[PATCH] cciss: Make cciss_seq_show handle holes in the h->drv[] array.

["Stephen M. Cameron" <scameron@beardog.cce.hp.com>]

From: Stephen M. Cameron <scameron@beardog.cce.hp.com>

cciss: Make cciss_seq_show handle holes in the h->drv[] array.
It is possible (and expected) for there to be holes in the h->drv[]
array, that is, some elements may be NULL pointers.  cciss_seq_show
needs to be made aware of this possibility to avoid an Oops.

To reproduce the Oops which this fixes:

1) Create two "arrays" in the Array Configuratino Utility and
   several logical drives on each array.
2) cat /proc/driver/cciss/cciss* in an infinite loop
3) delete some of the logical drives in the first "array."

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
---
 drivers/block/cciss.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 873e594..9291614 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -337,6 +337,9 @@ static int cciss_seq_show(struct seq_file *seq, void *v)
 	if (*pos > h->highest_lun)
 		return 0;
 
+	if (drv == NULL) /* it's possible for h->drv[] to have holes. */
+		return 0;
+
 	if (drv->heads == 0)
 		return 0;