ibmvnic: Allow multiple ltbs in txpool ltb_set

Allow multiple LTBs in the txpool's ltb_set. i.e rather than using
a single large LTB, use several smaller LTBs.

The first n-1 LTBs will all be of the same size. The size of the last
LTB in the set depends on the number of buffers and buffer (mtu) size.
This strategy hopefully allows more reuse of the initial LTBs and also
reduces the chances of an allocation failure (of the large LTB) when
system is low in memory.
Suggested-by: Brian King <brking@linux.ibm.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
Signed-off-by: Dany Madden <drt@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/ibm/ibmvnic.c

@@ -257,12 +257,14 @@ static int alloc_long_term_buff(struct ibmvnic_adapter *adapter,
 				struct ibmvnic_long_term_buff *ltb, int size)
 {
 	struct device *dev = &adapter->vdev->dev;
+	u64 prev = 0;
 	int rc;
 
 	if (!reuse_ltb(ltb, size)) {
 		dev_dbg(dev,
 			"LTB size changed from 0x%llx to 0x%x, reallocating\n",
 			 ltb->size, size);
+		prev = ltb->size;
 		free_long_term_buff(adapter, ltb);
 	}
 
@@ -283,8 +285,8 @@ static int alloc_long_term_buff(struct ibmvnic_adapter *adapter,
 		bitmap_set(adapter->map_ids, ltb->map_id, 1);
 
 		dev_dbg(dev,
-			"Allocated new LTB [map %d, size 0x%llx]\n",
-			 ltb->map_id, ltb->size);
+			"Allocated new LTB [map %d, size 0x%llx was 0x%llx]\n",
+			 ltb->map_id, ltb->size, prev);
 	}
 
 	/* Ensure ltb is zeroed - specially when reusing it. */
@@ -529,7 +531,21 @@ static void map_txpool_buf_to_ltb(struct ibmvnic_tx_pool *txpool,
 				  struct ibmvnic_long_term_buff **ltbp,
 				  unsigned int *offset)
 {
-	*ltbp = &txpool->long_term_buff;
+	struct ibmvnic_long_term_buff *ltb;
+	int nbufs;	/* # of buffers in one ltb */
+	int i;
+
+	WARN_ON_ONCE(bufidx >= txpool->num_buffers);
+
+	for (i = 0; i < txpool->ltb_set.num_ltbs; i++) {
+		ltb = &txpool->ltb_set.ltbs[i];
+		nbufs = ltb->size / txpool->buf_size;
+		if (bufidx < nbufs)
+			break;
+		bufidx -= nbufs;
+	}
+
+	*ltbp = ltb;
 	*offset = bufidx * txpool->buf_size;
 }
 
@@ -971,7 +987,7 @@ static void release_one_tx_pool(struct ibmvnic_adapter *adapter,
 {
 	kfree(tx_pool->tx_buff);
 	kfree(tx_pool->free_map);
-	free_long_term_buff(adapter, &tx_pool->long_term_buff);
+	free_ltb_set(adapter, &tx_pool->ltb_set);
 }
 
 /**
@@ -1161,17 +1177,16 @@ static int init_tx_pools(struct net_device *netdev)
 	for (i = 0; i < num_pools; i++) {
 		struct ibmvnic_tx_pool *tso_pool;
 		struct ibmvnic_tx_pool *tx_pool;
-		u32 ltb_size;
 
 		tx_pool = &adapter->tx_pool[i];
-		ltb_size = tx_pool->num_buffers * tx_pool->buf_size;
-		if (alloc_long_term_buff(adapter, &tx_pool->long_term_buff,
-					 ltb_size))
-			goto out;
 
-		dev_dbg(dev, "Updated LTB for tx pool %d [%p, %d, %d]\n",
-			i, tx_pool->long_term_buff.buff,
-			tx_pool->num_buffers, tx_pool->buf_size);
+		dev_dbg(dev, "Updating LTB for tx pool %d [%d, %d]\n",
+			i, tx_pool->num_buffers, tx_pool->buf_size);
+
+		rc = alloc_ltb_set(adapter, &tx_pool->ltb_set,
+				   tx_pool->num_buffers, tx_pool->buf_size);
+		if (rc)
+			goto out;
 
 		tx_pool->consumer_index = 0;
 		tx_pool->producer_index = 0;
@@ -1180,14 +1195,14 @@ static int init_tx_pools(struct net_device *netdev)
 			tx_pool->free_map[j] = j;
 
 		tso_pool = &adapter->tso_pool[i];
-		ltb_size = tso_pool->num_buffers * tso_pool->buf_size;
-		if (alloc_long_term_buff(adapter, &tso_pool->long_term_buff,
-					 ltb_size))
-			goto out;
 
-		dev_dbg(dev, "Updated LTB for tso pool %d [%p, %d, %d]\n",
-			i, tso_pool->long_term_buff.buff,
-			tso_pool->num_buffers, tso_pool->buf_size);
+		dev_dbg(dev, "Updating LTB for tso pool %d [%d, %d]\n",
+			i, tso_pool->num_buffers, tso_pool->buf_size);
+
+		rc = alloc_ltb_set(adapter, &tso_pool->ltb_set,
+				   tso_pool->num_buffers, tso_pool->buf_size);
+		if (rc)
+			goto out;
 
 		tso_pool->consumer_index = 0;
 		tso_pool->producer_index = 0;

drivers/net/ethernet/ibm/ibmvnic.h

@@ -856,7 +856,7 @@ struct ibmvnic_tx_pool {
 	int *free_map;
 	int consumer_index;
 	int producer_index;
-	struct ibmvnic_long_term_buff long_term_buff;
+	struct ibmvnic_ltb_set ltb_set;
 	int num_buffers;
 	int buf_size;
 } ____cacheline_aligned;