Merge tag 'driver-core-5.15-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core fixes from Greg KH:
 "Here are some driver core and kernfs fixes for reported issues for
  5.15-rc4. These fixes include:

   - kernfs positive dentry bugfix

   - debugfs_create_file_size error path fix

   - cpumask sysfs file bugfix to preserve the user/kernel abi (has been
     reported multiple times.)

   - devlink fixes for mdiobus devices as reported by the subsystem
     maintainers.

  Also included in here are some devlink debugging changes to make it
  easier for people to report problems when asked. They have already
  helped with the mdiobus and other subsystems reporting issues.

  All of these have been linux-next for a while with no reported issues"

* tag 'driver-core-5.15-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  kernfs: also call kernfs_set_rev() for positive dentry
  driver core: Add debug logs when fwnode links are added/deleted
  driver core: Create __fwnode_link_del() helper function
  driver core: Set deferred probe reason when deferred by driver core
  net: mdiobus: Set FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD for mdiobus parents
  driver core: fw_devlink: Add support for FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD
  driver core: fw_devlink: Improve handling of cyclic dependencies
  cpumask: Omit terminating null byte in cpumap_print_{list,bitmask}_to_buf
  debugfs: debugfs_create_file_size(): use IS_ERR to check for error

1 files changed, 63 insertions, 27 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index e65dd803a453..15986cc2fe5e 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -95,6 +95,8 @@ int fwnode_link_add(struct fwnode_handle *con, struct fwnode_handle *sup)
 
 	list_add(&link->s_hook, &sup->consumers);
 	list_add(&link->c_hook, &con->suppliers);
+	pr_debug("%pfwP Linked as a fwnode consumer to %pfwP\n",
+		 con, sup);
 out:
 	mutex_unlock(&fwnode_link_lock);
 
@@ -102,6 +104,21 @@ out:
 }
 
 /**
+ * __fwnode_link_del - Delete a link between two fwnode_handles.
+ * @link: the fwnode_link to be deleted
+ *
+ * The fwnode_link_lock needs to be held when this function is called.
+ */
+static void __fwnode_link_del(struct fwnode_link *link)
+{
+	pr_debug("%pfwP Dropping the fwnode link to %pfwP\n",
+		 link->consumer, link->supplier);
+	list_del(&link->s_hook);
+	list_del(&link->c_hook);
+	kfree(link);
+}
+
+/**
  * fwnode_links_purge_suppliers - Delete all supplier links of fwnode_handle.
  * @fwnode: fwnode whose supplier links need to be deleted
  *
@@ -112,11 +129,8 @@ static void fwnode_links_purge_suppliers(struct fwnode_handle *fwnode)
 	struct fwnode_link *link, *tmp;
 
 	mutex_lock(&fwnode_link_lock);
-	list_for_each_entry_safe(link, tmp, &fwnode->suppliers, c_hook) {
-		list_del(&link->s_hook);
-		list_del(&link->c_hook);
-		kfree(link);
-	}
+	list_for_each_entry_safe(link, tmp, &fwnode->suppliers, c_hook)
+		__fwnode_link_del(link);
 	mutex_unlock(&fwnode_link_lock);
 }
 
@@ -131,11 +145,8 @@ static void fwnode_links_purge_consumers(struct fwnode_handle *fwnode)
 	struct fwnode_link *link, *tmp;
 
 	mutex_lock(&fwnode_link_lock);
-	list_for_each_entry_safe(link, tmp, &fwnode->consumers, s_hook) {
-		list_del(&link->s_hook);
-		list_del(&link->c_hook);
-		kfree(link);
-	}
+	list_for_each_entry_safe(link, tmp, &fwnode->consumers, s_hook)
+		__fwnode_link_del(link);
 	mutex_unlock(&fwnode_link_lock);
 }
 
@@ -975,6 +986,7 @@ int device_links_check_suppliers(struct device *dev)
 {
 	struct device_link *link;
 	int ret = 0;
+	struct fwnode_handle *sup_fw;
 
 	/*
 	 * Device waiting for supplier to become available is not allowed to
@@ -983,10 +995,11 @@ int device_links_check_suppliers(struct device *dev)
 	mutex_lock(&fwnode_link_lock);
 	if (dev->fwnode && !list_empty(&dev->fwnode->suppliers) &&
 	    !fw_devlink_is_permissive()) {
-		dev_dbg(dev, "probe deferral - wait for supplier %pfwP\n",
-			list_first_entry(&dev->fwnode->suppliers,
-			struct fwnode_link,
-			c_hook)->supplier);
+		sup_fw = list_first_entry(&dev->fwnode->suppliers,
+					  struct fwnode_link,
+					  c_hook)->supplier;
+		dev_err_probe(dev, -EPROBE_DEFER, "wait for supplier %pfwP\n",
+			      sup_fw);
 		mutex_unlock(&fwnode_link_lock);
 		return -EPROBE_DEFER;
 	}
@@ -1001,8 +1014,9 @@ int device_links_check_suppliers(struct device *dev)
 		if (link->status != DL_STATE_AVAILABLE &&
 		    !(link->flags & DL_FLAG_SYNC_STATE_ONLY)) {
 			device_links_missing_supplier(dev);
-			dev_dbg(dev, "probe deferral - supplier %s not ready\n",
-				dev_name(link->supplier));
+			dev_err_probe(dev, -EPROBE_DEFER,
+				      "supplier %s not ready\n",
+				      dev_name(link->supplier));
 			ret = -EPROBE_DEFER;
 			break;
 		}
@@ -1722,6 +1736,25 @@ static int fw_devlink_create_devlink(struct device *con,
 	struct device *sup_dev;
 	int ret = 0;
 
+	/*
+	 * In some cases, a device P might also be a supplier to its child node
+	 * C. However, this would defer the probe of C until the probe of P
+	 * completes successfully. This is perfectly fine in the device driver
+	 * model. device_add() doesn't guarantee probe completion of the device
+	 * by the time it returns.
+	 *
+	 * However, there are a few drivers that assume C will finish probing
+	 * as soon as it's added and before P finishes probing. So, we provide
+	 * a flag to let fw_devlink know not to delay the probe of C until the
+	 * probe of P completes successfully.
+	 *
+	 * When such a flag is set, we can't create device links where P is the
+	 * supplier of C as that would delay the probe of C.
+	 */
+	if (sup_handle->flags & FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD &&
+	    fwnode_is_ancestor_of(sup_handle, con->fwnode))
+		return -EINVAL;
+
 	sup_dev = get_dev_from_fwnode(sup_handle);
 	if (sup_dev) {
 		/*
@@ -1772,14 +1805,21 @@ static int fw_devlink_create_devlink(struct device *con,
 	 * be broken by applying logic. Check for these types of cycles and
 	 * break them so that devices in the cycle probe properly.
 	 *
-	 * If the supplier's parent is dependent on the consumer, then
-	 * the consumer-supplier dependency is a false dependency. So,
-	 * treat it as an invalid link.
+	 * If the supplier's parent is dependent on the consumer, then the
+	 * consumer and supplier have a cyclic dependency. Since fw_devlink
+	 * can't tell which of the inferred dependencies are incorrect, don't
+	 * enforce probe ordering between any of the devices in this cyclic
+	 * dependency. Do this by relaxing all the fw_devlink device links in
+	 * this cycle and by treating the fwnode link between the consumer and
+	 * the supplier as an invalid dependency.
 	 */
 	sup_dev = fwnode_get_next_parent_dev(sup_handle);
 	if (sup_dev && device_is_dependent(con, sup_dev)) {
-		dev_dbg(con, "Not linking to %pfwP - False link\n",
-			sup_handle);
+		dev_info(con, "Fixing up cyclic dependency with %pfwP (%s)\n",
+			 sup_handle, dev_name(sup_dev));
+		device_links_write_lock();
+		fw_devlink_relax_cycle(con, sup_dev);
+		device_links_write_unlock();
 		ret = -EINVAL;
 	} else {
 		/*
@@ -1858,9 +1898,7 @@ static void __fw_devlink_link_to_consumers(struct device *dev)
 		if (!own_link || ret == -EAGAIN)
 			continue;
 
-		list_del(&link->s_hook);
-		list_del(&link->c_hook);
-		kfree(link);
+		__fwnode_link_del(link);
 	}
 }
 
@@ -1912,9 +1950,7 @@ static void __fw_devlink_link_to_suppliers(struct device *dev,
 		if (!own_link || ret == -EAGAIN)
 			continue;
 
-		list_del(&link->s_hook);
-		list_del(&link->c_hook);
-		kfree(link);
+		__fwnode_link_del(link);
 
 		/* If no device link was created, nothing more to do. */
 		if (ret)