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    Subject[PATCH 4.19 122/133] 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>
    @@ -23,7 +23,7 @@
    #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)
    @@ -31,7 +31,7 @@ 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")
    @@ -47,18 +47,18 @@ 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);

    @@ -70,14 +70,14 @@ 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);
    @@ -240,9 +240,9 @@ 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);

    @@ -261,9 +261,9 @@ static int ssc_remove(struct platform_de

    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;
    }

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