[PATCH net-next 06/11] s390/qeth: simplify max MTU handling

Julian Wiedmann
2018-07-19T10:43:53Z

When the MPC initialization code discovers the HW-specific max MTU,
apply the resulting changes straight to the netdevice.

If this is the device's first initialization, also set its MTU
(HiperSockets: the max MTU; else: a layer-specific default value).
Then cap the current MTU by the new max MTU.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
---
drivers/s390/net/qeth_core.h | 2 -
drivers/s390/net/qeth_core_main.c | 82 +++++++++++++++++++++------------------
drivers/s390/net/qeth_l2_main.c | 1 -
drivers/s390/net/qeth_l3_main.c | 1 -
4 files changed, 45 insertions(+), 41 deletions(-)

diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h
index 04b900c7060d..6f02a6cbe59e 100644
--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -660,8 +660,6 @@ struct qeth_card_info {
int mac_bits;
enum qeth_card_types type;
enum qeth_link_types link_type;
- int initial_mtu;
- int max_mtu;
int broadcast_capable;
int unique_id;
bool layer_enforced;
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 39c429787c4d..ab3d63f98779 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -2278,19 +2278,42 @@ static int qeth_cm_setup(struct qeth_card *card)

}

-static int qeth_get_initial_mtu_for_card(struct qeth_card *card)
+static int qeth_update_max_mtu(struct qeth_card *card, unsigned int max_mtu)
{
- switch (card->info.type) {
- case QETH_CARD_TYPE_IQD:
- return card->info.max_mtu;
- case QETH_CARD_TYPE_OSD:
- case QETH_CARD_TYPE_OSX:
- if (!card->options.layer2)
- return ETH_DATA_LEN - 8; /* L3: allow for LLC + SNAP */
- /* fall through */
- default:
- return ETH_DATA_LEN;
+ struct net_device *dev = card->dev;
+ unsigned int new_mtu;
+
+ if (!max_mtu) {
+ /* IQD needs accurate max MTU to set up its RX buffers: */
+ if (IS_IQD(card))
+ return -EINVAL;
+ /* tolerate quirky HW: */
+ max_mtu = ETH_MAX_MTU;
+ }
+
+ rtnl_lock();
+ if (IS_IQD(card)) {
+ /* move any device with default MTU to new max MTU: */
+ new_mtu = (dev->mtu == dev->max_mtu) ? max_mtu : dev->mtu;
+
+ /* adjust RX buffer size to new max MTU: */
+ card->qdio.in_buf_size = max_mtu + 2 * PAGE_SIZE;
+ if (dev->max_mtu && dev->max_mtu != max_mtu)
+ qeth_free_qdio_buffers(card);
+ } else {
+ if (dev->mtu)
+ new_mtu = dev->mtu;
+ /* default MTUs for first setup: */
+ else if (card->options.layer2)
+ new_mtu = ETH_DATA_LEN;
+ else
+ new_mtu = ETH_DATA_LEN - 8; /* allow for LLC + SNAP */
}
+
+ dev->max_mtu = max_mtu;
+ dev->mtu = min(new_mtu, max_mtu);
+ rtnl_unlock();
+ return 0;
}

static int qeth_get_mtu_outof_framesize(int framesize)
@@ -2316,8 +2339,7 @@ static int qeth_mtu_is_valid(struct qeth_card *card, int mtu)
case QETH_CARD_TYPE_OSM:
case QETH_CARD_TYPE_OSX:
case QETH_CARD_TYPE_IQD:
- return ((mtu >= 576) &&
- (mtu <= card->info.max_mtu));
+ return ((mtu >= 576) && (mtu <= card->dev->max_mtu));
case QETH_CARD_TYPE_OSN:
default:
return 1;
@@ -2342,28 +2364,10 @@ static int qeth_ulp_enable_cb(struct qeth_card *card, struct qeth_reply *reply,
if (card->info.type == QETH_CARD_TYPE_IQD) {
memcpy(&framesize, QETH_ULP_ENABLE_RESP_MAX_MTU(iob->data), 2);
mtu = qeth_get_mtu_outof_framesize(framesize);
- if (!mtu) {
- iob->rc = -EINVAL;
- QETH_DBF_TEXT_(SETUP, 2, " rc%d", iob->rc);
- return 0;
- }
- if (card->info.initial_mtu && (card->info.initial_mtu != mtu)) {
- /* frame size has changed */
- if ((card->dev->mtu == card->info.initial_mtu) ||
- (card->dev->mtu > mtu))
- card->dev->mtu = mtu;
- qeth_free_qdio_buffers(card);
- }
- card->info.initial_mtu = mtu;
- card->info.max_mtu = mtu;
- card->qdio.in_buf_size = mtu + 2 * PAGE_SIZE;
} else {
- card->info.max_mtu = *(__u16 *)QETH_ULP_ENABLE_RESP_MAX_MTU(
- iob->data);
- card->info.initial_mtu = min(card->info.max_mtu,
- qeth_get_initial_mtu_for_card(card));
- card->qdio.in_buf_size = QETH_IN_BUF_SIZE_DEFAULT;
+ mtu = *(__u16 *)QETH_ULP_ENABLE_RESP_MAX_MTU(iob->data);
}
+ *(u16 *)reply->param = mtu;

memcpy(&len, QETH_ULP_ENABLE_RESP_DIFINFO_LEN(iob->data), 2);
if (len >= QETH_MPC_DIFINFO_LEN_INDICATES_LINK_TYPE) {
@@ -2382,6 +2386,7 @@ static int qeth_ulp_enable(struct qeth_card *card)
int rc;
char prot_type;
struct qeth_cmd_buffer *iob;
+ u16 max_mtu;

/*FIXME: trace view callbacks*/
QETH_DBF_TEXT(SETUP, 2, "ulpenabl");
@@ -2404,9 +2409,10 @@ static int qeth_ulp_enable(struct qeth_card *card)
memcpy(QETH_ULP_ENABLE_FILTER_TOKEN(iob->data),
&card->token.ulp_filter_w, QETH_MPC_TOKEN_LENGTH);
rc = qeth_send_control_data(card, ULP_ENABLE_SIZE, iob,
- qeth_ulp_enable_cb, NULL);
- return rc;
-
+ qeth_ulp_enable_cb, &max_mtu);
+ if (rc)
+ return rc;
+ return qeth_update_max_mtu(card, max_mtu);
}

static int qeth_ulp_setup_cb(struct qeth_card *card, struct qeth_reply *reply,
@@ -5691,7 +5697,9 @@ static struct net_device *qeth_alloc_netdev(struct qeth_card *card)
dev->ml_priv = card;
dev->watchdog_timeo = QETH_TX_TIMEOUT;
dev->min_mtu = 64;
- dev->max_mtu = ETH_MAX_MTU;
+ /* initialized when device first goes online: */
+ dev->max_mtu = 0;
+ dev->mtu = 0;
SET_NETDEV_DEV(dev, &card->gdev->dev);
netif_carrier_off(dev);
return dev;
diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index 8392fc7e809c..00d8bb1d2a41 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -944,7 +944,6 @@ static int qeth_l2_setup_netdev(struct qeth_card *card)
return 0;

card->dev->priv_flags |= IFF_UNICAST_FLT;
- card->dev->mtu = card->info.initial_mtu;
card->dev->netdev_ops = &qeth_l2_netdev_ops;
if (card->info.type == QETH_CARD_TYPE_OSN) {
card->dev->ethtool_ops = &qeth_l2_osn_ops;
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index 72c8f323801b..e5fa8e5ac1b3 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -2579,7 +2579,6 @@ static int qeth_l3_setup_netdev(struct qeth_card *card)
} else
return -ENODEV;

- card->dev->mtu = card->info.initial_mtu;
card->dev->ethtool_ops = &qeth_l3_ethtool_ops;
card->dev->priv_flags &= ~IFF_TX_SKB_SHARING;
card->dev->needed_headroom = sizeof(struct qeth_hdr) - ETH_HLEN;
--
2.16.4