qed: Add support for MPA header being split over two tcp packets

There is a special case where an MPA header is split over to tcp
packets, in this case we need to wait for the next packet to
get the fpdu length. We use the incomplete_bytes to mark this
fpdu as a "special" one which requires updating the length with
the next packet

Signed-off-by: Michal Kalderon <Michal.Kalderon@cavium.com>
Signed-off-by: Ariel Elior <Ariel.Elior@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: mkalderon

drivers/net/ethernet/qlogic/qed/qed_iwarp.c

@@ -1742,6 +1742,7 @@ enum qed_iwarp_mpa_pkt_type {
 	QED_IWARP_MPA_PKT_UNALIGNED
 };
 
+#define QED_IWARP_INVALID_FPDU_LENGTH 0xffff
 #define QED_IWARP_MPA_FPDU_LENGTH_SIZE (2)
 #define QED_IWARP_MPA_CRC32_DIGEST_SIZE (4)
 
@@ -1774,6 +1775,15 @@ qed_iwarp_mpa_classify(struct qed_hwfn *p_hwfn,
 		goto out;
 	}
 
+	/* special case of one byte remaining...
+	 * lower byte will be read next packet
+	 */
+	if (tcp_payload_len == 1) {
+		fpdu->fpdu_length = *mpa_data << BITS_PER_BYTE;
+		pkt_type = QED_IWARP_MPA_PKT_PARTIAL;
+		goto out;
+	}
+
 	mpa_len = ntohs(*((u16 *)(mpa_data)));
 	fpdu->fpdu_length = QED_IWARP_FPDU_LEN_WITH_PAD(mpa_len);
 
@@ -1802,14 +1812,37 @@ qed_iwarp_init_fpdu(struct qed_iwarp_ll2_buff *buf,
 	fpdu->mpa_frag = buf->data_phys_addr + pkt_data->first_mpa_offset;
 	fpdu->mpa_frag_virt = (u8 *)(buf->data) + pkt_data->first_mpa_offset;
 
-	if (tcp_payload_size < fpdu->fpdu_length)
+	if (tcp_payload_size == 1)
+		fpdu->incomplete_bytes = QED_IWARP_INVALID_FPDU_LENGTH;
+	else if (tcp_payload_size < fpdu->fpdu_length)
 		fpdu->incomplete_bytes = fpdu->fpdu_length - tcp_payload_size;
 	else
 		fpdu->incomplete_bytes = 0;	/* complete fpdu */
 
 	fpdu->mpa_frag_len = fpdu->fpdu_length - fpdu->incomplete_bytes;
 }
 
+static void
+qed_iwarp_update_fpdu_length(struct qed_hwfn *p_hwfn,
+			     struct qed_iwarp_fpdu *fpdu, u8 *mpa_data)
+{
+	u16 mpa_len;
+
+	/* Update incomplete packets if needed */
+	if (fpdu->incomplete_bytes == QED_IWARP_INVALID_FPDU_LENGTH) {
+		/* Missing lower byte is now available */
+		mpa_len = fpdu->fpdu_length | *mpa_data;
+		fpdu->fpdu_length = QED_IWARP_FPDU_LEN_WITH_PAD(mpa_len);
+		fpdu->mpa_frag_len = fpdu->fpdu_length;
+		/* one byte of hdr */
+		fpdu->incomplete_bytes = fpdu->fpdu_length - 1;
+		DP_VERBOSE(p_hwfn,
+			   QED_MSG_RDMA,
+			   "MPA_ALIGN: Partial header mpa_len=%x fpdu_length=%x incomplete_bytes=%x\n",
+			   mpa_len, fpdu->fpdu_length, fpdu->incomplete_bytes);
+	}
+}
+
 static int
 qed_iwarp_send_fpdu(struct qed_hwfn *p_hwfn,
 		    struct qed_iwarp_fpdu *fpdu,
@@ -1960,6 +1993,7 @@ qed_iwarp_process_mpa_pkt(struct qed_hwfn *p_hwfn,
 			curr_pkt->first_mpa_offset += fpdu->fpdu_length;
 			break;
 		case QED_IWARP_MPA_PKT_UNALIGNED:
+			qed_iwarp_update_fpdu_length(p_hwfn, fpdu, mpa_data);
 			rc = qed_iwarp_send_fpdu(p_hwfn, fpdu, curr_pkt, buf,
 						 mpa_buf->tcp_payload_len,
 						 pkt_type);

drivers/net/ethernet/qlogic/qed/qed_iwarp.h

@@ -69,6 +69,12 @@ struct qed_iwarp_ll2_mpa_buf {
 	u8 placement_offset;
 };
 
+/* In some cases a fpdu will arrive with only one byte of the header, in this
+ * case the fpdu_length will be partial (contain only higher byte and
+ * incomplete bytes will contain the invalid value
+ */
+#define QED_IWARP_INVALID_INCOMPLETE_BYTES 0xffff
+
 struct qed_iwarp_fpdu {
 	struct qed_iwarp_ll2_buff *mpa_buf;
 	void *mpa_frag_virt;