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Merge tag 'driver-core-5.1-rc1' of git://git.kernel.org/pub/scm/linux…
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…/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the big driver core patchset for 5.1-rc1

  More patches than "normal" here this merge window, due to some work in
  the driver core by Alexander Duyck to rework the async probe
  functionality to work better for a number of devices, and independant
  work from Rafael for the device link functionality to make it work
  "correctly".

  Also in here is:

   - lots of BUS_ATTR() removals, the macro is about to go away

   - firmware test fixups

   - ihex fixups and simplification

   - component additions (also includes i915 patches)

   - lots of minor coding style fixups and cleanups.

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

* tag 'driver-core-5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (65 commits)
  driver core: platform: remove misleading err_alloc label
  platform: set of_node in platform_device_register_full()
  firmware: hardcode the debug message for -ENOENT
  driver core: Add missing description of new struct device_link field
  driver core: Fix PM-runtime for links added during consumer probe
  drivers/component: kerneldoc polish
  async: Add cmdline option to specify drivers to be async probed
  driver core: Fix possible supplier PM-usage counter imbalance
  PM-runtime: Fix __pm_runtime_set_status() race with runtime resume
  driver: platform: Support parsing GpioInt 0 in platform_get_irq()
  selftests: firmware: fix verify_reqs() return value
  Revert "selftests: firmware: remove use of non-standard diff -Z option"
  Revert "selftests: firmware: add CONFIG_FW_LOADER_USER_HELPER_FALLBACK to config"
  device: Fix comment for driver_data in struct device
  kernfs: Allocating memory for kernfs_iattrs with kmem_cache.
  sysfs: remove unused include of kernfs-internal.h
  driver core: Postpone DMA tear-down until after devres release
  driver core: Document limitation related to DL_FLAG_RPM_ACTIVE
  PM-runtime: Take suppliers into account in __pm_runtime_set_status()
  device.h: Add __cold to dev_<level> logging functions
  ...
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@torvalds
torvalds committed Mar 6, 2019
2 parents 45763bf + 36cf3b1 commit e431f2d
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4 changes: 4 additions & 0 deletions Documentation/admin-guide/kernel-parameters.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -915,6 +915,10 @@
The filter can be disabled or changed to another
driver later using sysfs.

driver_async_probe= [KNL]
List of driver names to be probed asynchronously.
Format: <driver_name1>,<driver_name2>...

drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>]
Broken monitors, graphic adapters, KVMs and EDIDless
panels may send no or incorrect EDID data sets.
Expand Down
84 changes: 60 additions & 24 deletions Documentation/driver-api/device_link.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -28,8 +28,8 @@ suspend/resume and shutdown ordering.

Device links allow representation of such dependencies in the driver core.

In its standard form, a device link combines *both* dependency types:
It guarantees correct suspend/resume and shutdown ordering between a
In its standard or *managed* form, a device link combines *both* dependency
types: It guarantees correct suspend/resume and shutdown ordering between a
"supplier" device and its "consumer" devices, and it guarantees driver
presence on the supplier. The consumer devices are not probed before the
supplier is bound to a driver, and they're unbound before the supplier
Expand Down Expand Up @@ -62,18 +62,24 @@ device ``->probe`` callback or a boot-time PCI quirk.

Another example for an inconsistent state would be a device link that
represents a driver presence dependency, yet is added from the consumer's
``->probe`` callback while the supplier hasn't probed yet: Had the driver
core known about the device link earlier, it wouldn't have probed the
``->probe`` callback while the supplier hasn't started to probe yet: Had the
driver core known about the device link earlier, it wouldn't have probed the
consumer in the first place. The onus is thus on the consumer to check
presence of the supplier after adding the link, and defer probing on
non-presence.

If a device link is added in the ``->probe`` callback of the supplier or
consumer driver, it is typically deleted in its ``->remove`` callback for
symmetry. That way, if the driver is compiled as a module, the device
link is added on module load and orderly deleted on unload. The same
restrictions that apply to device link addition (e.g. exclusion of a
parallel suspend/resume transition) apply equally to deletion.
non-presence. [Note that it is valid to create a link from the consumer's
``->probe`` callback while the supplier is still probing, but the consumer must
know that the supplier is functional already at the link creation time (that is
the case, for instance, if the consumer has just acquired some resources that
would not have been available had the supplier not been functional then).]

If a device link with ``DL_FLAG_STATELESS`` set (i.e. a stateless device link)
is added in the ``->probe`` callback of the supplier or consumer driver, it is
typically deleted in its ``->remove`` callback for symmetry. That way, if the
driver is compiled as a module, the device link is added on module load and
orderly deleted on unload. The same restrictions that apply to device link
addition (e.g. exclusion of a parallel suspend/resume transition) apply equally
to deletion. Device links with ``DL_FLAG_STATELESS`` unset (i.e. managed
device links) are deleted automatically by the driver core.

Several flags may be specified on device link addition, two of which
have already been mentioned above: ``DL_FLAG_STATELESS`` to express that no
Expand All @@ -83,25 +89,55 @@ integration is desired.

Two other flags are specifically targeted at use cases where the device
link is added from the consumer's ``->probe`` callback: ``DL_FLAG_RPM_ACTIVE``
can be specified to runtime resume the supplier upon addition of the
device link. ``DL_FLAG_AUTOREMOVE_CONSUMER`` causes the device link to be
automatically purged when the consumer fails to probe or later unbinds.
This obviates the need to explicitly delete the link in the ``->remove``
callback or in the error path of the ``->probe`` callback.
can be specified to runtime resume the supplier and prevent it from suspending
before the consumer is runtime suspended. ``DL_FLAG_AUTOREMOVE_CONSUMER``
causes the device link to be automatically purged when the consumer fails to
probe or later unbinds.

Similarly, when the device link is added from supplier's ``->probe`` callback,
``DL_FLAG_AUTOREMOVE_SUPPLIER`` causes the device link to be automatically
purged when the supplier fails to probe or later unbinds.

If neither ``DL_FLAG_AUTOREMOVE_CONSUMER`` nor ``DL_FLAG_AUTOREMOVE_SUPPLIER``
is set, ``DL_FLAG_AUTOPROBE_CONSUMER`` can be used to request the driver core
to probe for a driver for the consumer driver on the link automatically after
a driver has been bound to the supplier device.

Note, however, that any combinations of ``DL_FLAG_AUTOREMOVE_CONSUMER``,
``DL_FLAG_AUTOREMOVE_SUPPLIER`` or ``DL_FLAG_AUTOPROBE_CONSUMER`` with
``DL_FLAG_STATELESS`` are invalid and cannot be used.

Limitations
===========

Driver authors should be aware that a driver presence dependency (i.e. when
``DL_FLAG_STATELESS`` is not specified on link addition) may cause probing of
the consumer to be deferred indefinitely. This can become a problem if the
consumer is required to probe before a certain initcall level is reached.
Worse, if the supplier driver is blacklisted or missing, the consumer will
never be probed.
Driver authors should be aware that a driver presence dependency for managed
device links (i.e. when ``DL_FLAG_STATELESS`` is not specified on link addition)
may cause probing of the consumer to be deferred indefinitely. This can become
a problem if the consumer is required to probe before a certain initcall level
is reached. Worse, if the supplier driver is blacklisted or missing, the
consumer will never be probed.

Moreover, managed device links cannot be deleted directly. They are deleted
by the driver core when they are not necessary any more in accordance with the
``DL_FLAG_AUTOREMOVE_CONSUMER`` and ``DL_FLAG_AUTOREMOVE_SUPPLIER`` flags.
However, stateless device links (i.e. device links with ``DL_FLAG_STATELESS``
set) are expected to be removed by whoever called :c:func:`device_link_add()`
to add them with the help of either :c:func:`device_link_del()` or
:c:func:`device_link_remove()`.

Passing ``DL_FLAG_RPM_ACTIVE`` along with ``DL_FLAG_STATELESS`` to
:c:func:`device_link_add()` may cause the PM-runtime usage counter of the
supplier device to remain nonzero after a subsequent invocation of either
:c:func:`device_link_del()` or :c:func:`device_link_remove()` to remove the
device link returned by it. This happens if :c:func:`device_link_add()` is
called twice in a row for the same consumer-supplier pair without removing the
link between these calls, in which case allowing the PM-runtime usage counter
of the supplier to drop on an attempt to remove the link may cause it to be
suspended while the consumer is still PM-runtime-active and that has to be
avoided. [To work around this limitation it is sufficient to let the consumer
runtime suspend at least once, or call :c:func:`pm_runtime_set_suspended()` for
it with PM-runtime disabled, between the :c:func:`device_link_add()` and
:c:func:`device_link_del()` or :c:func:`device_link_remove()` calls.]

Sometimes drivers depend on optional resources. They are able to operate
in a degraded mode (reduced feature set or performance) when those resources
Expand Down Expand Up @@ -285,4 +321,4 @@ API
===

.. kernel-doc:: drivers/base/core.c
:functions: device_link_add device_link_del
:functions: device_link_add device_link_del device_link_remove
2 changes: 1 addition & 1 deletion Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -583,7 +583,7 @@ export KBUILD_MODULES KBUILD_BUILTIN
ifeq ($(KBUILD_EXTMOD),)
# Objects we will link into vmlinux / subdirs we need to visit
init-y := init/
drivers-y := drivers/ sound/ firmware/
drivers-y := drivers/ sound/
net-y := net/
libs-y := lib/
core-y := usr/
Expand Down
10 changes: 4 additions & 6 deletions arch/powerpc/platforms/pseries/ibmebus.c
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Original file line number Diff line number Diff line change
Expand Up @@ -261,8 +261,7 @@ static char *ibmebus_chomp(const char *in, size_t count)
return out;
}

static ssize_t ibmebus_store_probe(struct bus_type *bus,
const char *buf, size_t count)
static ssize_t probe_store(struct bus_type *bus, const char *buf, size_t count)
{
struct device_node *dn = NULL;
struct device *dev;
Expand Down Expand Up @@ -298,10 +297,9 @@ static ssize_t ibmebus_store_probe(struct bus_type *bus,
return rc;
return count;
}
static BUS_ATTR(probe, 0200, NULL, ibmebus_store_probe);
static BUS_ATTR_WO(probe);

static ssize_t ibmebus_store_remove(struct bus_type *bus,
const char *buf, size_t count)
static ssize_t remove_store(struct bus_type *bus, const char *buf, size_t count)
{
struct device *dev;
char *path;
Expand All @@ -325,7 +323,7 @@ static ssize_t ibmebus_store_remove(struct bus_type *bus,
return -ENODEV;
}
}
static BUS_ATTR(remove, 0200, NULL, ibmebus_store_remove);
static BUS_ATTR_WO(remove);

static struct attribute *ibmbus_bus_attrs[] = {
&bus_attr_probe.attr,
Expand Down
12 changes: 12 additions & 0 deletions drivers/base/base.h
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Original file line number Diff line number Diff line change
Expand Up @@ -60,12 +60,17 @@ struct driver_private {
* @knode_parent - node in sibling list
* @knode_driver - node in driver list
* @knode_bus - node in bus list
* @knode_class - node in class list
* @deferred_probe - entry in deferred_probe_list which is used to retry the
* binding of drivers which were unable to get all the resources needed by
* the device; typically because it depends on another driver getting
* probed first.
* @async_driver - pointer to device driver awaiting probe via async_probe
* @device - pointer back to the struct device that this structure is
* associated with.
* @dead - This device is currently either in the process of or has been
* removed from the system. Any asynchronous events scheduled for this
* device should exit without taking any action.
*
* Nothing outside of the driver core should ever touch these fields.
*/
Expand All @@ -74,15 +79,20 @@ struct device_private {
struct klist_node knode_parent;
struct klist_node knode_driver;
struct klist_node knode_bus;
struct klist_node knode_class;
struct list_head deferred_probe;
struct device_driver *async_driver;
struct device *device;
u8 dead:1;
};
#define to_device_private_parent(obj) \
container_of(obj, struct device_private, knode_parent)
#define to_device_private_driver(obj) \
container_of(obj, struct device_private, knode_driver)
#define to_device_private_bus(obj) \
container_of(obj, struct device_private, knode_bus)
#define to_device_private_class(obj) \
container_of(obj, struct device_private, knode_class)

/* initialisation functions */
extern int devices_init(void);
Expand Down Expand Up @@ -124,6 +134,8 @@ extern int driver_add_groups(struct device_driver *drv,
const struct attribute_group **groups);
extern void driver_remove_groups(struct device_driver *drv,
const struct attribute_group **groups);
int device_driver_attach(struct device_driver *drv, struct device *dev);
void device_driver_detach(struct device *dev);

extern char *make_class_name(const char *name, struct kobject *kobj);

Expand Down
66 changes: 20 additions & 46 deletions drivers/base/bus.c
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Original file line number Diff line number Diff line change
Expand Up @@ -187,11 +187,7 @@ static ssize_t unbind_store(struct device_driver *drv, const char *buf,

dev = bus_find_device_by_name(bus, NULL, buf);
if (dev && dev->driver == drv) {
if (dev->parent && dev->bus->need_parent_lock)
device_lock(dev->parent);
device_release_driver(dev);
if (dev->parent && dev->bus->need_parent_lock)
device_unlock(dev->parent);
device_driver_detach(dev);
err = count;
}
put_device(dev);
Expand All @@ -214,13 +210,7 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf,

dev = bus_find_device_by_name(bus, NULL, buf);
if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
if (dev->parent && bus->need_parent_lock)
device_lock(dev->parent);
device_lock(dev);
err = driver_probe_device(drv, dev);
device_unlock(dev);
if (dev->parent && bus->need_parent_lock)
device_unlock(dev->parent);
err = device_driver_attach(drv, dev);

if (err > 0) {
/* success */
Expand All @@ -236,12 +226,12 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf,
}
static DRIVER_ATTR_IGNORE_LOCKDEP(bind, S_IWUSR, NULL, bind_store);

static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
static ssize_t drivers_autoprobe_show(struct bus_type *bus, char *buf)
{
return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
}

static ssize_t store_drivers_autoprobe(struct bus_type *bus,
static ssize_t drivers_autoprobe_store(struct bus_type *bus,
const char *buf, size_t count)
{
if (buf[0] == '0')
Expand All @@ -251,7 +241,7 @@ static ssize_t store_drivers_autoprobe(struct bus_type *bus,
return count;
}

static ssize_t store_drivers_probe(struct bus_type *bus,
static ssize_t drivers_probe_store(struct bus_type *bus,
const char *buf, size_t count)
{
struct device *dev;
Expand Down Expand Up @@ -586,9 +576,8 @@ static void remove_bind_files(struct device_driver *drv)
driver_remove_file(drv, &driver_attr_unbind);
}

static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
show_drivers_autoprobe, store_drivers_autoprobe);
static BUS_ATTR_WO(drivers_probe);
static BUS_ATTR_RW(drivers_autoprobe);

static int add_probe_files(struct bus_type *bus)
{
Expand Down Expand Up @@ -621,17 +610,6 @@ static ssize_t uevent_store(struct device_driver *drv, const char *buf,
}
static DRIVER_ATTR_WO(uevent);

static void driver_attach_async(void *_drv, async_cookie_t cookie)
{
struct device_driver *drv = _drv;
int ret;

ret = driver_attach(drv);

pr_debug("bus: '%s': driver %s async attach completed: %d\n",
drv->bus->name, drv->name, ret);
}

/**
* bus_add_driver - Add a driver to the bus.
* @drv: driver.
Expand Down Expand Up @@ -664,15 +642,9 @@ int bus_add_driver(struct device_driver *drv)

klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
if (drv->bus->p->drivers_autoprobe) {
if (driver_allows_async_probing(drv)) {
pr_debug("bus: '%s': probing driver %s asynchronously\n",
drv->bus->name, drv->name);
async_schedule(driver_attach_async, drv);
} else {
error = driver_attach(drv);
if (error)
goto out_unregister;
}
error = driver_attach(drv);
if (error)
goto out_unregister;
}
module_add_driver(drv->owner, drv);

Expand Down Expand Up @@ -774,13 +746,8 @@ EXPORT_SYMBOL_GPL(bus_rescan_devices);
*/
int device_reprobe(struct device *dev)
{
if (dev->driver) {
if (dev->parent && dev->bus->need_parent_lock)
device_lock(dev->parent);
device_release_driver(dev);
if (dev->parent && dev->bus->need_parent_lock)
device_unlock(dev->parent);
}
if (dev->driver)
device_driver_detach(dev);
return bus_rescan_devices_helper(dev, NULL);
}
EXPORT_SYMBOL_GPL(device_reprobe);
Expand Down Expand Up @@ -838,7 +805,14 @@ static ssize_t bus_uevent_store(struct bus_type *bus,
rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
return rc ? rc : count;
}
static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
/*
* "open code" the old BUS_ATTR() macro here. We want to use BUS_ATTR_WO()
* here, but can not use it as earlier in the file we have
* DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
* function name.
*/
static struct bus_attribute bus_attr_uevent = __ATTR(uevent, S_IWUSR, NULL,
bus_uevent_store);

/**
* bus_register - register a driver-core subsystem
Expand Down
14 changes: 10 additions & 4 deletions drivers/base/class.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -117,16 +117,22 @@ static void class_put(struct class *cls)
kset_put(&cls->p->subsys);
}

static struct device *klist_class_to_dev(struct klist_node *n)
{
struct device_private *p = to_device_private_class(n);
return p->device;
}

static void klist_class_dev_get(struct klist_node *n)
{
struct device *dev = container_of(n, struct device, knode_class);
struct device *dev = klist_class_to_dev(n);

get_device(dev);
}

static void klist_class_dev_put(struct klist_node *n)
{
struct device *dev = container_of(n, struct device, knode_class);
struct device *dev = klist_class_to_dev(n);

put_device(dev);
}
Expand Down Expand Up @@ -277,7 +283,7 @@ void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
struct klist_node *start_knode = NULL;

if (start)
start_knode = &start->knode_class;
start_knode = &start->p->knode_class;
klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
iter->type = type;
}
Expand All @@ -304,7 +310,7 @@ struct device *class_dev_iter_next(struct class_dev_iter *iter)
knode = klist_next(&iter->ki);
if (!knode)
return NULL;
dev = container_of(knode, struct device, knode_class);
dev = klist_class_to_dev(knode);
if (!iter->type || iter->type == dev->type)
return dev;
}
Expand Down
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