[PATCH] PM: sleep: Don't wait for SYNC_STATE_ONLY device links

[Pin-yen Lin]

Device links with DL_FLAG_SYNC_STATE_ONLY should not affect suspend
and resume, and functions like device_reorder_to_tail() and
device_link_add() doesn't try to reorder the consumers with such flag.

However, dpm_wait_for_consumers() and dpm_wait_for_suppliers() doesn't
check this flag before triggering dpm_wait, leading to potential hang
during suspend/resume.

Add DL_FLAG_SYNC_STATE_ONLY in dpm_wait_for_consumers() and
dpm_wait_for_suppliers() to fix this.

Fixes: 05ef983e0d65a ("driver core: Add device link support for SYNC_STATE_ONLY flag")
Signed-off-by: Pin-yen Lin <treapking@xxxxxxxxxxxx>
---

 drivers/base/power/main.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 2ea6e05e6ec90..3271f4af2cb65 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -282,7 +282,8 @@ static void dpm_wait_for_suppliers(struct device *dev, bool async)
 	 * walking.
 	 */
 	list_for_each_entry_rcu_locked(link, &dev->links.suppliers, c_node)
-		if (READ_ONCE(link->status) != DL_STATE_DORMANT)
+		if (READ_ONCE(link->status) != DL_STATE_DORMANT &&
+		    !device_link_test(link, DL_FLAG_SYNC_STATE_ONLY))
 			dpm_wait(link->supplier, async);
 
 	device_links_read_unlock(idx);
@@ -339,7 +340,8 @@ static void dpm_wait_for_consumers(struct device *dev, bool async)
 	 * unregistration).
 	 */
 	list_for_each_entry_rcu_locked(link, &dev->links.consumers, s_node)
-		if (READ_ONCE(link->status) != DL_STATE_DORMANT)
+		if (READ_ONCE(link->status) != DL_STATE_DORMANT &&
+		    !device_link_test(link, DL_FLAG_SYNC_STATE_ONLY))
 			dpm_wait(link->consumer, async);
 
 	device_links_read_unlock(idx);
-- 
2.51.0.384.g4c02a37b29-goog