1 files changed, 201 insertions, 45 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 0073b09bb99f..4aeaa0c92bda 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -179,10 +179,31 @@ void device_pm_move_to_tail(struct device *dev)
  * of the link.  If DL_FLAG_PM_RUNTIME is not set, DL_FLAG_RPM_ACTIVE will be
  * ignored.
  *
- * If the DL_FLAG_AUTOREMOVE_CONSUMER is set, the link will be removed
- * automatically when the consumer device driver unbinds from it.
- * The combination of both DL_FLAG_AUTOREMOVE_CONSUMER and DL_FLAG_STATELESS
- * set is invalid and will cause NULL to be returned.
+ * If DL_FLAG_STATELESS is set in @flags, the link is not going to be managed by
+ * the driver core and, in particular, the caller of this function is expected
+ * to drop the reference to the link acquired by it directly.
+ *
+ * If that flag is not set, however, the caller of this function is handing the
+ * management of the link over to the driver core entirely and its return value
+ * can only be used to check whether or not the link is present.  In that case,
+ * the DL_FLAG_AUTOREMOVE_CONSUMER and DL_FLAG_AUTOREMOVE_SUPPLIER device link
+ * flags can be used to indicate to the driver core when the link can be safely
+ * deleted.  Namely, setting one of them in @flags indicates to the driver core
+ * that the link is not going to be used (by the given caller of this function)
+ * after unbinding the consumer or supplier driver, respectively, from its
+ * device, so the link can be deleted at that point.  If none of them is set,
+ * the link will be maintained until one of the devices pointed to by it (either
+ * the consumer or the supplier) is unregistered.
+ *
+ * Also, if DL_FLAG_STATELESS, DL_FLAG_AUTOREMOVE_CONSUMER and
+ * DL_FLAG_AUTOREMOVE_SUPPLIER are not set in @flags (that is, a persistent
+ * managed device link is being added), the DL_FLAG_AUTOPROBE_CONSUMER flag can
+ * be used to request the driver core to automaticall probe for a consmer
+ * driver after successfully binding a driver to the supplier device.
+ *
+ * The combination of DL_FLAG_STATELESS and either DL_FLAG_AUTOREMOVE_CONSUMER
+ * or DL_FLAG_AUTOREMOVE_SUPPLIER set in @flags at the same time is invalid and
+ * will cause NULL to be returned upfront.
  *
  * A side effect of the link creation is re-ordering of dpm_list and the
  * devices_kset list by moving the consumer device and all devices depending
@@ -199,10 +220,22 @@ struct device_link *device_link_add(struct device *consumer,
 	struct device_link *link;
 
 	if (!consumer || !supplier ||
-	    ((flags & DL_FLAG_STATELESS) &&
-	     (flags & DL_FLAG_AUTOREMOVE_CONSUMER)))
+	    (flags & DL_FLAG_STATELESS &&
+	     flags & (DL_FLAG_AUTOREMOVE_CONSUMER |
+		      DL_FLAG_AUTOREMOVE_SUPPLIER |
+		      DL_FLAG_AUTOPROBE_CONSUMER)) ||
+	    (flags & DL_FLAG_AUTOPROBE_CONSUMER &&
+	     flags & (DL_FLAG_AUTOREMOVE_CONSUMER |
+		      DL_FLAG_AUTOREMOVE_SUPPLIER)))
 		return NULL;
 
+	if (flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) {
+		if (pm_runtime_get_sync(supplier) < 0) {
+			pm_runtime_put_noidle(supplier);
+			return NULL;
+		}
+	}
+
 	device_links_write_lock();
 	device_pm_lock();
 
@@ -217,35 +250,71 @@ struct device_link *device_link_add(struct device *consumer,
 		goto out;
 	}
 
-	list_for_each_entry(link, &supplier->links.consumers, s_node)
-		if (link->consumer == consumer) {
+	/*
+	 * DL_FLAG_AUTOREMOVE_SUPPLIER indicates that the link will be needed
+	 * longer than for DL_FLAG_AUTOREMOVE_CONSUMER and setting them both
+	 * together doesn't make sense, so prefer DL_FLAG_AUTOREMOVE_SUPPLIER.
+	 */
+	if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
+		flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
+
+	list_for_each_entry(link, &supplier->links.consumers, s_node) {
+		if (link->consumer != consumer)
+			continue;
+
+		/*
+		 * Don't return a stateless link if the caller wants a stateful
+		 * one and vice versa.
+		 */
+		if (WARN_ON((flags & DL_FLAG_STATELESS) != (link->flags & DL_FLAG_STATELESS))) {
+			link = NULL;
+			goto out;
+		}
+
+		if (flags & DL_FLAG_PM_RUNTIME) {
+			if (!(link->flags & DL_FLAG_PM_RUNTIME)) {
+				pm_runtime_new_link(consumer);
+				link->flags |= DL_FLAG_PM_RUNTIME;
+			}
+			if (flags & DL_FLAG_RPM_ACTIVE)
+				refcount_inc(&link->rpm_active);
+		}
+
+		if (flags & DL_FLAG_STATELESS) {
 			kref_get(&link->kref);
 			goto out;
 		}
 
+		/*
+		 * If the life time of the link following from the new flags is
+		 * longer than indicated by the flags of the existing link,
+		 * update the existing link to stay around longer.
+		 */
+		if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER) {
+			if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
+				link->flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
+				link->flags |= DL_FLAG_AUTOREMOVE_SUPPLIER;
+			}
+		} else if (!(flags & DL_FLAG_AUTOREMOVE_CONSUMER)) {
+			link->flags &= ~(DL_FLAG_AUTOREMOVE_CONSUMER |
+					 DL_FLAG_AUTOREMOVE_SUPPLIER);
+		}
+		goto out;
+	}
+
 	link = kzalloc(sizeof(*link), GFP_KERNEL);
 	if (!link)
 		goto out;
 
+	refcount_set(&link->rpm_active, 1);
+
 	if (flags & DL_FLAG_PM_RUNTIME) {
-		if (flags & DL_FLAG_RPM_ACTIVE) {
-			if (pm_runtime_get_sync(supplier) < 0) {
-				pm_runtime_put_noidle(supplier);
-				kfree(link);
-				link = NULL;
-				goto out;
-			}
-			link->rpm_active = true;
-		}
+		if (flags & DL_FLAG_RPM_ACTIVE)
+			refcount_inc(&link->rpm_active);
+
 		pm_runtime_new_link(consumer);
-		/*
-		 * If the link is being added by the consumer driver at probe
-		 * time, balance the decrementation of the supplier's runtime PM
-		 * usage counter after consumer probe in driver_probe_device().
-		 */
-		if (consumer->links.status == DL_DEV_PROBING)
-			pm_runtime_get_noresume(supplier);
 	}
+
 	get_device(supplier);
 	link->supplier = supplier;
 	INIT_LIST_HEAD(&link->s_node);
@@ -260,17 +329,26 @@ struct device_link *device_link_add(struct device *consumer,
 		link->status = DL_STATE_NONE;
 	} else {
 		switch (supplier->links.status) {
-		case DL_DEV_DRIVER_BOUND:
+		case DL_DEV_PROBING:
 			switch (consumer->links.status) {
 			case DL_DEV_PROBING:
 				/*
-				 * Some callers expect the link creation during
-				 * consumer driver probe to resume the supplier
-				 * even without DL_FLAG_RPM_ACTIVE.
+				 * A consumer driver can create a link to a
+				 * supplier that has not completed its probing
+				 * yet as long as it knows that the supplier is
+				 * already functional (for example, it has just
+				 * acquired some resources from the supplier).
 				 */
-				if (flags & DL_FLAG_PM_RUNTIME)
-					pm_runtime_resume(supplier);
-
+				link->status = DL_STATE_CONSUMER_PROBE;
+				break;
+			default:
+				link->status = DL_STATE_DORMANT;
+				break;
+			}
+			break;
+		case DL_DEV_DRIVER_BOUND:
+			switch (consumer->links.status) {
+			case DL_DEV_PROBING:
 				link->status = DL_STATE_CONSUMER_PROBE;
 				break;
 			case DL_DEV_DRIVER_BOUND:
@@ -291,6 +369,14 @@ struct device_link *device_link_add(struct device *consumer,
 	}
 
 	/*
+	 * Some callers expect the link creation during consumer driver probe to
+	 * resume the supplier even without DL_FLAG_RPM_ACTIVE.
+	 */
+	if (link->status == DL_STATE_CONSUMER_PROBE &&
+	    flags & DL_FLAG_PM_RUNTIME)
+		pm_runtime_resume(supplier);
+
+	/*
 	 * Move the consumer and all of the devices depending on it to the end
 	 * of dpm_list and the devices_kset list.
 	 *
@@ -302,17 +388,24 @@ struct device_link *device_link_add(struct device *consumer,
 	list_add_tail_rcu(&link->s_node, &supplier->links.consumers);
 	list_add_tail_rcu(&link->c_node, &consumer->links.suppliers);
 
-	dev_info(consumer, "Linked as a consumer to %s\n", dev_name(supplier));
+	dev_dbg(consumer, "Linked as a consumer to %s\n", dev_name(supplier));
 
  out:
 	device_pm_unlock();
 	device_links_write_unlock();
+
+	if ((flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) && !link)
+		pm_runtime_put(supplier);
+
 	return link;
 }
 EXPORT_SYMBOL_GPL(device_link_add);
 
 static void device_link_free(struct device_link *link)
 {
+	while (refcount_dec_not_one(&link->rpm_active))
+		pm_runtime_put(link->supplier);
+
 	put_device(link->consumer);
 	put_device(link->supplier);
 	kfree(link);
@@ -328,8 +421,8 @@ static void __device_link_del(struct kref *kref)
 {
 	struct device_link *link = container_of(kref, struct device_link, kref);
 
-	dev_info(link->consumer, "Dropping the link to %s\n",
-		 dev_name(link->supplier));
+	dev_dbg(link->consumer, "Dropping the link to %s\n",
+		dev_name(link->supplier));
 
 	if (link->flags & DL_FLAG_PM_RUNTIME)
 		pm_runtime_drop_link(link->consumer);
@@ -355,8 +448,16 @@ static void __device_link_del(struct kref *kref)
 }
 #endif /* !CONFIG_SRCU */
 
+static void device_link_put_kref(struct device_link *link)
+{
+	if (link->flags & DL_FLAG_STATELESS)
+		kref_put(&link->kref, __device_link_del);
+	else
+		WARN(1, "Unable to drop a managed device link reference\n");
+}
+
 /**
- * device_link_del - Delete a link between two devices.
+ * device_link_del - Delete a stateless link between two devices.
  * @link: Device link to delete.
  *
  * The caller must ensure proper synchronization of this function with runtime
@@ -368,14 +469,14 @@ void device_link_del(struct device_link *link)
 {
 	device_links_write_lock();
 	device_pm_lock();
-	kref_put(&link->kref, __device_link_del);
+	device_link_put_kref(link);
 	device_pm_unlock();
 	device_links_write_unlock();
 }
 EXPORT_SYMBOL_GPL(device_link_del);
 
 /**
- * device_link_remove - remove a link between two devices.
+ * device_link_remove - Delete a stateless link between two devices.
  * @consumer: Consumer end of the link.
  * @supplier: Supplier end of the link.
  *
@@ -394,7 +495,7 @@ void device_link_remove(void *consumer, struct device *supplier)
 
 	list_for_each_entry(link, &supplier->links.consumers, s_node) {
 		if (link->consumer == consumer) {
-			kref_put(&link->kref, __device_link_del);
+			device_link_put_kref(link);
 			break;
 		}
 	}
@@ -474,8 +575,21 @@ void device_links_driver_bound(struct device *dev)
 		if (link->flags & DL_FLAG_STATELESS)
 			continue;
 
+		/*
+		 * Links created during consumer probe may be in the "consumer
+		 * probe" state to start with if the supplier is still probing
+		 * when they are created and they may become "active" if the
+		 * consumer probe returns first.  Skip them here.
+		 */
+		if (link->status == DL_STATE_CONSUMER_PROBE ||
+		    link->status == DL_STATE_ACTIVE)
+			continue;
+
 		WARN_ON(link->status != DL_STATE_DORMANT);
 		WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
+
+		if (link->flags & DL_FLAG_AUTOPROBE_CONSUMER)
+			driver_deferred_probe_add(link->consumer);
 	}
 
 	list_for_each_entry(link, &dev->links.suppliers, c_node) {
@@ -512,18 +626,49 @@ static void __device_links_no_driver(struct device *dev)
 			continue;
 
 		if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER)
-			kref_put(&link->kref, __device_link_del);
-		else if (link->status != DL_STATE_SUPPLIER_UNBIND)
+			__device_link_del(&link->kref);
+		else if (link->status == DL_STATE_CONSUMER_PROBE ||
+			 link->status == DL_STATE_ACTIVE)
 			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
 	}
 
 	dev->links.status = DL_DEV_NO_DRIVER;
 }
 
+/**
+ * device_links_no_driver - Update links after failing driver probe.
+ * @dev: Device whose driver has just failed to probe.
+ *
+ * Clean up leftover links to consumers for @dev and invoke
+ * %__device_links_no_driver() to update links to suppliers for it as
+ * appropriate.
+ *
+ * Links with the DL_FLAG_STATELESS flag set are ignored.
+ */
 void device_links_no_driver(struct device *dev)
 {
+	struct device_link *link;
+
 	device_links_write_lock();
+
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		if (link->flags & DL_FLAG_STATELESS)
+			continue;
+
+		/*
+		 * The probe has failed, so if the status of the link is
+		 * "consumer probe" or "active", it must have been added by
+		 * a probing consumer while this device was still probing.
+		 * Change its state to "dormant", as it represents a valid
+		 * relationship, but it is not functionally meaningful.
+		 */
+		if (link->status == DL_STATE_CONSUMER_PROBE ||
+		    link->status == DL_STATE_ACTIVE)
+			WRITE_ONCE(link->status, DL_STATE_DORMANT);
+	}
+
 	__device_links_no_driver(dev);
+
 	device_links_write_unlock();
 }
 
@@ -539,11 +684,11 @@ void device_links_no_driver(struct device *dev)
  */
 void device_links_driver_cleanup(struct device *dev)
 {
-	struct device_link *link;
+	struct device_link *link, *ln;
 
 	device_links_write_lock();
 
-	list_for_each_entry(link, &dev->links.consumers, s_node) {
+	list_for_each_entry_safe(link, ln, &dev->links.consumers, s_node) {
 		if (link->flags & DL_FLAG_STATELESS)
 			continue;
 
@@ -557,7 +702,7 @@ void device_links_driver_cleanup(struct device *dev)
 		 */
 		if (link->status == DL_STATE_SUPPLIER_UNBIND &&
 		    link->flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
-			kref_put(&link->kref, __device_link_del);
+			__device_link_del(&link->kref);
 
 		WRITE_ONCE(link->status, DL_STATE_DORMANT);
 	}
@@ -1966,7 +2111,7 @@ int device_add(struct device *dev)
 	if (dev->class) {
 		mutex_lock(&dev->class->p->mutex);
 		/* tie the class to the device */
-		klist_add_tail(&dev->knode_class,
+		klist_add_tail(&dev->p->knode_class,
 			       &dev->class->p->klist_devices);
 
 		/* notify any interfaces that the device is here */
@@ -2080,6 +2225,17 @@ void device_del(struct device *dev)
 	struct kobject *glue_dir = NULL;
 	struct class_interface *class_intf;
 
+	/*
+	 * Hold the device lock and set the "dead" flag to guarantee that
+	 * the update behavior is consistent with the other bitfields near
+	 * it and that we cannot have an asynchronous probe routine trying
+	 * to run while we are tearing out the bus/class/sysfs from
+	 * underneath the device.
+	 */
+	device_lock(dev);
+	dev->p->dead = true;
+	device_unlock(dev);
+
 	/* Notify clients of device removal.  This call must come
 	 * before dpm_sysfs_remove().
 	 */
@@ -2105,7 +2261,7 @@ void device_del(struct device *dev)
 			if (class_intf->remove_dev)
 				class_intf->remove_dev(dev, class_intf);
 		/* remove the device from the class list */
-		klist_del(&dev->knode_class);
+		klist_del(&dev->p->knode_class);
 		mutex_unlock(&dev->class->p->mutex);
 	}
 	device_remove_file(dev, &dev_attr_uevent);