mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-06 10:57:46 +00:00
driver core: Fix possible supplier PM-usage counter imbalance
[ Upstream commit4c06c4e6cf
] If a stateless device link to a certain supplier with DL_FLAG_PM_RUNTIME set in the flags is added and then removed by the consumer driver's probe callback, the supplier's PM-runtime usage counter will be nonzero after that which effectively causes the supplier to remain "always on" going forward. Namely, device_link_add() called to add the link invokes device_link_rpm_prepare() which notices that the consumer driver is probing, so it increments the supplier's PM-runtime usage counter with the assumption that the link will stay around until pm_runtime_put_suppliers() is called by driver_probe_device(), but if the link goes away before that point, the supplier's PM-runtime usage counter will remain nonzero. To prevent that from happening, first rework pm_runtime_get_suppliers() and pm_runtime_put_suppliers() to use the rpm_active refounts of device links and make the latter only drop rpm_active and the supplier's PM-runtime usage counter for each link by one, unless rpm_active is one already for it. Next, modify device_link_add() to bump up the new link's rpm_active refcount and the suppliers PM-runtime usage counter by two, to prevent pm_runtime_put_suppliers(), if it is called subsequently, from suspending the supplier prematurely (in case its PM-runtime usage counter goes down to 0 in there). Due to the way rpm_put_suppliers() works, this change does not affect runtime suspend of the consumer ends of new device links (or, generally, device links for which DL_FLAG_PM_RUNTIME has just been set). Fixes:e2f3cd831a
("driver core: Fix handling of runtime PM flags in device_link_add()") Reported-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> Tested-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
0ed24039e2
commit
3d6b7c14f8
3 changed files with 33 additions and 19 deletions
|
@ -165,19 +165,6 @@ void device_pm_move_to_tail(struct device *dev)
|
|||
device_links_read_unlock(idx);
|
||||
}
|
||||
|
||||
static void device_link_rpm_prepare(struct device *consumer,
|
||||
struct device *supplier)
|
||||
{
|
||||
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);
|
||||
}
|
||||
|
||||
/**
|
||||
* device_link_add - Create a link between two devices.
|
||||
* @consumer: Consumer end of the link.
|
||||
|
@ -262,11 +249,11 @@ struct device_link *device_link_add(struct device *consumer,
|
|||
|
||||
if (flags & DL_FLAG_PM_RUNTIME) {
|
||||
if (!(link->flags & DL_FLAG_PM_RUNTIME)) {
|
||||
device_link_rpm_prepare(consumer, supplier);
|
||||
pm_runtime_new_link(consumer);
|
||||
link->flags |= DL_FLAG_PM_RUNTIME;
|
||||
}
|
||||
if (flags & DL_FLAG_RPM_ACTIVE)
|
||||
refcount_inc(&link->rpm_active);
|
||||
pm_runtime_active_link(link, supplier);
|
||||
}
|
||||
|
||||
kref_get(&link->kref);
|
||||
|
@ -281,9 +268,9 @@ struct device_link *device_link_add(struct device *consumer,
|
|||
|
||||
if (flags & DL_FLAG_PM_RUNTIME) {
|
||||
if (flags & DL_FLAG_RPM_ACTIVE)
|
||||
refcount_inc(&link->rpm_active);
|
||||
pm_runtime_active_link(link, supplier);
|
||||
|
||||
device_link_rpm_prepare(consumer, supplier);
|
||||
pm_runtime_new_link(consumer);
|
||||
}
|
||||
|
||||
get_device(supplier);
|
||||
|
|
|
@ -1570,8 +1570,10 @@ void pm_runtime_get_suppliers(struct device *dev)
|
|||
idx = device_links_read_lock();
|
||||
|
||||
list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
|
||||
if (link->flags & DL_FLAG_PM_RUNTIME)
|
||||
if (link->flags & DL_FLAG_PM_RUNTIME) {
|
||||
refcount_inc(&link->rpm_active);
|
||||
pm_runtime_get_sync(link->supplier);
|
||||
}
|
||||
|
||||
device_links_read_unlock(idx);
|
||||
}
|
||||
|
@ -1588,7 +1590,8 @@ void pm_runtime_put_suppliers(struct device *dev)
|
|||
idx = device_links_read_lock();
|
||||
|
||||
list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
|
||||
if (link->flags & DL_FLAG_PM_RUNTIME)
|
||||
if (link->flags & DL_FLAG_PM_RUNTIME &&
|
||||
refcount_dec_not_one(&link->rpm_active))
|
||||
pm_runtime_put(link->supplier);
|
||||
|
||||
device_links_read_unlock(idx);
|
||||
|
@ -1601,6 +1604,26 @@ void pm_runtime_new_link(struct device *dev)
|
|||
spin_unlock_irq(&dev->power.lock);
|
||||
}
|
||||
|
||||
/**
|
||||
* pm_runtime_active_link - Set up new device link as active for PM-runtime.
|
||||
* @link: Device link to be set up as active.
|
||||
* @supplier: Supplier end of the link.
|
||||
*
|
||||
* Add 2 to the rpm_active refcount of @link and increment the PM-runtime
|
||||
* usage counter of @supplier once more in case the link is being added while
|
||||
* the consumer driver is probing and pm_runtime_put_suppliers() will be called
|
||||
* subsequently.
|
||||
*
|
||||
* Note that this doesn't prevent rpm_put_suppliers() from decreasing the link's
|
||||
* rpm_active refcount down to one, so runtime suspend of the consumer end of
|
||||
* @link is not affected.
|
||||
*/
|
||||
void pm_runtime_active_link(struct device_link *link, struct device *supplier)
|
||||
{
|
||||
refcount_add(2, &link->rpm_active);
|
||||
pm_runtime_get_noresume(supplier);
|
||||
}
|
||||
|
||||
void pm_runtime_drop_link(struct device *dev)
|
||||
{
|
||||
spin_lock_irq(&dev->power.lock);
|
||||
|
|
|
@ -59,6 +59,8 @@ extern void pm_runtime_clean_up_links(struct device *dev);
|
|||
extern void pm_runtime_get_suppliers(struct device *dev);
|
||||
extern void pm_runtime_put_suppliers(struct device *dev);
|
||||
extern void pm_runtime_new_link(struct device *dev);
|
||||
extern void pm_runtime_active_link(struct device_link *link,
|
||||
struct device *supplier);
|
||||
extern void pm_runtime_drop_link(struct device *dev);
|
||||
|
||||
static inline void pm_suspend_ignore_children(struct device *dev, bool enable)
|
||||
|
@ -176,6 +178,8 @@ static inline void pm_runtime_clean_up_links(struct device *dev) {}
|
|||
static inline void pm_runtime_get_suppliers(struct device *dev) {}
|
||||
static inline void pm_runtime_put_suppliers(struct device *dev) {}
|
||||
static inline void pm_runtime_new_link(struct device *dev) {}
|
||||
static inline void pm_runtime_active_link(struct device_link *link,
|
||||
struct device *supplier) {}
|
||||
static inline void pm_runtime_drop_link(struct device *dev) {}
|
||||
|
||||
#endif /* !CONFIG_PM */
|
||||
|
|
Loading…
Reference in a new issue