On 24/06/2020 13:35:41+0200, Michał Mirosław wrote:
> 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: [email protected]
> Fixes: 099343c64e16 ("ARM: at91: atmel-ssc: add device tree support")
> Signed-off-by: Michał Mirosław <[email protected]>
Acked-by: Alexandre Belloni <[email protected]>
> ---
> v2: rebased onto v5.7.5, added Fixes tag
> ---
> drivers/misc/atmel-ssc.c | 24 ++++++++++++------------
> 1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/misc/atmel-ssc.c b/drivers/misc/atmel-ssc.c
> index ab4144ea1f11..d6cd5537126c 100644
> --- a/drivers/misc/atmel-ssc.c
> +++ b/drivers/misc/atmel-ssc.c
> @@ -10,7 +10,7 @@
> #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>
> @@ -20,7 +20,7 @@
> #include "../../sound/soc/atmel/atmel_ssc_dai.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)
> @@ -28,7 +28,7 @@ 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);
> @@ -237,9 +237,9 @@ 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);
>
> @@ -258,9 +258,9 @@ static int ssc_remove(struct platform_device *pdev)
>
> ssc_sound_dai_remove(ssc);
>
> - spin_lock(&user_lock);
> + mutex_lock(&user_lock);
> list_del(&ssc->list);
> - spin_unlock(&user_lock);
> + mutex_unlock(&user_lock);
>
> return 0;
> }
> --
> 2.20.1
>
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
