pciehp: use completion to wait irq_thread 'pciehp_ist'

hulk inclusion
category: bugfix
bugzilla: NA
CVE: NA
-------------------

When I use the following command to power on a slot which has been
powered off already.
echo 1 > /sys/bus/pci/slots/22/power
It prints the following error:
-bash: echo: write error: No such device
But the slot is actually powered on and the devices is probed.

In function 'pciehp_sysfs_enable_slot()', we use 'wait_event()' to wait
until 'ctrl->pending_events' is cleared in 'pciehp_ist()'. But in some
situation, when 'pciehp_ist()' is woken up on a nearby CPU after
'pciehp_request' is called, 'ctrl->pending_events' is cleared before we
go into sleep state. 'wait_event()' will check the condition before
going into sleep. So we return immediately and '-ENODEV' is return.

This patch use struct completion to wait until irq_thread 'pciehp_ist'
is completed.

Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: Yao Hongbo <yaohongbo@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>

drivers/pci/hotplug/pciehp.h

@@ -126,7 +126,7 @@ struct controller {
 	unsigned int power_fault_detected;
 	atomic_t pending_events;
 	int request_result;
-	wait_queue_head_t requester;
+	struct completion requester;
 };
 
 /**

drivers/pci/hotplug/pciehp_ctrl.c

@@ -403,9 +403,9 @@ int pciehp_sysfs_enable_slot(struct slot *p_slot)
 		 * card before the thread wakes up, so initialize to -ENODEV.
 		 */
 		ctrl->request_result = -ENODEV;
+		reinit_completion(&ctrl->requester);
 		pciehp_request(ctrl, PCI_EXP_SLTSTA_PDC);
-		wait_event(ctrl->requester,
-			   !atomic_read(&ctrl->pending_events));
+		wait_for_completion(&ctrl->requester);
 		return ctrl->request_result;
 	case POWERON_STATE:
 		ctrl_info(ctrl, "Slot(%s): Already in powering on state\n",
@@ -436,9 +436,9 @@ int pciehp_sysfs_disable_slot(struct slot *p_slot)
 	case BLINKINGOFF_STATE:
 	case ON_STATE:
 		mutex_unlock(&p_slot->lock);
+		reinit_completion(&ctrl->requester);
 		pciehp_request(ctrl, DISABLE_SLOT);
-		wait_event(ctrl->requester,
-			   !atomic_read(&ctrl->pending_events));
+		wait_for_completion(&ctrl->requester);
 		return ctrl->request_result;
 	case POWEROFF_STATE:
 		ctrl_info(ctrl, "Slot(%s): Already in powering off state\n",

drivers/pci/hotplug/pciehp_hpc.c

@@ -739,7 +739,7 @@ static irqreturn_t pciehp_ist(int irq, void *dev_id)
 	up_read(&ctrl->reset_lock);
 
 	pci_config_pm_runtime_put(pdev);
-	wake_up(&ctrl->requester);
+	complete(&ctrl->requester);
 	return IRQ_HANDLED;
 }
 
@@ -953,7 +953,7 @@ struct controller *pcie_init(struct pcie_device *dev)
 	ctrl->slot_cap = slot_cap;
 	mutex_init(&ctrl->ctrl_lock);
 	init_rwsem(&ctrl->reset_lock);
-	init_waitqueue_head(&ctrl->requester);
+	init_completion(&ctrl->requester);
 	init_waitqueue_head(&ctrl->queue);
 	dbg_ctrl(ctrl);