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PM: runtime: Simplify locking in pm_runtime_put_suppliers()

PATCH In review Rafael J. Wysocki 2 participants 2 messages Dec 17, 2021 – Dec 21, 2021

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#0 lore raw

PATCH 1/1 PM: runtime: Simplify locking in pm_runtime_put_suppliers()

From: Rafael J. Wysocki <[email protected]>

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.

---
 drivers/base/power/runtime.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)
drivers/base/power/runtime.c +8 -4
Index: 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);
 		}
Reviewed-by on v1 1/1
#1 lore raw
Quoted 8 lines · Rafael J. Wysocki

From: Rafael J. Wysocki <[email protected]>

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.

Quoted 6 lines

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.

Kind regards
Uffe

Quoted 40 lines
---
 drivers/base/power/runtime.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

Index: linux-pm/drivers/base/power/runtime.c
===================================================================

drivers/base/power/runtime.c +8 -4
@@ -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);
                }