[SCSI] libsas: fix loopback topology bug during discovery

In some test envirenment, there is loopback topology test. We should
handle this during discovery.

Signed-off-by: Jack Wang <jack_wang@usish.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index 505ffe35829..f3f693b772a 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -244,6 +244,11 @@ static int sas_ex_phy_discover_helper(struct domain_device *dev, u8 *disc_req,
                  * dev to host FIS as described in section G.5 of
                  * sas-2 r 04b */
                 dr = &((struct smp_resp *)disc_resp)->disc;
+                if (memcmp(dev->sas_addr, dr->attached_sas_addr,
+                          SAS_ADDR_SIZE) == 0) {
+                        sas_printk("Found loopback topology, just ignore it!\n");
+                        return 0;
+                }
                 if (!(dr->attached_dev_type == 0 &&
                       dr->attached_sata_dev))
                         break;