[PATCH 02/24] ibtrs: private headers with IBTRS protocol structs and helpers

From: Roman Pen <roman.penyaev@profitbricks.com>
To: linux-block@vger.kernel.org, linux-rdma@vger.kernel.org
Cc: Jens Axboe <axboe@kernel.dk>,
	Christoph Hellwig <hch@infradead.org>,
	Sagi Grimberg <sagi@grimberg.me>,
	Bart Van Assche <bart.vanassche@sandisk.com>,
	Or Gerlitz <ogerlitz@mellanox.com>,
	Roman Pen <roman.penyaev@profitbricks.com>,
	Danil Kipnis <danil.kipnis@profitbricks.com>,
	Jack Wang <jinpu.wang@profitbricks.com>
Subject: [PATCH 02/24] ibtrs: private headers with IBTRS protocol structs and helpers
Date: Fri,  2 Feb 2018 15:08:42 +0100	[thread overview]
Message-ID: <20180202140904.2017-3-roman.penyaev@profitbricks.com> (raw)
In-Reply-To: <20180202140904.2017-1-roman.penyaev@profitbricks.com>

These are common private headers with IBTRS protocol structures,
logging, sysfs and other helper functions, which are used on
both client and server sides.

Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com>
Signed-off-by: Danil Kipnis <danil.kipnis@profitbricks.com>
Cc: Jack Wang <jinpu.wang@profitbricks.com>
---
 drivers/infiniband/ulp/ibtrs/ibtrs-log.h |  94 ++++++
 drivers/infiniband/ulp/ibtrs/ibtrs-pri.h | 494 +++++++++++++++++++++++++++++++
 2 files changed, 588 insertions(+)

diff --git a/drivers/infiniband/ulp/ibtrs/ibtrs-log.h b/drivers/infiniband/ulp/ibtrs/ibtrs-log.h
new file mode 100644
index 000000000000..308593785c64
--- /dev/null
+++ b/drivers/infiniband/ulp/ibtrs/ibtrs-log.h
@@ -0,0 +1,94 @@
+/*
+ * InfiniBand Transport Layer
+ *
+ * Copyright (c) 2014 - 2017 ProfitBricks GmbH. All rights reserved.
+ * Authors: Fabian Holler <mail@fholler.de>
+ *          Jack Wang <jinpu.wang@profitbricks.com>
+ *          Kleber Souza <kleber.souza@profitbricks.com>
+ *          Danil Kipnis <danil.kipnis@profitbricks.com>
+ *          Roman Penyaev <roman.penyaev@profitbricks.com>
+ *          Milind Dumbare <Milind.dumbare@gmail.com>
+ *
+ * Copyright (c) 2017 - 2018 ProfitBricks GmbH. All rights reserved.
+ * Authors: Danil Kipnis <danil.kipnis@profitbricks.com>
+ *          Roman Penyaev <roman.penyaev@profitbricks.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef IBTRS_LOG_H
+#define IBTRS_LOG_H
+
+#define P1 )
+#define P2 ))
+#define P3 )))
+#define P4 ))))
+#define P(N) P ## N
+
+#define CAT(a, ...) PRIMITIVE_CAT(a, __VA_ARGS__)
+#define PRIMITIVE_CAT(a, ...) a ## __VA_ARGS__
+
+#define COUNT_ARGS(...) COUNT_ARGS_(,##__VA_ARGS__,6,5,4,3,2,1,0)
+#define COUNT_ARGS_(z,a,b,c,d,e,f,cnt,...) cnt
+
+#define LIST(...)						\
+	__VA_ARGS__,						\
+	({ unknown_type(); NULL; })				\
+	CAT(P, COUNT_ARGS(__VA_ARGS__))				\
+
+#define EMPTY()
+#define DEFER(id) id EMPTY()
+
+#define _CASE(obj, type, member)				\
+	__builtin_choose_expr(					\
+	__builtin_types_compatible_p(				\
+		typeof(obj), type),				\
+		((type)obj)->member
+#define CASE(o, t, m) DEFER(_CASE)(o,t,m)
+
+/*
+ * Below we define retrieving of sessname from common IBTRS types.
+ * Client or server related types have to be defined by special
+ * TYPES_TO_SESSNAME macro.
+ */
+
+void unknown_type(void);
+
+#ifndef TYPES_TO_SESSNAME
+#define TYPES_TO_SESSNAME(...) ({ unknown_type(); NULL; })
+#endif
+
+#define ibtrs_prefix(obj)					\
+	_CASE(obj, struct ibtrs_con *,  sess->sessname),	\
+	_CASE(obj, struct ibtrs_sess *, sessname),		\
+	TYPES_TO_SESSNAME(obj)					\
+	))
+
+#define ibtrs_log(fn, obj, fmt, ...)				\
+	fn("<%s>: " fmt, ibtrs_prefix(obj), ##__VA_ARGS__)
+
+#define ibtrs_err(obj, fmt, ...)	\
+	ibtrs_log(pr_err, obj, fmt, ##__VA_ARGS__)
+#define ibtrs_err_rl(obj, fmt, ...)	\
+	ibtrs_log(pr_err_ratelimited, obj, fmt, ##__VA_ARGS__)
+#define ibtrs_wrn(obj, fmt, ...)	\
+	ibtrs_log(pr_warn, obj, fmt, ##__VA_ARGS__)
+#define ibtrs_wrn_rl(obj, fmt, ...) \
+	ibtrs_log(pr_warn_ratelimited, obj, fmt, ##__VA_ARGS__)
+#define ibtrs_info(obj, fmt, ...) \
+	ibtrs_log(pr_info, obj, fmt, ##__VA_ARGS__)
+#define ibtrs_info_rl(obj, fmt, ...) \
+	ibtrs_log(pr_info_ratelimited, obj, fmt, ##__VA_ARGS__)
+
+#endif /* IBTRS_LOG_H */
diff --git a/drivers/infiniband/ulp/ibtrs/ibtrs-pri.h b/drivers/infiniband/ulp/ibtrs/ibtrs-pri.h
new file mode 100644
index 000000000000..b3b51af8607e
--- /dev/null
+++ b/drivers/infiniband/ulp/ibtrs/ibtrs-pri.h
@@ -0,0 +1,494 @@
+/*
+ * InfiniBand Transport Layer
+ *
+ * Copyright (c) 2014 - 2017 ProfitBricks GmbH. All rights reserved.
+ * Authors: Fabian Holler <mail@fholler.de>
+ *          Jack Wang <jinpu.wang@profitbricks.com>
+ *          Kleber Souza <kleber.souza@profitbricks.com>
+ *          Danil Kipnis <danil.kipnis@profitbricks.com>
+ *          Roman Penyaev <roman.penyaev@profitbricks.com>
+ *          Milind Dumbare <Milind.dumbare@gmail.com>
+ *
+ * Copyright (c) 2017 - 2018 ProfitBricks GmbH. All rights reserved.
+ * Authors: Danil Kipnis <danil.kipnis@profitbricks.com>
+ *          Roman Penyaev <roman.penyaev@profitbricks.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef IBTRS_PRI_H
+#define IBTRS_PRI_H
+
+#include <linux/uuid.h>
+#include <rdma/rdma_cm.h>
+#include <rdma/ib_verbs.h>
+#include <rdma/ib.h>
+
+#include "ibtrs.h"
+
+#define IBTRS_VER_MAJOR 1
+#define IBTRS_VER_MINOR 0
+#define IBTRS_VER_STRING __stringify(IBTRS_VER_MAJOR) "." \
+			 __stringify(IBTRS_VER_MINOR)
+
+enum ibtrs_imm_consts {
+	MAX_IMM_TYPE_BITS = 4,
+	MAX_IMM_TYPE_MASK = ((1 << MAX_IMM_TYPE_BITS) - 1),
+	MAX_IMM_PAYL_BITS = 28,
+	MAX_IMM_PAYL_MASK = ((1 << MAX_IMM_PAYL_BITS) - 1),
+
+	IBTRS_IO_REQ_IMM = 0, /* client to server */
+	IBTRS_IO_RSP_IMM = 1, /* server to client */
+	IBTRS_HB_MSG_IMM = 2,
+	IBTRS_HB_ACK_IMM = 3,
+};
+
+enum {
+	SERVICE_CON_QUEUE_DEPTH = 512,
+
+	MIN_RTR_CNT = 1,
+	MAX_RTR_CNT = 7,
+
+	MAX_PATHS_NUM = 128,
+
+	/*
+	 * With the current size of the tag allocated on the client, 4K
+	 * is the maximum number of tags we can allocate.  This number is
+	 * also used on the client to allocate the IU for the user connection
+	 * to receive the RDMA addresses from the server.
+	 */
+	MAX_SESS_QUEUE_DEPTH = 4096,
+	/*
+	 * Size of user message atached to a request (@vec, @nr) is limited
+	 * by the IO_MSG_SIZE. max_req_size allocated by the server should
+	 * cover both: the user message and the ibtrs message attached
+	 * to an IO. ibtrs_msg_req_rdma_write attached to a read has variable
+	 * size: max number of descriptors we can send is limited by
+	 * max_desc = (max_req_size - IO_MSG_SIZE) / sizeof(desc)
+	 */
+	IO_MSG_SIZE = 512,
+
+	IBTRS_HB_INTERVAL_MS = 5000,
+	IBTRS_HB_MISSED_MAX = 5,
+
+	IBTRS_MAGIC = 0x1BBD,
+	IBTRS_VERSION = (IBTRS_VER_MAJOR << 8) | IBTRS_VER_MINOR,
+};
+
+struct ibtrs_ib_dev {
+	struct list_head	entry;
+	struct kref		ref;
+	struct ib_pd		*pd;
+	struct ib_device	*dev;
+	struct ib_device_attr	attrs;
+	u32			lkey;
+	u32			rkey;
+};
+
+struct ibtrs_con {
+	struct ibtrs_sess	*sess;
+	struct ib_qp		*qp;
+	struct ib_cq		*cq;
+	struct rdma_cm_id	*cm_id;
+	unsigned		cid;
+};
+
+typedef void (ibtrs_hb_handler_t)(struct ibtrs_con *con, int err);
+
+struct ibtrs_sess {
+	struct list_head	entry;
+	struct sockaddr_storage dst_addr;
+	struct sockaddr_storage src_addr;
+	char			sessname[NAME_MAX];
+	uuid_t			uuid;
+	struct ibtrs_con	**con;
+	unsigned int		con_num;
+	unsigned int		recon_cnt;
+	struct ibtrs_ib_dev	*ib_dev;
+	int			ib_dev_ref;
+	struct ib_cqe		*hb_cqe;
+	ibtrs_hb_handler_t	*hb_err_handler;
+	struct workqueue_struct *hb_wq;
+	struct delayed_work	hb_dwork;
+	unsigned		hb_interval_ms;
+	unsigned		hb_missed_cnt;
+	unsigned		hb_missed_max;
+};
+
+struct ibtrs_iu {
+	struct list_head        list;
+	struct ib_cqe           cqe;
+	dma_addr_t              dma_addr;
+	void                    *buf;
+	size_t                  size;
+	enum dma_data_direction direction;
+	u32			tag;
+};
+
+/**
+ * enum ibtrs_msg_types - IBTRS message types.
+ * @IBTRS_MSG_INFO_REQ:		Client additional info request to the server
+ * @IBTRS_MSG_INFO_RSP:		Server additional info response to the client
+ * @IBTRS_MSG_WRITE:		Client writes data per RDMA to server
+ * @IBTRS_MSG_READ:		Client requests data transfer from server
+ * @IBTRS_MSG_USER:		Data transfer per Infiniband message
+ */
+enum ibtrs_msg_types {
+	IBTRS_MSG_INFO_REQ,
+	IBTRS_MSG_INFO_RSP,
+	IBTRS_MSG_WRITE,
+	IBTRS_MSG_READ,
+	IBTRS_MSG_USER,
+};
+
+/**
+ * struct ibtrs_msg_conn_req - Client connection request to the server
+ * @magic:	   IBTRS magic
+ * @version:	   IBTRS protocol version
+ * @cid:	   Current connection id
+ * @cid_num:	   Number of connections per session
+ * @recon_cnt:	   Reconnections counter
+ * @sess_uuid:	   UUID of a session (path)
+ * @paths_uuid:	   UUID of a group of sessions (paths)
+ *
+ * NOTE: max size 56 bytes, see man rdma_connect().
+ */
+struct ibtrs_msg_conn_req {
+	u8		__cma_version; /* Is set to 0 by cma.c in case of
+					* AF_IB, do not touch that. */
+	u8		__ip_version;  /* On sender side that should be
+					* set to 0, or cma_save_ip_info()
+					* extract garbage and will fail. */
+	__le16		magic;
+	__le16		version;
+	__le16		cid;
+	__le16		cid_num;
+	__le16		recon_cnt;
+	uuid_t		sess_uuid;
+	uuid_t		paths_uuid;
+	u8		reserved[12];
+};
+
+/**
+ * struct ibtrs_msg_conn_rsp - Server connection response to the client
+ * @magic:	   IBTRS magic
+ * @version:	   IBTRS protocol version
+ * @errno:	   If rdma_accept() then 0, if rdma_reject() indicates error
+ * @queue_depth:   max inflight messages (queue-depth) in this session
+ * @rkey:	   remote key to allow client to access buffers
+ * @max_io_size:   max io size server supports
+ * @max_req_size:  max infiniband message size server supports
+ * @uuid:	   Server UUID
+ *
+ * NOTE: size is 56 bytes, max possible is 136 bytes, see man rdma_accept().
+ */
+struct ibtrs_msg_conn_rsp {
+	__le16		magic;
+	__le16		version;
+	__le16		errno;
+	__le16		queue_depth;
+	__le32		rkey;
+	__le32		max_io_size;
+	__le32		max_req_size;
+	uuid_t		uuid;
+	u8		reserved[20];
+};
+
+/**
+ * struct ibtrs_msg_info_req
+ * @type:		@IBTRS_MSG_INFO_REQ
+ * @sessname:		Session name chosen by client
+ */
+struct ibtrs_msg_info_req {
+	__le16		type;
+	u8		sessname[NAME_MAX];
+	u8		reserved[15];
+};
+
+/**
+ * struct ibtrs_msg_info_rsp
+ * @type:		@IBTRS_MSG_INFO_RSP
+ * @addr_num:		Number of rdma addresses
+ * @addr:		RDMA addresses of buffers
+ */
+struct ibtrs_msg_info_rsp {
+	__le16		type;
+	__le16		addr_num;
+	u8		reserved[4];
+	__le64		addr[];
+};
+
+/*
+ *  Data Layout in RDMA-Bufs:
+ *
+ * +---------RDMA-BUF--------+
+ * |         Slice N	     |
+ * | +---------------------+ |
+ * | |      I/O data       | |
+ * | |---------------------| |
+ * | |      IBNBD MSG	   | |
+ * | |---------------------| |
+ * | |	    IBTRS MSG	   | |
+ * | +---------------------+ |
+ * +-------------------------+
+ * |	     Slice N+1	     |
+ * | +---------------------+ |
+ * | |       I/O data	   | |
+ * | |---------------------| |
+ * | |	     IBNBD MSG     | |
+ * | |---------------------| |
+ * | |       IBTRS MSG     | |
+ * | +---------------------+ |
+ * +-------------------------+
+ */
+
+/**
+ * struct ibtrs_msg_user - Data exchanged a Infiniband message
+ * @type:		@IBTRS_MSG_USER
+ * @psize:		Payload size
+ * @payl:		Payload data
+ */
+struct ibtrs_msg_user {
+	__le16			type;
+	__le16			psize;
+	u8			payl[];
+};
+
+/**
+ * struct ibtrs_sg_desc - RDMA-Buffer entry description
+ * @addr:	Address of RDMA destination buffer
+ * @key:	Authorization rkey to write to the buffer
+ * @len:	Size of the buffer
+ */
+struct ibtrs_sg_desc {
+	__le64			addr;
+	__le32			key;
+	__le32			len;
+};
+
+/**
+ * struct ibtrs_msg_rdma_read - RDMA data transfer request from client
+ * @type:		always @IBTRS_MSG_READ
+ * @usr_len:		length of user payload
+ * @sg_cnt:		number of @desc entries
+ * @desc:		RDMA bufferst where the server can write the result to
+ */
+struct ibtrs_msg_rdma_read {
+	__le16			type;
+	__le16			usr_len;
+	__le32			sg_cnt;
+	struct ibtrs_sg_desc    desc[];
+};
+
+/**
+ * struct_msg_rdma_write - Message transferred to server with RDMA-Write
+ * @type:		always @IBTRS_MSG_WRITE
+ * @usr_len:		length of user payload
+ */
+struct ibtrs_msg_rdma_write {
+	__le16			type;
+	__le16			usr_len;
+};
+
+/* ibtrs.c */
+
+struct ibtrs_iu *ibtrs_iu_alloc(u32 tag, size_t size, gfp_t t,
+				struct ib_device *dev, enum dma_data_direction,
+				void (*done)(struct ib_cq *cq, struct ib_wc *wc));
+void ibtrs_iu_free(struct ibtrs_iu *iu, enum dma_data_direction dir,
+		   struct ib_device *dev);
+int ibtrs_iu_post_recv(struct ibtrs_con *con, struct ibtrs_iu *iu);
+int ibtrs_iu_post_send(struct ibtrs_con *con, struct ibtrs_iu *iu, size_t size);
+int ibtrs_iu_post_rdma_write_imm(struct ibtrs_con *con, struct ibtrs_iu *iu,
+				 struct ib_sge *sge, unsigned int num_sge,
+				 u32 rkey, u64 rdma_addr, u32 imm_data,
+				 enum ib_send_flags flags);
+
+int ibtrs_post_recv_empty(struct ibtrs_con *con, struct ib_cqe *cqe);
+int ibtrs_post_rdma_write_imm_empty(struct ibtrs_con *con, struct ib_cqe *cqe,
+				    u32 imm_data, enum ib_send_flags flags);
+
+struct ibtrs_ib_dev *ibtrs_ib_dev_find_get(struct rdma_cm_id *cm_id);
+void ibtrs_ib_dev_put(struct ibtrs_ib_dev *dev);
+
+int ibtrs_cq_qp_create(struct ibtrs_sess *ibtrs_sess, struct ibtrs_con *con,
+		       u32 max_send_sge, int cq_vector, u16 cq_size,
+		       u16 wr_queue_size, enum ib_poll_context poll_ctx);
+void ibtrs_cq_qp_destroy(struct ibtrs_con *con);
+
+void ibtrs_init_hb(struct ibtrs_sess *sess, struct ib_cqe *cqe,
+		   unsigned interval_ms, unsigned missed_max,
+		   ibtrs_hb_handler_t *err_handler,
+		   struct workqueue_struct *wq);
+void ibtrs_start_hb(struct ibtrs_sess *sess);
+void ibtrs_stop_hb(struct ibtrs_sess *sess);
+void ibtrs_send_hb_ack(struct ibtrs_sess *sess);
+
+#define XX(a) case (a): return #a
+static inline const char *ib_wc_opcode_str(enum ib_wc_opcode opcode)
+{
+	switch (opcode) {
+	XX(IB_WC_SEND);
+	XX(IB_WC_RDMA_WRITE);
+	XX(IB_WC_RDMA_READ);
+	XX(IB_WC_COMP_SWAP);
+	XX(IB_WC_FETCH_ADD);
+	/* recv-side); inbound completion */
+	XX(IB_WC_RECV);
+	XX(IB_WC_RECV_RDMA_WITH_IMM);
+	default: return "IB_WC_OPCODE_UNKNOWN";
+	}
+}
+
+static inline int sockaddr_cmp(const struct sockaddr *a,
+			       const struct sockaddr *b)
+{
+	switch (a->sa_family) {
+	case AF_IB:
+		return memcmp(&((struct sockaddr_ib *)a)->sib_addr,
+			      &((struct sockaddr_ib *)b)->sib_addr,
+			      sizeof(struct ib_addr));
+	case AF_INET:
+		return memcmp(&((struct sockaddr_in *)a)->sin_addr,
+			      &((struct sockaddr_in *)b)->sin_addr,
+			      sizeof(struct in_addr));
+	case AF_INET6:
+		return memcmp(&((struct sockaddr_in6 *)a)->sin6_addr,
+			      &((struct sockaddr_in6 *)b)->sin6_addr,
+			      sizeof(struct in6_addr));
+	default:
+		return -ENOENT;
+	}
+}
+
+static inline void sockaddr_to_str(const struct sockaddr *addr,
+				   char *buf, size_t len)
+{
+	switch (addr->sa_family) {
+	case AF_IB:
+		scnprintf(buf, len, "gid:%pI6",
+			  &((struct sockaddr_ib *)addr)->sib_addr.sib_raw);
+		return;
+	case AF_INET:
+		scnprintf(buf, len, "ip:%pI4",
+			  &((struct sockaddr_in *)addr)->sin_addr);
+		return;
+	case AF_INET6:
+		scnprintf(buf, len, "ip:%pI6c",
+			  &((struct sockaddr_in6 *)addr)->sin6_addr);
+		return;
+	}
+	scnprintf(buf, len, "<invalid address family>");
+	pr_err("Invalid address family\n");
+}
+
+/**
+ * kvec_length() - Total number of bytes covered by an kvec.
+ */
+static inline size_t kvec_length(const struct kvec *vec, size_t nr)
+{
+	size_t seg, ret = 0;
+
+	for (seg = 0; seg < nr; seg++)
+		ret += vec[seg].iov_len;
+	return ret;
+}
+
+/**
+ * copy_from_kvec() - Copy kvec to the buffer.
+ */
+static inline void copy_from_kvec(void *data, const struct kvec *vec,
+				  size_t copy)
+{
+	size_t seg, len;
+
+	for (seg = 0; copy; seg++) {
+		len = min(vec[seg].iov_len, copy);
+		memcpy(data, vec[seg].iov_base, len);
+		data += len;
+		copy -= len;
+	}
+}
+
+static inline u32 ibtrs_to_imm(u32 type, u32 payload)
+{
+	BUILD_BUG_ON(32 != MAX_IMM_PAYL_BITS + MAX_IMM_TYPE_BITS);
+	return ((type & MAX_IMM_TYPE_MASK) << MAX_IMM_PAYL_BITS) |
+		(payload & MAX_IMM_PAYL_MASK);
+}
+
+static inline void ibtrs_from_imm(u32 imm, u32 *type, u32 *payload)
+{
+	*payload = (imm & MAX_IMM_PAYL_MASK);
+	*type = (imm >> MAX_IMM_PAYL_BITS);
+}
+
+static inline u32 ibtrs_to_io_req_imm(u32 addr)
+{
+	return ibtrs_to_imm(IBTRS_IO_REQ_IMM, addr);
+}
+
+static inline u32 ibtrs_to_io_rsp_imm(u32 msg_id, int errno)
+{
+	u32 payload;
+
+	/* 9 bits for errno, 19 bits for msg_id */
+	payload = (abs(errno) & 0x1ff) << 19 | (msg_id & 0x7ffff);
+	return ibtrs_to_imm(IBTRS_IO_RSP_IMM, payload);
+}
+
+static inline void ibtrs_from_io_rsp_imm(u32 payload, u32 *msg_id, int *errno)
+{
+	/* 9 bits for errno, 19 bits for msg_id */
+	*msg_id = (payload & 0x7ffff);
+	*errno = -(int)((payload >> 19) & 0x1ff);
+}
+
+#define STAT_STORE_FUNC(type, store, reset)				\
+static ssize_t store##_store(struct kobject *kobj,			\
+			     struct kobj_attribute *attr,		\
+			     const char *buf, size_t count)		\
+{									\
+	int ret = -EINVAL;						\
+	type *sess = container_of(kobj, type, kobj_stats);		\
+									\
+	if (sysfs_streq(buf, "1"))					\
+		ret = reset(&sess->stats, true);			\
+	else if (sysfs_streq(buf, "0"))					\
+		ret = reset(&sess->stats, false);			\
+	if (ret)							\
+		return ret;						\
+									\
+	return count;							\
+}
+
+#define STAT_SHOW_FUNC(type, show, print)				\
+static ssize_t show##_show(struct kobject *kobj,			\
+			   struct kobj_attribute *attr,			\
+			   char *page)					\
+{									\
+	type *sess = container_of(kobj, type, kobj_stats);		\
+									\
+	return print(&sess->stats, page, PAGE_SIZE);			\
+}
+
+#define STAT_ATTR(type, stat, print, reset)				\
+STAT_STORE_FUNC(type, stat, reset)					\
+STAT_SHOW_FUNC(type, stat, print)					\
+static struct kobj_attribute stat##_attr =				\
+		__ATTR(stat, 0644,					\
+		       stat##_show,					\
+		       stat##_store)
+
+#endif /* IBTRS_PRI_H */
-- 
2.13.1
