[SCSI] add missing scan mutex to scsi_scan_target()

This patch (as543) adds a private entry point to scsi_scan_target, for use
when the caller already owns the scan_mutex, and updates the kerneldoc for
that routine (which was badly out-of-date).  It converts scsi_scan_channel
to use the new entry point.  Lastly, it modifies scsi_get_host_dev to make
it acquire the scan_mutex, necessary since the routine adds a new
scsi_device even if it doesn't do any actual scanning.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 40 insertions, 27 deletions

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 19c9a232a754..76577fae60fa 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1276,27 +1276,8 @@ void scsi_rescan_device(struct device *dev)
 }
 EXPORT_SYMBOL(scsi_rescan_device);
 
-/**
- * scsi_scan_target - scan a target id, possibly including all LUNs on the
- *     target.
- * @sdevsca:    Scsi_Device handle for scanning
- * @shost:      host to scan
- * @channel:    channel to scan
- * @id:         target id to scan
- *
- * Description:
- *     Scan the target id on @shost, @channel, and @id. Scan at least LUN
- *     0, and possibly all LUNs on the target id.
- *
- *     Use the pre-allocated @sdevscan as a handle for the scanning. This
- *     function sets sdevscan->host, sdevscan->id and sdevscan->lun; the
- *     scanning functions modify sdevscan->lun.
- *
- *     First try a REPORT LUN scan, if that does not scan the target, do a
- *     sequential scan of LUNs on the target id.
- **/
-void scsi_scan_target(struct device *parent, unsigned int channel,
-                      unsigned int id, unsigned int lun, int rescan)
+static void __scsi_scan_target(struct device *parent, unsigned int channel,
+                unsigned int id, unsigned int lun, int rescan)
 {
         struct Scsi_Host *shost = dev_to_shost(parent);
         int bflags = 0;
@@ -1310,9 +1291,7 @@ void scsi_scan_target(struct device *parent, unsigned int channel,
                  */
                 return;
 
-
         starget = scsi_alloc_target(parent, channel, id);
-
         if (!starget)
                 return;
 
@@ -1358,6 +1337,33 @@ void scsi_scan_target(struct device *parent, unsigned int channel,
 
         put_device(&starget->dev);
 }
+
+/**
+ * scsi_scan_target - scan a target id, possibly including all LUNs on the
+ *     target.
+ * @parent:     host to scan
+ * @channel:    channel to scan
+ * @id:         target id to scan
+ * @lun:        Specific LUN to scan or SCAN_WILD_CARD
+ * @rescan:     passed to LUN scanning routines
+ *
+ * Description:
+ *     Scan the target id on @parent, @channel, and @id. Scan at least LUN 0,
+ *     and possibly all LUNs on the target id.
+ *
+ *     First try a REPORT LUN scan, if that does not scan the target, do a
+ *     sequential scan of LUNs on the target id.
+ **/
+void scsi_scan_target(struct device *parent, unsigned int channel,
+                      unsigned int id, unsigned int lun, int rescan)
+{
+        struct Scsi_Host *shost = dev_to_shost(parent);
+
+        down(&shost->scan_mutex);
+        if (scsi_host_scan_allowed(shost))
+                __scsi_scan_target(parent, channel, id, lun, rescan);
+        up(&shost->scan_mutex);
+}
 EXPORT_SYMBOL(scsi_scan_target);
 
 static void scsi_scan_channel(struct Scsi_Host *shost, unsigned int channel,
@@ -1383,10 +1389,12 @@ static void scsi_scan_channel(struct Scsi_Host *shost, unsigned int channel,
                                 order_id = shost->max_id - id - 1;
                         else
                                 order_id = id;
-                        scsi_scan_target(&shost->shost_gendev, channel, order_id, lun, rescan);
+                        __scsi_scan_target(&shost->shost_gendev, channel,
+                                        order_id, lun, rescan);
                 }
         else
-                scsi_scan_target(&shost->shost_gendev, channel, id, lun, rescan);
+                __scsi_scan_target(&shost->shost_gendev, channel,
+                                id, lun, rescan);
 }
 
 int scsi_scan_host_selected(struct Scsi_Host *shost, unsigned int channel,
@@ -1484,12 +1492,15 @@ void scsi_forget_host(struct Scsi_Host *shost)
  */
 struct scsi_device *scsi_get_host_dev(struct Scsi_Host *shost)
 {
-        struct scsi_device *sdev;
+        struct scsi_device *sdev = NULL;
         struct scsi_target *starget;
 
+        down(&shost->scan_mutex);
+        if (!scsi_host_scan_allowed(shost))
+                goto out;
         starget = scsi_alloc_target(&shost->shost_gendev, 0, shost->this_id);
         if (!starget)
-                return NULL;
+                goto out;
 
         sdev = scsi_alloc_sdev(starget, 0, NULL);
         if (sdev) {
@@ -1497,6 +1508,8 @@ struct scsi_device *scsi_get_host_dev(struct Scsi_Host *shost)
                 sdev->borken = 0;
         }
         put_device(&starget->dev);
+ out:
+        up(&shost->scan_mutex);
         return sdev;
 }
 EXPORT_SYMBOL(scsi_get_host_dev);