Re: [PATCH rdma-next v2 06/14] RDMA/restrack: Improve readability in task name management

[Jason Gunthorpe <jgg@nvidia.com>]

On Mon, Sep 07, 2020 at 03:21:48PM +0300, Leon Romanovsky wrote:
> diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
> index feed3c04979a..3fc3c821743d 100644
> +++ b/drivers/infiniband/core/cma.c
> @@ -467,10 +467,13 @@ static void _cma_attach_to_dev(struct rdma_id_private *id_priv,
>  	id_priv->id.route.addr.dev_addr.transport =
>  		rdma_node_get_transport(cma_dev->device->node_type);
>  	list_add_tail(&id_priv->list, &cma_dev->id_list);
> -	if (id_priv->res.kern_name)
> -		rdma_restrack_add(&id_priv->res);
> -	else
> -		rdma_restrack_uadd(&id_priv->res);
> +	/*
> +	 * For example UCMA doesn't set kern_name and below function will
> +	 * attach to "current" task.
> +	 */
> +	rdma_restrack_set_name(&id_priv->res, id_priv->res.kern_name);
> +	rdma_restrack_add(&id_priv->res);

I don't understand why the set_name was added here, looks wrong. For
the non-null case we either already have a task set because
rdma_create_id did it, or this is spawned from a listening_id and this
is WQ, so no reason to capture a WQ as the task.

I suppose the idea is that the rdma_restrack_set_name() in
rdma_accept() fixes this, but that isn't allowed either, there is no
locking so calling rdma_restrack_set_name() after rdma_restrack_add()
can't be done.

Without adding a bunch of locking someplace I think everything must
flow from the orignial rdma_cm_listen which was created in a
reasonable context, ie instead of passing name around the parent
restrack should be passed.

I came up with something like this

Can you put this and the patches here in a series please, up to this
patch all looks OK otherwise.

Jason

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index aecc60a5f8c3fe..b123811f33234a 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -457,7 +457,6 @@ static void _cma_attach_to_dev(struct rdma_id_private *id_priv,
 	 * For example UCMA doesn't set kern_name and below function will
 	 * attach to "current" task.
 	 */
-	rdma_restrack_set_name(&id_priv->res, id_priv->res.kern_name);
 	rdma_restrack_add(&id_priv->res);
 
 	trace_cm_id_attach(id_priv, cma_dev->device);
@@ -825,10 +824,10 @@ static void cma_id_put(struct rdma_id_private *id_priv)
 		complete(&id_priv->comp);
 }
 
-struct rdma_cm_id *__rdma_create_id(struct net *net,
-				    rdma_cm_event_handler event_handler,
-				    void *context, enum rdma_ucm_port_space ps,
-				    enum ib_qp_type qp_type, const char *caller)
+static struct rdma_id_private *
+__rdma_create_id(struct net *net, rdma_cm_event_handler event_handler,
+		 void *context, enum rdma_ucm_port_space ps,
+		 enum ib_qp_type qp_type, const struct rdma_id_private *parent)
 {
 	struct rdma_id_private *id_priv;
 
@@ -856,11 +855,44 @@ struct rdma_cm_id *__rdma_create_id(struct net *net,
 	id_priv->seq_num &= 0x00ffffff;
 
 	rdma_restrack_new(&id_priv->res, RDMA_RESTRACK_CM_ID);
-	rdma_restrack_set_name(&id_priv->res, caller);
+	if (parent)
+		rdma_restrack_parent_name(&id_priv->res, &parent->res);
 
-	return &id_priv->id;
+	return id_priv;
+}
+
+struct rdma_cm_id *
+__rdma_create_kernel_id(struct net *net, rdma_cm_event_handler event_handler,
+			void *context, enum rdma_ucm_port_space ps,
+			enum ib_qp_type qp_type, const char *caller)
+{
+	struct rdma_id_private *ret;
+
+	ret = __rdma_create_id(net, event_handler, context, ps, qp_type, NULL);
+	if (IS_ERR(ret))
+		return ERR_CAST(ret);
+
+	rdma_restrack_set_name(&ret->res, caller);
+	return &ret->id;
+}
+EXPORT_SYMBOL(__rdma_create_kernel_id);
+
+struct rdma_cm_id *rdma_create_user_id(rdma_cm_event_handler event_handler,
+				       void *context,
+				       enum rdma_ucm_port_space ps,
+				       enum ib_qp_type qp_type)
+{
+	struct rdma_id_private *ret;
+
+	ret = __rdma_create_id(current->nsproxy->net_ns, event_handler, context,
+			       ps, qp_type, NULL);
+	if (IS_ERR(ret))
+		return ERR_CAST(ret);
+
+	rdma_restrack_set_name(&ret->res, NULL);
+	return &ret->id;
 }
-EXPORT_SYMBOL(__rdma_create_id);
+EXPORT_SYMBOL(rdma_create_user_id);
 
 static int cma_init_ud_qp(struct rdma_id_private *id_priv, struct ib_qp *qp)
 {
@@ -2032,14 +2064,15 @@ cma_ib_new_conn_id(const struct rdma_cm_id *listen_id,
 	int ret;
 
 	listen_id_priv = container_of(listen_id, struct rdma_id_private, id);
-	id = __rdma_create_id(listen_id->route.addr.dev_addr.net,
-			    listen_id->event_handler, listen_id->context,
-			    listen_id->ps, ib_event->param.req_rcvd.qp_type,
-			    listen_id_priv->res.kern_name);
-	if (IS_ERR(id))
+	id_priv = __rdma_create_id(listen_id->route.addr.dev_addr.net,
+				   listen_id->event_handler, listen_id->context,
+				   listen_id->ps,
+				   ib_event->param.req_rcvd.qp_type,
+				   listen_id_priv);
+	if (IS_ERR(id_priv))
 		return NULL;
 
-	id_priv = container_of(id, struct rdma_id_private, id);
+	id = &id_priv->id;
 	if (cma_save_net_info((struct sockaddr *)&id->route.addr.src_addr,
 			      (struct sockaddr *)&id->route.addr.dst_addr,
 			      listen_id, ib_event, ss_family, service_id))
@@ -2093,13 +2126,13 @@ cma_ib_new_udp_id(const struct rdma_cm_id *listen_id,
 	int ret;
 
 	listen_id_priv = container_of(listen_id, struct rdma_id_private, id);
-	id = __rdma_create_id(net, listen_id->event_handler, listen_id->context,
-			      listen_id->ps, IB_QPT_UD,
-			      listen_id_priv->res.kern_name);
-	if (IS_ERR(id))
+	id_priv = __rdma_create_id(net, listen_id->event_handler,
+				   listen_id->context, listen_id->ps, IB_QPT_UD,
+				   listen_id_priv);
+	if (IS_ERR(id_priv))
 		return NULL;
 
-	id_priv = container_of(id, struct rdma_id_private, id);
+	id = &id_priv->id;
 	if (cma_save_net_info((struct sockaddr *)&id->route.addr.src_addr,
 			      (struct sockaddr *)&id->route.addr.dst_addr,
 			      listen_id, ib_event, ss_family,
@@ -2335,7 +2368,6 @@ static int cma_iw_handler(struct iw_cm_id *iw_id, struct iw_cm_event *iw_event)
 static int iw_conn_req_handler(struct iw_cm_id *cm_id,
 			       struct iw_cm_event *iw_event)
 {
-	struct rdma_cm_id *new_cm_id;
 	struct rdma_id_private *listen_id, *conn_id;
 	struct rdma_cm_event event = {};
 	int ret = -ECONNABORTED;
@@ -2355,16 +2387,14 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id,
 		goto out;
 
 	/* Create a new RDMA id for the new IW CM ID */
-	new_cm_id = __rdma_create_id(listen_id->id.route.addr.dev_addr.net,
-				     listen_id->id.event_handler,
-				     listen_id->id.context,
-				     RDMA_PS_TCP, IB_QPT_RC,
-				     listen_id->res.kern_name);
-	if (IS_ERR(new_cm_id)) {
+	conn_id = __rdma_create_id(listen_id->id.route.addr.dev_addr.net,
+				   listen_id->id.event_handler,
+				   listen_id->id.context, RDMA_PS_TCP,
+				   IB_QPT_RC, listen_id);
+	if (IS_ERR(conn_id)) {
 		ret = -ENOMEM;
 		goto out;
 	}
-	conn_id = container_of(new_cm_id, struct rdma_id_private, id);
 	mutex_lock_nested(&conn_id->handler_mutex, SINGLE_DEPTH_NESTING);
 	conn_id->state = RDMA_CM_CONNECT;
 
@@ -2469,7 +2499,6 @@ static void cma_listen_on_dev(struct rdma_id_private *id_priv,
 			      struct cma_device *cma_dev)
 {
 	struct rdma_id_private *dev_id_priv;
-	struct rdma_cm_id *id;
 	struct net *net = id_priv->id.route.addr.dev_addr.net;
 	int ret;
 
@@ -2478,13 +2507,12 @@ static void cma_listen_on_dev(struct rdma_id_private *id_priv,
 	if (cma_family(id_priv) == AF_IB && !rdma_cap_ib_cm(cma_dev->device, 1))
 		return;
 
-	id = __rdma_create_id(net, cma_listen_handler, id_priv, id_priv->id.ps,
-			      id_priv->id.qp_type, id_priv->res.kern_name);
-	if (IS_ERR(id))
+	dev_id_priv =
+		__rdma_create_id(net, cma_listen_handler, id_priv,
+				 id_priv->id.ps, id_priv->id.qp_type, id_priv);
+	if (IS_ERR(dev_id_priv))
 		return;
 
-	dev_id_priv = container_of(id, struct rdma_id_private, id);
-
 	dev_id_priv->state = RDMA_CM_ADDR_BOUND;
 	memcpy(cma_src_addr(dev_id_priv), cma_src_addr(id_priv),
 	       rdma_addr_size(cma_src_addr(id_priv)));
@@ -2497,7 +2525,7 @@ static void cma_listen_on_dev(struct rdma_id_private *id_priv,
 	dev_id_priv->tos_set = id_priv->tos_set;
 	dev_id_priv->tos = id_priv->tos;
 
-	ret = rdma_listen(id, id_priv->backlog);
+	ret = rdma_listen(&dev_id_priv->id, id_priv->backlog);
 	if (ret)
 		dev_warn(&cma_dev->device->dev,
 			 "RDMA CMA: cma_listen_on_dev, error %d\n", ret);
@@ -4152,8 +4180,25 @@ static int cma_send_sidr_rep(struct rdma_id_private *id_priv,
 	return ib_send_cm_sidr_rep(id_priv->cm_id.ib, &rep);
 }
 
-int __rdma_accept(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
-		  const char *caller)
+/**
+ * rdma_accept - Called to accept a connection request or response.
+ * @id: Connection identifier associated with the request.
+ * @conn_param: Information needed to establish the connection.  This must be
+ *   provided if accepting a connection request.  If accepting a connection
+ *   response, this parameter must be NULL.
+ *
+ * Typically, this routine is only called by the listener to accept a connection
+ * request.  It must also be called on the active side of a connection if the
+ * user is performing their own QP transitions.
+ *
+ * In the case of error, a reject message is sent to the remote side and the
+ * state of the qp associated with the id is modified to error, such that any
+ * previously posted receive buffers would be flushed.
+ *
+ * This function is for use by kernel ULPs and must be called from under the
+ * handler callback.
+ */
+int rdma_accept(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);
@@ -4161,8 +4206,6 @@ int __rdma_accept(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
 
 	lockdep_assert_held(&id_priv->handler_mutex);
 
-	rdma_restrack_set_name(&id_priv->res, caller);
-
 	if (READ_ONCE(id_priv->state) != RDMA_CM_CONNECT)
 		return -EINVAL;
 
@@ -4201,10 +4244,10 @@ int __rdma_accept(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
 	rdma_reject(id, NULL, 0, IB_CM_REJ_CONSUMER_DEFINED);
 	return ret;
 }
-EXPORT_SYMBOL(__rdma_accept);
+EXPORT_SYMBOL(rdma_accept);
 
-int __rdma_accept_ece(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
-		      const char *caller, struct rdma_ucm_ece *ece)
+int rdma_accept_ece(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
+		    struct rdma_ucm_ece *ece)
 {
 	struct rdma_id_private *id_priv =
 		container_of(id, struct rdma_id_private, id);
@@ -4212,9 +4255,9 @@ int __rdma_accept_ece(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
 	id_priv->ece.vendor_id = ece->vendor_id;
 	id_priv->ece.attr_mod = ece->attr_mod;
 
-	return __rdma_accept(id, conn_param, caller);
+	return rdma_accept(id, conn_param);
 }
-EXPORT_SYMBOL(__rdma_accept_ece);
+EXPORT_SYMBOL(rdma_accept_ece);
 
 void rdma_lock_handler(struct rdma_cm_id *id)
 {
diff --git a/drivers/infiniband/core/restrack.c b/drivers/infiniband/core/restrack.c
index 0c67acf2169d69..4aeeaaed0f17dd 100644
--- a/drivers/infiniband/core/restrack.c
+++ b/drivers/infiniband/core/restrack.c
@@ -189,7 +189,7 @@ EXPORT_SYMBOL(rdma_restrack_set_name);
  * @parent: parent resource entry
  */
 void rdma_restrack_parent_name(struct rdma_restrack_entry *dst,
-			       struct rdma_restrack_entry *parent)
+			       const struct rdma_restrack_entry *parent)
 {
 	if (rdma_is_kernel_res(parent))
 		dst->kern_name = parent->kern_name;
diff --git a/drivers/infiniband/core/restrack.h b/drivers/infiniband/core/restrack.h
index 49c1d84cca2da4..6a04fc41f73801 100644
--- a/drivers/infiniband/core/restrack.h
+++ b/drivers/infiniband/core/restrack.h
@@ -32,5 +32,5 @@ void rdma_restrack_new(struct rdma_restrack_entry *res,
 void rdma_restrack_set_name(struct rdma_restrack_entry *res,
 			    const char *caller);
 void rdma_restrack_parent_name(struct rdma_restrack_entry *dst,
-			       struct rdma_restrack_entry *parent);
+			       const struct rdma_restrack_entry *parent);
 #endif /* _RDMA_CORE_RESTRACK_H_ */
diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index a5595bd489b089..2901847a01021a 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -456,8 +456,7 @@ static ssize_t ucma_create_id(struct ucma_file *file, const char __user *inbuf,
 		return -ENOMEM;
 
 	ctx->uid = cmd.uid;
-	cm_id = __rdma_create_id(current->nsproxy->net_ns,
-				 ucma_event_handler, ctx, cmd.ps, qp_type, NULL);
+	cm_id = rdma_create_user_id(ucma_event_handler, ctx, cmd.ps, qp_type);
 	if (IS_ERR(cm_id)) {
 		ret = PTR_ERR(cm_id);
 		goto err1;
@@ -1126,7 +1125,7 @@ static ssize_t ucma_accept(struct ucma_file *file, const char __user *inbuf,
 		ucma_copy_conn_param(ctx->cm_id, &conn_param, &cmd.conn_param);
 		mutex_lock(&ctx->mutex);
 		rdma_lock_handler(ctx->cm_id);
-		ret = __rdma_accept_ece(ctx->cm_id, &conn_param, NULL, &ece);
+		ret = rdma_accept_ece(ctx->cm_id, &conn_param, &ece);
 		if (!ret) {
 			/* The uid must be set atomically with the handler */
 			ctx->uid = cmd.uid;
@@ -1136,7 +1135,7 @@ static ssize_t ucma_accept(struct ucma_file *file, const char __user *inbuf,
 	} else {
 		mutex_lock(&ctx->mutex);
 		rdma_lock_handler(ctx->cm_id);
-		ret = __rdma_accept_ece(ctx->cm_id, NULL, NULL, &ece);
+		ret = rdma_accept_ece(ctx->cm_id, NULL, &ece);
 		rdma_unlock_handler(ctx->cm_id);
 		mutex_unlock(&ctx->mutex);
 	}
diff --git a/include/rdma/rdma_cm.h b/include/rdma/rdma_cm.h
index c1334c9a7aa858..c672ae1da26bb5 100644
--- a/include/rdma/rdma_cm.h
+++ b/include/rdma/rdma_cm.h
@@ -110,11 +110,14 @@ struct rdma_cm_id {
 	u8			 port_num;
 };
 
-struct rdma_cm_id *__rdma_create_id(struct net *net,
-				    rdma_cm_event_handler event_handler,
-				    void *context, enum rdma_ucm_port_space ps,
-				    enum ib_qp_type qp_type,
-				    const char *caller);
+struct rdma_cm_id *
+__rdma_create_kernel_id(struct net *net, rdma_cm_event_handler event_handler,
+			void *context, enum rdma_ucm_port_space ps,
+			enum ib_qp_type qp_type, const char *caller);
+struct rdma_cm_id *rdma_create_user_id(rdma_cm_event_handler event_handler,
+				       void *context,
+				       enum rdma_ucm_port_space ps,
+				       enum ib_qp_type qp_type);
 
 /**
  * rdma_create_id - Create an RDMA identifier.
@@ -132,9 +135,9 @@ struct rdma_cm_id *__rdma_create_id(struct net *net,
  * The event handler callback serializes on the id's mutex and is
  * allowed to sleep.
  */
-#define rdma_create_id(net, event_handler, context, ps, qp_type) \
-	__rdma_create_id((net), (event_handler), (context), (ps), (qp_type), \
-			 KBUILD_MODNAME)
+#define rdma_create_id(net, event_handler, context, ps, qp_type)               \
+	__rdma_create_kernel_id(net, event_handler, context, ps, qp_type,      \
+				KBUILD_MODNAME)
 
 /**
   * rdma_destroy_id - Destroys an RDMA identifier.
@@ -250,34 +253,12 @@ int rdma_connect_ece(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
  */
 int rdma_listen(struct rdma_cm_id *id, int backlog);
 
-int __rdma_accept(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
-		  const char *caller);
+int rdma_accept(struct rdma_cm_id *id, struct rdma_conn_param *conn_param);
 
 void rdma_lock_handler(struct rdma_cm_id *id);
 void rdma_unlock_handler(struct rdma_cm_id *id);
-int __rdma_accept_ece(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
-		      const char *caller, struct rdma_ucm_ece *ece);
-
-/**
- * rdma_accept - Called to accept a connection request or response.
- * @id: Connection identifier associated with the request.
- * @conn_param: Information needed to establish the connection.  This must be
- *   provided if accepting a connection request.  If accepting a connection
- *   response, this parameter must be NULL.
- *
- * Typically, this routine is only called by the listener to accept a connection
- * request.  It must also be called on the active side of a connection if the
- * user is performing their own QP transitions.
- *
- * In the case of error, a reject message is sent to the remote side and the
- * state of the qp associated with the id is modified to error, such that any
- * previously posted receive buffers would be flushed.
- *
- * This function is for use by kernel ULPs and must be called from under the
- * handler callback.
- */
-#define rdma_accept(id, conn_param) \
-	__rdma_accept((id), (conn_param),  KBUILD_MODNAME)
+int rdma_accept_ece(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
+		    struct rdma_ucm_ece *ece);
 
 /**
  * rdma_notify - Notifies the RDMA CM of an asynchronous event that has
diff --git a/include/rdma/restrack.h b/include/rdma/restrack.h
index 10bfed0fcd3262..d3a1cc5be7bcef 100644
--- a/include/rdma/restrack.h
+++ b/include/rdma/restrack.h
@@ -110,7 +110,7 @@ int rdma_restrack_count(struct ib_device *dev,
  * rdma_is_kernel_res() - check the owner of resource
  * @res:  resource entry
  */
-static inline bool rdma_is_kernel_res(struct rdma_restrack_entry *res)
+static inline bool rdma_is_kernel_res(const struct rdma_restrack_entry *res)
 {
 	return !res->user;
 }