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From:   Lai Jiangshan <jiangshanlai@gmail.com>
To:     linux-kernel@vger.kernel.org
Cc:     Valentin Schneider <valentin.schneider@arm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Qian Cai <cai@redhat.com>,
        Vincent Donnefort <vincent.donnefort@arm.com>,
        Lai Jiangshan <laijs@linux.alibaba.com>,
        Hillf Danton <hdanton@sina.com>, Tejun Heo <tj@kernel.org>,
        Lai Jiangshan <jiangshanlai@gmail.com>
Subject: [PATCH -tip V2 01/10] workqueue: restore unbound_workers' cpumask correctly
Date:   Sat, 19 Dec 2020 01:09:10 +0800
Message-Id: <20201218170919.2950-2-jiangshanlai@gmail.com>
In-Reply-To: <20201218170919.2950-1-jiangshanlai@gmail.com>
References: <20201218170919.2950-1-jiangshanlai@gmail.com>
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From: Lai Jiangshan <laijs@linux.alibaba.com>

When we restore workers' cpumask, we should restore them to the
designed pool->attrs->cpumask. And we need to only do it at
the first time.

Cc: Hillf Danton <hdanton@sina.com>
Reported-by: Hillf Danton <hdanton@sina.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
 kernel/workqueue.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index c71da2a59e12..aba71ab359dd 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5031,9 +5031,13 @@ static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
 
 	cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask);
 
+	/* is @cpu the first one onlined for the @pool? */
+	if (cpumask_weight(&cpumask) > 1)
+		return;
+
 	/* as we're called from CPU_ONLINE, the following shouldn't fail */
 	for_each_pool_worker(worker, pool)
-		WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0);
+		WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask) < 0);
 }
 
 int workqueue_prepare_cpu(unsigned int cpu)
-- 
2.19.1.6.gb485710b