[PATCH 6.18 264/752] net/rds: No shortcut out of RDS_CONN_ERROR

Sasha Levin
2026-02-28T17:51:49Z

From: Gerd Rausch <gerd.rausch@oracle.com>

[ Upstream commit ad22d24be635c6beab6a1fdd3f8b1f3c478d15da ]

RDS connections carry a state "rds_conn_path::cp_state"
and transitions from one state to another and are conditional
upon an expected state: "rds_conn_path_transition."

There is one exception to this conditionality, which is
"RDS_CONN_ERROR" that can be enforced by "rds_conn_path_drop"
regardless of what state the condition is currently in.

But as soon as a connection enters state "RDS_CONN_ERROR",
the connection handling code expects it to go through the
shutdown-path.

The RDS/TCP multipath changes added a shortcut out of
"RDS_CONN_ERROR" straight back to "RDS_CONN_CONNECTING"
via "rds_tcp_accept_one_path" (e.g. after "rds_tcp_state_change").

A subsequent "rds_tcp_reset_callbacks" can then transition
the state to "RDS_CONN_RESETTING" with a shutdown-worker queued.

That'll trip up "rds_conn_init_shutdown", which was
never adjusted to handle "RDS_CONN_RESETTING" and subsequently
drops the connection with the dreaded "DR_INV_CONN_STATE",
which leaves "RDS_SHUTDOWN_WORK_QUEUED" on forever.

So we do two things here:

a) Don't shortcut "RDS_CONN_ERROR", but take the longer
path through the shutdown code.

b) Add "RDS_CONN_RESETTING" to the expected states in
"rds_conn_init_shutdown" so that we won't error out
and get stuck, if we ever hit weird state transitions
like this again."

Signed-off-by: Gerd Rausch <gerd.rausch@oracle.com>
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Link: https://patch.msgid.link/20260122055213.83608-2-achender@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/rds/connection.c | 2 ++
net/rds/tcp_listen.c | 5 -----
2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/net/rds/connection.c b/net/rds/connection.c
index 68bc88cce84ec..ad8027e6f54ef 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -382,6 +382,8 @@ void rds_conn_shutdown(struct rds_conn_path *cp)
if (!rds_conn_path_transition(cp, RDS_CONN_UP,
RDS_CONN_DISCONNECTING) &&
!rds_conn_path_transition(cp, RDS_CONN_ERROR,
+ RDS_CONN_DISCONNECTING) &&
+ !rds_conn_path_transition(cp, RDS_CONN_RESETTING,
RDS_CONN_DISCONNECTING)) {
rds_conn_path_error(cp,
"shutdown called in state %d\n",
diff --git a/net/rds/tcp_listen.c b/net/rds/tcp_listen.c
index 91e34af3fe5d5..65c5425a02de4 100644
--- a/net/rds/tcp_listen.c
+++ b/net/rds/tcp_listen.c
@@ -59,9 +59,6 @@ void rds_tcp_keepalive(struct socket *sock)
* socket and force a reconneect from smaller -> larger ip addr. The reason
* we special case cp_index 0 is to allow the rds probe ping itself to itself
* get through efficiently.
- * Since reconnects are only initiated from the node with the numerically
- * smaller ip address, we recycle conns in RDS_CONN_ERROR on the passive side
- * by moving them to CONNECTING in this function.
*/
static
struct rds_tcp_connection *rds_tcp_accept_one_path(struct rds_connection *conn)
@@ -86,8 +83,6 @@ struct rds_tcp_connection *rds_tcp_accept_one_path(struct rds_connection *conn)
struct rds_conn_path *cp = &conn->c_path[i];

if (rds_conn_path_transition(cp, RDS_CONN_DOWN,
- RDS_CONN_CONNECTING) ||
- rds_conn_path_transition(cp, RDS_CONN_ERROR,
RDS_CONN_CONNECTING)) {
return cp->cp_transport_data;
}
--
2.51.0