Remove dependency on devlink_mutex during devlinks xarray iteration.
The reason is that devlink_register/unregister() functions taking
devlink_mutex would deadlock during devlink reload operation of devlink
instance which registers/unregisters nested devlink instances.
The devlinks xarray consistency is ensured internally by xarray.
There is a reference taken when working with devlink using
devlink_try_get(). But there is no guarantee that devlink pointer
picked during xarray iteration is not freed before devlink_try_get()
is called.
Make sure that devlink_try_get() works with valid pointer.
Achieve it by:
1) Splitting devlink_put() so the completion is sent only
after grace period. Completion unblocks the devlink_unregister()
routine, which is followed-up by devlink_free()
2) During devlinks xa_array iteration, get devlink pointer from xa_array
holding RCU read lock and taking reference using devlink_try_get()
before unlock.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
30bab7cdb5