[PATCH] bnx2fc: reduce stack usage in __bnx2fc_enable

From: Arnd Bergmann
Date: Wed Oct 07 2015 - 09:11:27 EST


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.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Fixes: 2971ff67bd3 ("bnx2fc: Read npiv table from nvram and create vports.")
---
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.

diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
index d5cdc4776707..72ba0dfae3e0 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
@@ -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;
}

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