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Subject[PATCH 27/30] hpsa: fix bug in adjust_hpsa_scsi_table
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From: Stephen M. Cameron <scameron@beardog.cce.hp.com>

hpsa: 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>
---
drivers/scsi/hpsa.c | 26 ++++++++++++++++++++------
1 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index 2764cb6..6b40221 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()
*/


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