[PATCH librdmacm 3/4] rsocket: Modify when control messages are available

[sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org]

From: Sean Hefty <sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

Rsockets currently tracks how many control messages (i.e.
entries in the send queue) that are available using a
single ctrl_avail counter.  Seems simple enough.

However, control messages currently require the use of
inline data.  In order to support control messages that
do not use inline data, we need to associate each
control message with a specific data buffer.  This will
become easier to manage if we modify how we track when
control messages are available.

We replace the single ctrl_avail counter with two new
counters.  The new counters conceptually treat control
messages as if each message had its own sequence number.
The sequence number will then be able to correspond to
a specific data buffer in a follow up patch.

ctrl_seqno will be used to indicate the current control
message being sent.  ctrl_max_seqno will track the
highest control message that may be sent.

A side effect of this change is that we will be able to
see how many control messages have been sent.  This also
separates the updating of the control count on the
sending  side, versus the receiving side.

Signed-off-by: Sean Hefty <sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 src/rsocket.c |   46 ++++++++++++++++++++++++++++++----------------
 1 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/src/rsocket.c b/src/rsocket.c
index ea18ba7..77b3979 100644
--- a/src/rsocket.c
+++ b/src/rsocket.c
@@ -308,7 +308,8 @@ struct rsocket {
 			uint64_t	  tcp_opts;
 			unsigned int	  keepalive_time;
 
-			int		  ctrl_avail;
+			unsigned int	  ctrl_seqno;
+			unsigned int	  ctrl_max_seqno;
 			uint16_t	  sseq_no;
 			uint16_t	  sseq_comp;
 			uint16_t	  rseq_no;
@@ -563,6 +564,7 @@ static void rs_remove(struct rsocket *rs)
 	pthread_mutex_unlock(&mut);
 }
 
+/* We only inherit from listening sockets */
 static struct rsocket *rs_alloc(struct rsocket *inherited_rs, int type)
 {
 	struct rsocket *rs;
@@ -585,7 +587,7 @@ static struct rsocket *rs_alloc(struct rsocket *inherited_rs, int type)
 		rs->sq_size = inherited_rs->sq_size;
 		rs->rq_size = inherited_rs->rq_size;
 		if (type == SOCK_STREAM) {
-			rs->ctrl_avail = inherited_rs->ctrl_avail;
+			rs->ctrl_max_seqno = inherited_rs->ctrl_max_seqno;
 			rs->target_iomap_size = inherited_rs->target_iomap_size;
 		}
 	} else {
@@ -595,7 +597,7 @@ static struct rsocket *rs_alloc(struct rsocket *inherited_rs, int type)
 		rs->sq_size = def_sqsize;
 		rs->rq_size = def_rqsize;
 		if (type == SOCK_STREAM) {
-			rs->ctrl_avail = RS_QP_CTRL_SIZE;
+			rs->ctrl_max_seqno = RS_QP_CTRL_SIZE;
 			rs->target_iomap_size = def_iomap_size;
 		}
 	}
@@ -723,7 +725,7 @@ static int rs_init_bufs(struct rsocket *rs)
 
 	rs->rbuf_free_offset = rs->rbuf_size >> 1;
 	rs->rbuf_bytes_avail = rs->rbuf_size >> 1;
-	rs->sqe_avail = rs->sq_size - rs->ctrl_avail;
+	rs->sqe_avail = rs->sq_size - rs->ctrl_max_seqno;
 	rs->rseq_comp = rs->rq_size >> 1;
 	return 0;
 }
@@ -1786,11 +1788,11 @@ static void rs_send_credits(struct rsocket *rs)
 	struct ibv_sge ibsge;
 	struct rs_sge sge;
 
-	rs->ctrl_avail--;
+	rs->ctrl_seqno++;
 	rs->rseq_comp = rs->rseq_no + (rs->rq_size >> 1);
 	if (rs->rbuf_bytes_avail >= (rs->rbuf_size >> 1)) {
 		if (rs->opts & RS_OPT_MSG_SEND)
-			rs->ctrl_avail--;
+			rs->ctrl_seqno++;
 
 		if (!(rs->opts & RS_OPT_SWAP_SGL)) {
 			sge.addr = (uintptr_t) &rs->rbuf[rs->rbuf_free_offset];
@@ -1824,16 +1826,27 @@ static void rs_send_credits(struct rsocket *rs)
 	}
 }
 
+static inline int rs_ctrl_avail(struct rsocket *rs)
+{
+	return rs->ctrl_seqno != rs->ctrl_max_seqno;
+}
+
+/* Protocols that do not support RDMA write with immediate may require 2 msgs */
+static inline int rs_2ctrl_avail(struct rsocket *rs)
+{
+	return (int)((rs->ctrl_seqno + 1) - rs->ctrl_max_seqno) < 0;
+}
+
 static int rs_give_credits(struct rsocket *rs)
 {
 	if (!(rs->opts & RS_OPT_MSG_SEND)) {
 		return ((rs->rbuf_bytes_avail >= (rs->rbuf_size >> 1)) ||
 			((short) ((short) rs->rseq_no - (short) rs->rseq_comp) >= 0)) &&
-		       rs->ctrl_avail && (rs->state & rs_connected);
+		       rs_ctrl_avail(rs) && (rs->state & rs_connected);
 	} else {
 		return ((rs->rbuf_bytes_avail >= (rs->rbuf_size >> 1)) ||
 			((short) ((short) rs->rseq_no - (short) rs->rseq_comp) >= 0)) &&
-		       (rs->ctrl_avail > 1) && (rs->state & rs_connected);
+		       rs_2ctrl_avail(rs) && (rs->state & rs_connected);
 	}
 }
 
@@ -1895,10 +1908,10 @@ static int rs_poll_cq(struct rsocket *rs)
 		} else {
 			switch  (rs_msg_op(rs_wr_data(wc.wr_id))) {
 			case RS_OP_SGL:
-				rs->ctrl_avail++;
+				rs->ctrl_max_seqno++;
 				break;
 			case RS_OP_CTRL:
-				rs->ctrl_avail++;
+				rs->ctrl_max_seqno++;
 				if (rs_msg_data(rs_wr_data(wc.wr_id)) == RS_CTRL_DISCONNECT)
 					rs->state = rs_disconnected;
 				break;
@@ -2237,7 +2250,7 @@ static int rs_conn_can_send(struct rsocket *rs)
 
 static int rs_conn_can_send_ctrl(struct rsocket *rs)
 {
-	return rs->ctrl_avail || !(rs->state & rs_connected);
+	return rs_ctrl_avail(rs) || !(rs->state & rs_connected);
 }
 
 static int rs_have_rdata(struct rsocket *rs)
@@ -2252,7 +2265,8 @@ static int rs_conn_have_rdata(struct rsocket *rs)
 
 static int rs_conn_all_sends_done(struct rsocket *rs)
 {
-	return ((rs->sqe_avail + rs->ctrl_avail) == rs->sq_size) ||
+	return ((((int) rs->ctrl_max_seqno) - ((int) rs->ctrl_seqno)) +
+		rs->sqe_avail == rs->sq_size) ||
 	       !(rs->state & rs_connected);
 }
 
@@ -3189,14 +3203,14 @@ int rshutdown(int socket, int how)
 				goto out;
 			ctrl = RS_CTRL_DISCONNECT;
 		}
-		if (!rs->ctrl_avail) {
+		if (!rs_ctrl_avail(rs)) {
 			ret = rs_process_cq(rs, 0, rs_conn_can_send_ctrl);
 			if (ret)
 				goto out;
 		}
 
-		if ((rs->state & rs_connected) && rs->ctrl_avail) {
-			rs->ctrl_avail--;
+		if ((rs->state & rs_connected) && rs_ctrl_avail(rs)) {
+			rs->ctrl_seqno++;
 			ret = rs_post_msg(rs, rs_msg_set(RS_OP_CTRL, ctrl));
 		}
 	}
@@ -4158,7 +4172,7 @@ static void tcp_svc_process_sock(struct rs_svc *svc)
 static void tcp_svc_send_keepalive(struct rsocket *rs)
 {
 	fastlock_acquire(&rs->cq_lock);
-	if ((rs->ctrl_avail > 1) && (rs->state & rs_connected))
+	if (rs_2ctrl_avail(rs) && (rs->state & rs_connected))
 		rs_send_credits(rs);
 	fastlock_release(&rs->cq_lock);
 }	
-- 
1.7.3

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