New subject: [tip: sched/core] sched/core: Add clearing of ->dl_server in put_prev_task_balance()

27 May 2024

From: "Joel Fernandes (Google)" joel@joelfernandes.org
Paths using put_prev_task_balance() need to do a pick shortly
after. Make sure they also clear the ->dl_server on prev as a
part of that.
Cc: stable@vger.kernel.org
Fixes: 63ba8422f876 ("sched/deadline: Introduce deadline servers")
Signed-off-by: Joel Fernandes (Google) joel@joelfernandes.org
Signed-off-by: Daniel Bristot de Oliveira bristot@kernel.org
---
 kernel/sched/core.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index bcf2c4cc0522..08c409457152 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6006,6 +6006,14 @@ static void put_prev_task_balance(struct rq *rq, struct task_struct *prev,
 #endif
put_prev_task(rq, prev);
+
+	/*
+	 * We've updated @prev and no longer need the server link, clear it.
+	 * Must be done before ->pick_next_task() because that can (re)set
+	 * ->dl_server.
+	 */
+	if (prev->dl_server)
+		prev->dl_server = NULL;
 }
/*
@@ -6049,14 +6057,6 @@ __pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 restart:
    put_prev_task_balance(rq, prev, rf);
-	/*
-	 * We've updated @prev and no longer need the server link, clear it.
-	 * Must be done before ->pick_next_task() because that can (re)set
-	 * ->dl_server.
-	 */
-	if (prev->dl_server)
-		prev->dl_server = NULL;
-
    for_each_class(class) {
    	p = class->pick_next_task(rq);
    	if (p)
-- 
2.45.1



    

[PATCH V7 2/9] sched/core: Add clearing of ->dl_server in put_prev_task_balance()