rds: stop using dmapool

RDMA ULPs should only perform DMA through the ib_dma_* API instead of
using the hidden dma_device directly. In addition using the dma coherent
API family that dmapool is a part of can be very ineffcient on plaforms
that are not DMA coherent. Switch to use slab allocations and the
ib_dma_* APIs instead.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Christoph Hellwig <[e-mail]>
Acked-by: Santosh Shilimkar <[e-mail]>
Signed-off-by: Jason Gunthorpe <[e-mail]>

net/rds/ib.c

···
  * SOFTWARE.
  *
  */
-#include <linux/dmapool.h>
 #include <linux/kernel.h>
 #include <linux/in.h>
 #include <linux/if.h>
···
 		rds_ib_destroy_mr_pool(rds_ibdev->mr_1m_pool);
 	if (rds_ibdev->pd)
 		ib_dealloc_pd(rds_ibdev->pd);
-	dma_pool_destroy(rds_ibdev->rid_hdrs_pool);
 
 	list_for_each_entry_safe(i_ipaddr, i_next, &rds_ibdev->ipaddr_list, list) {
 		list_del(&i_ipaddr->list);
···
 	if (IS_ERR(rds_ibdev->pd)) {
 		ret = PTR_ERR(rds_ibdev->pd);
 		rds_ibdev->pd = NULL;
-		goto put_dev;
-	}
-	rds_ibdev->rid_hdrs_pool = dma_pool_create(device->name,
-						   device->dma_device,
-						   sizeof(struct rds_header),
-						   L1_CACHE_BYTES, 0);
-	if (!rds_ibdev->rid_hdrs_pool) {
-		ret = -ENOMEM;
 		goto put_dev;
 	}
 

net/rds/ib.h

···
 	struct list_head	conn_list;
 	struct ib_device	*dev;
 	struct ib_pd		*pd;
-	struct dma_pool		*rid_hdrs_pool; /* RDS headers DMA pool */
 	u8			odp_capable:1;
 
 	unsigned int		max_mrs;
···
 int rds_ib_cm_initiate_connect(struct rdma_cm_id *cm_id, bool isv6);
 void rds_ib_cm_connect_complete(struct rds_connection *conn,
 				struct rdma_cm_event *event);
-struct rds_header **rds_dma_hdrs_alloc(struct ib_device *ibdev,
-				       struct dma_pool *pool,
-				       dma_addr_t **dma_addrs, u32 num_hdrs);
-void rds_dma_hdrs_free(struct dma_pool *pool, struct rds_header **hdrs,
-		       dma_addr_t *dma_addrs, u32 num_hdrs);
 
 #define rds_ib_conn_error(conn, fmt...) \
 	__rds_ib_conn_error(conn, KERN_WARNING "RDS/IB: " fmt)

net/rds/ib_cm.c

···
  * SOFTWARE.
  *
  */
-#include <linux/dmapool.h>
 #include <linux/kernel.h>
 #include <linux/in.h>
 #include <linux/slab.h>
···
 	rds_ibdev->vector_load[index]--;
 }
 
+static void rds_dma_hdr_free(struct ib_device *dev, struct rds_header *hdr,
+		dma_addr_t dma_addr, enum dma_data_direction dir)
+{
+	ib_dma_unmap_single(dev, dma_addr, sizeof(*hdr), dir);
+	kfree(hdr);
+}
+
+static struct rds_header *rds_dma_hdr_alloc(struct ib_device *dev,
+		dma_addr_t *dma_addr, enum dma_data_direction dir)
+{
+	struct rds_header *hdr;
+
+	hdr = kzalloc_node(sizeof(*hdr), GFP_KERNEL, ibdev_to_node(dev));
+	if (!hdr)
+		return NULL;
+
+	*dma_addr = ib_dma_map_single(dev, hdr, sizeof(*hdr),
+				      DMA_BIDIRECTIONAL);
+	if (ib_dma_mapping_error(dev, *dma_addr)) {
+		kfree(hdr);
+		return NULL;
+	}
+
+	return hdr;
+}
+
+/* Free the DMA memory used to store struct rds_header.
+ *
+ * @dev: the RDS IB device
+ * @hdrs: pointer to the array storing DMA memory pointers
+ * @dma_addrs: pointer to the array storing DMA addresses
+ * @num_hdars: number of headers to free.
+ */
+static void rds_dma_hdrs_free(struct rds_ib_device *dev,
+		struct rds_header **hdrs, dma_addr_t *dma_addrs, u32 num_hdrs,
+		enum dma_data_direction dir)
+{
+	u32 i;
+
+	for (i = 0; i < num_hdrs; i++)
+		rds_dma_hdr_free(dev->dev, hdrs[i], dma_addrs[i], dir);
+	kvfree(hdrs);
+	kvfree(dma_addrs);
+}
+
+
 /* Allocate DMA coherent memory to be used to store struct rds_header for
  * sending/receiving packets.  The pointers to the DMA memory and the
  * associated DMA addresses are stored in two arrays.
  *
- * @ibdev: the IB device
- * @pool: the DMA memory pool
+ * @dev: the RDS IB device
  * @dma_addrs: pointer to the array for storing DMA addresses
  * @num_hdrs: number of headers to allocate
  *
  * It returns the pointer to the array storing the DMA memory pointers.  On
  * error, NULL pointer is returned.
  */
-struct rds_header **rds_dma_hdrs_alloc(struct ib_device *ibdev,
-				       struct dma_pool *pool,
-				       dma_addr_t **dma_addrs, u32 num_hdrs)
+static struct rds_header **rds_dma_hdrs_alloc(struct rds_ib_device *dev,
+		dma_addr_t **dma_addrs, u32 num_hdrs,
+		enum dma_data_direction dir)
 {
 	struct rds_header **hdrs;
 	dma_addr_t *hdr_daddrs;
 	u32 i;
 
 	hdrs = kvmalloc_node(sizeof(*hdrs) * num_hdrs, GFP_KERNEL,
-			     ibdev_to_node(ibdev));
+			     ibdev_to_node(dev->dev));
 	if (!hdrs)
 		return NULL;
 
 	hdr_daddrs = kvmalloc_node(sizeof(*hdr_daddrs) * num_hdrs, GFP_KERNEL,
-				   ibdev_to_node(ibdev));
+				   ibdev_to_node(dev->dev));
 	if (!hdr_daddrs) {
 		kvfree(hdrs);
 		return NULL;
 	}
 
 	for (i = 0; i < num_hdrs; i++) {
-		hdrs[i] = dma_pool_zalloc(pool, GFP_KERNEL, &hdr_daddrs[i]);
+		hdrs[i] = rds_dma_hdr_alloc(dev->dev, &hdr_daddrs[i], dir);
 		if (!hdrs[i]) {
-			rds_dma_hdrs_free(pool, hdrs, hdr_daddrs, i);
+			rds_dma_hdrs_free(dev, hdrs, hdr_daddrs, i, dir);
 			return NULL;
 		}
 	}
 
 	*dma_addrs = hdr_daddrs;
 	return hdrs;
-}
-
-/* Free the DMA memory used to store struct rds_header.
- *
- * @pool: the DMA memory pool
- * @hdrs: pointer to the array storing DMA memory pointers
- * @dma_addrs: pointer to the array storing DMA addresses
- * @num_hdars: number of headers to free.
- */
-void rds_dma_hdrs_free(struct dma_pool *pool, struct rds_header **hdrs,
-		       dma_addr_t *dma_addrs, u32 num_hdrs)
-{
-	u32 i;
-
-	for (i = 0; i < num_hdrs; i++)
-		dma_pool_free(pool, hdrs[i], dma_addrs[i]);
-	kvfree(hdrs);
-	kvfree(dma_addrs);
 }
 
 /*
···
 	struct rds_ib_device *rds_ibdev;
 	unsigned long max_wrs;
 	int ret, fr_queue_space;
-	struct dma_pool *pool;
 
 	/*
 	 * It's normal to see a null device if an incoming connection races
···
 		goto recv_cq_out;
 	}
 
-	pool = rds_ibdev->rid_hdrs_pool;
-	ic->i_send_hdrs = rds_dma_hdrs_alloc(dev, pool, &ic->i_send_hdrs_dma,
-					     ic->i_send_ring.w_nr);
+	ic->i_send_hdrs = rds_dma_hdrs_alloc(rds_ibdev, &ic->i_send_hdrs_dma,
+					     ic->i_send_ring.w_nr,
+					     DMA_TO_DEVICE);
 	if (!ic->i_send_hdrs) {
 		ret = -ENOMEM;
 		rdsdebug("DMA send hdrs alloc failed\n");
 		goto qp_out;
 	}
 
-	ic->i_recv_hdrs = rds_dma_hdrs_alloc(dev, pool, &ic->i_recv_hdrs_dma,
-					     ic->i_recv_ring.w_nr);
+	ic->i_recv_hdrs = rds_dma_hdrs_alloc(rds_ibdev, &ic->i_recv_hdrs_dma,
+					     ic->i_recv_ring.w_nr,
+					     DMA_FROM_DEVICE);
 	if (!ic->i_recv_hdrs) {
 		ret = -ENOMEM;
 		rdsdebug("DMA recv hdrs alloc failed\n");
 		goto send_hdrs_dma_out;
 	}
 
-	ic->i_ack = dma_pool_zalloc(pool, GFP_KERNEL,
-				    &ic->i_ack_dma);
+	ic->i_ack = rds_dma_hdr_alloc(rds_ibdev->dev, &ic->i_ack_dma,
+				      DMA_TO_DEVICE);
 	if (!ic->i_ack) {
 		ret = -ENOMEM;
 		rdsdebug("DMA ack header alloc failed\n");
···
 	vfree(ic->i_sends);
 
 ack_dma_out:
-	dma_pool_free(pool, ic->i_ack, ic->i_ack_dma);
+	rds_dma_hdr_free(rds_ibdev->dev, ic->i_ack, ic->i_ack_dma,
+			 DMA_TO_DEVICE);
 	ic->i_ack = NULL;
 
 recv_hdrs_dma_out:
-	rds_dma_hdrs_free(pool, ic->i_recv_hdrs, ic->i_recv_hdrs_dma,
-			  ic->i_recv_ring.w_nr);
+	rds_dma_hdrs_free(rds_ibdev, ic->i_recv_hdrs, ic->i_recv_hdrs_dma,
+			  ic->i_recv_ring.w_nr, DMA_FROM_DEVICE);
 	ic->i_recv_hdrs = NULL;
 	ic->i_recv_hdrs_dma = NULL;
 
 send_hdrs_dma_out:
-	rds_dma_hdrs_free(pool, ic->i_send_hdrs, ic->i_send_hdrs_dma,
-			  ic->i_send_ring.w_nr);
+	rds_dma_hdrs_free(rds_ibdev, ic->i_send_hdrs, ic->i_send_hdrs_dma,
+			  ic->i_send_ring.w_nr, DMA_TO_DEVICE);
 	ic->i_send_hdrs = NULL;
 	ic->i_send_hdrs_dma = NULL;
 
···
 		}
 
 		if (ic->rds_ibdev) {
-			struct dma_pool *pool;
-
-			pool = ic->rds_ibdev->rid_hdrs_pool;
-
 			/* then free the resources that ib callbacks use */
 			if (ic->i_send_hdrs) {
-				rds_dma_hdrs_free(pool, ic->i_send_hdrs,
+				rds_dma_hdrs_free(ic->rds_ibdev,
+						  ic->i_send_hdrs,
 						  ic->i_send_hdrs_dma,
-						  ic->i_send_ring.w_nr);
+						  ic->i_send_ring.w_nr,
+						  DMA_TO_DEVICE);
 				ic->i_send_hdrs = NULL;
 				ic->i_send_hdrs_dma = NULL;
 			}
 
 			if (ic->i_recv_hdrs) {
-				rds_dma_hdrs_free(pool, ic->i_recv_hdrs,
+				rds_dma_hdrs_free(ic->rds_ibdev,
+						  ic->i_recv_hdrs,
 						  ic->i_recv_hdrs_dma,
-						  ic->i_recv_ring.w_nr);
+						  ic->i_recv_ring.w_nr,
+						  DMA_FROM_DEVICE);
 				ic->i_recv_hdrs = NULL;
 				ic->i_recv_hdrs_dma = NULL;
 			}
 
 			if (ic->i_ack) {
-				dma_pool_free(pool, ic->i_ack, ic->i_ack_dma);
+				rds_dma_hdr_free(ic->rds_ibdev->dev, ic->i_ack,
+						 ic->i_ack_dma, DMA_TO_DEVICE);
 				ic->i_ack = NULL;
 			}
 		} else {

net/rds/ib_recv.c

···
 	seq = rds_ib_get_ack(ic);
 
 	rdsdebug("send_ack: ic %p ack %llu\n", ic, (unsigned long long) seq);
+
+	ib_dma_sync_single_for_cpu(ic->rds_ibdev->dev, ic->i_ack_dma,
+				   sizeof(*hdr), DMA_TO_DEVICE);
 	rds_message_populate_header(hdr, 0, 0, 0);
 	hdr->h_ack = cpu_to_be64(seq);
 	hdr->h_credit = adv_credits;
 	rds_message_make_checksum(hdr);
+	ib_dma_sync_single_for_device(ic->rds_ibdev->dev, ic->i_ack_dma,
+				      sizeof(*hdr), DMA_TO_DEVICE);
+
 	ic->i_ack_queued = jiffies;
 
 	ret = ib_post_send(ic->i_cm_id->qp, &ic->i_ack_wr, NULL);
···
 	struct rds_ib_connection *ic = conn->c_transport_data;
 	struct rds_ib_incoming *ibinc = ic->i_ibinc;
 	struct rds_header *ihdr, *hdr;
+	dma_addr_t dma_addr = ic->i_recv_hdrs_dma[recv - ic->i_recvs];
 
 	/* XXX shut down the connection if port 0,0 are seen? */
 
···
 
 	ihdr = ic->i_recv_hdrs[recv - ic->i_recvs];
 
+	ib_dma_sync_single_for_cpu(ic->rds_ibdev->dev, dma_addr,
+				   sizeof(*ihdr), DMA_FROM_DEVICE);
 	/* Validate the checksum. */
 	if (!rds_message_verify_checksum(ihdr)) {
 		rds_ib_conn_error(conn, "incoming message "
···
 		       "forcing a reconnect\n",
 		       &conn->c_faddr);
 		rds_stats_inc(s_recv_drop_bad_checksum);
-		return;
+		goto done;
 	}
 
 	/* Process the ACK sequence which comes with every packet */
···
 		 */
 		rds_ib_frag_free(ic, recv->r_frag);
 		recv->r_frag = NULL;
-		return;
+		goto done;
 	}
 
 	/*
···
 		    hdr->h_dport != ihdr->h_dport) {
 			rds_ib_conn_error(conn,
 				"fragment header mismatch; forcing reconnect\n");
-			return;
+			goto done;
 		}
 	}
 
···
 
 		rds_inc_put(&ibinc->ii_inc);
 	}
+done:
+	ib_dma_sync_single_for_device(ic->rds_ibdev->dev, dma_addr,
+				      sizeof(*ihdr), DMA_FROM_DEVICE);
 }
 
 void rds_ib_recv_cqe_handler(struct rds_ib_connection *ic,

net/rds/ib_send.c

···
 		send->s_sge[0].length = sizeof(struct rds_header);
 		send->s_sge[0].lkey = ic->i_pd->local_dma_lkey;
 
+		ib_dma_sync_single_for_cpu(ic->rds_ibdev->dev,
+					   ic->i_send_hdrs_dma[pos],
+					   sizeof(struct rds_header),
+					   DMA_TO_DEVICE);
 		memcpy(ic->i_send_hdrs[pos], &rm->m_inc.i_hdr,
 		       sizeof(struct rds_header));
 
···
 			adv_credits = 0;
 			rds_ib_stats_inc(s_ib_tx_credit_updates);
 		}
+		ib_dma_sync_single_for_device(ic->rds_ibdev->dev,
+					      ic->i_send_hdrs_dma[pos],
+					      sizeof(struct rds_header),
+					      DMA_TO_DEVICE);
 
 		if (prev)
 			prev->s_wr.next = &send->s_wr;