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author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-02-01 01:49:14 +0100 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-02-01 10:04:08 +0100 |
commit | e2f3cd831a280fc226118d9369bf3f77aab58c56 (patch) | |
tree | fcd245c394874d3055fd0aa4e2c487cbbf88b354 /drivers/base/power | |
parent | 5db25c9eb893df8f6b93c1d97b8006d768e1b6f5 (diff) | |
download | talos-op-linux-e2f3cd831a280fc226118d9369bf3f77aab58c56.tar.gz talos-op-linux-e2f3cd831a280fc226118d9369bf3f77aab58c56.zip |
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 'drivers/base/power')
-rw-r--r-- | drivers/base/power/runtime.c | 26 |
1 files changed, 11 insertions, 15 deletions
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 457be03b744d..8bc9a432de70 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -259,11 +259,8 @@ static int rpm_get_suppliers(struct device *dev) list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) { int retval; - if (!(link->flags & DL_FLAG_PM_RUNTIME)) - continue; - - if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND || - link->rpm_active) + if (!(link->flags & DL_FLAG_PM_RUNTIME) || + READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND) continue; retval = pm_runtime_get_sync(link->supplier); @@ -272,7 +269,7 @@ static int rpm_get_suppliers(struct device *dev) pm_runtime_put_noidle(link->supplier); return retval; } - link->rpm_active = true; + refcount_inc(&link->rpm_active); } return 0; } @@ -281,12 +278,13 @@ static void rpm_put_suppliers(struct device *dev) { struct device_link *link; - list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) - if (link->rpm_active && - READ_ONCE(link->status) != DL_STATE_SUPPLIER_UNBIND) { + list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) { + if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND) + continue; + + while (refcount_dec_not_one(&link->rpm_active)) pm_runtime_put(link->supplier); - link->rpm_active = false; - } + } } /** @@ -1539,7 +1537,7 @@ void pm_runtime_remove(struct device *dev) * * Check links from this device to any consumers and if any of them have active * runtime PM references to the device, drop the usage counter of the device - * (once per link). + * (as many times as needed). * * Links with the DL_FLAG_STATELESS flag set are ignored. * @@ -1561,10 +1559,8 @@ void pm_runtime_clean_up_links(struct device *dev) if (link->flags & DL_FLAG_STATELESS) continue; - if (link->rpm_active) { + while (refcount_dec_not_one(&link->rpm_active)) pm_runtime_put_noidle(dev); - link->rpm_active = false; - } } device_links_read_unlock(idx); |