[PATCH 13/20] fcoe: Use NETIF_F_FCOE_MTU flag to set up max frame size (lport->mfs)

Robert Love
2009-10-21T23:28:14Z

From: Yi Zou <yi.zou@intel.com>

Add a define of FCOE_MTU as 2158 bytes and use FCOE_MTU when the LLD is found
to support NETIF_F_FCOE_MTU. The lport->mfs is then calculated out of the
2158 FCOE_MTU. Otherwise, we stick with the netdev->mtu, i.e., LAN MTU. Also,
change the notification on NETDEV_CHANGEMTU event to bypass changing mfs when
LAN MTU is changed if NETIF_F_FCOE_MTU is supported.

Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
---

drivers/scsi/fcoe/fcoe.c | 10 ++++++++--
drivers/scsi/fcoe/fcoe.h | 6 ++++++
2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index 8702c8d..c66b9fa 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -439,8 +439,12 @@ static int fcoe_netdev_config(struct fc_lport *lp, struct net_device *netdev)
* user-configured limit. If the MFS is too low, fcoe_link_ok()
* will return 0, so do this first.
*/
- mfs = netdev->mtu - (sizeof(struct fcoe_hdr) +
- sizeof(struct fcoe_crc_eof));
+ mfs = netdev->mtu;
+ if (netdev->features & NETIF_F_FCOE_MTU) {
+ mfs = FCOE_MTU;
+ FCOE_NETDEV_DBG(netdev, "Supports FCOE_MTU of %d bytes\n", mfs);
+ }
+ mfs -= (sizeof(struct fcoe_hdr) + sizeof(struct fcoe_crc_eof));
if (fc_set_mfs(lp, mfs))
return -EINVAL;

@@ -1570,6 +1574,8 @@ static int fcoe_device_notification(struct notifier_block *notifier,
case NETDEV_CHANGE:
break;
case NETDEV_CHANGEMTU:
+ if (netdev->features & NETIF_F_FCOE_MTU)
+ break;
mfs = netdev->mtu - (sizeof(struct fcoe_hdr) +
sizeof(struct fcoe_crc_eof));
if (mfs >= FC_MIN_MAX_FRAME)
diff --git a/drivers/scsi/fcoe/fcoe.h b/drivers/scsi/fcoe/fcoe.h
index ce7f60f..c578082 100644
--- a/drivers/scsi/fcoe/fcoe.h
+++ b/drivers/scsi/fcoe/fcoe.h
@@ -40,6 +40,12 @@
#define FCOE_MIN_XID 0x0000 /* the min xid supported by fcoe_sw */
#define FCOE_MAX_XID 0x0FFF /* the max xid supported by fcoe_sw */

+/*
+ * Max MTU for FCoE: 14 (FCoE header) + 24 (FC header) + 2112 (max FC payload)
+ * + 4 (FC CRC) + 4 (FCoE trailer) = 2158 bytes
+ */
+#define FCOE_MTU 2158
+
unsigned int fcoe_debug_logging;
module_param_named(debug_logging, fcoe_debug_logging, int, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(debug_logging, "a bit mask of logging levels");