[PATCH v8 04/12] PCI: liveupdate: Document driver binding responsibilities

Document how driver binding works during a Live Update and what the PCI
core expects of drivers and users. Note that this is only a description
of the current division of responsibilities. These can change in the
future if we decide.

Reviewed-by: Pasha Tatashin <[email protected]>
Reviewed-by: Pranjal Shrivastava <[email protected]>
Reviewed-by: Samiullah Khawaja <[email protected]>
Signed-off-by: David Matlack <[email protected]>
---
 drivers/pci/liveupdate.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c
index 5ce5f8b36902..0f7a018ddc66 100644
--- a/drivers/pci/liveupdate.c
+++ b/drivers/pci/liveupdate.c
@@ -71,6 +71,22 @@
  *
  *  * The device cannot be a Virtual Function (VF).
  *  * The device cannot be behind a PCI-to-PCI bridge.
+ *
+ * Driver Binding
+ * ==============
+ *
+ * In the outgoing kernel, it is the driver's responsibility to ensure that it
+ * does not release a device between pci_liveupdate_preserve() and
+ * pci_liveupdate_unpreserve().
+ *
+ * In the incoming kernel, it is the driver's responsibility to ensure that it
+ * does not release a preserved device between probe() and
+ * pci_liveupdate_finish().
+ *
+ * It is the user's responsibility to ensure that incoming preserved devices are
+ * bound to the correct driver. i.e. The PCI core does not protect against a
+ * device getting preserved by driver A in the outgoing kernel and then getting
+ * bound to driver B in the incoming kernel. This may change in the future.
  */
 
 #define pr_fmt(fmt) "PCI: liveupdate: " fmt
-- 
2.55.0.487.gaf234c4eb3-goog