[SCSI] libsas: Don't issue commands to devices that have been hot-removed

sd will get hung up issuing commands to flush write cache if a SAS
device behind the expander is unplugged without warning.  Change libsas
to reject commands to domain devices that have already gone away.

[maciej.trela@intel.com: removed setting ->gone in sas_deform_port() to
 permit sync cache commands at module removal]

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Tested-by: Haipao Fan <haipao.fan@intel.com>
Signed-off-by: Maciej Trela <maciej.trela@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

4 files changed, 15 insertions, 0 deletions

diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index ddbade7beec9..e1a395b438ee 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -162,6 +162,10 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
         unsigned int xfer = 0;
         unsigned int si;
 
+        /* If the device fell off, no sense in issuing commands */
+        if (dev->gone)
+                return AC_ERR_SYSTEM;
+
         task = sas_alloc_task(GFP_ATOMIC);
         if (!task)
                 return AC_ERR_SYSTEM;
diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index 83dd5070a15c..61d81f858a5a 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -1724,6 +1724,7 @@ static void sas_unregister_ex_tree(struct domain_device *dev)
         struct domain_device *child, *n;
 
         list_for_each_entry_safe(child, n, &ex->children, siblings) {
+                child->gone = 1;
                 if (child->dev_type == EDGE_DEV ||
                     child->dev_type == FANOUT_DEV)
                         sas_unregister_ex_tree(child);
@@ -1744,6 +1745,7 @@ static void sas_unregister_devs_sas_addr(struct domain_device *parent,
                         &ex_dev->children, siblings) {
                         if (SAS_ADDR(child->sas_addr) ==
                             SAS_ADDR(phy->attached_sas_addr)) {
+                                child->gone = 1;
                                 if (child->dev_type == EDGE_DEV ||
                                     child->dev_type == FANOUT_DEV)
                                         sas_unregister_ex_tree(child);
@@ -1752,6 +1754,7 @@ static void sas_unregister_devs_sas_addr(struct domain_device *parent,
                                 break;
                         }
                 }
+                parent->gone = 1;
                 sas_disable_routing(parent, phy->attached_sas_addr);
         }
         memset(phy->attached_sas_addr, 0, SAS_ADDR_SIZE);
diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index f0cfba9a1fc8..1787bd2eb4a6 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -228,6 +228,13 @@ int sas_queuecommand(struct scsi_cmnd *cmd,
                         goto out;
                 }
 
+                /* If the device fell off, no sense in issuing commands */
+                if (dev->gone) {
+                        cmd->result = DID_BAD_TARGET << 16;
+                        scsi_done(cmd);
+                        goto out;
+                }
+
                 res = -ENOMEM;
                 task = sas_create_task(cmd, dev, GFP_ATOMIC);
                 if (!task)
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index d06e13be717b..3dec1949f69c 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -205,6 +205,7 @@ struct domain_device {
         };
 
         void *lldd_dev;
+        int gone;
 };
 
 struct sas_discovery_event {