RDMA/restrack: Add general infrastructure to track RDMA resources

The RDMA subsystem has very strict set of objects to work with, but it
completely lacks tracking facilities and has no visibility of resource
utilization.

The following patch adds such infrastructure to keep track of RDMA
resources to help with debugging of user space applications. The primary
user of this infrastructure is RDMA nldev netlink (following patches), to
be exposed to userspace via rdmatool, but it is not limited too that.

At this stage, the main three objects (PD, CQ and QP) are added, and more
will be added later.

Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 157 insertions, 0 deletions

diff --git a/include/rdma/restrack.h b/include/rdma/restrack.h
new file mode 100644
index 000000000000..c2d81167c858
--- /dev/null
+++ b/include/rdma/restrack.h
@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause) */
+/*
+ * Copyright (c) 2017-2018 Mellanox Technologies. All rights reserved.
+ */
+
+#ifndef _RDMA_RESTRACK_H_
+#define _RDMA_RESTRACK_H_
+
+#include <linux/typecheck.h>
+#include <linux/rwsem.h>
+#include <linux/sched.h>
+#include <linux/kref.h>
+#include <linux/completion.h>
+
+/**
+ * enum rdma_restrack_type - HW objects to track
+ */
+enum rdma_restrack_type {
+	/**
+	 * @RDMA_RESTRACK_PD: Protection domain (PD)
+	 */
+	RDMA_RESTRACK_PD,
+	/**
+	 * @RDMA_RESTRACK_CQ: Completion queue (CQ)
+	 */
+	RDMA_RESTRACK_CQ,
+	/**
+	 * @RDMA_RESTRACK_QP: Queue pair (QP)
+	 */
+	RDMA_RESTRACK_QP,
+	/**
+	 * @RDMA_RESTRACK_XRCD: XRC domain (XRCD)
+	 */
+	RDMA_RESTRACK_XRCD,
+	/**
+	 * @RDMA_RESTRACK_MAX: Last entry, used for array dclarations
+	 */
+	RDMA_RESTRACK_MAX
+};
+
+#define RDMA_RESTRACK_HASH_BITS	8
+/**
+ * struct rdma_restrack_root - main resource tracking management
+ * entity, per-device
+ */
+struct rdma_restrack_root {
+	/*
+	 * @rwsem: Read/write lock to protect lists
+	 */
+	struct rw_semaphore	rwsem;
+	/**
+	 * @hash: global database for all resources per-device
+	 */
+	DECLARE_HASHTABLE(hash, RDMA_RESTRACK_HASH_BITS);
+};
+
+/**
+ * struct rdma_restrack_entry - metadata per-entry
+ */
+struct rdma_restrack_entry {
+	/**
+	 * @valid: validity indicator
+	 *
+	 * The entries are filled during rdma_restrack_add,
+	 * can be attempted to be free during rdma_restrack_del.
+	 *
+	 * As an example for that, see mlx5 QPs with type MLX5_IB_QPT_HW_GSI
+	 */
+	bool			valid;
+	/*
+	 * @kref: Protect destroy of the resource
+	 */
+	struct kref		kref;
+	/*
+	 * @comp: Signal that all consumers of resource are completed their work
+	 */
+	struct completion	comp;
+	/**
+	 * @task: owner of resource tracking entity
+	 *
+	 * There are two types of entities: created by user and created
+	 * by kernel.
+	 *
+	 * This is relevant for the entities created by users.
+	 * For the entities created by kernel, this pointer will be NULL.
+	 */
+	struct task_struct	*task;
+	/**
+	 * @kern_name: name of owner for the kernel created entities.
+	 */
+	const char		*kern_name;
+	/**
+	 * @node: hash table entry
+	 */
+	struct hlist_node	node;
+	/**
+	 * @type: various objects in restrack database
+	 */
+	enum rdma_restrack_type	type;
+};
+
+/**
+ * rdma_restrack_init() - initialize resource tracking
+ * @res:  resource tracking root
+ */
+void rdma_restrack_init(struct rdma_restrack_root *res);
+
+/**
+ * rdma_restrack_clean() - clean resource tracking
+ * @res:  resource tracking root
+ */
+void rdma_restrack_clean(struct rdma_restrack_root *res);
+
+/**
+ * rdma_restrack_count() - the current usage of specific object
+ * @res:  resource entry
+ * @type: actual type of object to operate
+ * @ns:   PID namespace
+ */
+int rdma_restrack_count(struct rdma_restrack_root *res,
+			enum rdma_restrack_type type,
+			struct pid_namespace *ns);
+
+/**
+ * rdma_restrack_add() - add object to the reource tracking database
+ * @res:  resource entry
+ */
+void rdma_restrack_add(struct rdma_restrack_entry *res);
+
+/**
+ * rdma_restrack_del() - delete object from the reource tracking database
+ * @res:  resource entry
+ * @type: actual type of object to operate
+ */
+void rdma_restrack_del(struct rdma_restrack_entry *res);
+
+/**
+ * rdma_is_kernel_res() - check the owner of resource
+ * @res:  resource entry
+ */
+static inline bool rdma_is_kernel_res(struct rdma_restrack_entry *res)
+{
+	return !res->task;
+}
+
+/**
+ * rdma_restrack_get() - grab to protect resource from release
+ * @res:  resource entry
+ */
+int __must_check rdma_restrack_get(struct rdma_restrack_entry *res);
+
+/**
+ * rdma_restrack_put() - relase resource
+ * @res:  resource entry
+ */
+int rdma_restrack_put(struct rdma_restrack_entry *res);
+#endif /* _RDMA_RESTRACK_H_ */