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Subject[PATCH 4.9 82/86] misc: atmel-ssc: lock with mutex instead of spinlock
Date
From: Michał Mirosław <mirq-linux@rere.qmqm.pl>

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: 099343c64e16 ("ARM: at91: atmel-ssc: add device tree support")
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Link: https://lore.kernel.org/r/50f0d7fa107f318296afb49477c3571e4d6978c5.1592998403.git.mirq-linux@rere.qmqm.pl
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/misc/atmel-ssc.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)

--- a/drivers/misc/atmel-ssc.c
+++ b/drivers/misc/atmel-ssc.c
@@ -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_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")
@@ -45,18 +45,18 @@ struct ssc_device *ssc_request(unsigned
}

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);

@@ -68,14 +68,14 @@ 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);
@@ -195,9 +195,9 @@ static int ssc_probe(struct platform_dev
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);

@@ -211,9 +211,9 @@ static int ssc_remove(struct platform_de
{
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;
}

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