cxl/port: Use __free() to drop put_device() for cxl_port

Using scope-based resource management __free() marco with a new helper
called put_cxl_port() to drop open coded the put_device() used to
dereference the 'struct device' in cxl_port.
Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Li Ming <ming4.li@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://patch.msgid.link/20240830013138.2256244-1-ming4.li@intel.comSigned-off-by: Dave Jiang <dave.jiang@intel.com>

drivers/cxl/core/pci.c

@@ -915,15 +915,13 @@ static void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds)
 	struct pci_dev *pdev = to_pci_dev(cxlds->dev);
 	struct aer_capability_regs aer_regs;
 	struct cxl_dport *dport;
-	struct cxl_port *port;
 	int severity;
 
-	port = cxl_pci_find_port(pdev, &dport);
+	struct cxl_port *port __free(put_cxl_port) =
+		cxl_pci_find_port(pdev, &dport);
 	if (!port)
 		return;
 
-	put_device(&port->dev);
-
 	if (!cxl_rch_get_aer_info(dport->regs.dport_aer, &aer_regs))
 		return;
 

drivers/cxl/core/port.c

@@ -1477,12 +1477,11 @@ static void cxl_detach_ep(void *data)
 			.cxlmd = cxlmd,
 			.depth = i,
 		};
-		struct device *dev;
 		struct cxl_ep *ep;
 		bool died = false;
 
-		dev = bus_find_device(&cxl_bus_type, NULL, &ctx,
-				      port_has_memdev);
+		struct device *dev __free(put_device) =
+			bus_find_device(&cxl_bus_type, NULL, &ctx, port_has_memdev);
 		if (!dev)
 			continue;
 		port = to_cxl_port(dev);
@@ -1512,7 +1511,6 @@ static void cxl_detach_ep(void *data)
 				dev_name(&port->dev));
 			delete_switch_port(port);
 		}
-		put_device(&port->dev);
 		device_unlock(&parent_port->dev);
 	}
 }
@@ -1540,7 +1538,6 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
 			      struct device *dport_dev)
 {
 	struct device *dparent = grandparent(dport_dev);
-	struct cxl_port *port, *parent_port = NULL;
 	struct cxl_dport *dport, *parent_dport;
 	resource_size_t component_reg_phys;
 	int rc;
@@ -1556,12 +1553,18 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
 		return -ENXIO;
 	}
 
-	parent_port = find_cxl_port(dparent, &parent_dport);
+	struct cxl_port *parent_port __free(put_cxl_port) =
+		find_cxl_port(dparent, &parent_dport);
 	if (!parent_port) {
 		/* iterate to create this parent_port */
 		return -EAGAIN;
 	}
 
+	/*
+	 * Definition with __free() here to keep the sequence of
+	 * dereferencing the device of the port before the parent_port releasing.
+	 */
+	struct cxl_port *port __free(put_cxl_port) = NULL;
 	device_lock(&parent_port->dev);
 	if (!parent_port->dev.driver) {
 		dev_warn(&cxlmd->dev,
@@ -1596,10 +1599,8 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
 			 */
 			rc = -ENXIO;
 		}
-		put_device(&port->dev);
 	}
 
-	put_device(&parent_port->dev);
 	return rc;
 }
 
@@ -1630,7 +1631,6 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
 		struct device *dport_dev = grandparent(iter);
 		struct device *uport_dev;
 		struct cxl_dport *dport;
-		struct cxl_port *port;
 
 		/*
 		 * The terminal "grandparent" in PCI is NULL and @platform_bus
@@ -1649,7 +1649,8 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
 		dev_dbg(dev, "scan: iter: %s dport_dev: %s parent: %s\n",
 			dev_name(iter), dev_name(dport_dev),
 			dev_name(uport_dev));
-		port = find_cxl_port(dport_dev, &dport);
+		struct cxl_port *port __free(put_cxl_port) =
+			find_cxl_port(dport_dev, &dport);
 		if (port) {
 			dev_dbg(&cxlmd->dev,
 				"found already registered port %s:%s\n",
@@ -1664,18 +1665,13 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
 			 * the parent_port lock as the current port may be being
 			 * reaped.
 			 */
-			if (rc && rc != -EBUSY) {
-				put_device(&port->dev);
+			if (rc && rc != -EBUSY)
 				return rc;
-			}
 
 			/* Any more ports to add between this one and the root? */
-			if (!dev_is_cxl_root_child(&port->dev)) {
-				put_device(&port->dev);
+			if (!dev_is_cxl_root_child(&port->dev))
 				continue;
-			}
 
-			put_device(&port->dev);
 			return 0;
 		}
 

drivers/cxl/cxl.h

@@ -744,6 +744,7 @@ struct cxl_root *find_cxl_root(struct cxl_port *port);
 void put_cxl_root(struct cxl_root *cxl_root);
 DEFINE_FREE(put_cxl_root, struct cxl_root *, if (_T) put_cxl_root(_T))
 
+DEFINE_FREE(put_cxl_port, struct cxl_port *, if (!IS_ERR_OR_NULL(_T)) put_device(&_T->dev))
 int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd);
 void cxl_bus_rescan(void);
 void cxl_bus_drain(void);

drivers/cxl/mem.c

@@ -109,7 +109,6 @@ static int cxl_mem_probe(struct device *dev)
 	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
 	struct cxl_dev_state *cxlds = cxlmd->cxlds;
 	struct device *endpoint_parent;
-	struct cxl_port *parent_port;
 	struct cxl_dport *dport;
 	struct dentry *dentry;
 	int rc;
@@ -146,7 +145,8 @@ static int cxl_mem_probe(struct device *dev)
 	if (rc)
 		return rc;
 
-	parent_port = cxl_mem_find_port(cxlmd, &dport);
+	struct cxl_port *parent_port __free(put_cxl_port) =
+		cxl_mem_find_port(cxlmd, &dport);
 	if (!parent_port) {
 		dev_err(dev, "CXL port topology not found\n");
 		return -ENXIO;
@@ -179,7 +179,6 @@ static int cxl_mem_probe(struct device *dev)
 	rc = devm_cxl_add_endpoint(endpoint_parent, cxlmd, dport);
 unlock:
 	device_unlock(endpoint_parent);
-	put_device(&parent_port->dev);
 	if (rc)
 		return rc;
 

drivers/cxl/pci.c

@@ -473,7 +473,6 @@ static bool is_cxl_restricted(struct pci_dev *pdev)
 static int cxl_rcrb_get_comp_regs(struct pci_dev *pdev,
 				  struct cxl_register_map *map)
 {
-	struct cxl_port *port;
 	struct cxl_dport *dport;
 	resource_size_t component_reg_phys;
 
@@ -482,14 +481,12 @@ static int cxl_rcrb_get_comp_regs(struct pci_dev *pdev,
 		.resource = CXL_RESOURCE_NONE,
 	};
 
-	port = cxl_pci_find_port(pdev, &dport);
+	struct cxl_port *port __free(put_cxl_port) =
+		cxl_pci_find_port(pdev, &dport);
 	if (!port)
 		return -EPROBE_DEFER;
 
 	component_reg_phys = cxl_rcd_component_reg_phys(&pdev->dev, dport);
-
-	put_device(&port->dev);
-
 	if (component_reg_phys == CXL_RESOURCE_NONE)
 		return -ENXIO;