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Revert "driver core: Add support for linking devices during device addition"

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This reverts commit 5302dd7dd0.

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 <frowand.list@gmail.com>
Cc: Saravana Kannan <saravanak@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kroah-Hartman 2019-08-27 21:41:16 +02:00
parent 33cbfe5449
commit bfb3943bed
2 changed files with 0 additions and 97 deletions
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83
drivers/base/core.c
View File

@ -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,

14
include/linux/device.h
View File

@ -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;
};