sfc: Allow changing the DMA ring sizes dynamically via ethtool

This requires some reorganisation of channel setup and teardown to
ensure that we can always roll-back a failed change.

Based on work by Steve Hodgson <shodgson@solarflare.com>

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 172 insertions, 46 deletions

diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
index 6166e220716..f702f1fb63b 100644
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -201,10 +201,13 @@ MODULE_PARM_DESC(debug, "Bitmapped debugging message enable value");
  * Utility functions and prototypes
  *
  *************************************************************************/
-static void efx_remove_channel(struct efx_channel *channel);
+
+static void efx_remove_channels(struct efx_nic *efx);
 static void efx_remove_port(struct efx_nic *efx);
 static void efx_fini_napi(struct efx_nic *efx);
-static void efx_fini_channels(struct efx_nic *efx);
+static void efx_fini_struct(struct efx_nic *efx);
+static void efx_start_all(struct efx_nic *efx);
+static void efx_stop_all(struct efx_nic *efx);
 
 #define EFX_ASSERT_RESET_SERIALISED(efx)                \
         do {                                            \
@@ -413,6 +416,63 @@ static void efx_remove_eventq(struct efx_channel *channel)
  *
  *************************************************************************/
 
+/* Allocate and initialise a channel structure, optionally copying
+ * parameters (but not resources) from an old channel structure. */
+static struct efx_channel *
+efx_alloc_channel(struct efx_nic *efx, int i, struct efx_channel *old_channel)
+{
+        struct efx_channel *channel;
+        struct efx_rx_queue *rx_queue;
+        struct efx_tx_queue *tx_queue;
+        int j;
+
+        if (old_channel) {
+                channel = kmalloc(sizeof(*channel), GFP_KERNEL);
+                if (!channel)
+                        return NULL;
+
+                *channel = *old_channel;
+
+                memset(&channel->eventq, 0, sizeof(channel->eventq));
+
+                rx_queue = &channel->rx_queue;
+                rx_queue->buffer = NULL;
+                memset(&rx_queue->rxd, 0, sizeof(rx_queue->rxd));
+
+                for (j = 0; j < EFX_TXQ_TYPES; j++) {
+                        tx_queue = &channel->tx_queue[j];
+                        if (tx_queue->channel)
+                                tx_queue->channel = channel;
+                        tx_queue->buffer = NULL;
+                        memset(&tx_queue->txd, 0, sizeof(tx_queue->txd));
+                }
+        } else {
+                channel = kzalloc(sizeof(*channel), GFP_KERNEL);
+                if (!channel)
+                        return NULL;
+
+                channel->efx = efx;
+                channel->channel = i;
+
+                for (j = 0; j < EFX_TXQ_TYPES; j++) {
+                        tx_queue = &channel->tx_queue[j];
+                        tx_queue->efx = efx;
+                        tx_queue->queue = i * EFX_TXQ_TYPES + j;
+                        tx_queue->channel = channel;
+                }
+        }
+
+        spin_lock_init(&channel->tx_stop_lock);
+        atomic_set(&channel->tx_stop_count, 1);
+
+        rx_queue = &channel->rx_queue;
+        rx_queue->efx = efx;
+        setup_timer(&rx_queue->slow_fill, efx_rx_slow_fill,
+                    (unsigned long)rx_queue);
+
+        return channel;
+}
+
 static int efx_probe_channel(struct efx_channel *channel)
 {
         struct efx_tx_queue *tx_queue;
@@ -469,11 +529,38 @@ static void efx_set_channel_names(struct efx_nic *efx)
                                 number -= efx->n_rx_channels;
                         }
                 }
-                snprintf(channel->name, sizeof(channel->name),
+                snprintf(efx->channel_name[channel->channel],
+                         sizeof(efx->channel_name[0]),
                          "%s%s-%d", efx->name, type, number);
         }
 }
 
+static int efx_probe_channels(struct efx_nic *efx)
+{
+        struct efx_channel *channel;
+        int rc;
+
+        /* Restart special buffer allocation */
+        efx->next_buffer_table = 0;
+
+        efx_for_each_channel(channel, efx) {
+                rc = efx_probe_channel(channel);
+                if (rc) {
+                        netif_err(efx, probe, efx->net_dev,
+                                  "failed to create channel %d\n",
+                                  channel->channel);
+                        goto fail;
+                }
+        }
+        efx_set_channel_names(efx);
+
+        return 0;
+
+fail:
+        efx_remove_channels(efx);
+        return rc;
+}
+
 /* Channels are shutdown and reinitialised whilst the NIC is running
  * to propagate configuration changes (mtu, checksum offload), or
  * to clear hardware error conditions
@@ -611,6 +698,75 @@ static void efx_remove_channel(struct efx_channel *channel)
         efx_remove_eventq(channel);
 }
 
+static void efx_remove_channels(struct efx_nic *efx)
+{
+        struct efx_channel *channel;
+
+        efx_for_each_channel(channel, efx)
+                efx_remove_channel(channel);
+}
+
+int
+efx_realloc_channels(struct efx_nic *efx, u32 rxq_entries, u32 txq_entries)
+{
+        struct efx_channel *other_channel[EFX_MAX_CHANNELS], *channel;
+        u32 old_rxq_entries, old_txq_entries;
+        unsigned i;
+        int rc;
+
+        efx_stop_all(efx);
+        efx_fini_channels(efx);
+
+        /* Clone channels */
+        memset(other_channel, 0, sizeof(other_channel));
+        for (i = 0; i < efx->n_channels; i++) {
+                channel = efx_alloc_channel(efx, i, efx->channel[i]);
+                if (!channel) {
+                        rc = -ENOMEM;
+                        goto out;
+                }
+                other_channel[i] = channel;
+        }
+
+        /* Swap entry counts and channel pointers */
+        old_rxq_entries = efx->rxq_entries;
+        old_txq_entries = efx->txq_entries;
+        efx->rxq_entries = rxq_entries;
+        efx->txq_entries = txq_entries;
+        for (i = 0; i < efx->n_channels; i++) {
+                channel = efx->channel[i];
+                efx->channel[i] = other_channel[i];
+                other_channel[i] = channel;
+        }
+
+        rc = efx_probe_channels(efx);
+        if (rc)
+                goto rollback;
+
+        /* Destroy old channels */
+        for (i = 0; i < efx->n_channels; i++)
+                efx_remove_channel(other_channel[i]);
+out:
+        /* Free unused channel structures */
+        for (i = 0; i < efx->n_channels; i++)
+                kfree(other_channel[i]);
+
+        efx_init_channels(efx);
+        efx_start_all(efx);
+        return rc;
+
+rollback:
+        /* Swap back */
+        efx->rxq_entries = old_rxq_entries;
+        efx->txq_entries = old_txq_entries;
+        for (i = 0; i < efx->n_channels; i++) {
+                channel = efx->channel[i];
+                efx->channel[i] = other_channel[i];
+                other_channel[i] = channel;
+        }
+        goto out;
+}
+
 void efx_schedule_slow_fill(struct efx_rx_queue *rx_queue)
 {
         mod_timer(&rx_queue->slow_fill, jiffies + msecs_to_jiffies(100));
@@ -1182,41 +1338,28 @@ static void efx_remove_nic(struct efx_nic *efx)
 
 static int efx_probe_all(struct efx_nic *efx)
 {
-        struct efx_channel *channel;
         int rc;
 
-        /* Create NIC */
         rc = efx_probe_nic(efx);
         if (rc) {
                 netif_err(efx, probe, efx->net_dev, "failed to create NIC\n");
                 goto fail1;
         }
 
-        /* Create port */
         rc = efx_probe_port(efx);
         if (rc) {
                 netif_err(efx, probe, efx->net_dev, "failed to create port\n");
                 goto fail2;
         }
 
-        /* Create channels */
         efx->rxq_entries = efx->txq_entries = EFX_DEFAULT_DMAQ_SIZE;
-        efx_for_each_channel(channel, efx) {
-                rc = efx_probe_channel(channel);
-                if (rc) {
-                        netif_err(efx, probe, efx->net_dev,
-                                  "failed to create channel %d\n",
-                                  channel->channel);
-                        goto fail3;
-                }
-        }
-        efx_set_channel_names(efx);
+        rc = efx_probe_channels(efx);
+        if (rc)
+                goto fail3;
 
         return 0;
 
  fail3:
-        efx_for_each_channel(channel, efx)
-                efx_remove_channel(channel);
         efx_remove_port(efx);
  fail2:
         efx_remove_nic(efx);
@@ -1346,10 +1489,7 @@ static void efx_stop_all(struct efx_nic *efx)
 
 static void efx_remove_all(struct efx_nic *efx)
 {
-        struct efx_channel *channel;
-
-        efx_for_each_channel(channel, efx)
-                efx_remove_channel(channel);
+        efx_remove_channels(efx);
         efx_remove_port(efx);
         efx_remove_nic(efx);
 }
@@ -2058,10 +2198,7 @@ static struct efx_phy_operations efx_dummy_phy_operations = {
 static int efx_init_struct(struct efx_nic *efx, struct efx_nic_type *type,
                            struct pci_dev *pci_dev, struct net_device *net_dev)
 {
-        struct efx_channel *channel;
-        struct efx_tx_queue *tx_queue;
-        struct efx_rx_queue *rx_queue;
-        int i, j;
+        int i;
 
         /* Initialise common structures */
         memset(efx, 0, sizeof(*efx));
@@ -2089,24 +2226,9 @@ static int efx_init_struct(struct efx_nic *efx, struct efx_nic_type *type,
         INIT_WORK(&efx->mac_work, efx_mac_work);
 
         for (i = 0; i < EFX_MAX_CHANNELS; i++) {
-                efx->channel[i] = kzalloc(sizeof(*channel), GFP_KERNEL);
-                channel = efx->channel[i];
-                channel->efx = efx;
-                channel->channel = i;
-                spin_lock_init(&channel->tx_stop_lock);
-                atomic_set(&channel->tx_stop_count, 1);
-
-                for (j = 0; j < EFX_TXQ_TYPES; j++) {
-                        tx_queue = &channel->tx_queue[j];
-                        tx_queue->efx = efx;
-                        tx_queue->queue = i * EFX_TXQ_TYPES + j;
-                        tx_queue->channel = channel;
-                }
-
-                rx_queue = &channel->rx_queue;
-                rx_queue->efx = efx;
-                setup_timer(&rx_queue->slow_fill, efx_rx_slow_fill,
-                            (unsigned long)rx_queue);
+                efx->channel[i] = efx_alloc_channel(efx, i, NULL);
+                if (!efx->channel[i])
+                        goto fail;
         }
 
         efx->type = type;
@@ -2122,9 +2244,13 @@ static int efx_init_struct(struct efx_nic *efx, struct efx_nic_type *type,
                  pci_name(pci_dev));
         efx->workqueue = create_singlethread_workqueue(efx->workqueue_name);
         if (!efx->workqueue)
-                return -ENOMEM;
+                goto fail;
 
         return 0;
+
+fail:
+        efx_fini_struct(efx);
+        return -ENOMEM;
 }
 
 static void efx_fini_struct(struct efx_nic *efx)