[V2,2/2] PCI/DOE: Remove asynchronous task support

diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index 9240df53ed87..58977e0712b6 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -490,21 +490,14 @@  static struct pci_doe_mb *find_cdat_doe(struct device *uport)
 		    CXL_DOE_TABLE_ACCESS_TABLE_TYPE_CDATA) |		\
 	 FIELD_PREP(CXL_DOE_TABLE_ACCESS_ENTRY_HANDLE, (entry_handle)))
 
-static void cxl_doe_task_complete(struct pci_doe_task *task)
-{
-	complete(task->private);
-}
-
 struct cdat_doe_task {
 	u32 request_pl;
 	u32 response_pl[32];
-	struct completion c;
 	struct pci_doe_task task;
 };
 
 #define DECLARE_CDAT_DOE_TASK(req, cdt)                       \
 struct cdat_doe_task cdt = {                                  \
-	.c = COMPLETION_INITIALIZER_ONSTACK(cdt.c),           \
 	.request_pl = req,				      \
 	.task = {                                             \
 		.prot.vid = PCI_DVSEC_VENDOR_ID_CXL,        \
@@ -513,8 +506,6 @@  struct cdat_doe_task cdt = {                                  \
 		.request_pl_sz = sizeof(cdt.request_pl),      \
 		.response_pl = cdt.response_pl,               \
 		.response_pl_sz = sizeof(cdt.response_pl),    \
-		.complete = cxl_doe_task_complete,            \
-		.private = &cdt.c,                            \
 	}                                                     \
 }
 
@@ -525,12 +516,12 @@  static int cxl_cdat_get_length(struct device *dev,
 	DECLARE_CDAT_DOE_TASK(CDAT_DOE_REQ(0), t);
 	int rc;
 
-	rc = pci_doe_submit_task(cdat_doe, &t.task);
+	rc = pci_doe_submit_task_wait(cdat_doe, &t.task);
 	if (rc < 0) {
 		dev_err(dev, "DOE submit failed: %d", rc);
 		return rc;
 	}
-	wait_for_completion(&t.c);
+
 	if (t.task.rv < sizeof(u32))
 		return -EIO;
 
@@ -554,12 +545,11 @@  static int cxl_cdat_read_table(struct device *dev,
 		u32 *entry;
 		int rc;
 
-		rc = pci_doe_submit_task(cdat_doe, &t.task);
+		rc = pci_doe_submit_task_wait(cdat_doe, &t.task);
 		if (rc < 0) {
 			dev_err(dev, "DOE submit failed: %d", rc);
 			return rc;
 		}
-		wait_for_completion(&t.c);
 		/* 1 DW header + 1 DW data min */
 		if (t.task.rv < (2 * sizeof(u32)))
 			return -EIO;
diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
index 260313e9052e..41c7bf5794a5 100644
--- a/drivers/pci/doe.c
+++ b/drivers/pci/doe.c
@@ -18,7 +18,6 @@ 
 #include <linux/mutex.h>
 #include <linux/pci.h>
 #include <linux/pci-doe.h>
-#include <linux/workqueue.h>
 
 #define PCI_DOE_PROTOCOL_DISCOVERY 0
 
@@ -39,7 +38,7 @@ 
  * @cap_offset: Capability offset
  * @prots: Array of protocols supported (encoded as long values)
  * @wq: Wait queue for work item
- * @work_queue: Queue of pci_doe_work items
+ * @lock: Lock state of doe_mb during task processing
  * @flags: Bit array of PCI_DOE_FLAG_* flags
  */
 struct pci_doe_mb {
@@ -48,7 +47,7 @@  struct pci_doe_mb {
 	struct xarray prots;
 
 	wait_queue_head_t wq;
-	struct workqueue_struct *work_queue;
+	struct mutex lock;
 	unsigned long flags;
 };
 
@@ -198,7 +197,6 @@  static int pci_doe_recv_resp(struct pci_doe_mb *doe_mb, struct pci_doe_task *tas
 static void signal_task_complete(struct pci_doe_task *task, int rv)
 {
 	task->rv = rv;
-	task->complete(task);
 }
 
 static void signal_task_abort(struct pci_doe_task *task, int rv)
@@ -218,10 +216,8 @@  static void signal_task_abort(struct pci_doe_task *task, int rv)
 	signal_task_complete(task, rv);
 }
 
-static void doe_statemachine_work(struct work_struct *work)
+static void exec_task(struct pci_doe_task *task)
 {
-	struct pci_doe_task *task = container_of(work, struct pci_doe_task,
-						 work);
 	struct pci_doe_mb *doe_mb = task->doe_mb;
 	struct pci_dev *pdev = doe_mb->pdev;
 	int offset = doe_mb->cap_offset;
@@ -278,18 +274,12 @@  static void doe_statemachine_work(struct work_struct *work)
 	signal_task_complete(task, rc);
 }
 
-static void pci_doe_task_complete(struct pci_doe_task *task)
-{
-	complete(task->private);
-}
-
 static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid,
 			     u8 *protocol)
 {
 	u32 request_pl = FIELD_PREP(PCI_DOE_DATA_OBJECT_DISC_REQ_3_INDEX,
 				    *index);
 	u32 response_pl;
-	DECLARE_COMPLETION_ONSTACK(c);
 	struct pci_doe_task task = {
 		.prot.vid = PCI_VENDOR_ID_PCI_SIG,
 		.prot.type = PCI_DOE_PROTOCOL_DISCOVERY,
@@ -297,17 +287,13 @@  static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 *index, u16 *vid,
 		.request_pl_sz = sizeof(request_pl),
 		.response_pl = &response_pl,
 		.response_pl_sz = sizeof(response_pl),
-		.complete = pci_doe_task_complete,
-		.private = &c,
 	};
 	int rc;
 
-	rc = pci_doe_submit_task(doe_mb, &task);
+	rc = pci_doe_submit_task_wait(doe_mb, &task);
 	if (rc < 0)
 		return rc;
 
-	wait_for_completion(&c);
-
 	if (task.rv != sizeof(response_pl))
 		return -EIO;
 
@@ -359,13 +345,6 @@  static void pci_doe_xa_destroy(void *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);
-}
-
 /**
  * pcim_doe_create_mb() - Create a DOE mailbox object
  *
@@ -391,25 +370,13 @@  struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset)
 	doe_mb->pdev = pdev;
 	doe_mb->cap_offset = cap_offset;
 	init_waitqueue_head(&doe_mb->wq);
+	mutex_init(&doe_mb->lock);
 
 	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),
-						pci_name(pdev),
-						doe_mb->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 = 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) {
@@ -456,24 +423,25 @@  bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type)
 EXPORT_SYMBOL_GPL(pci_doe_supports_prot);
 
 /**
- * pci_doe_submit_task() - Submit a task to be processed by the state machine
+ * pci_doe_submit_task_wait() - Submit and execute a task
  *
  * @doe_mb: DOE mailbox capability to submit to
- * @task: task to be queued
+ * @task: task to be run
  *
- * Submit a DOE task (request/response) to the DOE mailbox to be processed.
- * Returns upon queueing the task object.  If the queue is full this function
- * will sleep until there is room in the queue.
- *
- * task->complete will be called when the state machine is done processing this
- * task.
+ * Submit and run DOE task (request/response) to the DOE mailbox to be
+ * processed.
  *
  * Excess data will be discarded.
  *
- * RETURNS: 0 when task has been successfully queued, -ERRNO on error
+ * Context: non-interrupt
+ *
+ * RETURNS: 0 when task was executed, the @task->rv holds the status
+ * result of the executed opertion, -ERRNO on failure to submit.
  */
-int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task)
+int pci_doe_submit_task_wait(struct pci_doe_mb *doe_mb, struct pci_doe_task *task)
 {
+	int rc;
+
 	if (!pci_doe_supports_prot(doe_mb, task->prot.vid, task->prot.type))
 		return -EINVAL;
 
@@ -489,8 +457,13 @@  int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task)
 		return -EIO;
 
 	task->doe_mb = doe_mb;
-	INIT_WORK(&task->work, doe_statemachine_work);
-	queue_work(doe_mb->work_queue, &task->work);
+
+	rc = mutex_lock_interruptible(&doe_mb->lock);
+	if (rc)
+		return rc;
+	exec_task(task);
+	mutex_unlock(&doe_mb->lock);
+
 	return 0;
 }
-EXPORT_SYMBOL_GPL(pci_doe_submit_task);
+EXPORT_SYMBOL_GPL(pci_doe_submit_task_wait);
diff --git a/include/linux/pci-doe.h b/include/linux/pci-doe.h
index ed9b4df792b8..c94122a66221 100644
--- a/include/linux/pci-doe.h
+++ b/include/linux/pci-doe.h
@@ -30,8 +30,6 @@  struct pci_doe_mb;
  * @response_pl_sz: Size of the response payload (bytes)
  * @rv: Return value.  Length of received response or error (bytes)
  * @complete: Called when task is complete
- * @private: Private data for the consumer
- * @work: Used internally by the mailbox
  * @doe_mb: Used internally by the mailbox
  *
  * The payload sizes and rv are specified in bytes with the following
@@ -50,11 +48,6 @@  struct pci_doe_task {
 	u32 *response_pl;
 	size_t response_pl_sz;
 	int rv;
-	void (*complete)(struct pci_doe_task *task);
-	void *private;
-
-	/* No need for the user to initialize these fields */
-	struct work_struct work;
 	struct pci_doe_mb *doe_mb;
 };
 
@@ -72,6 +65,5 @@  struct pci_doe_task {
 
 struct pci_doe_mb *pcim_doe_create_mb(struct pci_dev *pdev, u16 cap_offset);
 bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type);
-int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task);
-
+int pci_doe_submit_task_wait(struct pci_doe_mb *doe_mb, struct pci_doe_task *task);
 #endif