From bfb3943bed670a0655aa2f9dcf82222ff09d6dd1 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Tue, 27 Aug 2019 21:41:16 +0200 Subject: [PATCH] Revert "driver core: Add support for linking devices during device addition" This reverts commit 5302dd7dd0b6d04c63cdce51d1e9fda9ef0be886. Based on a lot of email and in-person discussions, this patch series is being reworked to address a number of issues that were pointed out that needed to be taken care of before it should be merged. It will be resubmitted with those changes hopefully soon. Cc: Frank Rowand Cc: Saravana Kannan Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 83 ------------------------------------------ include/linux/device.h | 14 ------- 2 files changed, 97 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 605905de0ccaa..066badad988c3 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -44,8 +44,6 @@ early_param("sysfs.deprecated", sysfs_deprecated_setup); #endif /* Device links support. */ -static LIST_HEAD(wait_for_suppliers); -static DEFINE_MUTEX(wfs_lock); #ifdef CONFIG_SRCU static DEFINE_MUTEX(device_links_lock); @@ -420,51 +418,6 @@ struct device_link *device_link_add(struct device *consumer, } EXPORT_SYMBOL_GPL(device_link_add); -/** - * device_link_wait_for_supplier - Mark device as waiting for supplier - * @consumer: Consumer device - * - * Marks the consumer device as waiting for suppliers to become available. The - * consumer device will never be probed until it's unmarked as waiting for - * suppliers. The caller is responsible for adding the link to the supplier - * once the supplier device is present. - * - * This function is NOT meant to be called from the probe function of the - * consumer but rather from code that creates/adds the consumer device. - */ -static void device_link_wait_for_supplier(struct device *consumer) -{ - mutex_lock(&wfs_lock); - list_add_tail(&consumer->links.needs_suppliers, &wait_for_suppliers); - mutex_unlock(&wfs_lock); -} - -/** - * device_link_check_waiting_consumers - Try to unmark waiting consumers - * - * Loops through all consumers waiting on suppliers and tries to add all their - * supplier links. If that succeeds, the consumer device is unmarked as waiting - * for suppliers. Otherwise, they are left marked as waiting on suppliers, - * - * The add_links bus callback is expected to return 0 if it has found and added - * all the supplier links for the consumer device. It should return an error if - * it isn't able to do so. - * - * The caller of device_link_wait_for_supplier() is expected to call this once - * it's aware of potential suppliers becoming available. - */ -static void device_link_check_waiting_consumers(void) -{ - struct device *dev, *tmp; - - mutex_lock(&wfs_lock); - list_for_each_entry_safe(dev, tmp, &wait_for_suppliers, - links.needs_suppliers) - if (!dev->bus->add_links(dev)) - list_del_init(&dev->links.needs_suppliers); - mutex_unlock(&wfs_lock); -} - static void device_link_free(struct device_link *link) { while (refcount_dec_not_one(&link->rpm_active)) @@ -599,19 +552,6 @@ int device_links_check_suppliers(struct device *dev) struct device_link *link; int ret = 0; - /* - * If a device is waiting for one or more suppliers (in - * wait_for_suppliers list), it is not ready to probe yet. So just - * return -EPROBE_DEFER without having to check the links with existing - * suppliers. - */ - mutex_lock(&wfs_lock); - if (!list_empty(&dev->links.needs_suppliers)) { - mutex_unlock(&wfs_lock); - return -EPROBE_DEFER; - } - mutex_unlock(&wfs_lock); - device_links_write_lock(); list_for_each_entry(link, &dev->links.suppliers, c_node) { @@ -896,10 +836,6 @@ static void device_links_purge(struct device *dev) { struct device_link *link, *ln; - mutex_lock(&wfs_lock); - list_del(&dev->links.needs_suppliers); - mutex_unlock(&wfs_lock); - /* * Delete all of the remaining links from this device to any other * devices (either consumers or suppliers). @@ -1764,7 +1700,6 @@ void device_initialize(struct device *dev) #endif INIT_LIST_HEAD(&dev->links.consumers); INIT_LIST_HEAD(&dev->links.suppliers); - INIT_LIST_HEAD(&dev->links.needs_suppliers); dev->links.status = DL_DEV_NO_DRIVER; } EXPORT_SYMBOL_GPL(device_initialize); @@ -2251,24 +2186,6 @@ int device_add(struct device *dev) BUS_NOTIFY_ADD_DEVICE, dev); kobject_uevent(&dev->kobj, KOBJ_ADD); - - /* - * Check if any of the other devices (consumers) have been waiting for - * this device (supplier) to be added so that they can create a device - * link to it. - * - * This needs to happen after device_pm_add() because device_link_add() - * requires the supplier be registered before it's called. - * - * But this also needs to happe before bus_probe_device() to make sure - * waiting consumers can link to it before the driver is bound to the - * device and the driver sync_state callback is called for this device. - */ - device_link_check_waiting_consumers(); - - if (dev->bus && dev->bus->add_links && dev->bus->add_links(dev)) - device_link_wait_for_supplier(dev); - bus_probe_device(dev); if (parent) klist_add_tail(&dev->p->knode_parent, diff --git a/include/linux/device.h b/include/linux/device.h index 73210745cc6b3..ec598ede94553 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -78,17 +78,6 @@ extern void bus_remove_file(struct bus_type *, struct bus_attribute *); * -EPROBE_DEFER it will queue the device for deferred probing. * @uevent: Called when a device is added, removed, or a few other things * that generate uevents to add the environment variables. - * @add_links: Called, perhaps multiple times per device, after a device is - * added to this bus. The function is expected to create device - * links to all the suppliers of the input device that are - * available at the time this function is called. As in, the - * function should NOT stop at the first failed device link if - * other unlinked supplier devices are present in the system. - * - * Return 0 if device links have been successfully created to all - * the suppliers of this device. Return an error if some of the - * suppliers are not yet available and this function needs to be - * reattempted in the future. * @probe: Called when a new device or driver add to this bus, and callback * the specific driver's probe to initial the matched device. * @remove: Called when a device removed from this bus. @@ -133,7 +122,6 @@ struct bus_type { int (*match)(struct device *dev, struct device_driver *drv); int (*uevent)(struct device *dev, struct kobj_uevent_env *env); - int (*add_links)(struct device *dev); int (*probe)(struct device *dev); int (*remove)(struct device *dev); void (*shutdown)(struct device *dev); @@ -1143,13 +1131,11 @@ enum dl_dev_state { * struct dev_links_info - Device data related to device links. * @suppliers: List of links to supplier devices. * @consumers: List of links to consumer devices. - * @needs_suppliers: Hook to global list of devices waiting for suppliers. * @status: Driver status information. */ struct dev_links_info { struct list_head suppliers; struct list_head consumers; - struct list_head needs_suppliers; enum dl_dev_state status; }; -- 2.30.2