From: Jason Gunthorpe <j...@nvidia.com> [ Upstream commit cc9c037343898eb7a775e6b81d092ee21eeff218 ]
The REQ flows are concerned that once the handler is called on the new cm_id the ULP can choose to trigger a rdma_destroy_id() concurrently at any time. However, this is not true, while the ULP can call rdma_destroy_id(), it immediately blocks on the handler_mutex which prevents anything harmful from running concurrently. Remove the confusing extra locking and refcounts and make the handler_mutex protecting state during destroy more clear. Link: https://lore.kernel.org/r/20200723070707.1771101-4-l...@kernel.org Signed-off-by: Leon Romanovsky <leo...@mellanox.com> Signed-off-by: Jason Gunthorpe <j...@nvidia.com> Signed-off-by: Sasha Levin <sas...@kernel.org> --- drivers/infiniband/core/cma.c | 31 ++++++------------------------- 1 file changed, 6 insertions(+), 25 deletions(-) diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c index 04151c301e851..11f43204fee77 100644 --- a/drivers/infiniband/core/cma.c +++ b/drivers/infiniband/core/cma.c @@ -1831,21 +1831,21 @@ static void cma_leave_mc_groups(struct rdma_id_private *id_priv) void rdma_destroy_id(struct rdma_cm_id *id) { - struct rdma_id_private *id_priv; + struct rdma_id_private *id_priv = + container_of(id, struct rdma_id_private, id); enum rdma_cm_state state; - id_priv = container_of(id, struct rdma_id_private, id); - trace_cm_id_destroy(id_priv); - state = cma_exch(id_priv, RDMA_CM_DESTROYING); - cma_cancel_operation(id_priv, state); - /* * Wait for any active callback to finish. New callbacks will find * the id_priv state set to destroying and abort. */ mutex_lock(&id_priv->handler_mutex); + trace_cm_id_destroy(id_priv); + state = cma_exch(id_priv, RDMA_CM_DESTROYING); mutex_unlock(&id_priv->handler_mutex); + cma_cancel_operation(id_priv, state); + rdma_restrack_del(&id_priv->res); if (id_priv->cma_dev) { if (rdma_cap_ib_cm(id_priv->id.device, 1)) { @@ -2205,19 +2205,9 @@ static int cma_ib_req_handler(struct ib_cm_id *cm_id, cm_id->context = conn_id; cm_id->cm_handler = cma_ib_handler; - /* - * Protect against the user destroying conn_id from another thread - * until we're done accessing it. - */ - cma_id_get(conn_id); ret = cma_cm_event_handler(conn_id, &event); if (ret) goto err3; - /* - * Acquire mutex to prevent user executing rdma_destroy_id() - * while we're accessing the cm_id. - */ - mutex_lock(&lock); if (cma_comp(conn_id, RDMA_CM_CONNECT) && (conn_id->id.qp_type != IB_QPT_UD)) { trace_cm_send_mra(cm_id->context); @@ -2226,13 +2216,11 @@ static int cma_ib_req_handler(struct ib_cm_id *cm_id, mutex_unlock(&lock); mutex_unlock(&conn_id->handler_mutex); mutex_unlock(&listen_id->handler_mutex); - cma_id_put(conn_id); if (net_dev) dev_put(net_dev); return 0; err3: - cma_id_put(conn_id); /* Destroy the CM ID by returning a non-zero value. */ conn_id->cm_id.ib = NULL; err2: @@ -2409,11 +2397,6 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id, memcpy(cma_src_addr(conn_id), laddr, rdma_addr_size(laddr)); memcpy(cma_dst_addr(conn_id), raddr, rdma_addr_size(raddr)); - /* - * Protect against the user destroying conn_id from another thread - * until we're done accessing it. - */ - cma_id_get(conn_id); ret = cma_cm_event_handler(conn_id, &event); if (ret) { /* User wants to destroy the CM ID */ @@ -2421,13 +2404,11 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id, cma_exch(conn_id, RDMA_CM_DESTROYING); mutex_unlock(&conn_id->handler_mutex); mutex_unlock(&listen_id->handler_mutex); - cma_id_put(conn_id); rdma_destroy_id(&conn_id->id); return ret; } mutex_unlock(&conn_id->handler_mutex); - cma_id_put(conn_id); out: mutex_unlock(&listen_id->handler_mutex); -- 2.25.1
