[SCSI] cxgb3i: Outgoing pdus need to observe skb's MAX_SKB_FRAGS

Need to make sure the outgoing pdu can fit into a single skb.  When
calulating the max. outgoing pdu payload size, take into consideration
of
- data can be held in the skb's fragment list, assume 512 bytes per
  fragment, and
- data can be held in the headroom.
Signed-off-by: Karen Xie <kxie@chelsio.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/cxgb3i/cxgb3i_ddp.c

@@ -639,10 +639,11 @@ static int ddp_init(struct t3cdev *tdev)
 	write_unlock(&cxgb3i_ddp_rwlock);
 
 	ddp_log_info("nppods %u (0x%x ~ 0x%x), bits %u, mask 0x%x,0x%x "
-			"pkt %u,%u.\n",
+			"pkt %u/%u, %u/%u.\n",
 			ppmax, ddp->llimit, ddp->ulimit, ddp->idx_bits,
 			ddp->idx_mask, ddp->rsvd_tag_mask,
-			ddp->max_txsz, ddp->max_rxsz);
+			ddp->max_txsz, uinfo.max_txsz,
+			ddp->max_rxsz, uinfo.max_rxsz);
 	return 0;
 
 free_ddp_map:
@@ -654,8 +655,8 @@ static int ddp_init(struct t3cdev *tdev)
  * cxgb3i_adapter_ddp_init - initialize the adapter's ddp resource
  * @tdev: t3cdev adapter
  * @tformat: tag format
- * @txsz: max tx pkt size, filled in by this func.
- * @rxsz: max rx pkt size, filled in by this func.
+ * @txsz: max tx pdu payload size, filled in by this func.
+ * @rxsz: max rx pdu payload size, filled in by this func.
  * initialize the ddp pagepod manager for a given adapter if needed and
  * setup the tag format for a given iscsi entity
  */
@@ -685,10 +686,12 @@ int cxgb3i_adapter_ddp_init(struct t3cdev *tdev,
 		      tformat->sw_bits, tformat->rsvd_bits,
 		      tformat->rsvd_shift, tformat->rsvd_mask);
 
-	*txsz = ddp->max_txsz;
-	*rxsz = ddp->max_rxsz;
-	ddp_log_info("ddp max pkt size: %u, %u.\n",
-		     ddp->max_txsz, ddp->max_rxsz);
+	*txsz = min_t(unsigned int, ULP2_MAX_PDU_PAYLOAD,
+			ddp->max_txsz - ISCSI_PDU_NONPAYLOAD_LEN);
+	*rxsz = min_t(unsigned int, ULP2_MAX_PDU_PAYLOAD,
+			ddp->max_rxsz - ISCSI_PDU_NONPAYLOAD_LEN);
+	ddp_log_info("max payload size: %u/%u, %u/%u.\n",
+		     *txsz, ddp->max_txsz, *rxsz, ddp->max_rxsz);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(cxgb3i_adapter_ddp_init);

drivers/scsi/cxgb3i/cxgb3i_ddp.h

@@ -85,8 +85,9 @@ struct cxgb3i_ddp_info {
 	struct sk_buff **gl_skb;
 };
 
+#define ISCSI_PDU_NONPAYLOAD_LEN	312 /* bhs(48) + ahs(256) + digest(8) */
 #define ULP2_MAX_PKT_SIZE	16224
-#define ULP2_MAX_PDU_PAYLOAD	(ULP2_MAX_PKT_SIZE - ISCSI_PDU_NONPAYLOAD_MAX)
+#define ULP2_MAX_PDU_PAYLOAD	(ULP2_MAX_PKT_SIZE - ISCSI_PDU_NONPAYLOAD_LEN)
 #define PPOD_PAGES_MAX		4
 #define PPOD_PAGES_SHIFT	2	/* 4 pages per pod */
 

drivers/scsi/cxgb3i/cxgb3i_iscsi.c

@@ -403,17 +403,15 @@ static inline int cxgb3i_conn_max_xmit_dlength(struct iscsi_conn *conn)
 {
 	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 	struct cxgb3i_conn *cconn = tcp_conn->dd_data;
-	unsigned int max = min_t(unsigned int, ULP2_MAX_PDU_PAYLOAD,
-				 cconn->hba->snic->tx_max_size -
-				 ISCSI_PDU_NONPAYLOAD_MAX);
+	unsigned int max = max(512 * MAX_SKB_FRAGS, SKB_TX_HEADROOM);
 
+	max = min(cconn->hba->snic->tx_max_size, max);
 	if (conn->max_xmit_dlength)
-		conn->max_xmit_dlength = min_t(unsigned int,
-						conn->max_xmit_dlength, max);
+		conn->max_xmit_dlength = min(conn->max_xmit_dlength, max);
 	else
 		conn->max_xmit_dlength = max;
 	align_pdu_size(conn->max_xmit_dlength);
-	cxgb3i_log_info("conn 0x%p, max xmit %u.\n",
+	cxgb3i_api_debug("conn 0x%p, max xmit %u.\n",
 			 conn, conn->max_xmit_dlength);
 	return 0;
 }
@@ -428,9 +426,7 @@ static inline int cxgb3i_conn_max_recv_dlength(struct iscsi_conn *conn)
 {
 	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 	struct cxgb3i_conn *cconn = tcp_conn->dd_data;
-	unsigned int max = min_t(unsigned int, ULP2_MAX_PDU_PAYLOAD,
-				 cconn->hba->snic->rx_max_size -
-				 ISCSI_PDU_NONPAYLOAD_MAX);
+	unsigned int max = cconn->hba->snic->rx_max_size;
 
 	align_pdu_size(max);
 	if (conn->max_recv_dlength) {
@@ -440,8 +436,7 @@ static inline int cxgb3i_conn_max_recv_dlength(struct iscsi_conn *conn)
 					 conn->max_recv_dlength, max);
 			return -EINVAL;
 		}
-		conn->max_recv_dlength = min_t(unsigned int,
-						conn->max_recv_dlength, max);
+		conn->max_recv_dlength = min(conn->max_recv_dlength, max);
 		align_pdu_size(conn->max_recv_dlength);
 	} else
 		conn->max_recv_dlength = max;

drivers/scsi/cxgb3i/cxgb3i_offload.h

@@ -225,6 +225,7 @@ struct sge_opaque_hdr {
 /* for TX: a skb must have a headroom of at least TX_HEADER_LEN bytes */
 #define TX_HEADER_LEN \
 		(sizeof(struct tx_data_wr) + sizeof(struct sge_opaque_hdr))
+#define SKB_TX_HEADROOM		SKB_MAX_HEAD(TX_HEADER_LEN)
 
 /*
  * get and set private ip for iscsi traffic

drivers/scsi/cxgb3i/cxgb3i_pdu.h

@@ -53,7 +53,7 @@ struct cpl_rx_data_ddp_norss {
 #define ULP2_FLAG_DCRC_ERROR		0x20
 #define ULP2_FLAG_PAD_ERROR		0x40
 
-void cxgb3i_conn_closing(struct s3_conn *);
+void cxgb3i_conn_closing(struct s3_conn *c3cn);
 void cxgb3i_conn_pdu_ready(struct s3_conn *c3cn);
 void cxgb3i_conn_tx_open(struct s3_conn *c3cn);
 #endif