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From:   George Stark <gnstark@salutedevices.com>
To:     <pavel@ucw.cz>, <lee@kernel.org>, <vadimp@nvidia.com>,
        <mpe@ellerman.id.au>, <npiggin@gmail.com>,
        <christophe.leroy@csgroup.eu>, <hdegoede@redhat.com>,
        <mazziesaccount@gmail.com>, <andy.shevchenko@gmail.com>,
        <jic23@kernel.org>
CC:     <linux-leds@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linuxppc-dev@lists.ozlabs.org>, <kernel@salutedevices.com>,
        George Stark <gnstark@salutedevices.com>
Subject: [PATCH v2 01/10] devm-helpers: introduce devm_mutex_init
Date:   Mon, 4 Dec 2023 21:05:54 +0300
Message-ID: <20231204180603.470421-2-gnstark@salutedevices.com>
In-Reply-To: <20231204180603.470421-1-gnstark@salutedevices.com>
References: <20231204180603.470421-1-gnstark@salutedevices.com>
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Using of devm API leads to certain order of releasing resources.
So all dependent resources which are not devm-wrapped should be deleted
with respect to devm-release order. Mutex is one of such objects that
often is bound to other resources and has no own devm wrapping.
Since mutex_destroy() actually does nothing in non-debug builds
frequently calling mutex_destroy() is just ignored which is safe for now
but wrong formally and can lead to a problem if mutex_destroy() is
extended so introduce devm_mutex_init().

Signed-off-by: George Stark <gnstark@salutedevices.com>
---
 include/linux/devm-helpers.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/include/linux/devm-helpers.h b/include/linux/devm-helpers.h
index 74891802200d..2f56e476776f 100644
--- a/include/linux/devm-helpers.h
+++ b/include/linux/devm-helpers.h
@@ -76,4 +76,22 @@ static inline int devm_work_autocancel(struct device *dev,
 	return devm_add_action(dev, devm_work_drop, w);
 }
 
+static inline void devm_mutex_release(void *res)
+{
+	mutex_destroy(res);
+}
+
+/**
+ * devm_mutex_init - Resource-managed mutex initialization
+ * @dev:	Device which lifetime work is bound to
+ * @lock:	Pointer to a mutex
+ *
+ * Initialize mutex which is automatically destroyed when driver is detached.
+ */
+static inline int devm_mutex_init(struct device *dev, struct mutex *lock)
+{
+	mutex_init(lock);
+	return devm_add_action_or_reset(dev, devm_mutex_release, lock);
+}
+
 #endif
-- 
2.38.4