[PATCH net-next v8 03/13] net/rds: ib: refuse to attach a connection to a device being removed
flat view
COOLING6d
From: Allison Henderson <achender@kernel.org>
Date: 2026-10-03 16:32:17
Also in:
linux-rdma
Subsystem:
networking [general], rds - reliable datagram sockets, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Allison Henderson, Linus Torvalds
Revision v8 of 9 in this series.
Revisions (9)
rds_ib_remove_one() drops every connection on the device's conn_list
in rds_ib_dev_shutdown(), then clears the client data so that no new
connect can find the device. A connect that is already past
rds_ib_get_client_data() when the walk runs is not covered by either:
rds_ib_setup_qp() goes on to rds_ib_add_conn(), which moves the
connection onto the conn_list the walk has just finished with, and
builds a QP on a device that is on its way out. Nothing drops that
connection afterwards - the device's shutdown walk is over, and the
connection never returns to ib_nodev_conns, which is the only list the
transport exit sweeps - so it outlives the device, and the module.
Make rds_ib_dev_shutdown() mark the device as shutting down under
rds_ibdev->spinlock before it walks conn_list, and have
rds_ib_add_conn() refuse, under the same lock, to attach a connection
to a device so marked. Every connection is then either on the list
when the walk drops it, or refused: the connect fails, the connection
stays on ib_nodev_conns, and either its own drop or the exit sweep
tears it down. rds_ib_setup_qp() has not taken anything from the
device at that point, so the failure needs no unwinding beyond the
client-data reference it already releases.
This mirrors the UEK gate on the device removal flag in
rds_ib_add_conn().
Fixes: fc19de38be92 ("RDS/IB: disconnect when IB devices are removed")
Assisted-by: Claude-Code:claude-fable-5
Signed-off-by: Allison Henderson <achender@kernel.org>
---
net/rds/ib.c | 5 +++++
net/rds/ib.h | 7 ++++++-
net/rds/ib_cm.c | 4 +++-
net/rds/ib_rdma.c | 17 +++++++++++++++--
4 files changed, 29 insertions(+), 4 deletions(-)
diff --git a/net/rds/ib.c b/net/rds/ib.c
index 4ea9838d090c..a7647ec01a11 100644
--- a/net/rds/ib.c
+++ b/net/rds/ib.c@@ -86,6 +86,11 @@ static void rds_ib_dev_shutdown(struct rds_ib_device *rds_ibdev) unsigned long flags; spin_lock_irqsave(&rds_ibdev->spinlock, flags); + /* Close the device to new connections under the same lock that + * rds_ib_add_conn() attaches them under, so that every + * connection is either dropped by the walk below or refused. + */ + rds_ibdev->shutting_down = true; list_for_each_entry(ic, &rds_ibdev->conn_list, ib_node) rds_conn_path_drop(&ic->conn->c_path[0], true); spin_unlock_irqrestore(&rds_ibdev->spinlock, flags);
diff --git a/net/rds/ib.h b/net/rds/ib.h
index 1901226368c9..d1a3d421d439 100644
--- a/net/rds/ib.h
+++ b/net/rds/ib.h@@ -258,6 +258,10 @@ struct rds_ib_device { unsigned int max_initiator_depth; unsigned int max_responder_resources; spinlock_t spinlock; /* protect the above */ + /* set under spinlock by rds_ib_dev_shutdown(): the device is + * going away and no connection may attach to it any more + */ + bool shutting_down; refcount_t refcount; struct work_struct free_work; int *vector_load;
@@ -384,7 +388,8 @@ void rds_ib_cm_connect_complete(struct rds_connection *conn, struct rds_ib_device *rds_ib_get_device(__be32 ipaddr); int rds_ib_update_ipaddr(struct rds_ib_device *rds_ibdev, struct in6_addr *ipaddr); -void rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn); +int rds_ib_add_conn(struct rds_ib_device *rds_ibdev, + struct rds_connection *conn); void rds_ib_remove_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn); void rds_ib_destroy_nodev_conns(void); void rds_ib_mr_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc);
diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c
index 8b16bd7c40ce..82ecbb9a3da1 100644
--- a/net/rds/ib_cm.c
+++ b/net/rds/ib_cm.c@@ -524,7 +524,9 @@ static int rds_ib_setup_qp(struct rds_connection *conn) fr_queue_space = RDS_IB_DEFAULT_FR_WR; /* add the conn now so that connection establishment has the dev */ - rds_ib_add_conn(rds_ibdev, conn); + ret = rds_ib_add_conn(rds_ibdev, conn); + if (ret) + goto out; max_wrs = rds_ibdev->max_wrs < rds_ib_sysctl_max_send_wr + 1 ? rds_ibdev->max_wrs - 1 : rds_ib_sysctl_max_send_wr;
diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c
index db7e92e7bd29..50c02f47cf68 100644
--- a/net/rds/ib_rdma.c
+++ b/net/rds/ib_rdma.c@@ -119,7 +119,8 @@ int rds_ib_update_ipaddr(struct rds_ib_device *rds_ibdev, return 0; } -void rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn) +int rds_ib_add_conn(struct rds_ib_device *rds_ibdev, + struct rds_connection *conn) { struct rds_ib_connection *ic = conn->c_transport_data;
@@ -127,15 +128,27 @@ void rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *con spin_lock_irq(&ib_nodev_conns_lock); BUG_ON(list_empty(&ib_nodev_conns)); BUG_ON(list_empty(&ic->ib_node)); - list_del(&ic->ib_node); spin_lock(&rds_ibdev->spinlock); + /* rds_ib_dev_shutdown() has walked conn_list, or is about to + * with this lock held: a connection attached now would never be + * dropped by it, so leave the connection on the nodev list for + * the caller to fail and the transport exit to find. + */ + if (rds_ibdev->shutting_down) { + spin_unlock(&rds_ibdev->spinlock); + spin_unlock_irq(&ib_nodev_conns_lock); + return -ENODEV; + } + list_del(&ic->ib_node); list_add_tail(&ic->ib_node, &rds_ibdev->conn_list); spin_unlock(&rds_ibdev->spinlock); spin_unlock_irq(&ib_nodev_conns_lock); ic->rds_ibdev = rds_ibdev; refcount_inc(&rds_ibdev->refcount); + + return 0; } void rds_ib_remove_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
--
2.25.1