[PATCH] PM: runtime: Simplify locking in pm_runtime_put_suppliers()

From: Rafael J. Wysocki
Date: Fri Dec 17 2021 - 14:16:07 EST


From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

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@xxxxxxxxx>
---
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);
}