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SubjectRe: [PATCH] PM: runtime: Simplify locking in pm_runtime_put_suppliers()
On Fri, 17 Dec 2021 at 20:16, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Notice that pm_runtime_put_suppliers() cannot be called with
> disabled interrupts, because it may sleep (due to the device
> links read locking in the non-SRCU case), and so it can use
> spin_lock_irq() and spin_unlock_irq() for the locking.
>
> Update the function accordingly and while at it move the "put"
> local variable in it into the inner block where it is used.
>
> This change is not expected to have any visible functional impact.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Kind regards
Uffe

> ---
> drivers/base/power/runtime.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> Index: linux-pm/drivers/base/power/runtime.c
> ===================================================================
> --- linux-pm.orig/drivers/base/power/runtime.c
> +++ linux-pm/drivers/base/power/runtime.c
> @@ -1748,8 +1748,6 @@ void pm_runtime_get_suppliers(struct dev
> void pm_runtime_put_suppliers(struct device *dev)
> {
> struct device_link *link;
> - unsigned long flags;
> - bool put;
> int idx;
>
> idx = device_links_read_lock();
> @@ -1757,11 +1755,17 @@ void pm_runtime_put_suppliers(struct dev
> list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
> device_links_read_lock_held())
> if (link->supplier_preactivated) {
> + bool put;
> +
> link->supplier_preactivated = false;
> - spin_lock_irqsave(&dev->power.lock, flags);
> +
> + spin_lock_irq(&dev->power.lock);
> +
> put = pm_runtime_status_suspended(dev) &&
> refcount_dec_not_one(&link->rpm_active);
> - spin_unlock_irqrestore(&dev->power.lock, flags);
> +
> + spin_unlock_irq(&dev->power.lock);
> +
> if (put)
> pm_runtime_put(link->supplier);
> }
>
>
>

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