pciehp: update workqueue usage

* Rename pciehp_wq to pciehp_ordered_wq and add non-ordered pciehp_wq
  which is used instead of the system workqueue.  This is to remove
  the use of flush_scheduled_work() which is deprecated and scheduled
  for removal.

* With cmwq in place, there's no point in creating workqueues lazily.
  Create both pciehp_wq and pciehp_ordered_wq upfront.

* Include workqueue.h from pciehp.h.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 0cd4204..50a23da 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -41,8 +41,6 @@
 #include "../pci.h"
 #include "pciehp.h"
 
-static atomic_t pciehp_num_controllers = ATOMIC_INIT(0);
-
 static inline int pciehp_readw(struct controller *ctrl, int reg, u16 *value)
 {
 	struct pci_dev *dev = ctrl->pcie->port;
@@ -805,8 +803,8 @@
 {
 	struct slot *slot = ctrl->slot;
 	cancel_delayed_work(&slot->work);
-	flush_scheduled_work();
 	flush_workqueue(pciehp_wq);
+	flush_workqueue(pciehp_ordered_wq);
 	kfree(slot);
 }
 
@@ -912,16 +910,6 @@
 	/* Disable sotfware notification */
 	pcie_disable_notification(ctrl);
 
-	/*
-	 * If this is the first controller to be initialized,
-	 * initialize the pciehp work queue
-	 */
-	if (atomic_add_return(1, &pciehp_num_controllers) == 1) {
-		pciehp_wq = create_singlethread_workqueue("pciehpd");
-		if (!pciehp_wq)
-			goto abort_ctrl;
-	}
-
 	ctrl_info(ctrl, "HPC vendor_id %x device_id %x ss_vid %x ss_did %x\n",
 		  pdev->vendor, pdev->device, pdev->subsystem_vendor,
 		  pdev->subsystem_device);
@@ -941,11 +929,5 @@
 {
 	pcie_shutdown_notification(ctrl);
 	pcie_cleanup_slot(ctrl);
-	/*
-	 * If this is the last controller to be released, destroy the
-	 * pciehp work queue
-	 */
-	if (atomic_dec_and_test(&pciehp_num_controllers))
-		destroy_workqueue(pciehp_wq);
 	kfree(ctrl);
 }