hpsa: fix NULL dereference in hpsa_put_ctlr_into_performant_mode()

Initialize local variable trans_support before it is used rather than after. It is supposed to contain the value of a register on the controller containing bits that describe which transport modes the controller supports (e.g. "performant", "ioaccel1", "ioaccel2"). A NULL pointer dereference will almost certainly occur if trans_support is not initialized at the right point. If for example the uninitialized trans_support value does not have the bit set for ioaccel2 support when it should be, then ioaccel2_alloc_cmds_and_bft() will not get called as it should be and the h->ioaccel2_blockFetchTable array will remain NULL instead of being allocated. Too late, trans_support finally gets initialized with the correct value with ioaccel2 mode bit set, which later causes calc_bucket_map() to be called to fill in h->ioaccel2_blockFetchTable[]. However h->ioaccel2_blockFetchTable is NULL because it didn't get allocated because earlier trans_support wasn't initialized at the right point.

---
 drivers/scsi/hpsa.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

index 8cf4a0c..9a6e4a2 100644
@@ -7463,6 +7463,10 @@ static void hpsa_put_ctlr_into_performant_mode(struct ctlr_info *h)
 	if (hpsa_simple_mode)
 		return;
 
+	trans_support = readl(&(h->cfgtable->TransportSupport));
+	if (!(trans_support & PERFORMANT_MODE))
+		return;
+
 	/* Check for I/O accelerator mode support */
 	if (trans_support & CFGTBL_Trans_io_accel1) {
 		transMethod |= CFGTBL_Trans_io_accel1 |

@@ -7479,10 +7483,6 @@ static void hpsa_put_ctlr_into_performant_mode(struct ctlr_info *h)
 	}
 
 	/* TODO, check that this next line h->nreply_queues is correct */
-	trans_support = readl(&(h->cfgtable->TransportSupport));
-	if (!(trans_support & PERFORMANT_MODE))
-		return;
-
 	h->nreply_queues = h->msix_vector > 0 ? h->msix_vector : 1;
 	hpsa_get_max_perf_mode_cmds(h);
 	/* Performant mode ring buffer and supporting data structures */

1.7.1