[SCSI] host state model update: mediate host add/remove race

Add support to not allow additions to a host when it is being removed.

Signed-off-by: Mike Anderson <andmike@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

3 files changed, 25 insertions, 7 deletions

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 67c4c0c3aa5e..8640ad1c17e2 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -133,7 +133,9 @@ EXPORT_SYMBOL(scsi_host_set_state);
  **/
 void scsi_remove_host(struct Scsi_Host *shost)
 {
+        down(&shost->scan_mutex);
         scsi_host_set_state(shost, SHOST_CANCEL);
+        up(&shost->scan_mutex);
         scsi_forget_host(shost);
         scsi_proc_host_rm(shost);
 
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 2d3c4ac475f2..076cbe3b5a05 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1251,9 +1251,12 @@ struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel,
 
         get_device(&starget->dev);
         down(&shost->scan_mutex);
-        res = scsi_probe_and_add_lun(starget, lun, NULL, &sdev, 1, hostdata);
-        if (res != SCSI_SCAN_LUN_PRESENT)
-                sdev = ERR_PTR(-ENODEV);
+        if (scsi_host_scan_allowed(shost)) {
+                res = scsi_probe_and_add_lun(starget, lun, NULL, &sdev, 1,
+                                             hostdata);
+                if (res != SCSI_SCAN_LUN_PRESENT)
+                        sdev = ERR_PTR(-ENODEV);
+        }
         up(&shost->scan_mutex);
         scsi_target_reap(starget);
         put_device(&starget->dev);
@@ -1403,11 +1406,15 @@ int scsi_scan_host_selected(struct Scsi_Host *shost, unsigned int channel,
                 return -EINVAL;
 
         down(&shost->scan_mutex);
-        if (channel == SCAN_WILD_CARD) 
-                for (channel = 0; channel <= shost->max_channel; channel++)
+        if (scsi_host_scan_allowed(shost)) {
+                if (channel == SCAN_WILD_CARD)
+                        for (channel = 0; channel <= shost->max_channel;
+                             channel++)
+                                scsi_scan_channel(shost, channel, id, lun,
+                                                  rescan);
+                else
                         scsi_scan_channel(shost, channel, id, lun, rescan);
-        else
-                scsi_scan_channel(shost, channel, id, lun, rescan);
+        }
         up(&shost->scan_mutex);
 
         return 0;
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 0b1e275b2699..1ea5b51d1749 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -650,6 +650,15 @@ static inline struct device *scsi_get_device(struct Scsi_Host *shost)
         return shost->shost_gendev.parent;
 }
 
+/**
+ * scsi_host_scan_allowed - Is scanning of this host allowed
+ * @shost:      Pointer to Scsi_Host.
+ **/
+static inline int scsi_host_scan_allowed(struct Scsi_Host *shost)
+{
+        return shost->shost_state == SHOST_RUNNING;
+}
+
 extern void scsi_unblock_requests(struct Scsi_Host *);
 extern void scsi_block_requests(struct Scsi_Host *);