staging: vchiq: Factor out bulk transfer for VCHIQ_BULK_MODE_WAITING

The bulk transfer is VCHIQ_BULK_MODE_WAITING is used by VCHIQ ioctl
interface. It is factored out to a separate function from
vchiq_bulk_transfer() to bulk_xfer_waiting_interruptible().

This is a part of vchiq_bulk_transfer refactoring. Each bulk mode
will have their dedicated functions to execute bulk transfers.
Each mode will be handled separately in subsequent patches.

bulk_xfer_waiting_interruptible() is suffixed with "_interruptible"
to denote that it can be interrupted when a signal is received.
-EAGAIN maybe returned in those cases, similar to what
vchiq_bulk_transfer() does.

Adjust the vchiq_irq_queue_bulk_tx_rx() in the vchiq-dev.c to call
bulk_xfer_waiting_interruptible() for waiting mode. A temporary
goto label has been introduced to jump the call execution over
vchiq_bulk_transfer() for waiting mode only. When all dedicated bulk
transfer calls are introduced, this label shall be dropped.

No function changes intended in this patch.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Tested-by: Stefan Wahren <wahrenst@gmx.net>
Link: https://lore.kernel.org/r/20240910051007.297227-2-umang.jain@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c

@@ -3023,10 +3023,6 @@ int vchiq_bulk_transfer(struct vchiq_instance *instance, unsigned int handle,
 		bulk_waiter->actual = 0;
 		bulk_waiter->bulk = NULL;
 		break;
-	case VCHIQ_BULK_MODE_WAITING:
-		bulk_waiter = userdata;
-		bulk = bulk_waiter->bulk;
-		goto waiting;
 	default:
 		goto error_exit;
 	}
@@ -3115,11 +3111,8 @@ int vchiq_bulk_transfer(struct vchiq_instance *instance, unsigned int handle,
 		state->id, service->localport, dir_char, queue->local_insert,
 		queue->remote_insert, queue->process);
 
-waiting:
 	vchiq_service_put(service);
 
-	status = 0;
-
 	if (bulk_waiter) {
 		bulk_waiter->bulk = bulk;
 		if (wait_for_completion_interruptible(&bulk_waiter->event))
@@ -3128,7 +3121,7 @@ int vchiq_bulk_transfer(struct vchiq_instance *instance, unsigned int handle,
 			status = -EINVAL;
 	}
 
-	return status;
+	return 0;
 
 unlock_both_error_exit:
 	mutex_unlock(&state->slot_mutex);
@@ -3143,6 +3136,50 @@ int vchiq_bulk_transfer(struct vchiq_instance *instance, unsigned int handle,
 	return status;
 }
 
+/*
+ * This function is called by VCHIQ ioctl interface and is interruptible.
+ * It may receive -EAGAIN to indicate that a signal has been received
+ * and the call should be retried after being returned to user context.
+ */
+int
+vchiq_bulk_xfer_waiting_interruptible(struct vchiq_instance *instance,
+				      unsigned int handle, struct bulk_waiter *userdata)
+{
+	struct vchiq_service *service = find_service_by_handle(instance, handle);
+	struct bulk_waiter *bulk_waiter;
+	int status = -EINVAL;
+
+	if (!service)
+		return -EINVAL;
+
+	if (!userdata)
+		goto error_exit;
+
+	if (service->srvstate != VCHIQ_SRVSTATE_OPEN)
+		goto error_exit;
+
+	if (vchiq_check_service(service))
+		goto error_exit;
+
+	bulk_waiter = userdata;
+
+	vchiq_service_put(service);
+
+	status = 0;
+
+	if (wait_for_completion_interruptible(&bulk_waiter->event))
+		return -EAGAIN;
+	else if (bulk_waiter->actual == VCHIQ_BULK_ACTUAL_ABORTED)
+		return -EINVAL;
+
+	return status;
+
+error_exit:
+	vchiq_service_put(service);
+
+	return status;
+}
+
 int
 vchiq_queue_message(struct vchiq_instance *instance, unsigned int handle,
 		    ssize_t (*copy_callback)(void *context, void *dest,

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.h

@@ -470,6 +470,10 @@ vchiq_shutdown_internal(struct vchiq_state *state, struct vchiq_instance *instan
 extern void
 remote_event_pollall(struct vchiq_state *state);
 
+extern int
+vchiq_bulk_xfer_waiting_interruptible(struct vchiq_instance *instance,
+				      unsigned int handle, struct bulk_waiter *userdata);
+
 extern int
 vchiq_bulk_transfer(struct vchiq_instance *instance, unsigned int handle, void *offset,
 		    void __user *uoffset, int size, void *userdata, enum vchiq_bulk_mode mode,

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_dev.c

@@ -324,6 +324,10 @@ static int vchiq_irq_queue_bulk_tx_rx(struct vchiq_instance *instance,
 		dev_dbg(service->state->dev, "arm: found bulk_waiter %pK for pid %d\n",
 			waiter, current->pid);
 		userdata = &waiter->bulk_waiter;
+
+		status = vchiq_bulk_xfer_waiting_interruptible(instance, args->handle, userdata);
+
+		goto bulk_transfer_handled;
 	} else {
 		userdata = args->userdata;
 	}
@@ -331,6 +335,7 @@ static int vchiq_irq_queue_bulk_tx_rx(struct vchiq_instance *instance,
 	status = vchiq_bulk_transfer(instance, args->handle, NULL, args->data, args->size,
 				     userdata, args->mode, dir);
 
+bulk_transfer_handled:
 	if (!waiter) {
 		ret = 0;
 		goto out;