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Commit 01209293 authored by Michał Mirosław's avatar Michał Mirosław Committed by Greg Kroah-Hartman
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misc: atmel-ssc: lock with mutex instead of spinlock 



commit b037d60a3b1d1227609fd858fa34321f41829911 upstream.

Uninterruptible context is not needed in the driver and causes lockdep
warning because of mutex taken in of_alias_get_id(). Convert the lock to
mutex to avoid the issue.

Cc: stable@vger.kernel.org
Fixes: 099343c6 ("ARM: at91: atmel-ssc: add device tree support")
Signed-off-by: default avatarMichał Mirosław <mirq-linux@rere.qmqm.pl>
Link: https://lore.kernel.org/r/50f0d7fa107f318296afb49477c3571e4d6978c5.1592998403.git.mirq-linux@rere.qmqm.pl


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c7c33666

drivers/misc/atmel-ssc.c

+12 −12
Original line number Diff line number Diff line
@@ -13,7 +13,7 @@ 
#include <linux/clk.h>

#include <linux/err.h>

#include <linux/io.h>

#include <linux/spinlock.h>

#include <linux/mutex.h>

#include <linux/atmel-ssc.h>

#include <linux/slab.h>

#include <linux/module.h>
@@ -21,7 +21,7 @@ 
#include <linux/of.h>



/* Serialize access to ssc_list and user count */

static DEFINE_SPINLOCK(user_lock);

static DEFINE_MUTEX(user_lock);

static LIST_HEAD(ssc_list);



struct ssc_device *ssc_request(unsigned int ssc_num)
@@ -29,7 +29,7 @@ struct ssc_device *ssc_request(unsigned int ssc_num) 
	int ssc_valid = 0;

	struct ssc_device *ssc;



	spin_lock(&user_lock);

	mutex_lock(&user_lock);

	list_for_each_entry(ssc, &ssc_list, list) {

		if (ssc->pdev->dev.of_node) {

			if (of_alias_get_id(ssc->pdev->dev.of_node, "ssc")
@@ -44,18 +44,18 @@ struct ssc_device *ssc_request(unsigned int ssc_num) 
	}



	if (!ssc_valid) {

		spin_unlock(&user_lock);

		mutex_unlock(&user_lock);

		pr_err("ssc: ssc%d platform device is missing\n", ssc_num);

		return ERR_PTR(-ENODEV);

	}



	if (ssc->user) {

		spin_unlock(&user_lock);

		mutex_unlock(&user_lock);

		dev_dbg(&ssc->pdev->dev, "module busy\n");

		return ERR_PTR(-EBUSY);

	}

	ssc->user++;

	spin_unlock(&user_lock);

	mutex_unlock(&user_lock);



	clk_prepare(ssc->clk);
@@ -67,14 +67,14 @@ void ssc_free(struct ssc_device *ssc) 
{

	bool disable_clk = true;



	spin_lock(&user_lock);

	mutex_lock(&user_lock);

	if (ssc->user)

		ssc->user--;

	else {

		disable_clk = false;

		dev_dbg(&ssc->pdev->dev, "device already free\n");

	}

	spin_unlock(&user_lock);

	mutex_unlock(&user_lock);



	if (disable_clk)

		clk_unprepare(ssc->clk);
@@ -194,9 +194,9 @@ static int ssc_probe(struct platform_device *pdev) 
		return -ENXIO;

	}



	spin_lock(&user_lock);

	mutex_lock(&user_lock);

	list_add_tail(&ssc->list, &ssc_list);

	spin_unlock(&user_lock);

	mutex_unlock(&user_lock);



	platform_set_drvdata(pdev, ssc);
@@ -210,9 +210,9 @@ static int ssc_remove(struct platform_device *pdev) 
{

	struct ssc_device *ssc = platform_get_drvdata(pdev);



	spin_lock(&user_lock);

	mutex_lock(&user_lock);

	list_del(&ssc->list);

	spin_unlock(&user_lock);

	mutex_unlock(&user_lock);



	return 0;

}