diff --git a/Documentation/driver-api/device_link.rst b/Documentation/driver-api/device_link.rst
index ae1e3d0394b091be307d1b08de55a982c1054421..1b5020ec6517b06ae01e0f57db976bc41ce81d5b 100644
--- a/Documentation/driver-api/device_link.rst
+++ b/Documentation/driver-api/device_link.rst
@@ -78,8 +78,8 @@ 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.
+to deletion. Device links managed by the driver core are deleted automatically
+by it.
Several flags may be specified on device link addition, two of which
have already been mentioned above: ``DL_FLAG_STATELESS`` to express that no
diff --git a/drivers/base/core.c b/drivers/base/core.c
index da84a73f2ba63b6ecfa6d84483770ceb32db0e93..21cd081622192f1a33c011d34a45013c8003e819 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -124,6 +124,50 @@ static int device_is_dependent(struct device *dev, void *target)
return ret;
}
+static void device_link_init_status(struct device_link *link,
+ struct device *consumer,
+ struct device *supplier)
+{
+ switch (supplier->links.status) {
+ case DL_DEV_PROBING:
+ switch (consumer->links.status) {
+ case DL_DEV_PROBING:
+ /*
+ * 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).
+ */
+ 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:
+ link->status = DL_STATE_ACTIVE;
+ break;
+ default:
+ link->status = DL_STATE_AVAILABLE;
+ break;
+ }
+ break;
+ case DL_DEV_UNBINDING:
+ link->status = DL_STATE_SUPPLIER_UNBIND;
+ break;
+ default:
+ link->status = DL_STATE_DORMANT;
+ break;
+ }
+}
+
static int device_reorder_to_tail(struct device *dev, void *not_used)
{
struct device_link *link;
@@ -165,6 +209,10 @@ void device_pm_move_to_tail(struct device *dev)
device_links_read_unlock(idx);
}
+#define DL_MANAGED_LINK_FLAGS (DL_FLAG_AUTOREMOVE_CONSUMER | \
+ DL_FLAG_AUTOREMOVE_SUPPLIER | \
+ DL_FLAG_AUTOPROBE_CONSUMER)
+
/**
* device_link_add - Create a link between two devices.
* @consumer: Consumer end of the link.
@@ -179,9 +227,9 @@ 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 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 DL_FLAG_STATELESS is set in @flags, the caller of this function is
+ * expected to release the link returned by it directly with the help of either
+ * device_link_del() or device_link_remove().
*
* 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
@@ -201,9 +249,16 @@ void device_pm_move_to_tail(struct device *dev)
* 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.
+ * The combination of DL_FLAG_STATELESS and one of DL_FLAG_AUTOREMOVE_CONSUMER,
+ * DL_FLAG_AUTOREMOVE_SUPPLIER, or DL_FLAG_AUTOPROBE_CONSUMER set in @flags at
+ * the same time is invalid and will cause NULL to be returned upfront.
+ * However, if a device link between the given @consumer and @supplier pair
+ * exists already when this function is called for them, the existing link will
+ * be returned regardless of its current type and status (the link's flags may
+ * be modified then). The caller of this function is then expected to treat
+ * the link as though it has just been created, so (in particular) if
+ * DL_FLAG_STATELESS was passed in @flags, the link needs to be released
+ * explicitly when not needed any more (as stated above).
*
* 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
@@ -220,10 +275,8 @@ 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 |
- DL_FLAG_AUTOREMOVE_SUPPLIER |
- DL_FLAG_AUTOPROBE_CONSUMER)) ||
+ (flags & ~(DL_FLAG_STATELESS | DL_MANAGED_LINK_FLAGS)) ||
+ (flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) ||
(flags & DL_FLAG_AUTOPROBE_CONSUMER &&
flags & (DL_FLAG_AUTOREMOVE_CONSUMER |
DL_FLAG_AUTOREMOVE_SUPPLIER)))
@@ -236,6 +289,9 @@ struct device_link *device_link_add(struct device *consumer,
}
}
+ if (!(flags & DL_FLAG_STATELESS))
+ flags |= DL_FLAG_MANAGED;
+
device_links_write_lock();
device_pm_lock();
@@ -262,15 +318,6 @@ struct device_link *device_link_add(struct device *consumer,
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);
@@ -281,6 +328,7 @@ struct device_link *device_link_add(struct device *consumer,
}
if (flags & DL_FLAG_STATELESS) {
+ link->flags |= DL_FLAG_STATELESS;
kref_get(&link->kref);
goto out;
}
@@ -299,6 +347,11 @@ struct device_link *device_link_add(struct device *consumer,
link->flags &= ~(DL_FLAG_AUTOREMOVE_CONSUMER |
DL_FLAG_AUTOREMOVE_SUPPLIER);
}
+ if (!(link->flags & DL_FLAG_MANAGED)) {
+ kref_get(&link->kref);
+ link->flags |= DL_FLAG_MANAGED;
+ device_link_init_status(link, consumer, supplier);
+ }
goto out;
}
@@ -325,48 +378,10 @@ struct device_link *device_link_add(struct device *consumer,
kref_init(&link->kref);
/* Determine the initial link state. */
- if (flags & DL_FLAG_STATELESS) {
+ if (flags & DL_FLAG_STATELESS)
link->status = DL_STATE_NONE;
- } else {
- switch (supplier->links.status) {
- case DL_DEV_PROBING:
- switch (consumer->links.status) {
- case DL_DEV_PROBING:
- /*
- * 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).
- */
- 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:
- link->status = DL_STATE_ACTIVE;
- break;
- default:
- link->status = DL_STATE_AVAILABLE;
- break;
- }
- break;
- case DL_DEV_UNBINDING:
- link->status = DL_STATE_SUPPLIER_UNBIND;
- break;
- default:
- link->status = DL_STATE_DORMANT;
- break;
- }
- }
+ else
+ device_link_init_status(link, consumer, supplier);
/*
* Some callers expect the link creation during consumer driver probe to
@@ -528,7 +543,7 @@ static void device_links_missing_supplier(struct device *dev)
* mark the link as "consumer probe in progress" to make the supplier removal
* wait for us to complete (or bad things may happen).
*
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
*/
int device_links_check_suppliers(struct device *dev)
{
@@ -538,7 +553,7 @@ int device_links_check_suppliers(struct device *dev)
device_links_write_lock();
list_for_each_entry(link, &dev->links.suppliers, c_node) {
- if (link->flags & DL_FLAG_STATELESS)
+ if (!(link->flags & DL_FLAG_MANAGED))
continue;
if (link->status != DL_STATE_AVAILABLE) {
@@ -563,7 +578,7 @@ int device_links_check_suppliers(struct device *dev)
*
* Also change the status of @dev's links to suppliers to "active".
*
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
*/
void device_links_driver_bound(struct device *dev)
{
@@ -572,7 +587,7 @@ void device_links_driver_bound(struct device *dev)
device_links_write_lock();
list_for_each_entry(link, &dev->links.consumers, s_node) {
- if (link->flags & DL_FLAG_STATELESS)
+ if (!(link->flags & DL_FLAG_MANAGED))
continue;
/*
@@ -593,7 +608,7 @@ void device_links_driver_bound(struct device *dev)
}
list_for_each_entry(link, &dev->links.suppliers, c_node) {
- if (link->flags & DL_FLAG_STATELESS)
+ if (!(link->flags & DL_FLAG_MANAGED))
continue;
WARN_ON(link->status != DL_STATE_CONSUMER_PROBE);
@@ -605,6 +620,13 @@ void device_links_driver_bound(struct device *dev)
device_links_write_unlock();
}
+static void device_link_drop_managed(struct device_link *link)
+{
+ link->flags &= ~DL_FLAG_MANAGED;
+ WRITE_ONCE(link->status, DL_STATE_NONE);
+ kref_put(&link->kref, __device_link_del);
+}
+
/**
* __device_links_no_driver - Update links of a device without a driver.
* @dev: Device without a drvier.
@@ -615,18 +637,18 @@ void device_links_driver_bound(struct device *dev)
* unless they already are in the "supplier unbind in progress" state in which
* case they need not be updated.
*
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
*/
static void __device_links_no_driver(struct device *dev)
{
struct device_link *link, *ln;
list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
- if (link->flags & DL_FLAG_STATELESS)
+ if (!(link->flags & DL_FLAG_MANAGED))
continue;
if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER)
- __device_link_del(&link->kref);
+ device_link_drop_managed(link);
else if (link->status == DL_STATE_CONSUMER_PROBE ||
link->status == DL_STATE_ACTIVE)
WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
@@ -643,7 +665,7 @@ static void __device_links_no_driver(struct device *dev)
* %__device_links_no_driver() to update links to suppliers for it as
* appropriate.
*
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
*/
void device_links_no_driver(struct device *dev)
{
@@ -652,7 +674,7 @@ void device_links_no_driver(struct device *dev)
device_links_write_lock();
list_for_each_entry(link, &dev->links.consumers, s_node) {
- if (link->flags & DL_FLAG_STATELESS)
+ if (!(link->flags & DL_FLAG_MANAGED))
continue;
/*
@@ -680,7 +702,7 @@ void device_links_no_driver(struct device *dev)
* invoke %__device_links_no_driver() to update links to suppliers for it as
* appropriate.
*
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
*/
void device_links_driver_cleanup(struct device *dev)
{
@@ -689,7 +711,7 @@ void device_links_driver_cleanup(struct device *dev)
device_links_write_lock();
list_for_each_entry_safe(link, ln, &dev->links.consumers, s_node) {
- if (link->flags & DL_FLAG_STATELESS)
+ if (!(link->flags & DL_FLAG_MANAGED))
continue;
WARN_ON(link->flags & DL_FLAG_AUTOREMOVE_CONSUMER);
@@ -702,7 +724,7 @@ void device_links_driver_cleanup(struct device *dev)
*/
if (link->status == DL_STATE_SUPPLIER_UNBIND &&
link->flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
- __device_link_del(&link->kref);
+ device_link_drop_managed(link);
WRITE_ONCE(link->status, DL_STATE_DORMANT);
}
@@ -724,7 +746,7 @@ void device_links_driver_cleanup(struct device *dev)
*
* Return 'false' if there are no probing or active consumers.
*
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
*/
bool device_links_busy(struct device *dev)
{
@@ -734,7 +756,7 @@ bool device_links_busy(struct device *dev)
device_links_write_lock();
list_for_each_entry(link, &dev->links.consumers, s_node) {
- if (link->flags & DL_FLAG_STATELESS)
+ if (!(link->flags & DL_FLAG_MANAGED))
continue;
if (link->status == DL_STATE_CONSUMER_PROBE
@@ -764,7 +786,7 @@ bool device_links_busy(struct device *dev)
* driver to unbind and start over (the consumer will not re-probe as we have
* changed the state of the link already).
*
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
*/
void device_links_unbind_consumers(struct device *dev)
{
@@ -776,7 +798,7 @@ void device_links_unbind_consumers(struct device *dev)
list_for_each_entry(link, &dev->links.consumers, s_node) {
enum device_link_state status;
- if (link->flags & DL_FLAG_STATELESS)
+ if (!(link->flags & DL_FLAG_MANAGED))
continue;
status = link->status;
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index b75335508d2c57834675a3e1878d3abd3b5f28a2..45a8fbe6987a8497d5542959fd860b9878d54052 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1624,7 +1624,7 @@ void pm_runtime_remove(struct device *dev)
* runtime PM references to the device, drop the usage counter of the device
* (as many times as needed).
*
- * Links with the DL_FLAG_STATELESS flag set are ignored.
+ * Links with the DL_FLAG_MANAGED flag unset are ignored.
*
* Since the device is guaranteed to be runtime-active at the point this is
* called, nothing else needs to be done here.
@@ -1641,7 +1641,7 @@ void pm_runtime_clean_up_links(struct device *dev)
idx = device_links_read_lock();
list_for_each_entry_rcu(link, &dev->links.consumers, s_node) {
- if (link->flags & DL_FLAG_STATELESS)
+ if (!(link->flags & DL_FLAG_MANAGED))
continue;
while (refcount_dec_not_one(&link->rpm_active))
diff --git a/include/linux/device.h b/include/linux/device.h
index c330b75c6c57cdbd46a360bff2b50c96bde4d515..c1c489921e4c9cd2d382a4edd9ae771917a15ec7 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -833,12 +833,13 @@ enum device_link_state {
/*
* Device link flags.
*
- * STATELESS: The core won't track the presence of supplier/consumer drivers.
+ * STATELESS: The core will not remove this link automatically.
* AUTOREMOVE_CONSUMER: Remove the link automatically on consumer driver unbind.
* PM_RUNTIME: If set, the runtime PM framework will use this link.
* RPM_ACTIVE: Run pm_runtime_get_sync() on the supplier during link creation.
* AUTOREMOVE_SUPPLIER: Remove the link automatically on supplier driver unbind.
* AUTOPROBE_CONSUMER: Probe consumer driver automatically after supplier binds.
+ * MANAGED: The core tracks presence of supplier/consumer drivers (internal).
*/
#define DL_FLAG_STATELESS BIT(0)
#define DL_FLAG_AUTOREMOVE_CONSUMER BIT(1)
@@ -846,6 +847,7 @@ enum device_link_state {
#define DL_FLAG_RPM_ACTIVE BIT(3)
#define DL_FLAG_AUTOREMOVE_SUPPLIER BIT(4)
#define DL_FLAG_AUTOPROBE_CONSUMER BIT(5)
+#define DL_FLAG_MANAGED BIT(6)
/**
* struct device_link - Device link representation.