netdev - [PATCH net-next 1/2] rds: tcp: allow progress of rds_conn_shutdown if the rds_connection is marked ERROR by an intervening FIN

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Date:   Fri, 31 Mar 2017 15:56:30 -0700
From:   Sowmini Varadhan <sowmini.varadhan@...cle.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, santosh.shilimkar@...cle.com,
        sowmini.varadhan@...cle.com
Subject: [PATCH net-next 1/2] rds: tcp: allow progress of rds_conn_shutdown if the rds_connection is marked ERROR by an intervening FIN

rds_conn_shutdown() runs in workq context, and marks the rds_connection
as DISCONNECTING before quiescing Tx/Rx paths. However, after all I/O
has quiesced, we may still find the rds_connection state to be
RDS_CONN_ERROR if an intervening FIN was processed in softirq context.

This is not a fatal error: rds_conn_shutdown() should continue the
shutdown, and there is no need to log noisy messages about this event.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
---
 net/rds/connection.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/net/rds/connection.c b/net/rds/connection.c
index 1fa75ab..6a5ebde 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -333,11 +333,19 @@ void rds_conn_shutdown(struct rds_conn_path *cp)
 		rds_conn_path_reset(cp);
 
 		if (!rds_conn_path_transition(cp, RDS_CONN_DISCONNECTING,
+					      RDS_CONN_DOWN) &&
+		    !rds_conn_path_transition(cp, RDS_CONN_ERROR,
 					      RDS_CONN_DOWN)) {
 			/* This can happen - eg when we're in the middle of tearing
 			 * down the connection, and someone unloads the rds module.
-			 * Quite reproduceable with loopback connections.
+			 * Quite reproducible with loopback connections.
 			 * Mostly harmless.
+			 *
+			 * Note that this also happens with rds-tcp because
+			 * we could have triggered rds_conn_path_drop in irq
+			 * mode from rds_tcp_state change on the receipt of
+			 * a FIN, thus we need to recheck for RDS_CONN_ERROR
+			 * here.
 			 */
 			rds_conn_path_error(cp, "%s: failed to transition "
 					    "to state DOWN, current state "
-- 
1.7.1