[SCSI] libsas: fix domain_device leak

Arrange for the deallocation of a struct domain_device object when it no
longer has:
1/ any children
2/ references by any scsi_targets
3/ references by a lldd

The comment about domain_device lifetime in
Documentation/scsi/libsas.txt is stale as it appears mainline never had
a version of a struct domain_device that was registered as a kobject.
We now manage domain_device reference counts on behalf of external
agents.

Reviewed-by: Jack Wang <jack_wang@usish.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 0 insertions, 15 deletions

diff --git a/Documentation/scsi/libsas.txt b/Documentation/scsi/libsas.txt
index aa54f54c4a50..3cc9c7843e15 100644
--- a/Documentation/scsi/libsas.txt
+++ b/Documentation/scsi/libsas.txt
@@ -398,21 +398,6 @@ struct sas_task {
         task_done -- callback when the task has finished execution
 };
 
-When an external entity, entity other than the LLDD or the
-SAS Layer, wants to work with a struct domain_device, it
-_must_ call kobject_get() when getting a handle on the
-device and kobject_put() when it is done with the device.
-
-This does two things:
-     A) implements proper kfree() for the device;
-     B) increments/decrements the kref for all players:
-     domain_device
-        all domain_device's ... (if past an expander)
-            port
-                host adapter
-                     pci device
-                         and up the ladder, etc.
-
 DISCOVERY
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