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    Subject[Replacement][PATCH 1/2 v2] PM: Use spinlock instead of mutex in clock management functions
    Date
    From: Rafael J. Wysocki <rjw@sisk.pl>

    The lock member of struct pm_clk_data is of type struct mutex,
    which is a problem, because the suspend and resume routines
    defined in drivers/base/power/clock_ops.c cannot be executed
    with interrupts disabled for this reason. Modify
    struct pm_clk_data so that its lock member is a spinlock.

    Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
    ---

    The previous [1/2] in this series was on top of the branch at

    git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git pm-domains

    but what is needed now is a version on top of the current mainline tree, which
    is this one.

    Thanks,
    Rafael

    ---
    drivers/base/power/clock_ops.c | 40 ++++++++++++++++++++++------------------
    1 file changed, 22 insertions(+), 18 deletions(-)

    Index: linux/drivers/base/power/clock_ops.c
    ===================================================================
    --- linux.orig/drivers/base/power/clock_ops.c
    +++ linux/drivers/base/power/clock_ops.c
    @@ -19,7 +19,7 @@

    struct pm_clk_data {
    struct list_head clock_list;
    - struct mutex lock;
    + spinlock_t lock;
    };

    enum pce_status {
    @@ -73,9 +73,9 @@ int pm_clk_add(struct device *dev, const
    }
    }

    - mutex_lock(&pcd->lock);
    + spin_lock_irq(&pcd->lock);
    list_add_tail(&ce->node, &pcd->clock_list);
    - mutex_unlock(&pcd->lock);
    + spin_unlock_irq(&pcd->lock);
    return 0;
    }

    @@ -83,8 +83,8 @@ int pm_clk_add(struct device *dev, const
    * __pm_clk_remove - Destroy PM clock entry.
    * @ce: PM clock entry to destroy.
    *
    - * This routine must be called under the mutex protecting the PM list of clocks
    - * corresponding the the @ce's device.
    + * This routine must be called under the spinlock protecting the PM list of
    + * clocks corresponding the the @ce's device.
    */
    static void __pm_clk_remove(struct pm_clock_entry *ce)
    {
    @@ -123,7 +123,7 @@ void pm_clk_remove(struct device *dev, c
    if (!pcd)
    return;

    - mutex_lock(&pcd->lock);
    + spin_lock_irq(&pcd->lock);

    list_for_each_entry(ce, &pcd->clock_list, node) {
    if (!con_id && !ce->con_id) {
    @@ -137,7 +137,7 @@ void pm_clk_remove(struct device *dev, c
    }
    }

    - mutex_unlock(&pcd->lock);
    + spin_unlock_irq(&pcd->lock);
    }

    /**
    @@ -158,7 +158,7 @@ int pm_clk_init(struct device *dev)
    }

    INIT_LIST_HEAD(&pcd->clock_list);
    - mutex_init(&pcd->lock);
    + spin_lock_init(&pcd->lock);
    dev->power.subsys_data = pcd;
    return 0;
    }
    @@ -181,12 +181,12 @@ void pm_clk_destroy(struct device *dev)

    dev->power.subsys_data = NULL;

    - mutex_lock(&pcd->lock);
    + spin_lock_irq(&pcd->lock);

    list_for_each_entry_safe_reverse(ce, c, &pcd->clock_list, node)
    __pm_clk_remove(ce);

    - mutex_unlock(&pcd->lock);
    + spin_unlock_irq(&pcd->lock);

    kfree(pcd);
    }
    @@ -220,13 +220,14 @@ int pm_clk_suspend(struct device *dev)
    {
    struct pm_clk_data *pcd = __to_pcd(dev);
    struct pm_clock_entry *ce;
    + unsigned long flags;

    dev_dbg(dev, "%s()\n", __func__);

    if (!pcd)
    return 0;

    - mutex_lock(&pcd->lock);
    + spin_lock_irqsave(&pcd->lock, flags);

    list_for_each_entry_reverse(ce, &pcd->clock_list, node) {
    if (ce->status == PCE_STATUS_NONE)
    @@ -238,7 +239,7 @@ int pm_clk_suspend(struct device *dev)
    }
    }

    - mutex_unlock(&pcd->lock);
    + spin_unlock_irqrestore(&pcd->lock, flags);

    return 0;
    }
    @@ -251,13 +252,14 @@ int pm_clk_resume(struct device *dev)
    {
    struct pm_clk_data *pcd = __to_pcd(dev);
    struct pm_clock_entry *ce;
    + unsigned long flags;

    dev_dbg(dev, "%s()\n", __func__);

    if (!pcd)
    return 0;

    - mutex_lock(&pcd->lock);
    + spin_lock_irqsave(&pcd->lock, flags);

    list_for_each_entry(ce, &pcd->clock_list, node) {
    if (ce->status == PCE_STATUS_NONE)
    @@ -269,7 +271,7 @@ int pm_clk_resume(struct device *dev)
    }
    }

    - mutex_unlock(&pcd->lock);
    + spin_unlock_irqrestore(&pcd->lock, flags);

    return 0;
    }
    @@ -344,6 +346,7 @@ int pm_clk_suspend(struct device *dev)
    {
    struct pm_clk_data *pcd = __to_pcd(dev);
    struct pm_clock_entry *ce;
    + unsigned long flags;

    dev_dbg(dev, "%s()\n", __func__);

    @@ -351,12 +354,12 @@ int pm_clk_suspend(struct device *dev)
    if (!pcd || !dev->driver)
    return 0;

    - mutex_lock(&pcd->lock);
    + spin_lock_irqsave(&pcd->lock, flags);

    list_for_each_entry_reverse(ce, &pcd->clock_list, node)
    clk_disable(ce->clk);

    - mutex_unlock(&pcd->lock);
    + spin_unlock_irqrestore(&pcd->lock, flags);

    return 0;
    }
    @@ -369,6 +372,7 @@ int pm_clk_resume(struct device *dev)
    {
    struct pm_clk_data *pcd = __to_pcd(dev);
    struct pm_clock_entry *ce;
    + unsigned long flags;

    dev_dbg(dev, "%s()\n", __func__);

    @@ -376,12 +380,12 @@ int pm_clk_resume(struct device *dev)
    if (!pcd || !dev->driver)
    return 0;

    - mutex_lock(&pcd->lock);
    + spin_lock_irqsave(&pcd->lock, flags);

    list_for_each_entry(ce, &pcd->clock_list, node)
    clk_enable(ce->clk);

    - mutex_unlock(&pcd->lock);
    + spin_unlock_irqrestore(&pcd->lock, flags);

    return 0;
    }


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