Commit ad22d24b authored by Gerd Rausch's avatar Gerd Rausch Committed by Jakub Kicinski
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net/rds: No shortcut out of RDS_CONN_ERROR 



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: default avatarGerd Rausch <gerd.rausch@oracle.com>
Signed-off-by: default avatarAllison Henderson <allison.henderson@oracle.com>
Link: https://patch.msgid.link/20260122055213.83608-2-achender@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 6a9e8b60

net/rds/connection.c

+2 −0
Original line number Diff line number Diff line
@@ -395,6 +395,8 @@ 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",

net/rds/tcp_listen.c

+0 −5
Original line number Diff line number Diff line
@@ -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;

		}