linux-kernel - [PATCH v4 5/9] PM / QoS: Teach lockdep about dev_pm_qos

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Message-ID: <20230807171148.210181-6-robdclark@gmail.com>
Date:   Mon,  7 Aug 2023 10:11:39 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Rob Clark <robdclark@...omium.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-pm@...r.kernel.org (open list:HIBERNATION (aka Software Suspend,
        aka swsusp)), linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v4 5/9] PM / QoS: Teach lockdep about dev_pm_qos_mtx locking order

From: Rob Clark <robdclark@...omium.org>

Annotate dev_pm_qos_mtx to teach lockdep to scream about allocations
that could trigger reclaim under dev_pm_qos_mtx.

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/base/power/qos.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
index 5ec06585b6d1..63cb1086f195 100644
--- a/drivers/base/power/qos.c
+++ b/drivers/base/power/qos.c
@@ -1017,3 +1017,14 @@ void dev_pm_qos_hide_latency_tolerance(struct device *dev)
 	pm_runtime_put(dev);
 }
 EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_tolerance);
+
+static int __init dev_pm_qos_init(void)
+{
+	/* Teach lockdep about lock ordering wrt. shrinker: */
+	fs_reclaim_acquire(GFP_KERNEL);
+	might_lock(&dev_pm_qos_mtx);
+	fs_reclaim_release(GFP_KERNEL);
+
+	return 0;
+}
+early_initcall(dev_pm_qos_init);
-- 
2.41.0