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 <guoqing.jiang@cloud.ionos.com>
Fixes: 2a7cec538169 ("RDMA/cma: Fix locking for the RDMA_CM_CONNECT state")
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Acked-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 7c2ab1f..a77750b 100644 (file)
--- 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 2f3ebc0..2bd18b0 100644 (file)
--- 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 776e892..f298adc 100644 (file)
--- 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, &param);
+       err = rdma_connect_locked(con->c.cm_id, &param);
        if (err)
-               rtrs_err(clt, "rdma_connect(): %d\n", err);
+               rtrs_err(clt, "rdma_connect_locked(): %d\n", err);
 
        return err;
 }

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index aad829a..8bbc48c 100644 (file)
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -1890,10 +1890,10 @@ static int nvme_rdma_route_resolved(struct nvme_rdma_queue *queue)
                priv.hsqsize = cpu_to_le16(queue->ctrl->ctrl.sqsize);
        }
 
-       ret = rdma_connect(queue->cm_id, &param);
+       ret = rdma_connect_locked(queue->cm_id, &param);
        if (ret) {
                dev_err(ctrl->ctrl.device,
-                       "rdma_connect failed (%d).\n", ret);
+                       "rdma_connect_locked failed (%d).\n", ret);
                goto out_destroy_queue_ib;
        }
 

diff --git a/include/rdma/rdma_cm.h b/include/rdma/rdma_cm.h
index c672ae1..32a67af 100644 (file)
--- a/include/rdma/rdma_cm.h
+++ b/include/rdma/rdma_cm.h
@@ -227,19 +227,9 @@ void rdma_destroy_qp(struct rdma_cm_id *id);
 int rdma_init_qp_attr(struct rdma_cm_id *id, struct ib_qp_attr *qp_attr,
                       int *qp_attr_mask);
 
-/**
- * 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);
+int rdma_connect_locked(struct rdma_cm_id *id,
+                       struct rdma_conn_param *conn_param);
 
 int rdma_connect_ece(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
                     struct rdma_ucm_ece *ece);

diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c
index 06603dd..b36b606 100644 (file)
--- a/net/rds/ib_cm.c
+++ b/net/rds/ib_cm.c
@@ -956,9 +956,10 @@ int rds_ib_cm_initiate_connect(struct rdma_cm_id *cm_id, bool isv6)
        rds_ib_cm_fill_conn_param(conn, &conn_param, &dp,
                                  conn->c_proposed_version,
                                  UINT_MAX, UINT_MAX, isv6);
-       ret = rdma_connect(cm_id, &conn_param);
+       ret = rdma_connect_locked(cm_id, &conn_param);
        if (ret)
-               rds_ib_conn_error(conn, "rdma_connect failed (%d)\n", ret);
+               rds_ib_conn_error(conn, "rdma_connect_locked failed (%d)\n",
+                                 ret);
 
 out:
        /* Beware - returning non-zero tells the rdma_cm to destroy