PCI/sysfs: Convert "reset" to static attribute

The "reset" sysfs attribute allows for resetting a PCI function.
Previously it was dynamically created either by pci_bus_add_device() or
the pci_sysfs_init() initcall, but since it doesn't need to be created or
removed dynamically, we can use a static attribute so the device model
takes care of addition and removal automatically.

Convert "reset" to a static attribute and use the .is_visible() callback to
check whether the device supports reset.

Clear reset_fn in pci_stop_dev() instead of pci_remove_capabilities_sysfs()
since we no longer explicitly remove the "reset" sysfs file.

[bhelgaas: commit log]
Suggested-by: Oliver O'Halloran <oohall@gmail.com>
Link: https://lore.kernel.org/r/20210416205856.3234481-4-kw@linux.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

2 files changed, 26 insertions, 27 deletions

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index fa8373685140..c469d9cad0a8 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1355,25 +1355,33 @@ static ssize_t reset_store(struct device *dev, struct device_attribute *attr,
 
 	return count;
 }
+static DEVICE_ATTR_WO(reset);
 
-static DEVICE_ATTR(reset, 0200, NULL, reset_store);
+static struct attribute *pci_dev_reset_attrs[] = {
+	&dev_attr_reset.attr,
+	NULL,
+};
 
-static int pci_create_capabilities_sysfs(struct pci_dev *dev)
+static umode_t pci_dev_reset_attr_is_visible(struct kobject *kobj,
+					     struct attribute *a, int n)
 {
-	int retval;
+	struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj));
 
-	pcie_vpd_create_sysfs_dev_files(dev);
+	if (!pdev->reset_fn)
+		return 0;
 
-	if (dev->reset_fn) {
-		retval = device_create_file(&dev->dev, &dev_attr_reset);
-		if (retval)
-			goto error;
-	}
-	return 0;
+	return a->mode;
+}
 
-error:
-	pcie_vpd_remove_sysfs_dev_files(dev);
-	return retval;
+static const struct attribute_group pci_dev_reset_attr_group = {
+	.attrs = pci_dev_reset_attrs,
+	.is_visible = pci_dev_reset_attr_is_visible,
+};
+
+
+static void pci_create_capabilities_sysfs(struct pci_dev *dev)
+{
+	pcie_vpd_create_sysfs_dev_files(dev);
 }
 
 int __must_check pci_create_sysfs_dev_files(struct pci_dev *pdev)
@@ -1385,30 +1393,18 @@ int __must_check pci_create_sysfs_dev_files(struct pci_dev *pdev)
 
 	retval = pci_create_resource_files(pdev);
 	if (retval)
-		goto err;
+		return retval;
 
 	/* add sysfs entries for various capabilities */
-	retval = pci_create_capabilities_sysfs(pdev);
-	if (retval)
-		goto err_resource_files;
-
+	pci_create_capabilities_sysfs(pdev);
 	pci_create_firmware_label_files(pdev);
 
 	return 0;
-
-err_resource_files:
-	pci_remove_resource_files(pdev);
-err:
-	return retval;
 }
 
 static void pci_remove_capabilities_sysfs(struct pci_dev *dev)
 {
 	pcie_vpd_remove_sysfs_dev_files(dev);
-	if (dev->reset_fn) {
-		device_remove_file(&dev->dev, &dev_attr_reset);
-		dev->reset_fn = 0;
-	}
 }
 
 /**
@@ -1517,6 +1513,7 @@ const struct attribute_group *pci_dev_groups[] = {
 	&pci_dev_group,
 	&pci_dev_config_attr_group,
 	&pci_dev_rom_attr_group,
+	&pci_dev_reset_attr_group,
 	NULL,
 };
 
diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index 95dec03d9f2a..dd12c2fcc7dc 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -19,6 +19,8 @@ static void pci_stop_dev(struct pci_dev *dev)
 	pci_pme_active(dev, false);
 
 	if (pci_dev_is_added(dev)) {
+		dev->reset_fn = 0;
+
 		device_release_driver(&dev->dev);
 		pci_proc_detach_device(dev);
 		pci_remove_sysfs_dev_files(dev);