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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2019-02-19 17:53:26 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-02-20 11:18:07 +0100
commit36003d4cf57ca431fb3f94d317bcca426a2394d6 (patch)
tree78888be63e3a3ef454fb6a6054092d6f6ff21c20 /drivers/base
parente4246b05507fc6102008bac0aee848f207bd96de (diff)
downloadlinux-36003d4cf57ca431fb3f94d317bcca426a2394d6.tar.bz2
driver core: Fix PM-runtime for links added during consumer probe
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 <jonathanh@nvidia.com> Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Ulf Hansson <ulf.hansson@linaro.org> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Tested-by: Thierry Reding <treding@nvidia.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/core.c4
-rw-r--r--drivers/base/power/runtime.c29
2 files changed, 8 insertions, 25 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 787190238753..4aeaa0c92bda 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -277,7 +277,7 @@ struct device_link *device_link_add(struct device *consumer,
link->flags |= DL_FLAG_PM_RUNTIME;
}
if (flags & DL_FLAG_RPM_ACTIVE)
- pm_runtime_active_link(link, supplier);
+ refcount_inc(&link->rpm_active);
}
if (flags & DL_FLAG_STATELESS) {
@@ -310,7 +310,7 @@ struct device_link *device_link_add(struct device *consumer,
if (flags & DL_FLAG_PM_RUNTIME) {
if (flags & DL_FLAG_RPM_ACTIVE)
- pm_runtime_active_link(link, supplier);
+ refcount_inc(&link->rpm_active);
pm_runtime_new_link(consumer);
}
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 6b8aa6bed064..70d2cb188601 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1626,6 +1626,7 @@ void pm_runtime_get_suppliers(struct device *dev)
list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
if (link->flags & DL_FLAG_PM_RUNTIME) {
+ link->supplier_preactivated = true;
refcount_inc(&link->rpm_active);
pm_runtime_get_sync(link->supplier);
}
@@ -1645,9 +1646,11 @@ 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 &&
- refcount_dec_not_one(&link->rpm_active))
- pm_runtime_put(link->supplier);
+ if (link->supplier_preactivated) {
+ link->supplier_preactivated = false;
+ if (refcount_dec_not_one(&link->rpm_active))
+ pm_runtime_put(link->supplier);
+ }
device_links_read_unlock(idx);
}
@@ -1659,26 +1662,6 @@ 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);