PCI/DOE: Allow mailbox creation without devres management

DOE mailbox creation is currently only possible through a devres-managed
API.  The lifetime of mailboxes thus ends with driver unbinding.

An upcoming commit will create DOE mailboxes upon device enumeration by
the PCI core.  Their lifetime shall not be limited by a driver.

Therefore rework pcim_doe_create_mb() into the non-devres-managed
pci_doe_create_mb().  Add pci_doe_destroy_mb() for mailbox destruction
on device removal.

Provide a devres-managed wrapper under the existing pcim_doe_create_mb()
name.

The error path of pcim_doe_create_mb() previously called xa_destroy() if
alloc_ordered_workqueue() failed.  That's unnecessary because the xarray
is still empty at that point.  It doesn't need to be destroyed until
it's been populated by pci_doe_cache_protocols().  Arrange the error
path of the new pci_doe_create_mb() accordingly.

pci_doe_cancel_tasks() is no longer used as callback for
devm_add_action(), so refactor it to accept a struct pci_doe_mb pointer
instead of a generic void pointer.
Tested-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Ming Li <ming4.li@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/7c9a63867d70233c5e9d26cd8bf956742cd6d650.1678543498.git.lukas@wunner.deSigned-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/pci/doe.c

@@ -37,7 +37,7 @@
  *
  * This state is used to manage a single DOE mailbox capability.  All fields
  * should be considered opaque to the consumers and the structure passed into
- * the helpers below after being created by devm_pci_doe_create()
+ * the helpers below after being created by pci_doe_create_mb().
  *
  * @pdev: PCI device this mailbox belongs to
  * @cap_offset: Capability offset
@@ -415,24 +415,8 @@ static int pci_doe_cache_protocols(struct pci_doe_mb *doe_mb)
 	return 0;
 }
 
-static void pci_doe_xa_destroy(void *mb)
+static void pci_doe_cancel_tasks(struct pci_doe_mb *doe_mb)
 {
-	struct pci_doe_mb *doe_mb = mb;
-
-	xa_destroy(&doe_mb->prots);
-}
-
-static void pci_doe_destroy_workqueue(void *mb)
-{
-	struct pci_doe_mb *doe_mb = mb;
-
-	destroy_workqueue(doe_mb->work_queue);
-}
-
-static void pci_doe_cancel_tasks(void *mb)
-{
-	struct pci_doe_mb *doe_mb = mb;
-
 	/* Stop all pending work items from starting */
 	set_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags);
 
@@ -442,7 +426,7 @@ static void pci_doe_cancel_tasks(void *mb)
 }
 
 /**
- * pcim_doe_create_mb() - Create a DOE mailbox object
+ * pci_doe_create_mb() - Create a DOE mailbox object
  *
  * @pdev: PCI device to create the DOE mailbox for
  * @cap_offset: Offset of the DOE mailbox
@@ -453,24 +437,20 @@ static void pci_doe_cancel_tasks(void *mb)
  * RETURNS: created mailbox object on success
  *	    ERR_PTR(-errno) on failure
  */
-struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset)
+static struct pci_doe_mb *pci_doe_create_mb(struct pci_dev *pdev,
+					    u16 cap_offset)
 {
 	struct pci_doe_mb *doe_mb;
-	struct device *dev = &pdev->dev;
 	int rc;
 
-	doe_mb = devm_kzalloc(dev, sizeof(*doe_mb), GFP_KERNEL);
+	doe_mb = kzalloc(sizeof(*doe_mb), GFP_KERNEL);
 	if (!doe_mb)
 		return ERR_PTR(-ENOMEM);
 
 	doe_mb->pdev = pdev;
 	doe_mb->cap_offset = cap_offset;
 	init_waitqueue_head(&doe_mb->wq);
-
 	xa_init(&doe_mb->prots);
-	rc = devm_add_action(dev, pci_doe_xa_destroy, doe_mb);
-	if (rc)
-		return ERR_PTR(rc);
 
 	doe_mb->work_queue = alloc_ordered_workqueue("%s %s DOE [%x]", 0,
 						dev_driver_string(&pdev->dev),
@@ -479,36 +459,85 @@ struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset)
 	if (!doe_mb->work_queue) {
 		pci_err(pdev, "[%x] failed to allocate work queue\n",
 			doe_mb->cap_offset);
-		return ERR_PTR(-ENOMEM);
+		rc = -ENOMEM;
+		goto err_free;
 	}
-	rc = devm_add_action_or_reset(dev, pci_doe_destroy_workqueue, doe_mb);
-	if (rc)
-		return ERR_PTR(rc);
 
 	/* Reset the mailbox by issuing an abort */
 	rc = pci_doe_abort(doe_mb);
 	if (rc) {
 		pci_err(pdev, "[%x] failed to reset mailbox with abort command : %d\n",
 			doe_mb->cap_offset, rc);
-		return ERR_PTR(rc);
+		goto err_destroy_wq;
 	}
 
 	/*
 	 * The state machine and the mailbox should be in sync now;
-	 * Set up cancel tasks prior to using the mailbox to query protocols.
+	 * Use the mailbox to query protocols.
 	 */
-	rc = devm_add_action_or_reset(dev, pci_doe_cancel_tasks, doe_mb);
-	if (rc)
-		return ERR_PTR(rc);
-
 	rc = pci_doe_cache_protocols(doe_mb);
 	if (rc) {
 		pci_err(pdev, "[%x] failed to cache protocols : %d\n",
 			doe_mb->cap_offset, rc);
-		return ERR_PTR(rc);
+		goto err_cancel;
 	}
 
 	return doe_mb;
+
+err_cancel:
+	pci_doe_cancel_tasks(doe_mb);
+	xa_destroy(&doe_mb->prots);
+err_destroy_wq:
+	destroy_workqueue(doe_mb->work_queue);
+err_free:
+	kfree(doe_mb);
+	return ERR_PTR(rc);
+}
+
+/**
+ * pci_doe_destroy_mb() - Destroy a DOE mailbox object
+ *
+ * @ptr: Pointer to DOE mailbox
+ *
+ * Destroy all internal data structures created for the DOE mailbox.
+ */
+static void pci_doe_destroy_mb(void *ptr)
+{
+	struct pci_doe_mb *doe_mb = ptr;
+
+	pci_doe_cancel_tasks(doe_mb);
+	xa_destroy(&doe_mb->prots);
+	destroy_workqueue(doe_mb->work_queue);
+	kfree(doe_mb);
+}
+
+/**
+ * pcim_doe_create_mb() - Create a DOE mailbox object
+ *
+ * @pdev: PCI device to create the DOE mailbox for
+ * @cap_offset: Offset of the DOE mailbox
+ *
+ * Create a single mailbox object to manage the mailbox protocol at the
+ * cap_offset specified.  The mailbox will automatically be destroyed on
+ * driver unbinding from @pdev.
+ *
+ * RETURNS: created mailbox object on success
+ *	    ERR_PTR(-errno) on failure
+ */
+struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset)
+{
+	struct pci_doe_mb *doe_mb;
+	int rc;
+
+	doe_mb = pci_doe_create_mb(pdev, cap_offset);
+	if (IS_ERR(doe_mb))
+		return doe_mb;
+
+	rc = devm_add_action_or_reset(&pdev->dev, pci_doe_destroy_mb, doe_mb);
+	if (rc)
+		return ERR_PTR(rc);
+
+	return doe_mb;
 }
 EXPORT_SYMBOL_GPL(pcim_doe_create_mb);