -6273,10 +6274,6 @@ static bool try_steal_cookie(int this, i
p = sched_core_next(p, cookie);
} while (p);

-unlock:
- double_rq_unlock(dst, src);
- local_irq_enable();
-
return success;
}