diff options
author | Rafael J. Wysocki | 2019-02-01 01:49:14 +0100 |
---|---|---|
committer | Greg Kroah-Hartman | 2019-02-01 10:04:08 +0100 |
commit | e2f3cd831a280fc226118d9369bf3f77aab58c56 (patch) | |
tree | fcd245c394874d3055fd0aa4e2c487cbbf88b354 /include/linux/device.h | |
parent | 5db25c9eb893df8f6b93c1d97b8006d768e1b6f5 (diff) |
driver core: Fix handling of runtime PM flags in device_link_add()
After commit ead18c23c263 ("driver core: Introduce device links
reference counting"), if there is a link between the given supplier
and the given consumer already, device_link_add() will refcount it
and return it unconditionally without updating its flags. It is
possible, however, that the second (or any subsequent) caller of
device_link_add() for the same consumer-supplier pair will pass
DL_FLAG_PM_RUNTIME, possibly along with DL_FLAG_RPM_ACTIVE, in flags
to it and the existing link may not behave as expected then.
First, if DL_FLAG_PM_RUNTIME is not set in the existing link's flags
at all, it needs to be set like during the original initialization of
the link.
Second, if DL_FLAG_RPM_ACTIVE is passed to device_link_add() in flags
(in addition to DL_FLAG_PM_RUNTIME), the existing link should to be
updated to reflect the "active" runtime PM configuration of the
consumer-supplier pair and extra care must be taken here to avoid
possible destructive races with runtime PM of the consumer.
To that end, redefine the rpm_active field in struct device_link
as a refcount, initialize it to 1 and make rpm_resume() (for the
consumer) and device_link_add() increment it whenever they acquire
a runtime PM reference on the supplier device. Accordingly, make
rpm_suspend() (for the consumer) and pm_runtime_clean_up_links()
decrement it and drop runtime PM references to the supplier
device in a loop until rpm_active becones 1 again.
Fixes: ead18c23c263 ("driver core: Introduce device links reference counting")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/device.h')
-rw-r--r-- | include/linux/device.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/device.h b/include/linux/device.h index d0e452fd0bff..5f49d2eff6ed 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -853,7 +853,7 @@ struct device_link { struct list_head c_node; enum device_link_state status; u32 flags; - bool rpm_active; + refcount_t rpm_active; struct kref kref; #ifdef CONFIG_SRCU struct rcu_head rcu_head; |