net/smc: cleanup function __smc_buf_create()

Split function __smc_buf_create() for better readability.
Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/smc/smc_core.c

@@ -487,51 +487,17 @@ static inline int smc_rmb_wnd_update_limit(int rmbe_size)
 	return min_t(int, rmbe_size / 10, SOCK_MIN_SNDBUF / 2);
 }
 
-static int __smc_buf_create(struct smc_sock *smc, bool is_rmb)
+static struct smc_buf_desc *smc_new_buf_create(struct smc_link_group *lgr,
+					       bool is_rmb, int bufsize)
 {
-	struct smc_connection *conn = &smc->conn;
-	struct smc_link_group *lgr = conn->lgr;
-	struct smc_buf_desc *buf_desc = NULL;
-	struct list_head *buf_list;
-	int bufsize, bufsize_short;
+	struct smc_buf_desc *buf_desc;
 	struct smc_link *lnk;
-	int sk_buf_size;
-	rwlock_t *lock;
 	int rc;
 
-	lnk = &lgr->lnk[SMC_SINGLE_LINK];
-	if (is_rmb)
-		/* use socket recv buffer size (w/o overhead) as start value */
-		sk_buf_size = smc->sk.sk_rcvbuf / 2;
-	else
-		/* use socket send buffer size (w/o overhead) as start value */
-		sk_buf_size = smc->sk.sk_sndbuf / 2;
-
-	for (bufsize_short = smc_compress_bufsize(smc->sk.sk_sndbuf / 2);
-	     bufsize_short >= 0; bufsize_short--) {
-
-		if (is_rmb) {
-			lock = &lgr->rmbs_lock;
-			buf_list = &lgr->rmbs[bufsize_short];
-		} else {
-			lock = &lgr->sndbufs_lock;
-			buf_list = &lgr->sndbufs[bufsize_short];
-		}
-		bufsize = smc_uncompress_bufsize(bufsize_short);
-		if ((1 << get_order(bufsize)) > SG_MAX_SINGLE_ALLOC)
-			continue;
-
-		/* check for reusable slot in the link group */
-		buf_desc = smc_buf_get_slot(lgr, bufsize_short, lock, buf_list);
-		if (buf_desc) {
-			memset(buf_desc->cpu_addr, 0, bufsize);
-			break; /* found reusable slot */
-		}
-
-		/* try to allocate the determined number of pages */
+	/* try to alloc a new buffer */
 	buf_desc = kzalloc(sizeof(*buf_desc), GFP_KERNEL);
 	if (!buf_desc)
-			break; /* give up with -ENOMEM */
+		return ERR_PTR(-ENOMEM);
 
 	buf_desc->cpu_addr =
 		(void *)__get_free_pages(GFP_KERNEL | __GFP_NOWARN |
@@ -540,28 +506,28 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_rmb)
 					 get_order(bufsize));
 	if (!buf_desc->cpu_addr) {
 		kfree(buf_desc);
-			buf_desc = NULL;
-			continue;
+		return ERR_PTR(-EAGAIN);
 	}
+	buf_desc->order = get_order(bufsize);
 
+	/* build the sg table from the pages */
+	lnk = &lgr->lnk[SMC_SINGLE_LINK];
 	rc = sg_alloc_table(&buf_desc->sgt[SMC_SINGLE_LINK], 1,
 			    GFP_KERNEL);
 	if (rc) {
 		smc_buf_free(buf_desc, lnk, is_rmb);
-			buf_desc = NULL;
-			continue;
+		return ERR_PTR(rc);
 	}
 	sg_set_buf(buf_desc->sgt[SMC_SINGLE_LINK].sgl,
 		   buf_desc->cpu_addr, bufsize);
 
 	/* map sg table to DMA address */
-		rc = smc_ib_buf_map_sg(lnk->smcibdev, buf_desc, is_rmb ?
-				       DMA_FROM_DEVICE : DMA_TO_DEVICE);
+	rc = smc_ib_buf_map_sg(lnk->smcibdev, buf_desc,
+			       is_rmb ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
 	/* SMC protocol depends on mapping to one DMA address only */
 	if (rc != 1)  {
 		smc_buf_free(buf_desc, lnk, is_rmb);
-			buf_desc = NULL;
-		continue; /* if mapping failed, try smaller one */
+		return ERR_PTR(-EAGAIN);
 	}
 
 	/* create a new memory region for the RMB */
@@ -572,10 +538,56 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_rmb)
 					      buf_desc);
 		if (rc) {
 			smc_buf_free(buf_desc, lnk, is_rmb);
-				buf_desc = NULL;
-				continue;
+			return ERR_PTR(rc);
+		}
 	}
+
+	return buf_desc;
+}
+
+static int __smc_buf_create(struct smc_sock *smc, bool is_rmb)
+{
+	struct smc_connection *conn = &smc->conn;
+	struct smc_link_group *lgr = conn->lgr;
+	struct smc_buf_desc *buf_desc = NULL;
+	struct list_head *buf_list;
+	int bufsize, bufsize_short;
+	int sk_buf_size;
+	rwlock_t *lock;
+
+	if (is_rmb)
+		/* use socket recv buffer size (w/o overhead) as start value */
+		sk_buf_size = smc->sk.sk_rcvbuf / 2;
+	else
+		/* use socket send buffer size (w/o overhead) as start value */
+		sk_buf_size = smc->sk.sk_sndbuf / 2;
+
+	for (bufsize_short = smc_compress_bufsize(smc->sk.sk_sndbuf / 2);
+	     bufsize_short >= 0; bufsize_short--) {
+
+		if (is_rmb) {
+			lock = &lgr->rmbs_lock;
+			buf_list = &lgr->rmbs[bufsize_short];
+		} else {
+			lock = &lgr->sndbufs_lock;
+			buf_list = &lgr->sndbufs[bufsize_short];
 		}
+		bufsize = smc_uncompress_bufsize(bufsize_short);
+		if ((1 << get_order(bufsize)) > SG_MAX_SINGLE_ALLOC)
+			continue;
+
+		/* check for reusable slot in the link group */
+		buf_desc = smc_buf_get_slot(lgr, bufsize_short, lock, buf_list);
+		if (buf_desc) {
+			memset(buf_desc->cpu_addr, 0, bufsize);
+			break; /* found reusable slot */
+		}
+
+		buf_desc = smc_new_buf_create(lgr, is_rmb, bufsize);
+		if (PTR_ERR(buf_desc) == -ENOMEM)
+			break;
+		if (IS_ERR(buf_desc))
+			continue;
 
 		buf_desc->used = 1;
 		write_lock_bh(lock);
@@ -584,7 +596,7 @@ static int __smc_buf_create(struct smc_sock *smc, bool is_rmb)
 		break; /* found */
 	}
 
-	if (!buf_desc || !buf_desc->cpu_addr)
+	if (IS_ERR(buf_desc))
 		return -ENOMEM;
 
 	if (is_rmb) {