netdev - [net][PATCH 1/5] rds: fix reordering with composite message notification

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Date:   Tue,  9 Jul 2019 22:32:40 -0700
From:   Santosh Shilimkar <santosh.shilimkar@...cle.com>
To:     netdev@...r.kernel.org, davem@...emloft.net
Cc:     santosh.shilimkar@...cle.com
Subject: [net][PATCH 1/5] rds: fix reordering with composite message notification

RDS composite message(rdma + control) user notification needs to be
triggered once the full message is delivered and such a fix was
added as part of commit 941f8d55f6d61 ("RDS: RDMA: Fix the composite
message user notification"). But rds_send_remove_from_sock is missing
data part notify check and hence at times the user don't get
notification which isn't desirable.

One way is to fix the rds_send_remove_from_sock to check of that case
but considering the ordering complexity with completion handler and
rdma + control messages are always dispatched back to back in same send
context, just delaying the signaled completion on rmda work request also
gets the desired behaviour. i.e Notifying application only after
RDMA + control message send completes. So patch updates the earlier
fix with this approach. The delay signaling completions of rdma op
till the control message send completes fix was done by Venkat
Venkatsubra in downstream kernel.

Reviewed-and-tested-by: Zhu Yanjun <yanjun.zhu@...cle.com>
Reviewed-by: Gerd Rausch <gerd.rausch@...cle.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@...cle.com>
---
 net/rds/ib_send.c | 29 +++++++++++++----------------
 net/rds/rdma.c    | 10 ----------
 net/rds/rds.h     |  1 -
 net/rds/send.c    |  4 +---
 4 files changed, 14 insertions(+), 30 deletions(-)

diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c
index 18f2341..dfe6237 100644
--- a/net/rds/ib_send.c
+++ b/net/rds/ib_send.c
@@ -69,6 +69,16 @@ static void rds_ib_send_complete(struct rds_message *rm,
 	complete(rm, notify_status);
 }
 
+static void rds_ib_send_unmap_data(struct rds_ib_connection *ic,
+				   struct rm_data_op *op,
+				   int wc_status)
+{
+	if (op->op_nents)
+		ib_dma_unmap_sg(ic->i_cm_id->device,
+				op->op_sg, op->op_nents,
+				DMA_TO_DEVICE);
+}
+
 static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
 				   struct rm_rdma_op *op,
 				   int wc_status)
@@ -129,21 +139,6 @@ static void rds_ib_send_unmap_atomic(struct rds_ib_connection *ic,
 		rds_ib_stats_inc(s_ib_atomic_fadd);
 }
 
-static void rds_ib_send_unmap_data(struct rds_ib_connection *ic,
-				   struct rm_data_op *op,
-				   int wc_status)
-{
-	struct rds_message *rm = container_of(op, struct rds_message, data);
-
-	if (op->op_nents)
-		ib_dma_unmap_sg(ic->i_cm_id->device,
-				op->op_sg, op->op_nents,
-				DMA_TO_DEVICE);
-
-	if (rm->rdma.op_active && rm->data.op_notify)
-		rds_ib_send_unmap_rdma(ic, &rm->rdma, wc_status);
-}
-
 /*
  * Unmap the resources associated with a struct send_work.
  *
@@ -902,7 +897,9 @@ int rds_ib_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op)
 		send->s_queued = jiffies;
 		send->s_op = NULL;
 
-		nr_sig += rds_ib_set_wr_signal_state(ic, send, op->op_notify);
+		if (!op->op_notify)
+			nr_sig += rds_ib_set_wr_signal_state(ic, send,
+							     op->op_notify);
 
 		send->s_wr.opcode = op->op_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
 		send->s_rdma_wr.remote_addr = remote_addr;
diff --git a/net/rds/rdma.c b/net/rds/rdma.c
index b340ed4..916f5ec 100644
--- a/net/rds/rdma.c
+++ b/net/rds/rdma.c
@@ -641,16 +641,6 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
 		}
 		op->op_notifier->n_user_token = args->user_token;
 		op->op_notifier->n_status = RDS_RDMA_SUCCESS;
-
-		/* Enable rmda notification on data operation for composite
-		 * rds messages and make sure notification is enabled only
-		 * for the data operation which follows it so that application
-		 * gets notified only after full message gets delivered.
-		 */
-		if (rm->data.op_sg) {
-			rm->rdma.op_notify = 0;
-			rm->data.op_notify = !!(args->flags & RDS_RDMA_NOTIFY_ME);
-		}
 	}
 
 	/* The cookie contains the R_Key of the remote memory region, and
diff --git a/net/rds/rds.h b/net/rds/rds.h
index 0d8f67c..f0066d1 100644
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -476,7 +476,6 @@ struct rds_message {
 		} rdma;
 		struct rm_data_op {
 			unsigned int		op_active:1;
-			unsigned int		op_notify:1;
 			unsigned int		op_nents;
 			unsigned int		op_count;
 			unsigned int		op_dmasg;
diff --git a/net/rds/send.c b/net/rds/send.c
index 166dd57..031b1e9 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -491,14 +491,12 @@ void rds_rdma_send_complete(struct rds_message *rm, int status)
 	struct rm_rdma_op *ro;
 	struct rds_notifier *notifier;
 	unsigned long flags;
-	unsigned int notify = 0;
 
 	spin_lock_irqsave(&rm->m_rs_lock, flags);
 
-	notify =  rm->rdma.op_notify | rm->data.op_notify;
 	ro = &rm->rdma;
 	if (test_bit(RDS_MSG_ON_SOCK, &rm->m_flags) &&
-	    ro->op_active && notify && ro->op_notifier) {
+	    ro->op_active && ro->op_notify && ro->op_notifier) {
 		notifier = ro->op_notifier;
 		rs = rm->m_rs;
 		sock_hold(rds_rs_to_sk(rs));
-- 
1.9.1