[PATCH net-next 09/12] ionic: change mtu without full queue rebuild

[Shannon Nelson]

We really don't need to tear down and rebuild the whole queue structure
when changing the MTU; we can simply stop the queues, clean and refill,
then restart the queues.

Signed-off-by: Shannon Nelson <snel...@pensando.io>
---
 .../net/ethernet/pensando/ionic/ionic_lif.c   | 45 ++++++++++++++++---
 1 file changed, 38 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/pensando/ionic/ionic_lif.c 
b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
index b77827e9355c..d82ae717bc6c 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_lif.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
@@ -36,6 +36,8 @@ static void ionic_lif_handle_fw_down(struct ionic_lif *lif);
 static void ionic_lif_handle_fw_up(struct ionic_lif *lif);
 static void ionic_lif_set_netdev_info(struct ionic_lif *lif);
 
+static void ionic_txrx_deinit(struct ionic_lif *lif);
+static int ionic_txrx_init(struct ionic_lif *lif);
 static int ionic_start_queues(struct ionic_lif *lif);
 static void ionic_stop_queues(struct ionic_lif *lif);
 static void ionic_lif_queue_identify(struct ionic_lif *lif);
@@ -593,6 +595,17 @@ static int ionic_qcqs_alloc(struct ionic_lif *lif)
        return err;
 }
 
+static void ionic_qcq_sanitize(struct ionic_qcq *qcq)
+{
+       qcq->q.tail_idx = 0;
+       qcq->q.head_idx = 0;
+       qcq->cq.tail_idx = 0;
+       qcq->cq.done_color = 1;
+       memset(qcq->q_base, 0, qcq->q_size);
+       memset(qcq->cq_base, 0, qcq->cq_size);
+       memset(qcq->sg_base, 0, qcq->sg_size);
+}
+
 static int ionic_lif_txq_init(struct ionic_lif *lif, struct ionic_qcq *qcq)
 {
        struct device *dev = lif->ionic->dev;
@@ -632,9 +645,7 @@ static int ionic_lif_txq_init(struct ionic_lif *lif, struct 
ionic_qcq *qcq)
        dev_dbg(dev, "txq_init.ver %d\n", ctx.cmd.q_init.ver);
        dev_dbg(dev, "txq_init.intr_index %d\n", ctx.cmd.q_init.intr_index);
 
-       q->tail_idx = 0;
-       q->head_idx = 0;
-       cq->tail_idx = 0;
+       ionic_qcq_sanitize(qcq);
 
        err = ionic_adminq_post_wait(lif, &ctx);
        if (err)
@@ -689,9 +700,7 @@ static int ionic_lif_rxq_init(struct ionic_lif *lif, struct 
ionic_qcq *qcq)
        dev_dbg(dev, "rxq_init.ver %d\n", ctx.cmd.q_init.ver);
        dev_dbg(dev, "rxq_init.intr_index %d\n", ctx.cmd.q_init.intr_index);
 
-       q->tail_idx = 0;
-       q->head_idx = 0;
-       cq->tail_idx = 0;
+       ionic_qcq_sanitize(qcq);
 
        err = ionic_adminq_post_wait(lif, &ctx);
        if (err)
@@ -1326,8 +1335,30 @@ static int ionic_change_mtu(struct net_device *netdev, 
int new_mtu)
                return err;
 
        netdev->mtu = new_mtu;
-       err = ionic_reset_queues(lif, NULL, NULL);
+       /* if we're not running, nothing more to do */
+       if (!netif_running(lif->netdev))
+               return 0;
+
+       /* stop and reinit the queues */
+       mutex_lock(&lif->queue_lock);
+       netif_device_detach(lif->netdev);
+       ionic_stop_queues(lif);
+       ionic_txrx_deinit(lif);
 
+       err = ionic_txrx_init(lif);
+       if (err)
+               goto err_out;
+
+       /* don't start the queues until we have link */
+       if (netif_carrier_ok(netdev)) {
+               err = ionic_start_queues(lif);
+               if (err)
+                       goto err_out;
+       }
+
+err_out:
+       netif_device_attach(lif->netdev);
+       mutex_unlock(&lif->queue_lock);
        return err;
 }
 
-- 
2.17.1