[PATCH v1 09/18] driver core: Allow only unprobed consumers for SYNC_STATE_ONLY device links

Saravana Kannan
2020-11-04T23:25:44Z

SYNC_STATE_ONLY device links only affect the behavior of sync_state()
callbacks. Specifically, they prevent sync_state() only callbacks from
being called on a device if one or more of its consumers haven't probed.

So, creating a SYNC_STATE_ONLY device link from an already probed
consumer is useless. So, don't allow creating such device links.

Signed-off-by: Saravana Kannan <saravanak@google.com>
---
drivers/base/core.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 1a1d9a55645c..4a0907574646 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -646,6 +646,17 @@ struct device_link *device_link_add(struct device *consumer,
goto out;
}

+ /*
+ * SYNC_STATE_ONLY links are useless once a consumer device has probed.
+ * So, only create it if the consumer hasn't probed yet.
+ */
+ if (flags & DL_FLAG_SYNC_STATE_ONLY &&
+ consumer->links.status != DL_DEV_NO_DRIVER &&
+ consumer->links.status != DL_DEV_PROBING) {
+ link = NULL;
+ goto out;
+ }
+
/*
* DL_FLAG_AUTOREMOVE_SUPPLIER indicates that the link will be needed
* longer than for DL_FLAG_AUTOREMOVE_CONSUMER and setting them both
--
2.29.1.341.ge80a0c044ae-goog