From 4fe1e6caac16b7bd20eacc1c363351e5d533ac35 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 19 Feb 2019 17:53:26 +0100 Subject: driver core: Fix PM-runtime for links added during consumer probe [ Upstream commit 36003d4cf57ca431fb3f94d317bcca426a2394d6 ] Commit 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance") introduced a regression that causes suppliers to be suspended prematurely for device links added during consumer driver probe if the initial PM-runtime status of the consumer is "suspended" and the consumer is resumed after adding the link and before pm_runtime_put_suppliers() is called. In that case, pm_runtime_put_suppliers() will drop the rpm_active refcount for the link by one and (since rpm_active is equal to two after the preceding consumer resume) the supplier's PM-runtime usage counter will be decremented, which may cause the supplier to suspend even though the consumer's PM-runtime status is "active". For this reason, partially revert commit 4c06c4e6cf63 as the problem it tried to fix needs to be addressed somewhat differently, and change pm_runtime_get_suppliers() and pm_runtime_put_suppliers() so that the latter only drops rpm_active references acquired by the former. [This requires adding a new field to struct device_link, but I coulnd't find a cleaner way to address the issue that would work in all cases.] This causes pm_runtime_put_suppliers() to effectively ignore device links added during consumer probe, so device_link_add() doesn't need to worry about ensuring that suppliers will remain active after pm_runtime_put_suppliers() for links created with DL_FLAG_RPM_ACTIVE set and it only needs to bump up rpm_active by one for those links, so pm_runtime_active_link() is not necessary any more. Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance") Reported-by: Jon Hunter Tested-by: Jon Hunter Tested-by: Ulf Hansson Reviewed-by: Ulf Hansson Signed-off-by: Rafael J. Wysocki Tested-by: Thierry Reding Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- include/linux/device.h | 1 + include/linux/pm_runtime.h | 4 ---- 2 files changed, 1 insertion(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/device.h b/include/linux/device.h index b8fd2a1f859d..e9d1c768f972 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -854,6 +854,7 @@ struct device_link { #ifdef CONFIG_SRCU struct rcu_head rcu_head; #endif + bool supplier_preactivated; /* Owned by consumer probe. */ }; /** diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h index bace7df51af4..f0fc4700b6ff 100644 --- a/include/linux/pm_runtime.h +++ b/include/linux/pm_runtime.h @@ -59,8 +59,6 @@ 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) @@ -178,8 +176,6 @@ 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 */ -- cgit v1.2.3