Date:   Tue, 31 Aug 2021 17:08:11 -0700
From:   Sukadev Bhattiprolu <sukadev@...ux.ibm.com>
To:     netdev@...r.kernel.org
Cc:     Brian King <brking@...ux.ibm.com>, cforno12@...ux.ibm.com,
        Dany Madden <drt@...ux.ibm.com>,
        Rick Lindsley <ricklind@...ux.ibm.com>
Subject: [PATCH net-next 8/9] ibmvnic: Reuse rx pools when possible

Rather than releasing the rx pools on and reallocating them on every
reset, reuse the rx pools unless the pool parameters (number of pools,
size of each pool or size of each buffer in a pool) have changed.

If the pool parameters changed, then release the old pools (if any)
and allocate new ones.

Specifically release rx pools, if:
	- adapter is removed,
	- pool parameters change during reset,
	- we encounter an error when opening the adapter in response
	  to a user request (in ibmvnic_open()).

and don't release them:
	- in __ibmvnic_close() or
	- on errors in __ibmvnic_open()

in the hope that we can reuse them on the next reset.

With these, reset_rx_pools() can be dropped because its optimzation is
now included in init_rx_pools() itself.

cleanup_rx_pools() releases all the skbs associated with the pool and
is called from ibmvnic_cleanup(), which is called on every reset. Since
we want to reuse skbs across resets, move cleanup_rx_pools() out of
ibmvnic_cleanup() and call it only when user closes the adapter.

Add two new adapter fields, ->prev_rx_buf_sz, ->prev_rx_pool_size to
keep track of the previous values and use them to decide whether to
reuse or realloc the pools.

Signed-off-by: Sukadev Bhattiprolu <sukadev@...ux.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 183 +++++++++++++++++++----------
 drivers/net/ethernet/ibm/ibmvnic.h |   3 +
 2 files changed, 122 insertions(+), 64 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 1bb5996c4313..ebd525b6fc87 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -368,20 +368,27 @@ static void replenish_rx_pool(struct ibmvnic_adapter *adapter,
 	 * be 0.
 	 */
 	for (i = ind_bufp->index; i < count; ++i) {
-		skb = netdev_alloc_skb(adapter->netdev, pool->buff_size);
+		index = pool->free_map[pool->next_free];
+
+		/* We maybe reusing the skb from earlier resets. Allocate
+		 * only if necessary. But since the LTB may have changed
+		 * during reset (see init_rx_pools()), update LTB below
+		 * even if reusing skb.
+		 */
+		skb = pool->rx_buff[index].skb;
 		if (!skb) {
-			dev_err(dev, "Couldn't replenish rx buff\n");
-			adapter->replenish_no_mem++;
-			break;
+			skb = netdev_alloc_skb(adapter->netdev,
+					       pool->buff_size);
+			if (!skb) {
+				dev_err(dev, "Couldn't replenish rx buff\n");
+				adapter->replenish_no_mem++;
+				break;
+			}
 		}
 
-		index = pool->free_map[pool->next_free];
 		pool->free_map[pool->next_free] = IBMVNIC_INVALID_MAP;
 		pool->next_free = (pool->next_free + 1) % pool->size;
 
-		if (pool->rx_buff[index].skb)
-			dev_err(dev, "Inconsistent free_map!\n");
-
 		/* Copy the skb to the long term mapped DMA buffer */
 		offset = index * pool->buff_size;
 		dst = pool->long_term_buff.buff + offset;
@@ -532,45 +539,6 @@ static int init_stats_token(struct ibmvnic_adapter *adapter)
 	return 0;
 }
 
-static int reset_rx_pools(struct ibmvnic_adapter *adapter)
-{
-	struct ibmvnic_rx_pool *rx_pool;
-	u64 buff_size;
-	int rx_scrqs;
-	int i, j, rc;
-
-	if (!adapter->rx_pool)
-		return -1;
-
-	buff_size = adapter->cur_rx_buf_sz;
-	rx_scrqs = adapter->num_active_rx_pools;
-	for (i = 0; i < rx_scrqs; i++) {
-		rx_pool = &adapter->rx_pool[i];
-
-		netdev_dbg(adapter->netdev, "Re-setting rx_pool[%d]\n", i);
-
-		rx_pool->buff_size = ALIGN(buff_size, L1_CACHE_BYTES);
-		rc = alloc_long_term_buff(adapter,
-					  &rx_pool->long_term_buff,
-					  rx_pool->size * rx_pool->buff_size);
-		if (rc)
-			return rc;
-
-		for (j = 0; j < rx_pool->size; j++)
-			rx_pool->free_map[j] = j;
-
-		memset(rx_pool->rx_buff, 0,
-		       rx_pool->size * sizeof(struct ibmvnic_rx_buff));
-
-		atomic_set(&rx_pool->available, 0);
-		rx_pool->next_alloc = 0;
-		rx_pool->next_free = 0;
-		rx_pool->active = 1;
-	}
-
-	return 0;
-}
-
 /**
  * Release any rx_pools attached to @adapter.
  * Safe to call this multiple times - even if no pools are attached.
@@ -589,6 +557,7 @@ static void release_rx_pools(struct ibmvnic_adapter *adapter)
 		netdev_dbg(adapter->netdev, "Releasing rx_pool[%d]\n", i);
 
 		kfree(rx_pool->free_map);
+
 		free_long_term_buff(adapter, &rx_pool->long_term_buff);
 
 		if (!rx_pool->rx_buff)
@@ -607,8 +576,53 @@ static void release_rx_pools(struct ibmvnic_adapter *adapter)
 	kfree(adapter->rx_pool);
 	adapter->rx_pool = NULL;
 	adapter->num_active_rx_pools = 0;
+	adapter->prev_rx_pool_size = 0;
+}
+
+/**
+ * Return true if we can reuse the existing rx pools.
+ * NOTE: This assumes that all pools have the same number of buffers
+ *       which is the case currently. If that changes, we must fix this.
+ */
+static bool reuse_rx_pools(struct ibmvnic_adapter *adapter)
+{
+	u64 old_num_pools, new_num_pools;
+	u64 old_pool_size, new_pool_size;
+	u64 old_buff_size, new_buff_size;
+
+	if (!adapter->rx_pool)
+		return false;
+
+	old_num_pools = adapter->num_active_rx_pools;
+	new_num_pools = adapter->req_rx_queues;
+
+	old_pool_size = adapter->prev_rx_pool_size;
+	new_pool_size = adapter->req_rx_add_entries_per_subcrq;
+
+	old_buff_size = adapter->prev_rx_buf_sz;
+	new_buff_size = adapter->cur_rx_buf_sz;
+
+	/* Require buff size to be exactly same for now */
+	if (old_buff_size != new_buff_size)
+		return false;
+
+	if (old_num_pools == new_num_pools && old_pool_size == new_pool_size)
+		return true;
+
+	if (old_num_pools < adapter->min_rx_queues ||
+	    old_num_pools > adapter->max_rx_queues ||
+	    old_pool_size < adapter->min_rx_add_entries_per_subcrq ||
+	    old_pool_size > adapter->max_rx_add_entries_per_subcrq)
+		return false;
+
+	return true;
 }
 
+/**
+ * Initialize the set of receiver pools in the adapter. Reuse existing
+ * pools if possible. Otherwise allocate a new set of pools before
+ * initializing them.
+ */
 static int init_rx_pools(struct net_device *netdev)
 {
 	struct ibmvnic_adapter *adapter = netdev_priv(netdev);
@@ -619,10 +633,18 @@ static int init_rx_pools(struct net_device *netdev)
 	u64 buff_size;
 	int i, j;
 
-	num_pools = adapter->num_active_rx_scrqs;
 	pool_size = adapter->req_rx_add_entries_per_subcrq;
+	num_pools = adapter->req_rx_queues;
 	buff_size = adapter->cur_rx_buf_sz;
 
+	if (reuse_rx_pools(adapter)) {
+		dev_dbg(dev, "Reusing rx pools\n");
+		goto update_ltb;
+	}
+
+	/* Allocate/populate the pools. */
+	release_rx_pools(adapter);
+
 	adapter->rx_pool = kcalloc(num_pools,
 				   sizeof(struct ibmvnic_rx_pool),
 				   GFP_KERNEL);
@@ -646,14 +668,12 @@ static int init_rx_pools(struct net_device *netdev)
 		rx_pool->size = pool_size;
 		rx_pool->index = i;
 		rx_pool->buff_size = ALIGN(buff_size, L1_CACHE_BYTES);
-		rx_pool->active = 1;
 
 		rx_pool->free_map = kcalloc(rx_pool->size, sizeof(int),
 					    GFP_KERNEL);
 		if (!rx_pool->free_map) {
 			dev_err(dev, "Couldn't alloc free_map %d\n", i);
-			release_rx_pools(adapter);
-			return -1;
+			goto out_release;
 		}
 
 		rx_pool->rx_buff = kcalloc(rx_pool->size,
@@ -661,25 +681,58 @@ static int init_rx_pools(struct net_device *netdev)
 					   GFP_KERNEL);
 		if (!rx_pool->rx_buff) {
 			dev_err(dev, "Couldn't alloc rx buffers\n");
-			release_rx_pools(adapter);
-			return -1;
+			goto out_release;
 		}
+	}
+
+	adapter->prev_rx_pool_size = pool_size;
+	adapter->prev_rx_buf_sz = adapter->cur_rx_buf_sz;
+
+update_ltb:
+	for (i = 0; i < num_pools; i++) {
+		rx_pool = &adapter->rx_pool[i];
+		dev_dbg(dev, "Updating LTB for rx pool %d [%d, %d]\n",
+			i, rx_pool->size, rx_pool->buff_size);
 
 		if (alloc_long_term_buff(adapter, &rx_pool->long_term_buff,
-					 rx_pool->size * rx_pool->buff_size)) {
-			release_rx_pools(adapter);
-			return -1;
-		}
+					 rx_pool->size * rx_pool->buff_size))
+			goto out;
+
+		for (j = 0; j < rx_pool->size; ++j) {
+			struct ibmvnic_rx_buff *rx_buff;
 
-		for (j = 0; j < rx_pool->size; ++j)
 			rx_pool->free_map[j] = j;
 
+			/* NOTE: Don't clear rx_buff->skb here - will leak
+			 * memory! replenish_rx_pool() will reuse skbs or
+			 * allocate as necessary.
+			 */
+			rx_buff = &rx_pool->rx_buff[j];
+			rx_buff->dma = 0;
+			rx_buff->data = 0;
+			rx_buff->size = 0;
+			rx_buff->pool_index = 0;
+		}
+
+		/* Mark pool "empty" so replenish_rx_pools() will
+		 * update the LTB info for each buffer
+		 */
 		atomic_set(&rx_pool->available, 0);
 		rx_pool->next_alloc = 0;
 		rx_pool->next_free = 0;
+		/* replenish_rx_pool() may have called deactivate_rx_pools()
+		 * on failover. Ensure pool is active now.
+		 */
+		rx_pool->active = 1;
 	}
-
 	return 0;
+out_release:
+	release_rx_pools(adapter);
+out:
+	/* We failed to allocate one or more LTBs or map them on the VIOS.
+	 * Hold onto the pools and any LTBs that we did allocate/map.
+	 */
+	return -1;
 }
 
 static int reset_one_tx_pool(struct ibmvnic_adapter *adapter,
@@ -1053,7 +1106,6 @@ static void release_resources(struct ibmvnic_adapter *adapter)
 	release_vpd_data(adapter);
 
 	release_tx_pools(adapter);
-	release_rx_pools(adapter);
 
 	release_napi(adapter);
 	release_login_buffer(adapter);
@@ -1326,6 +1378,7 @@ static int ibmvnic_open(struct net_device *netdev)
 		if (rc) {
 			netdev_err(netdev, "failed to initialize resources\n");
 			release_resources(adapter);
+			release_rx_pools(adapter);
 			goto out;
 		}
 	}
@@ -1455,7 +1508,6 @@ static void ibmvnic_cleanup(struct net_device *netdev)
 	ibmvnic_napi_disable(adapter);
 	ibmvnic_disable_irqs(adapter);
 
-	clean_rx_pools(adapter);
 	clean_tx_pools(adapter);
 }
 
@@ -1490,6 +1542,7 @@ static int ibmvnic_close(struct net_device *netdev)
 
 	rc = __ibmvnic_close(netdev);
 	ibmvnic_cleanup(netdev);
+	clean_rx_pools(adapter);
 
 	return rc;
 }
@@ -2218,7 +2271,6 @@ static int do_reset(struct ibmvnic_adapter *adapter,
 		    !adapter->rx_pool ||
 		    !adapter->tso_pool ||
 		    !adapter->tx_pool) {
-			release_rx_pools(adapter);
 			release_tx_pools(adapter);
 			release_napi(adapter);
 			release_vpd_data(adapter);
@@ -2235,9 +2287,10 @@ static int do_reset(struct ibmvnic_adapter *adapter,
 				goto out;
 			}
 
-			rc = reset_rx_pools(adapter);
+			rc = init_rx_pools(netdev);
 			if (rc) {
-				netdev_dbg(adapter->netdev, "reset rx pools failed (%d)\n",
+				netdev_dbg(netdev,
+					   "init rx pools failed (%d)\n",
 					   rc);
 				goto out;
 			}
@@ -5573,6 +5626,7 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
 	init_completion(&adapter->reset_done);
 	init_completion(&adapter->stats_done);
 	clear_bit(0, &adapter->resetting);
+	adapter->prev_rx_buf_sz = 0;
 
 	init_success = false;
 	do {
@@ -5673,6 +5727,7 @@ static void ibmvnic_remove(struct vio_dev *dev)
 	unregister_netdevice(netdev);
 
 	release_resources(adapter);
+	release_rx_pools(adapter);
 	release_sub_crqs(adapter, 1);
 	release_crq_queue(adapter);
 
diff --git a/drivers/net/ethernet/ibm/ibmvnic.h b/drivers/net/ethernet/ibm/ibmvnic.h
index e97f1aa98c05..b73a1b812368 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.h
+++ b/drivers/net/ethernet/ibm/ibmvnic.h
@@ -986,7 +986,10 @@ struct ibmvnic_adapter {
 	u32 num_active_rx_napi;
 	u32 num_active_tx_scrqs;
 	u32 num_active_tx_pools;
+
+	u32 prev_rx_pool_size;
 	u32 cur_rx_buf_sz;
+	u32 prev_rx_buf_sz;
 
 	struct tasklet_struct tasklet;
 	enum vnic_state state;
-- 
2.31.1

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