linux-kernel - [PATCH V7 3/9] sched/core: Clear prev->dl

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Message-ID: <7f7381ccba09efcb4a1c1ff808ed58385eccc222.1716811044.git.bristot@kernel.org>
Date: Mon, 27 May 2024 14:06:49 +0200
From: Daniel Bristot de Oliveira <bristot@...nel.org>
To: Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>,
	Daniel Bristot de Oliveira <bristot@...hat.com>,
	Valentin Schneider <vschneid@...hat.com>,
	linux-kernel@...r.kernel.org,
	Luca Abeni <luca.abeni@...tannapisa.it>,
	Tommaso Cucinotta <tommaso.cucinotta@...tannapisa.it>,
	Thomas Gleixner <tglx@...utronix.de>,
	Joel Fernandes <joel@...lfernandes.org>,
	Vineeth Pillai <vineeth@...byteword.org>,
	Shuah Khan <skhan@...uxfoundation.org>,
	bristot@...nel.org,
	Phil Auld <pauld@...hat.com>,
	Suleiman Souhlal <suleiman@...gle.com>,
	Youssef Esmat <youssefesmat@...gle.com>,
	stable@...r.kernel.org
Subject: [PATCH V7 3/9] sched/core: Clear prev->dl_server in CFS pick fast path

From: Youssef Esmat <youssefesmat@...gle.com>

In case the previous pick was a DL server pick, ->dl_server might be
set. Clear it in the fast path as well.

Cc: stable@...r.kernel.org
Fixes: 63ba8422f876 ("sched/deadline: Introduce deadline servers")
Signed-off-by: Youssef Esmat <youssefesmat@...gle.com>
Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@...nel.org>
---
 kernel/sched/core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 08c409457152..6d01863f93ca 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6044,6 +6044,13 @@ __pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 			p = pick_next_task_idle(rq);
 		}
 
+		/*
+		 * This is a normal CFS pick, but the previous could be a DL pick.
+		 * Clear it as previous is no longer picked.
+		 */
+		if (prev->dl_server)
+			prev->dl_server = NULL;
+
 		/*
 		 * This is the fast path; it cannot be a DL server pick;
 		 * therefore even if @p == @prev, ->dl_server must be NULL.
-- 
2.45.1