pciehp: Introduce hotplug_lock to serialize HP events

index 92d7fed..589339b 100644
@@ -77,6 +77,7 @@ struct slot {
 	struct hotplug_slot *hotplug_slot;
 	struct delayed_work work;	/* work for button event */
 	struct mutex lock;
+	struct mutex hotplug_lock;
 	struct workqueue_struct *wq;
 };
 

index bbd48bb..d01573d 100644
@@ -278,8 +278,11 @@ static int pciehp_probe(struct pcie_device *dev)
 	slot = ctrl->slot;
 	pciehp_get_adapter_status(slot, &occupied);
 	pciehp_get_power_status(slot, &poweron);
-	if (occupied && pciehp_force)
+	if (occupied && pciehp_force) {
+		mutex_lock(&slot->hotplug_lock);
 		pciehp_enable_slot(slot);
+		mutex_unlock(&slot->hotplug_lock);
+	}
 	/* If empty slot's power status is on, turn power off */
 	if (!occupied && poweron && POWER_CTRL(ctrl))
 		pciehp_power_off_slot(slot);

@@ -323,10 +326,12 @@ static int pciehp_resume (struct pcie_device *dev)
 
 	/* Check if slot is occupied */
 	pciehp_get_adapter_status(slot, &status);
+	mutex_lock(&slot->hotplug_lock);
 	if (status)
 		pciehp_enable_slot(slot);
 	else
 		pciehp_disable_slot(slot);
+	mutex_unlock(&slot->hotplug_lock);
 	return 0;
 }
 #endif /* PM */

index 36a8061..e6a5941 100644
@@ -314,6 +314,7 @@ static void pciehp_power_thread(struct work_struct *work)
 	struct power_work_info *info =
 		container_of(work, struct power_work_info, work);
 	struct slot *p_slot = info->p_slot;
+	int ret;
 
 	switch (info->req) {
 	case DISABLE_REQ:

@@ -321,7 +322,9 @@ static void pciehp_power_thread(struct work_struct *work)
 			 "Disabling domain:bus:device=%04x:%02x:00\n",
 			 pci_domain_nr(p_slot->ctrl->pcie->port->subordinate),
 			 p_slot->ctrl->pcie->port->subordinate->number);
+		mutex_lock(&p_slot->hotplug_lock);
 		pciehp_disable_slot(p_slot);
+		mutex_unlock(&p_slot->hotplug_lock);
 		mutex_lock(&p_slot->lock);
 		p_slot->state = STATIC_STATE;
 		mutex_unlock(&p_slot->lock);

@@ -331,7 +334,10 @@ static void pciehp_power_thread(struct work_struct *work)
 			 "Enabling domain:bus:device=%04x:%02x:00\n",
 			 pci_domain_nr(p_slot->ctrl->pcie->port->subordinate),
 			 p_slot->ctrl->pcie->port->subordinate->number);
-		if (pciehp_enable_slot(p_slot) && PWR_LED(p_slot->ctrl))
+		mutex_lock(&p_slot->hotplug_lock);
+		ret = pciehp_enable_slot(p_slot);
+		mutex_unlock(&p_slot->hotplug_lock);
+		if (ret && PWR_LED(p_slot->ctrl))
 			pciehp_green_led_off(p_slot);
 		mutex_lock(&p_slot->lock);
 		p_slot->state = STATIC_STATE;

@@ -575,6 +581,9 @@ static void interrupt_event_handler(struct work_struct *work)
 	kfree(info);
 }
 
+/*
+ * Note: This function must be called with slot->hotplug_lock held
+ */
 int pciehp_enable_slot(struct slot *p_slot)
 {
 	u8 getstatus = 0;

@@ -613,7 +622,9 @@ int pciehp_enable_slot(struct slot *p_slot)
 	return rc;
 }
 
-
+/*
+ * Note: This function must be called with slot->hotplug_lock held
+ */
 int pciehp_disable_slot(struct slot *p_slot)
 {
 	u8 getstatus = 0;

@@ -647,7 +658,9 @@ int pciehp_sysfs_enable_slot(struct slot *p_slot)
 	case STATIC_STATE:
 		p_slot->state = POWERON_STATE;
 		mutex_unlock(&p_slot->lock);
+		mutex_lock(&p_slot->hotplug_lock);
 		retval = pciehp_enable_slot(p_slot);
+		mutex_unlock(&p_slot->hotplug_lock);
 		mutex_lock(&p_slot->lock);
 		p_slot->state = STATIC_STATE;
 		break;

index c2f3e37..5c747a9 100644
@@ -815,6 +815,7 @@ 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;