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

[tip-bot2 for Joel Fernandes (Google)]

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

Commit-ID:     c245910049d04fbfa85bb2f5acd591c24e9907c7
Gitweb:        https://git.kernel.org/tip/c245910049d04fbfa85bb2f5acd591c24e9907c7
Author:        Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
AuthorDate:    Mon, 27 May 2024 14:06:48 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 29 Jul 2024 12:22:35 +02:00

sched/core: Add clearing of ->dl_server in put_prev_task_balance()

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.

Fixes: 63ba8422f876 ("sched/deadline: Introduce deadline servers")
Signed-off-by: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Tested-by: Juri Lelli <juri.lelli@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/d184d554434bedbad0581cb34656582d78655150.1716811044.git.bristot@xxxxxxxxxx
---
 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 0a71050..e61da3b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5801,6 +5801,14 @@ 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;
 }
 
 /*
@@ -5844,14 +5852,6 @@ __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)