linux-kernel - [PATCH AUTOSEL 6.10 100/197] pmdomain: core: Don't hold the genpd-lock when calling dev_pm_domain

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Message-ID: <20240925115823.1303019-100-sashal@kernel.org>
Date: Wed, 25 Sep 2024 07:51:59 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Ulf Hansson <ulf.hansson@...aro.org>,
	Raghavendra Kakarla <quic_rkakarla@...cinc.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Sasha Levin <sashal@...nel.org>,
	linux-pm@...r.kernel.org
Subject: [PATCH AUTOSEL 6.10 100/197] pmdomain: core: Don't hold the genpd-lock when calling dev_pm_domain_set()

From: Ulf Hansson <ulf.hansson@...aro.org>

[ Upstream commit b87eee38605c396f0e1fa435939960e5c6cd41d6 ]

There is no need to hold the genpd-lock, while assigning the
dev->pm_domain. In fact, it becomes a problem on a PREEMPT_RT based
configuration as the genpd-lock may be a raw spinlock, while the lock
acquired through the call to dev_pm_domain_set() is a regular spinlock.

To fix the problem, let's simply move the calls to dev_pm_domain_set()
outside the genpd-lock.

Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
Tested-by: Raghavendra Kakarla <quic_rkakarla@...cinc.com>  # qcm6490 with PREEMPT_RT set
Acked-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Link: https://lore.kernel.org/r/20240527142557.321610-3-ulf.hansson@linaro.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/pmdomain/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
index 623d15b68707e..c45819debde96 100644
--- a/drivers/pmdomain/core.c
+++ b/drivers/pmdomain/core.c
@@ -1694,7 +1694,6 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	genpd_lock(genpd);
 
 	genpd_set_cpumask(genpd, gpd_data->cpu);
-	dev_pm_domain_set(dev, &genpd->domain);
 
 	genpd->device_count++;
 	if (gd)
@@ -1703,6 +1702,7 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	list_add_tail(&gpd_data->base.list_node, &genpd->dev_list);
 
 	genpd_unlock(genpd);
+	dev_pm_domain_set(dev, &genpd->domain);
  out:
 	if (ret)
 		genpd_free_dev_data(dev, gpd_data);
@@ -1759,12 +1759,13 @@ static int genpd_remove_device(struct generic_pm_domain *genpd,
 		genpd->gd->max_off_time_changed = true;
 
 	genpd_clear_cpumask(genpd, gpd_data->cpu);
-	dev_pm_domain_set(dev, NULL);
 
 	list_del_init(&pdd->list_node);
 
 	genpd_unlock(genpd);
 
+	dev_pm_domain_set(dev, NULL);
+
 	if (genpd->detach_dev)
 		genpd->detach_dev(genpd, dev);
 
-- 
2.43.0