From: Andrea Righi <arighi@nvidia.com>
Date: Wed, 26 Mar 2025 19:18:49 +0000 (+0100)
Subject: sched_ext: idle: Fix return code of scx_select_cpu_dfl()
X-Git-Tag: v6.15-rc1~40^2~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=37477d9ecabd15323700313724479bea94d0421e;p=thirdparty%2Flinux.git

sched_ext: idle: Fix return code of scx_select_cpu_dfl()

Return -EBUSY when using %SCX_PICK_IDLE_CORE with scx_select_cpu_dfl()
if a fully idle SMT core cannot be found, instead of falling back to
@prev_cpu, which is not a fully idle SMT core in this case.

Fixes: c414c2171cd9e ("sched_ext: idle: Honor idle flags in the built-in idle selection policy")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---

diff --git a/kernel/sched/ext_idle.c b/kernel/sched/ext_idle.c
index 52c36a70a3d04..45061b5843806 100644
--- a/kernel/sched/ext_idle.c
+++ b/kernel/sched/ext_idle.c
@@ -544,7 +544,7 @@ s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags, u64
 		 * core.
 		 */
 		if (flags & SCX_PICK_IDLE_CORE) {
-			cpu = prev_cpu;
+			cpu = -EBUSY;
 			goto out_unlock;
 		}
 	}