linux-kernel - [PATCHv2 1/2] sched/deadline: Remove unnecessary comment in dl_add_task_root

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Message-ID: <20251125032630.8746-2-piliu@redhat.com>
Date: Tue, 25 Nov 2025 11:26:29 +0800
From: Pingfan Liu <piliu@...hat.com>
To: cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Pingfan Liu <piliu@...hat.com>,
	Tejun Heo <tj@...nel.org>,
	Waiman Long <longman@...hat.com>,
	Chen Ridong <chenridong@...weicloud.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Pierre Gondois <pierre.gondois@....com>,
	Ingo Molnar <mingo@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>
Subject: [PATCHv2 1/2] sched/deadline: Remove unnecessary comment in dl_add_task_root_domain()

The comments above dl_get_task_effective_cpus() and
dl_add_task_root_domain() already explain how to fetch a valid
root domain and protect against races. There's no need to repeat
this inside dl_add_task_root_domain(). Remove the redundant comment
to keep the code clean.

No functional change.

Signed-off-by: Pingfan Liu <piliu@...hat.com>
Cc: Tejun Heo <tj@...nel.org>
Cc: Waiman Long <longman@...hat.com>
Cc: Chen Ridong <chenridong@...weicloud.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Pierre Gondois <pierre.gondois@....com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Vincent Guittot <vincent.guittot@...aro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@....com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Ben Segall <bsegall@...gle.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Valentin Schneider <vschneid@...hat.com>
To: cgroups@...r.kernel.org
To: linux-kernel@...r.kernel.org
---
 kernel/sched/deadline.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 194a341e85864..0b6646259bcd7 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2952,20 +2952,11 @@ void dl_add_task_root_domain(struct task_struct *p)
 		return;
 	}
 
-	/*
-	 * Get an active rq, whose rq->rd traces the correct root
-	 * domain.
-	 * Ideally this would be under cpuset reader lock until rq->rd is
-	 * fetched.  However, sleepable locks cannot nest inside pi_lock, so we
-	 * rely on the caller of dl_add_task_root_domain() holds 'cpuset_mutex'
-	 * to guarantee the CPU stays in the cpuset.
-	 */
 	dl_get_task_effective_cpus(p, msk);
 	cpu = cpumask_first_and(cpu_active_mask, msk);
 	BUG_ON(cpu >= nr_cpu_ids);
 	rq = cpu_rq(cpu);
 	dl_b = &rq->rd->dl_bw;
-	/* End of fetching rd */
 
 	raw_spin_lock(&dl_b->lock);
 	__dl_add(dl_b, p->dl.dl_bw, cpumask_weight(rq->rd->span));
-- 
2.49.0