PCI: pciehp: Drop enable/disable lock

Previously slot enablement and disablement could happen concurrently.
But now it's under the exclusive control of the IRQ thread, rendering
the locking obsolete.  Drop it.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/hotplug/pciehp.h

@@ -67,16 +67,13 @@ do {									\
  *	an Attention Button press
  * @lock: protects reads and writes of @state;
  *	protects scheduling, execution and cancellation of @work
- * @hotplug_lock: serializes calls to pciehp_enable_slot() and
- *	pciehp_disable_slot()
  */
 struct slot {
 	u8 state;
 	struct controller *ctrl;
 	struct hotplug_slot *hotplug_slot;
 	struct delayed_work work;
 	struct mutex lock;
-	struct mutex hotplug_lock;
 };
 
 /**

drivers/pci/hotplug/pciehp_ctrl.c

@@ -277,9 +277,6 @@ void pciehp_handle_presence_change(struct slot *slot)
 	}
 }
 
-/*
- * Note: This function must be called with slot->hotplug_lock held
- */
 static int __pciehp_enable_slot(struct slot *p_slot)
 {
 	u8 getstatus = 0;
@@ -316,10 +313,7 @@ int pciehp_enable_slot(struct slot *slot)
 	struct controller *ctrl = slot->ctrl;
 	int ret;
 
-	mutex_lock(&slot->hotplug_lock);
 	ret = __pciehp_enable_slot(slot);
-	mutex_unlock(&slot->hotplug_lock);
-
 	if (ret && ATTN_BUTTN(ctrl))
 		pciehp_green_led_off(slot); /* may be blinking */
 
@@ -330,9 +324,6 @@ int pciehp_enable_slot(struct slot *slot)
 	return ret;
 }
 
-/*
- * Note: This function must be called with slot->hotplug_lock held
- */
 static int __pciehp_disable_slot(struct slot *p_slot)
 {
 	u8 getstatus = 0;
@@ -355,9 +346,7 @@ int pciehp_disable_slot(struct slot *slot)
 {
 	int ret;
 
-	mutex_lock(&slot->hotplug_lock);
 	ret = __pciehp_disable_slot(slot);
-	mutex_unlock(&slot->hotplug_lock);
 
 	mutex_lock(&slot->lock);
 	slot->state = OFF_STATE;

drivers/pci/hotplug/pciehp_hpc.c

@@ -781,7 +781,6 @@ static int pcie_init_slot(struct controller *ctrl)
 
 	slot->ctrl = ctrl;
 	mutex_init(&slot->lock);
-	mutex_init(&slot->hotplug_lock);
 	INIT_DELAYED_WORK(&slot->work, pciehp_queue_pushbutton_work);
 	ctrl->slot = slot;
 	return 0;