From 071ba4cc559de47160761b9500b72e8fa09d923d Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Mon, 26 Oct 2020 11:25:49 -0300 Subject: RDMA: Add rdma_connect_locked() There are two flows for handling RDMA_CM_EVENT_ROUTE_RESOLVED, either the handler triggers a completion and another thread does rdma_connect() or the handler directly calls rdma_connect(). In all cases rdma_connect() needs to hold the handler_mutex, but when handler's are invoked this is already held by the core code. This causes ULPs using the 2nd method to deadlock. Provide a rdma_connect_locked() and have all ULPs call it from their handlers. Link: https://lore.kernel.org/r/0-v2-53c22d5c1405+33-rdma_connect_locking_jgg@nvidia.com Reported-and-tested-by: Guoqing Jiang Fixes: 2a7cec538169 ("RDMA/cma: Fix locking for the RDMA_CM_CONNECT state") Acked-by: Santosh Shilimkar Acked-by: Jack Wang Reviewed-by: Christoph Hellwig Reviewed-by: Max Gurtovoy Reviewed-by: Sagi Grimberg Signed-off-by: Jason Gunthorpe --- drivers/infiniband/core/cma.c | 48 +++++++++++++++++++++++++------- drivers/infiniband/ulp/iser/iser_verbs.c | 2 +- drivers/infiniband/ulp/rtrs/rtrs-clt.c | 4 +-- 3 files changed, 41 insertions(+), 13 deletions(-) (limited to 'drivers/infiniband') diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c index 7c2ab1f2fbea..a77750b8954d 100644 --- a/drivers/infiniband/core/cma.c +++ b/drivers/infiniband/core/cma.c @@ -405,10 +405,10 @@ static int cma_comp_exch(struct rdma_id_private *id_priv, /* * The FSM uses a funny double locking where state is protected by both * the handler_mutex and the spinlock. State is not allowed to change - * away from a handler_mutex protected value without also holding + * to/from a handler_mutex protected value without also holding * handler_mutex. */ - if (comp == RDMA_CM_CONNECT) + if (comp == RDMA_CM_CONNECT || exch == RDMA_CM_CONNECT) lockdep_assert_held(&id_priv->handler_mutex); spin_lock_irqsave(&id_priv->lock, flags); @@ -4038,17 +4038,23 @@ out: return ret; } -int rdma_connect(struct rdma_cm_id *id, struct rdma_conn_param *conn_param) +/** + * rdma_connect_locked - Initiate an active connection request. + * @id: Connection identifier to connect. + * @conn_param: Connection information used for connected QPs. + * + * Same as rdma_connect() but can only be called from the + * RDMA_CM_EVENT_ROUTE_RESOLVED handler callback. + */ +int rdma_connect_locked(struct rdma_cm_id *id, + struct rdma_conn_param *conn_param) { struct rdma_id_private *id_priv = container_of(id, struct rdma_id_private, id); int ret; - mutex_lock(&id_priv->handler_mutex); - if (!cma_comp_exch(id_priv, RDMA_CM_ROUTE_RESOLVED, RDMA_CM_CONNECT)) { - ret = -EINVAL; - goto err_unlock; - } + if (!cma_comp_exch(id_priv, RDMA_CM_ROUTE_RESOLVED, RDMA_CM_CONNECT)) + return -EINVAL; if (!id->qp) { id_priv->qp_num = conn_param->qp_num; @@ -4066,11 +4072,33 @@ int rdma_connect(struct rdma_cm_id *id, struct rdma_conn_param *conn_param) ret = -ENOSYS; if (ret) goto err_state; - mutex_unlock(&id_priv->handler_mutex); return 0; err_state: cma_comp_exch(id_priv, RDMA_CM_CONNECT, RDMA_CM_ROUTE_RESOLVED); -err_unlock: + return ret; +} +EXPORT_SYMBOL(rdma_connect_locked); + +/** + * rdma_connect - Initiate an active connection request. + * @id: Connection identifier to connect. + * @conn_param: Connection information used for connected QPs. + * + * Users must have resolved a route for the rdma_cm_id to connect with by having + * called rdma_resolve_route before calling this routine. + * + * This call will either connect to a remote QP or obtain remote QP information + * for unconnected rdma_cm_id's. The actual operation is based on the + * rdma_cm_id's port space. + */ +int rdma_connect(struct rdma_cm_id *id, struct rdma_conn_param *conn_param) +{ + struct rdma_id_private *id_priv = + container_of(id, struct rdma_id_private, id); + int ret; + + mutex_lock(&id_priv->handler_mutex); + ret = rdma_connect_locked(id, conn_param); mutex_unlock(&id_priv->handler_mutex); return ret; } diff --git a/drivers/infiniband/ulp/iser/iser_verbs.c b/drivers/infiniband/ulp/iser/iser_verbs.c index 2f3ebc0a75d9..2bd18b006893 100644 --- a/drivers/infiniband/ulp/iser/iser_verbs.c +++ b/drivers/infiniband/ulp/iser/iser_verbs.c @@ -620,7 +620,7 @@ static void iser_route_handler(struct rdma_cm_id *cma_id) conn_param.private_data = (void *)&req_hdr; conn_param.private_data_len = sizeof(struct iser_cm_hdr); - ret = rdma_connect(cma_id, &conn_param); + ret = rdma_connect_locked(cma_id, &conn_param); if (ret) { iser_err("failure connecting: %d\n", ret); goto failure; diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c index 776e89231c52..f298adc02acb 100644 --- a/drivers/infiniband/ulp/rtrs/rtrs-clt.c +++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c @@ -1674,9 +1674,9 @@ static int rtrs_rdma_route_resolved(struct rtrs_clt_con *con) uuid_copy(&msg.sess_uuid, &sess->s.uuid); uuid_copy(&msg.paths_uuid, &clt->paths_uuid); - err = rdma_connect(con->c.cm_id, ¶m); + err = rdma_connect_locked(con->c.cm_id, ¶m); if (err) - rtrs_err(clt, "rdma_connect(): %d\n", err); + rtrs_err(clt, "rdma_connect_locked(): %d\n", err); return err; } -- cgit v1.2.3