From: Saravana Kannan saravanak@google.com
[ Upstream commit 8c3e315d4296421cd26b3300ee0ac117f0877f20 ]
When SYNC_STATE_ONLY support was added in commit 05ef983e0d65 ("driver core: Add device link support for SYNC_STATE_ONLY flag"), SYNC_STATE_ONLY links were treated similar to STATELESS links in terms of not blocking consumer probe if the supplier hasn't probed yet.
That caused a SYNC_STATE_ONLY device link's status to not get updated. Since SYNC_STATE_ONLY device link is no longer useful once the consumer probes, commit 21c27f06587d ("driver core: Fix SYNC_STATE_ONLY device link implementation") addresses the status update issue by deleting the SYNC_STATE_ONLY device link instead of complicating the status update code.
However, there are still some cases where we need to update the status of a SYNC_STATE_ONLY device link. This is because a SYNC_STATE_ONLY device link can later get converted into a normal MANAGED device link when a normal MANAGED device link is created between a supplier and consumer that already have a SYNC_STATE_ONLY device link between them.
If a SYNC_STATE_ONLY device link's status isn't maintained correctly till it's converted to a normal MANAGED device link, then the normal MANAGED device link will end up with a wrong link status. This can cause a warning stack trace[1] when the consumer device probes successfully.
This commit fixes the SYNC_STATE_ONLY device link status update issue where it wouldn't transition correctly from DL_STATE_DORMANT or DL_STATE_AVAILABLE to DL_STATE_CONSUMER_PROBE. It also resets the status back to DL_STATE_DORMANT or DL_STATE_AVAILABLE if the consumer probe fails.
[1] - https://lore.kernel.org/lkml/20200522204120.3b3c9ed6@apollo/ Fixes: 05ef983e0d65 ("driver core: Add device link support for SYNC_STATE_ONLY flag") Fixes: 21c27f06587d ("driver core: Fix SYNC_STATE_ONLY device link implementation") Reported-by: Michael Walle michael@walle.cc Tested-by: Michael Walle michael@walle.cc Signed-off-by: Saravana Kannan saravanak@google.com Reviewed-by: Rafael J. Wysocki rrafael.j.wysocki@intel.com Link: https://lore.kernel.org/r/20200526220928.49939-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/base/core.c | 34 ++++++++++++++++++++++++++-------- 1 file changed, 26 insertions(+), 8 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c index 0cad34f1eede..213106ed8a56 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -643,9 +643,17 @@ static void device_links_missing_supplier(struct device *dev) { struct device_link *link;
- list_for_each_entry(link, &dev->links.suppliers, c_node) - if (link->status == DL_STATE_CONSUMER_PROBE) + list_for_each_entry(link, &dev->links.suppliers, c_node) { + if (link->status != DL_STATE_CONSUMER_PROBE) + continue; + + if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) { WRITE_ONCE(link->status, DL_STATE_AVAILABLE); + } else { + WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY)); + WRITE_ONCE(link->status, DL_STATE_DORMANT); + } + } }
/** @@ -684,11 +692,11 @@ int device_links_check_suppliers(struct device *dev) device_links_write_lock();
list_for_each_entry(link, &dev->links.suppliers, c_node) { - if (!(link->flags & DL_FLAG_MANAGED) || - link->flags & DL_FLAG_SYNC_STATE_ONLY) + if (!(link->flags & DL_FLAG_MANAGED)) continue;
- if (link->status != DL_STATE_AVAILABLE) { + if (link->status != DL_STATE_AVAILABLE && + !(link->flags & DL_FLAG_SYNC_STATE_ONLY)) { device_links_missing_supplier(dev); ret = -EPROBE_DEFER; break; @@ -949,11 +957,21 @@ static void __device_links_no_driver(struct device *dev) if (!(link->flags & DL_FLAG_MANAGED)) continue;
- if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) + if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) { device_link_drop_managed(link); - else if (link->status == DL_STATE_CONSUMER_PROBE || - link->status == DL_STATE_ACTIVE) + continue; + } + + if (link->status != DL_STATE_CONSUMER_PROBE && + link->status != DL_STATE_ACTIVE) + continue; + + if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) { WRITE_ONCE(link->status, DL_STATE_AVAILABLE); + } else { + WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY)); + WRITE_ONCE(link->status, DL_STATE_DORMANT); + } }
dev->links.status = DL_DEV_NO_DRIVER;