[SCSI] hpsa: fix bug in adjust_hpsa_scsi_table

fix bug in adjust_hpsa_scsi_table which caused devices which have
changed size, etc. to do the wrong thing.

The problem was as follows:

The driver maintains its current idea of what devices are present
in the h->dev[] array.  When it updates this array, it scans the
hardware, and produces a new list of devices, call it sd[], for
scsi devices.

Then, it compares each item in h->dev[] vs. sd[], and any items which
are not present sd it removes from h->dev[], and any items present
in sd[], but different, it modifies in h->dev[].

Then, it looks for items in sd[] which are not present in h->dev[],
and adds those items into h->dev[].  All the while, it keeps track
of what items were added and removed to/from h->dev[].

Finally, it updates the SCSI mid-layer by removing and adding
the same devices it removed and added to/from h->dev[]. (modified
devices count as a remove then add.)

originally, when a "changed" device was discovered, it was
removed then added to h->dev[].  The item was added to the *end*
of h->dev[].  And, the item was removed from sd[] as well
(nulled out).  As it processed h->dev[], these newly added items
at the end of the list were encountered, and sd[] was searched,
but those items were nulled out.  So they ended up getting removed
immediately after they were added.

The solution is to have a way to replace items in the h->dev[]
array instead of doing a remove + add.  Then the "changed" items.
are not encountered a second time, and removed.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 20 insertions, 6 deletions

diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index 2764cb605693..6b40221a7220 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -675,6 +675,24 @@ lun_assigned:
         return 0;
 }
 
+/* Replace an entry from h->dev[] array. */
+static void hpsa_scsi_replace_entry(struct ctlr_info *h, int hostno,
+        int entry, struct hpsa_scsi_dev_t *new_entry,
+        struct hpsa_scsi_dev_t *added[], int *nadded,
+        struct hpsa_scsi_dev_t *removed[], int *nremoved)
+{
+        /* assumes h->devlock is held */
+        BUG_ON(entry < 0 || entry >= HPSA_MAX_SCSI_DEVS_PER_HBA);
+        removed[*nremoved] = h->dev[entry];
+        (*nremoved)++;
+        h->dev[entry] = new_entry;
+        added[*nadded] = new_entry;
+        (*nadded)++;
+        dev_info(&h->pdev->dev, "%s device c%db%dt%dl%d changed.\n",
+                scsi_device_type(new_entry->devtype), hostno, new_entry->bus,
+                        new_entry->target, new_entry->lun);
+}
+
 /* Remove an entry from h->dev[] array. */
 static void hpsa_scsi_remove_entry(struct ctlr_info *h, int hostno, int entry,
         struct hpsa_scsi_dev_t *removed[], int *nremoved)
@@ -835,12 +853,8 @@ static void adjust_hpsa_scsi_table(struct ctlr_info *h, int hostno,
                         continue; /* remove ^^^, hence i not incremented */
                 } else if (device_change == DEVICE_CHANGED) {
                         changes++;
-                        hpsa_scsi_remove_entry(h, hostno, i,
-                                removed, &nremoved);
-                        (void) hpsa_scsi_add_entry(h, hostno, sd[entry],
-                                added, &nadded);
-                        /* add can't fail, we just removed one. */
-
+                        hpsa_scsi_replace_entry(h, hostno, i, sd[entry],
+                                added, &nadded, removed, &nremoved);
                         /* Set it to NULL to prevent it from being freed
                          * at the bottom of hpsa_update_scsi_devices()
                          */