diff options
author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-02-01 01:49:14 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-02-01 10:04:08 +0100 |
commit | e2f3cd831a280fc226118d9369bf3f77aab58c56 (patch) | |
tree | fcd245c394874d3055fd0aa4e2c487cbbf88b354 /drivers/base/core.c | |
parent | 5db25c9eb893df8f6b93c1d97b8006d768e1b6f5 (diff) | |
download | linux-e2f3cd831a280fc226118d9369bf3f77aab58c56.tar.bz2 |
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/core.c')
-rw-r--r-- | drivers/base/core.c | 45 |
1 files changed, 30 insertions, 15 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c index 50610cd87e71..8611385e44b5 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -165,6 +165,19 @@ 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. @@ -201,7 +214,6 @@ struct device_link *device_link_add(struct device *consumer, struct device *supplier, u32 flags) { struct device_link *link; - bool rpm_put_supplier = false; if (!consumer || !supplier || (flags & DL_FLAG_STATELESS && @@ -213,7 +225,6 @@ struct device_link *device_link_add(struct device *consumer, pm_runtime_put_noidle(supplier); return NULL; } - rpm_put_supplier = true; } device_links_write_lock(); @@ -249,6 +260,15 @@ struct device_link *device_link_add(struct device *consumer, if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER) link->flags |= DL_FLAG_AUTOREMOVE_SUPPLIER; + if (flags & DL_FLAG_PM_RUNTIME) { + if (!(link->flags & DL_FLAG_PM_RUNTIME)) { + device_link_rpm_prepare(consumer, supplier); + link->flags |= DL_FLAG_PM_RUNTIME; + } + if (flags & DL_FLAG_RPM_ACTIVE) + refcount_inc(&link->rpm_active); + } + kref_get(&link->kref); goto out; } @@ -257,20 +277,15 @@ struct device_link *device_link_add(struct device *consumer, if (!link) goto out; + refcount_set(&link->rpm_active, 1); + if (flags & DL_FLAG_PM_RUNTIME) { - if (flags & DL_FLAG_RPM_ACTIVE) { - link->rpm_active = true; - rpm_put_supplier = false; - } - 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); + if (flags & DL_FLAG_RPM_ACTIVE) + refcount_inc(&link->rpm_active); + + device_link_rpm_prepare(consumer, supplier); } + get_device(supplier); link->supplier = supplier; INIT_LIST_HEAD(&link->s_node); @@ -333,7 +348,7 @@ struct device_link *device_link_add(struct device *consumer, device_pm_unlock(); device_links_write_unlock(); - if (rpm_put_supplier) + if ((flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) && !link) pm_runtime_put(supplier); return link; |