linux-kernel - [PATCH 4.4 72/96] RDS: RDMA: return appropriate error on rdma map failures

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Message-Id: <20171128100507.540894362@linuxfoundation.org>
Date:   Tue, 28 Nov 2017 11:23:21 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Santosh Shilimkar <santosh.shilimkar@...cle.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.4 72/96] RDS: RDMA: return appropriate error on rdma map failures

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Santosh Shilimkar <santosh.shilimkar@...cle.com>


[ Upstream commit 584a8279a44a800dea5a5c1e9d53a002e03016b4 ]

The first message to a remote node should prompt a new
connection even if it is RDMA operation. For RDMA operation
the MR mapping can fail because connections is not yet up.

Since the connection establishment is asynchronous,
we make sure the map failure because of unavailable
connection reach to the user by appropriate error code.
Before returning to the user, lets trigger the connection
so that its ready for the next retry.

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@...cle.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/rds/send.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -959,6 +959,11 @@ static int rds_cmsg_send(struct rds_sock
 			ret = rds_cmsg_rdma_map(rs, rm, cmsg);
 			if (!ret)
 				*allocated_mr = 1;
+			else if (ret == -ENODEV)
+				/* Accommodate the get_mr() case which can fail
+				 * if connection isn't established yet.
+				 */
+				ret = -EAGAIN;
 			break;
 		case RDS_CMSG_ATOMIC_CSWP:
 		case RDS_CMSG_ATOMIC_FADD:
@@ -1072,8 +1077,12 @@ int rds_sendmsg(struct socket *sock, str
 
 	/* Parse any control messages the user may have included. */
 	ret = rds_cmsg_send(rs, rm, msg, &allocated_mr);
-	if (ret)
+	if (ret) {
+		/* Trigger connection so that its ready for the next retry */
+		if (ret ==  -EAGAIN)
+			rds_conn_connect_if_down(conn);
 		goto out;
+	}
 
 	if (rm->rdma.op_active && !conn->c_trans->xmit_rdma) {
 		printk_ratelimited(KERN_NOTICE "rdma_op %p conn xmit_rdma %p\n",