bnx2fc: reduce stack usage in __bnx2fc_enable

When the bnx2fc driver was changed to read the npiv table from nvram, the stack of the __bnx2fc_enable function gained an additional 1028 byte structure that gcc rightfully warns about:

drivers/scsi/bnx2fc/bnx2fc_fcoe.c: In function '__bnx2fc_enable':
drivers/scsi/bnx2fc/bnx2fc_fcoe.c:2134:1: warning: the frame size of 1128 bytes is larger than 1024 bytes [-Wframe-larger-than=]

In order to avoid a possible kernel stack overflow and to get rid of the warning, this changes the function to use a dynamic allocation of the structure using kzalloc.

---
The original patch was merged through netdev along with the respective ethernet driver changes, but this should probably go through the scsi tree, as no ethernet changes are involved.

index d5cdc4776707..72ba0dfae3e0 100644
@@ -2092,7 +2092,7 @@ static int __bnx2fc_enable(struct fcoe_ctlr *ctlr)
 {
 	struct bnx2fc_interface *interface = fcoe_ctlr_priv(ctlr);
 	struct bnx2fc_hba *hba;
-	struct cnic_fc_npiv_tbl npiv_tbl;
+	struct cnic_fc_npiv_tbl *npiv_tbl;
 	struct fc_lport *lport;
 
 	if (interface->enabled == false) {

@@ -2124,11 +2124,16 @@ static int __bnx2fc_enable(struct fcoe_ctlr *ctlr)
 	if (!hba->cnic->get_fc_npiv_tbl)
 		goto done;
 
-	memset(&npiv_tbl, 0, sizeof(npiv_tbl));
-	if (hba->cnic->get_fc_npiv_tbl(hba->cnic, &npiv_tbl))
+	npiv_tbl = kzalloc(sizeof(struct cnic_fc_npiv_tbl), GFP_KERNEL);
+	if (!npiv_tbl)
 		goto done;
 
-	bnx2fc_npiv_create_vports(lport, &npiv_tbl);
+	if (hba->cnic->get_fc_npiv_tbl(hba->cnic, npiv_tbl))
+		goto done_free;
+
+	bnx2fc_npiv_create_vports(lport, npiv_tbl);
+done_free:
+	kfree(npiv_tbl);
 done:
 	return 0;
 }

Hi,

The enablement of the fcoe interface can still proceed if this particular allocation fails so returning 0 would be appropriate here.

This patch looks good to me.