[SCSI] libsas: Clean up discovery failure handler code

sas_rphy_delete does two things: it removes the sas_rphy from the transport
layer and frees the sas_rphy.  This can be broken down into two functions,
sas_rphy_remove and sas_rphy_free; sas_rphy_remove is of interest to
sas_discover_root_expander because it calls functions that require
sas_rphy_add as a prerequisite and can fail (namely sas_discover_expander).
In that case, sas_discover_root_expander needs to be able to undo the effects
of sas_rphy_add yet leave the job of freeing the sas_rphy to the caller of
sas_discover_root_expander.

This patch also removes some unnecessary code from sas_discover_end_dev
to eliminate an unnecessary cycle of sas_notify_lldd_gone/found for SAS
devices, thus eliminating a sas_rphy_remove call (and fixing a race condition
where a SCSI target scan can come in between the gone and found call).
It also moves the sas_rphy_free calls into sas_discover_domain and
sas_ex_discover_end_dev to complement the sas_rphy_allocation via
sas_get_port_device.

This patch does not change the semantics of sas_rphy_delete.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/scsi/scsi_transport_sas.h b/include/scsi/scsi_transport_sas.h
index 45d58598c3ee..9aedc19820b0 100644
--- a/include/scsi/scsi_transport_sas.h
+++ b/include/scsi/scsi_transport_sas.h
@@ -182,6 +182,7 @@ extern struct sas_rphy *sas_end_device_alloc(struct sas_port *);
 extern struct sas_rphy *sas_expander_alloc(struct sas_port *, enum sas_device_type);
 void sas_rphy_free(struct sas_rphy *);
 extern int sas_rphy_add(struct sas_rphy *);
+extern void sas_rphy_remove(struct sas_rphy *);
 extern void sas_rphy_delete(struct sas_rphy *);
 extern int scsi_is_sas_rphy(const struct device *);