diff mbox series

[v6,04/25] rtrs: core: lib functions shared between client and server modules

Message ID 20191230102942.18395-5-jinpuwang@gmail.com (mailing list archive)
State New, archived
Headers show
Series RTRS (former IBTRS) rdma transport library and RNBD (former IBNBD) rdma network block device | expand

Commit Message

Jinpu Wang Dec. 30, 2019, 10:29 a.m. UTC
From: Jack Wang <jinpu.wang@cloud.ionos.com>

This is a set of library functions existing as a rtrs-core module,
used by client and server modules.

Mainly these functions wrap IB and RDMA calls and provide a bit higher
abstraction for implementing of RTRS protocol on client or server
sides.

Signed-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
---
 drivers/infiniband/ulp/rtrs/rtrs.c | 628 +++++++++++++++++++++++++++++
 1 file changed, 628 insertions(+)
 create mode 100644 drivers/infiniband/ulp/rtrs/rtrs.c

Comments

Bart Van Assche Dec. 30, 2019, 10:25 p.m. UTC | #1
On 2019-12-30 02:29, Jack Wang wrote:
> + * InfiniBand Transport Layer

Is RTRS an InfiniBand or an RDMA transport layer?

> +MODULE_DESCRIPTION("RTRS Core");

Please write out RTRS in full and consider changing the word "Core" into
"client and server".

> +	WARN_ON(!queue_size);
> +	ius = kcalloc(queue_size, sizeof(*ius), gfp_mask);
> +
> +	if (unlikely(!ius))
> +		return NULL;

No blank line between the 'ius' assignment and the 'ius' check please.

> +int rtrs_iu_post_recv(struct rtrs_con *con, struct rtrs_iu *iu)
> +{
> +	struct rtrs_sess *sess = con->sess;
> +	struct ib_recv_wr wr;
> +	const struct ib_recv_wr *bad_wr;
> +	struct ib_sge list;
> +
> +	list.addr   = iu->dma_addr;
> +	list.length = iu->size;
> +	list.lkey   = sess->dev->ib_pd->local_dma_lkey;
> +
> +	if (WARN_ON(list.length == 0)) {
> +		rtrs_wrn(con->sess,
> +			  "Posting receive work request failed, sg list is empty\n");
> +		return -EINVAL;
> +	}
> +
> +	wr.next    = NULL;
> +	wr.wr_cqe  = &iu->cqe;
> +	wr.sg_list = &list;
> +	wr.num_sge = 1;
> +
> +	return ib_post_recv(con->qp, &wr, &bad_wr);
> +}
> +EXPORT_SYMBOL_GPL(rtrs_iu_post_recv);

The above code is fragile: although this is unlikely, if a member would
be added in struct ib_sge or in struct ib_recv_wr then the above code
will leave some member variables uninitialized. Has it been considered
to initialize these structures using a single assignment statement, e.g.
as follows:

	wr = (struct ib_recv_wr) {
		.wr_cqe = ...,
		.sg_list = ...,
		.num_sge = 1,
	};

> +int rtrs_post_recv_empty(struct rtrs_con *con, struct ib_cqe *cqe)
> +{
> +	struct ib_recv_wr wr;
> +	const struct ib_recv_wr *bad_wr;
> +
> +	wr.next    = NULL;
> +	wr.wr_cqe  = cqe;
> +	wr.sg_list = NULL;
> +	wr.num_sge = 0;
> +
> +	return ib_post_recv(con->qp, &wr, &bad_wr);
> +}
> +EXPORT_SYMBOL_GPL(rtrs_post_recv_empty);

Same comment for this function.

> +int rtrs_post_recv_empty_x2(struct rtrs_con *con, struct ib_cqe *cqe)
> +{
> +	struct ib_recv_wr wr_arr[2], *wr;
> +	const struct ib_recv_wr *bad_wr;
> +	int i;
> +
> +	memset(wr_arr, 0, sizeof(wr_arr));
> +	for (i = 0; i < ARRAY_SIZE(wr_arr); i++) {
> +		wr = &wr_arr[i];
> +		wr->wr_cqe  = cqe;
> +		if (i)
> +			/* Chain backwards */
> +			wr->next = &wr_arr[i - 1];
> +	}
> +
> +	return ib_post_recv(con->qp, wr, &bad_wr);
> +}
> +EXPORT_SYMBOL_GPL(rtrs_post_recv_empty_x2);

I have not yet seen any other RDMA code that is similar to the above
function. A comment above this function that explains its purpose would
be more than welcome.

> +int rtrs_iu_post_send(struct rtrs_con *con, struct rtrs_iu *iu, size_t size,
> +		       struct ib_send_wr *head)
> +{
> +	struct rtrs_sess *sess = con->sess;
> +	struct ib_send_wr wr;
> +	const struct ib_send_wr *bad_wr;
> +	struct ib_sge list;
> +
> +	if ((WARN_ON(size == 0)))
> +		return -EINVAL;

No superfluous parentheses please.

> +	list.addr   = iu->dma_addr;
> +	list.length = size;
> +	list.lkey   = sess->dev->ib_pd->local_dma_lkey;
> +
> +	memset(&wr, 0, sizeof(wr));
> +	wr.next       = NULL;
> +	wr.wr_cqe     = &iu->cqe;
> +	wr.sg_list    = &list;
> +	wr.num_sge    = 1;
> +	wr.opcode     = IB_WR_SEND;
> +	wr.send_flags = IB_SEND_SIGNALED;

Has it been considered to use designated initializers instead of a
memset() followed by multiple assignments? Same question for
rtrs_iu_post_rdma_write_imm() and rtrs_post_rdma_write_imm_empty().

> +static int create_qp(struct rtrs_con *con, struct ib_pd *pd,
> +		     u16 wr_queue_size, u32 max_sge)
> +{
> +	struct ib_qp_init_attr init_attr = {NULL};
> +	struct rdma_cm_id *cm_id = con->cm_id;
> +	int ret;
> +
> +	init_attr.cap.max_send_wr = wr_queue_size;
> +	init_attr.cap.max_recv_wr = wr_queue_size;

What code is responsible for ensuring that neither max_send_wr nor
max_recv_wr exceeds the device limits? Please document this in a comment
above this function.

> +	init_attr.cap.max_recv_sge = 1;
> +	init_attr.event_handler = qp_event_handler;
> +	init_attr.qp_context = con;
> +#undef max_send_sge
> +	init_attr.cap.max_send_sge = max_sge;

Is the "undef max_send_sge" really necessary? If so, please add a
comment that explains why it is necessary.

> +static int rtrs_str_gid_to_sockaddr(const char *addr, size_t len,
> +				     short port, struct sockaddr_storage *dst)
> +{
> +	struct sockaddr_ib *dst_ib = (struct sockaddr_ib *)dst;
> +	int ret;
> +
> +	/*
> +	 * We can use some of the I6 functions since GID is a valid
> +	 * IPv6 address format
> +	 */
> +	ret = in6_pton(addr, len, dst_ib->sib_addr.sib_raw, '\0', NULL);
> +	if (ret == 0)
> +		return -EINVAL;

What is "I6"?

Is the fourth argument to this function correct? From the comment above
in6_pton(): "@delim: the delimiter of the IPv6 address in @src, -1 means
no delimiter".

> +int sockaddr_to_str(const struct sockaddr *addr, char *buf, size_t len)
> +{
> +	int cnt;
> +
> +	switch (addr->sa_family) {
> +	case AF_IB:
> +		cnt = scnprintf(buf, len, "gid:%pI6",
> +			&((struct sockaddr_ib *)addr)->sib_addr.sib_raw);
> +		return cnt;
> +	case AF_INET:
> +		cnt = scnprintf(buf, len, "ip:%pI4",
> +			&((struct sockaddr_in *)addr)->sin_addr);
> +		return cnt;
> +	case AF_INET6:
> +		cnt = scnprintf(buf, len, "ip:%pI6c",
> +			  &((struct sockaddr_in6 *)addr)->sin6_addr);
> +		return cnt;
> +	}
> +	cnt = scnprintf(buf, len, "<invalid address family>");
> +	pr_err("Invalid address family\n");
> +	return cnt;
> +}
> +EXPORT_SYMBOL(sockaddr_to_str);

Is the pr_err() statement in the above function useful? Will anyone be
able to figure out what is going on if the "Invalid address family"
string appears in the system log? Please consider changing that pr_err()
statement into a WARN_ON_ONCE() statement.

> +	ret = rtrs_str_to_sockaddr(str, len, port, addr->dst);
> +
> +	return ret;

Please change this into a single return statement.

> +EXPORT_SYMBOL(rtrs_addr_to_sockaddr);
> +
> +void rtrs_ib_dev_pool_init(enum ib_pd_flags pd_flags,
> +			    struct rtrs_ib_dev_pool *pool)
> +{
> +	WARN_ON(pool->ops && (!pool->ops->alloc ^ !pool->ops->free));
> +	INIT_LIST_HEAD(&pool->list);
> +	mutex_init(&pool->mutex);
> +	pool->pd_flags = pd_flags;
> +}
> +EXPORT_SYMBOL(rtrs_ib_dev_pool_init);
> +
> +void rtrs_ib_dev_pool_deinit(struct rtrs_ib_dev_pool *pool)
> +{
> +	WARN_ON(!list_empty(&pool->list));
> +}
> +EXPORT_SYMBOL(rtrs_ib_dev_pool_deinit);

Since rtrs_ib_dev_pool_init() calls mutex_init(), should
rtrs_ib_dev_pool_deinit() call mutex_destroy()?

Thanks,

Bart.
Jinpu Wang Jan. 7, 2020, 12:22 p.m. UTC | #2
On Mon, Dec 30, 2019 at 11:25 PM Bart Van Assche <bvanassche@acm.org> wrote:
>
> On 2019-12-30 02:29, Jack Wang wrote:
> > + * InfiniBand Transport Layer
>
> Is RTRS an InfiniBand or an RDMA transport layer?
will fix.
>
> > +MODULE_DESCRIPTION("RTRS Core");
>
> Please write out RTRS in full and consider changing the word "Core" into
> "client and server".
will do.
>
> > +     WARN_ON(!queue_size);
> > +     ius = kcalloc(queue_size, sizeof(*ius), gfp_mask);
> > +
> > +     if (unlikely(!ius))
> > +             return NULL;
>
> No blank line between the 'ius' assignment and the 'ius' check please.
ok.
>
> > +int rtrs_iu_post_recv(struct rtrs_con *con, struct rtrs_iu *iu)
> > +{
> > +     struct rtrs_sess *sess = con->sess;
> > +     struct ib_recv_wr wr;
> > +     const struct ib_recv_wr *bad_wr;
> > +     struct ib_sge list;
> > +
> > +     list.addr   = iu->dma_addr;
> > +     list.length = iu->size;
> > +     list.lkey   = sess->dev->ib_pd->local_dma_lkey;
> > +
> > +     if (WARN_ON(list.length == 0)) {
> > +             rtrs_wrn(con->sess,
> > +                       "Posting receive work request failed, sg list is empty\n");
> > +             return -EINVAL;
> > +     }
> > +
> > +     wr.next    = NULL;
> > +     wr.wr_cqe  = &iu->cqe;
> > +     wr.sg_list = &list;
> > +     wr.num_sge = 1;
> > +
> > +     return ib_post_recv(con->qp, &wr, &bad_wr);
> > +}
> > +EXPORT_SYMBOL_GPL(rtrs_iu_post_recv);
>
> The above code is fragile: although this is unlikely, if a member would
> be added in struct ib_sge or in struct ib_recv_wr then the above code
> will leave some member variables uninitialized. Has it been considered
> to initialize these structures using a single assignment statement, e.g.
> as follows:
>
>         wr = (struct ib_recv_wr) {
>                 .wr_cqe = ...,
>                 .sg_list = ...,
>                 .num_sge = 1,
>         };
Will do.
>
> > +int rtrs_post_recv_empty(struct rtrs_con *con, struct ib_cqe *cqe)
> > +{
> > +     struct ib_recv_wr wr;
> > +     const struct ib_recv_wr *bad_wr;
> > +
> > +     wr.next    = NULL;
> > +     wr.wr_cqe  = cqe;
> > +     wr.sg_list = NULL;
> > +     wr.num_sge = 0;
> > +
> > +     return ib_post_recv(con->qp, &wr, &bad_wr);
> > +}
> > +EXPORT_SYMBOL_GPL(rtrs_post_recv_empty);
>
> Same comment for this function.
dito.
>
> > +int rtrs_post_recv_empty_x2(struct rtrs_con *con, struct ib_cqe *cqe)
> > +{
> > +     struct ib_recv_wr wr_arr[2], *wr;
> > +     const struct ib_recv_wr *bad_wr;
> > +     int i;
> > +
> > +     memset(wr_arr, 0, sizeof(wr_arr));
> > +     for (i = 0; i < ARRAY_SIZE(wr_arr); i++) {
> > +             wr = &wr_arr[i];
> > +             wr->wr_cqe  = cqe;
> > +             if (i)
> > +                     /* Chain backwards */
> > +                     wr->next = &wr_arr[i - 1];
> > +     }
> > +
> > +     return ib_post_recv(con->qp, wr, &bad_wr);
> > +}
> > +EXPORT_SYMBOL_GPL(rtrs_post_recv_empty_x2);
>
> I have not yet seen any other RDMA code that is similar to the above
> function. A comment above this function that explains its purpose would
> be more than welcome.
Will add comment.
>
> > +int rtrs_iu_post_send(struct rtrs_con *con, struct rtrs_iu *iu, size_t size,
> > +                    struct ib_send_wr *head)
> > +{
> > +     struct rtrs_sess *sess = con->sess;
> > +     struct ib_send_wr wr;
> > +     const struct ib_send_wr *bad_wr;
> > +     struct ib_sge list;
> > +
> > +     if ((WARN_ON(size == 0)))
> > +             return -EINVAL;
>
> No superfluous parentheses please.
ok

>
> > +     list.addr   = iu->dma_addr;
> > +     list.length = size;
> > +     list.lkey   = sess->dev->ib_pd->local_dma_lkey;
> > +
> > +     memset(&wr, 0, sizeof(wr));
> > +     wr.next       = NULL;
> > +     wr.wr_cqe     = &iu->cqe;
> > +     wr.sg_list    = &list;
> > +     wr.num_sge    = 1;
> > +     wr.opcode     = IB_WR_SEND;
> > +     wr.send_flags = IB_SEND_SIGNALED;
>
> Has it been considered to use designated initializers instead of a
> memset() followed by multiple assignments? Same question for
> rtrs_iu_post_rdma_write_imm() and rtrs_post_rdma_write_imm_empty().
Sounds good, will do.

>
> > +static int create_qp(struct rtrs_con *con, struct ib_pd *pd,
> > +                  u16 wr_queue_size, u32 max_sge)
> > +{
> > +     struct ib_qp_init_attr init_attr = {NULL};
> > +     struct rdma_cm_id *cm_id = con->cm_id;
> > +     int ret;
> > +
> > +     init_attr.cap.max_send_wr = wr_queue_size;
> > +     init_attr.cap.max_recv_wr = wr_queue_size;
>
> What code is responsible for ensuring that neither max_send_wr nor
> max_recv_wr exceeds the device limits? Please document this in a comment
> above this function.
rtrs-clt/srv queries device limits for ensuring the settings will not
exceed the limits.
will add comment.

>
> > +     init_attr.cap.max_recv_sge = 1;
> > +     init_attr.event_handler = qp_event_handler;
> > +     init_attr.qp_context = con;
> > +#undef max_send_sge
> > +     init_attr.cap.max_send_sge = max_sge;
>
> Is the "undef max_send_sge" really necessary? If so, please add a
> comment that explains why it is necessary.
it's not, will remove.
>
> > +static int rtrs_str_gid_to_sockaddr(const char *addr, size_t len,
> > +                                  short port, struct sockaddr_storage *dst)
> > +{
> > +     struct sockaddr_ib *dst_ib = (struct sockaddr_ib *)dst;
> > +     int ret;
> > +
> > +     /*
> > +      * We can use some of the I6 functions since GID is a valid
> > +      * IPv6 address format
> > +      */
> > +     ret = in6_pton(addr, len, dst_ib->sib_addr.sib_raw, '\0', NULL);
> > +     if (ret == 0)
> > +             return -EINVAL;
>
> What is "I6"?
IPv6, will fix.
>
> Is the fourth argument to this function correct? From the comment above
> in6_pton(): "@delim: the delimiter of the IPv6 address in @src, -1 means
> no delimiter".
'\0' means end of the string here, seems correct to me.
>
> > +int sockaddr_to_str(const struct sockaddr *addr, char *buf, size_t len)
> > +{
> > +     int cnt;
> > +
> > +     switch (addr->sa_family) {
> > +     case AF_IB:
> > +             cnt = scnprintf(buf, len, "gid:%pI6",
> > +                     &((struct sockaddr_ib *)addr)->sib_addr.sib_raw);
> > +             return cnt;
> > +     case AF_INET:
> > +             cnt = scnprintf(buf, len, "ip:%pI4",
> > +                     &((struct sockaddr_in *)addr)->sin_addr);
> > +             return cnt;
> > +     case AF_INET6:
> > +             cnt = scnprintf(buf, len, "ip:%pI6c",
> > +                       &((struct sockaddr_in6 *)addr)->sin6_addr);
> > +             return cnt;
> > +     }
> > +     cnt = scnprintf(buf, len, "<invalid address family>");
> > +     pr_err("Invalid address family\n");
> > +     return cnt;
> > +}
> > +EXPORT_SYMBOL(sockaddr_to_str);
>
> Is the pr_err() statement in the above function useful? Will anyone be
> able to figure out what is going on if the "Invalid address family"
> string appears in the system log? Please consider changing that pr_err()
> statement into a WARN_ON_ONCE() statement.
I expect the caller should also print something in syslog, combine
them togather will help.
>
> > +     ret = rtrs_str_to_sockaddr(str, len, port, addr->dst);
> > +
> > +     return ret;
>
> Please change this into a single return statement.
ok
>
> > +EXPORT_SYMBOL(rtrs_addr_to_sockaddr);
> > +
> > +void rtrs_ib_dev_pool_init(enum ib_pd_flags pd_flags,
> > +                         struct rtrs_ib_dev_pool *pool)
> > +{
> > +     WARN_ON(pool->ops && (!pool->ops->alloc ^ !pool->ops->free));
> > +     INIT_LIST_HEAD(&pool->list);
> > +     mutex_init(&pool->mutex);
> > +     pool->pd_flags = pd_flags;
> > +}
> > +EXPORT_SYMBOL(rtrs_ib_dev_pool_init);
> > +
> > +void rtrs_ib_dev_pool_deinit(struct rtrs_ib_dev_pool *pool)
> > +{
> > +     WARN_ON(!list_empty(&pool->list));
> > +}
> > +EXPORT_SYMBOL(rtrs_ib_dev_pool_deinit);
>
> Since rtrs_ib_dev_pool_init() calls mutex_init(), should
> rtrs_ib_dev_pool_deinit() call mutex_destroy()?
You're right.

>
> Thanks,
>
> Bart.
>
Thanks Bart.
diff mbox series

Patch

diff --git a/drivers/infiniband/ulp/rtrs/rtrs.c b/drivers/infiniband/ulp/rtrs/rtrs.c
new file mode 100644
index 000000000000..8498e3a4d4e3
--- /dev/null
+++ b/drivers/infiniband/ulp/rtrs/rtrs.c
@@ -0,0 +1,628 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * InfiniBand Transport Layer
+ *
+ * Copyright (c) 2014 - 2018 ProfitBricks GmbH. All rights reserved.
+ *
+ * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
+ *
+ * Copyright (c) 2019 1&1 IONOS SE. All rights reserved.
+ */
+#undef pr_fmt
+#define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt
+
+#include <linux/module.h>
+#include <linux/inet.h>
+
+#include "rtrs-pri.h"
+#include "rtrs-log.h"
+
+MODULE_DESCRIPTION("RTRS Core");
+MODULE_LICENSE("GPL");
+
+struct rtrs_iu *rtrs_iu_alloc(u32 queue_size, size_t size, gfp_t gfp_mask,
+				struct ib_device *dma_dev,
+				enum dma_data_direction dir,
+				void (*done)(struct ib_cq *cq,
+					     struct ib_wc *wc))
+{
+	struct rtrs_iu *ius, *iu;
+	int i;
+
+	WARN_ON(!queue_size);
+	ius = kcalloc(queue_size, sizeof(*ius), gfp_mask);
+
+	if (unlikely(!ius))
+		return NULL;
+	for (i = 0; i < queue_size; i++) {
+		iu = &ius[i];
+		iu->buf = kzalloc(size, gfp_mask);
+		if (unlikely(!iu->buf))
+			goto err;
+
+		iu->dma_addr = ib_dma_map_single(dma_dev, iu->buf, size, dir);
+		if (unlikely(ib_dma_mapping_error(dma_dev, iu->dma_addr)))
+			goto err;
+
+		iu->cqe.done  = done;
+		iu->size      = size;
+		iu->direction = dir;
+	}
+
+	return ius;
+
+err:
+	rtrs_iu_free(ius, dir, dma_dev, i);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(rtrs_iu_alloc);
+
+void rtrs_iu_free(struct rtrs_iu *ius, enum dma_data_direction dir,
+		   struct ib_device *ibdev, u32 queue_size)
+{
+	struct rtrs_iu *iu;
+	int i;
+
+	if (!ius)
+		return;
+
+	for (i = 0; i < queue_size; i++) {
+		iu = &ius[i];
+		ib_dma_unmap_single(ibdev, iu->dma_addr, iu->size, dir);
+		kfree(iu->buf);
+	}
+	kfree(ius);
+}
+EXPORT_SYMBOL_GPL(rtrs_iu_free);
+
+int rtrs_iu_post_recv(struct rtrs_con *con, struct rtrs_iu *iu)
+{
+	struct rtrs_sess *sess = con->sess;
+	struct ib_recv_wr wr;
+	const struct ib_recv_wr *bad_wr;
+	struct ib_sge list;
+
+	list.addr   = iu->dma_addr;
+	list.length = iu->size;
+	list.lkey   = sess->dev->ib_pd->local_dma_lkey;
+
+	if (WARN_ON(list.length == 0)) {
+		rtrs_wrn(con->sess,
+			  "Posting receive work request failed, sg list is empty\n");
+		return -EINVAL;
+	}
+
+	wr.next    = NULL;
+	wr.wr_cqe  = &iu->cqe;
+	wr.sg_list = &list;
+	wr.num_sge = 1;
+
+	return ib_post_recv(con->qp, &wr, &bad_wr);
+}
+EXPORT_SYMBOL_GPL(rtrs_iu_post_recv);
+
+int rtrs_post_recv_empty(struct rtrs_con *con, struct ib_cqe *cqe)
+{
+	struct ib_recv_wr wr;
+	const struct ib_recv_wr *bad_wr;
+
+	wr.next    = NULL;
+	wr.wr_cqe  = cqe;
+	wr.sg_list = NULL;
+	wr.num_sge = 0;
+
+	return ib_post_recv(con->qp, &wr, &bad_wr);
+}
+EXPORT_SYMBOL_GPL(rtrs_post_recv_empty);
+
+int rtrs_post_recv_empty_x2(struct rtrs_con *con, struct ib_cqe *cqe)
+{
+	struct ib_recv_wr wr_arr[2], *wr;
+	const struct ib_recv_wr *bad_wr;
+	int i;
+
+	memset(wr_arr, 0, sizeof(wr_arr));
+	for (i = 0; i < ARRAY_SIZE(wr_arr); i++) {
+		wr = &wr_arr[i];
+		wr->wr_cqe  = cqe;
+		if (i)
+			/* Chain backwards */
+			wr->next = &wr_arr[i - 1];
+	}
+
+	return ib_post_recv(con->qp, wr, &bad_wr);
+}
+EXPORT_SYMBOL_GPL(rtrs_post_recv_empty_x2);
+
+int rtrs_iu_post_send(struct rtrs_con *con, struct rtrs_iu *iu, size_t size,
+		       struct ib_send_wr *head)
+{
+	struct rtrs_sess *sess = con->sess;
+	struct ib_send_wr wr;
+	const struct ib_send_wr *bad_wr;
+	struct ib_sge list;
+
+	if ((WARN_ON(size == 0)))
+		return -EINVAL;
+
+	list.addr   = iu->dma_addr;
+	list.length = size;
+	list.lkey   = sess->dev->ib_pd->local_dma_lkey;
+
+	memset(&wr, 0, sizeof(wr));
+	wr.next       = NULL;
+	wr.wr_cqe     = &iu->cqe;
+	wr.sg_list    = &list;
+	wr.num_sge    = 1;
+	wr.opcode     = IB_WR_SEND;
+	wr.send_flags = IB_SEND_SIGNALED;
+
+	if (head) {
+		struct ib_send_wr *tail = head;
+
+		while (tail->next)
+			tail = tail->next;
+		tail->next = &wr;
+	} else {
+		head = &wr;
+	}
+
+	return ib_post_send(con->qp, head, &bad_wr);
+}
+EXPORT_SYMBOL_GPL(rtrs_iu_post_send);
+
+int rtrs_iu_post_rdma_write_imm(struct rtrs_con *con, struct rtrs_iu *iu,
+				 struct ib_sge *sge, unsigned int num_sge,
+				 u32 rkey, u64 rdma_addr, u32 imm_data,
+				 enum ib_send_flags flags,
+				 struct ib_send_wr *head)
+{
+	const struct ib_send_wr *bad_wr;
+	struct ib_rdma_wr wr;
+	int i;
+
+	wr.wr.next	  = NULL;
+	wr.wr.wr_cqe	  = &iu->cqe;
+	wr.wr.sg_list	  = sge;
+	wr.wr.num_sge	  = num_sge;
+	wr.rkey		  = rkey;
+	wr.remote_addr	  = rdma_addr;
+	wr.wr.opcode	  = IB_WR_RDMA_WRITE_WITH_IMM;
+	wr.wr.ex.imm_data = cpu_to_be32(imm_data);
+	wr.wr.send_flags  = flags;
+
+	/*
+	 * If one of the sges has 0 size, the operation will fail with an
+	 * length error
+	 */
+	for (i = 0; i < num_sge; i++)
+		if (WARN_ON(sge[i].length == 0))
+			return -EINVAL;
+
+	if (head) {
+		struct ib_send_wr *tail = head;
+
+		while (tail->next)
+			tail = tail->next;
+		tail->next = &wr.wr;
+	} else {
+		head = &wr.wr;
+	}
+
+	return ib_post_send(con->qp, head, &bad_wr);
+}
+EXPORT_SYMBOL_GPL(rtrs_iu_post_rdma_write_imm);
+
+int rtrs_post_rdma_write_imm_empty(struct rtrs_con *con, struct ib_cqe *cqe,
+				    u32 imm_data, enum ib_send_flags flags,
+				    struct ib_send_wr *head)
+{
+	struct ib_send_wr wr;
+	const struct ib_send_wr *bad_wr;
+
+	memset(&wr, 0, sizeof(wr));
+	wr.wr_cqe	= cqe;
+	wr.send_flags	= flags;
+	wr.opcode	= IB_WR_RDMA_WRITE_WITH_IMM;
+	wr.ex.imm_data	= cpu_to_be32(imm_data);
+
+	if (head) {
+		struct ib_send_wr *tail = head;
+
+		while (tail->next)
+			tail = tail->next;
+		tail->next = &wr;
+	} else {
+		head = &wr;
+	}
+
+	return ib_post_send(con->qp, head, &bad_wr);
+}
+EXPORT_SYMBOL_GPL(rtrs_post_rdma_write_imm_empty);
+
+static void qp_event_handler(struct ib_event *ev, void *ctx)
+{
+	struct rtrs_con *con = ctx;
+
+	switch (ev->event) {
+	case IB_EVENT_COMM_EST:
+		rtrs_info(con->sess, "QP event %s (%d) received\n",
+			   ib_event_msg(ev->event), ev->event);
+		rdma_notify(con->cm_id, IB_EVENT_COMM_EST);
+		break;
+	default:
+		rtrs_info(con->sess, "Unhandled QP event %s (%d) received\n",
+			   ib_event_msg(ev->event), ev->event);
+		break;
+	}
+}
+
+static int create_cq(struct rtrs_con *con, int cq_vector, u16 cq_size,
+		     enum ib_poll_context poll_ctx)
+{
+	struct rdma_cm_id *cm_id = con->cm_id;
+	struct ib_cq *cq;
+
+	cq = ib_alloc_cq(cm_id->device, con, cq_size,
+			 cq_vector, poll_ctx);
+	if (IS_ERR(cq)) {
+		rtrs_err(con->sess, "Creating completion queue failed, errno: %ld\n",
+			  PTR_ERR(cq));
+		return PTR_ERR(cq);
+	}
+	con->cq = cq;
+
+	return 0;
+}
+
+static int create_qp(struct rtrs_con *con, struct ib_pd *pd,
+		     u16 wr_queue_size, u32 max_sge)
+{
+	struct ib_qp_init_attr init_attr = {NULL};
+	struct rdma_cm_id *cm_id = con->cm_id;
+	int ret;
+
+	init_attr.cap.max_send_wr = wr_queue_size;
+	init_attr.cap.max_recv_wr = wr_queue_size;
+	init_attr.cap.max_recv_sge = 1;
+	init_attr.event_handler = qp_event_handler;
+	init_attr.qp_context = con;
+#undef max_send_sge
+	init_attr.cap.max_send_sge = max_sge;
+
+	init_attr.qp_type = IB_QPT_RC;
+	init_attr.send_cq = con->cq;
+	init_attr.recv_cq = con->cq;
+	init_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
+
+	ret = rdma_create_qp(cm_id, pd, &init_attr);
+	if (unlikely(ret)) {
+		rtrs_err(con->sess, "Creating QP failed, err: %d\n", ret);
+		return ret;
+	}
+	con->qp = cm_id->qp;
+
+	return ret;
+}
+
+int rtrs_cq_qp_create(struct rtrs_sess *sess, struct rtrs_con *con,
+		       u32 max_send_sge, int cq_vector, u16 cq_size,
+		       u16 wr_queue_size, enum ib_poll_context poll_ctx)
+{
+	int err;
+
+	err = create_cq(con, cq_vector, cq_size, poll_ctx);
+	if (unlikely(err))
+		return err;
+
+	err = create_qp(con, sess->dev->ib_pd, wr_queue_size, max_send_sge);
+	if (unlikely(err)) {
+		ib_free_cq(con->cq);
+		con->cq = NULL;
+		return err;
+	}
+	con->sess = sess;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(rtrs_cq_qp_create);
+
+void rtrs_cq_qp_destroy(struct rtrs_con *con)
+{
+	if (con->qp) {
+		rdma_destroy_qp(con->cm_id);
+		con->qp = NULL;
+	}
+	if (con->cq) {
+		ib_free_cq(con->cq);
+		con->cq = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(rtrs_cq_qp_destroy);
+
+static void schedule_hb(struct rtrs_sess *sess)
+{
+	queue_delayed_work(sess->hb_wq, &sess->hb_dwork,
+			   msecs_to_jiffies(sess->hb_interval_ms));
+}
+
+void rtrs_send_hb_ack(struct rtrs_sess *sess)
+{
+	struct rtrs_con *usr_con = sess->con[0];
+	u32 imm;
+	int err;
+
+	imm = rtrs_to_imm(RTRS_HB_ACK_IMM, 0);
+	err = rtrs_post_rdma_write_imm_empty(usr_con, sess->hb_cqe, imm,
+					      IB_SEND_SIGNALED, NULL);
+	if (unlikely(err)) {
+		sess->hb_err_handler(usr_con);
+		return;
+	}
+}
+EXPORT_SYMBOL_GPL(rtrs_send_hb_ack);
+
+static void hb_work(struct work_struct *work)
+{
+	struct rtrs_con *usr_con;
+	struct rtrs_sess *sess;
+	u32 imm;
+	int err;
+
+	sess = container_of(to_delayed_work(work), typeof(*sess), hb_dwork);
+	usr_con = sess->con[0];
+
+	if (sess->hb_missed_cnt > sess->hb_missed_max) {
+		sess->hb_err_handler(usr_con);
+		return;
+	}
+	if (sess->hb_missed_cnt++) {
+		/* Reschedule work without sending hb */
+		schedule_hb(sess);
+		return;
+	}
+	imm = rtrs_to_imm(RTRS_HB_MSG_IMM, 0);
+	err = rtrs_post_rdma_write_imm_empty(usr_con, sess->hb_cqe, imm,
+					      IB_SEND_SIGNALED, NULL);
+	if (unlikely(err)) {
+		sess->hb_err_handler(usr_con);
+		return;
+	}
+
+	schedule_hb(sess);
+}
+
+void rtrs_init_hb(struct rtrs_sess *sess, struct ib_cqe *cqe,
+		   unsigned int interval_ms, unsigned int missed_max,
+		   rtrs_hb_handler_t *err_handler,
+		   struct workqueue_struct *wq)
+{
+	sess->hb_cqe = cqe;
+	sess->hb_interval_ms = interval_ms;
+	sess->hb_err_handler = err_handler;
+	sess->hb_wq = wq;
+	sess->hb_missed_max = missed_max;
+	sess->hb_missed_cnt = 0;
+	INIT_DELAYED_WORK(&sess->hb_dwork, hb_work);
+}
+EXPORT_SYMBOL_GPL(rtrs_init_hb);
+
+void rtrs_start_hb(struct rtrs_sess *sess)
+{
+	schedule_hb(sess);
+}
+EXPORT_SYMBOL_GPL(rtrs_start_hb);
+
+void rtrs_stop_hb(struct rtrs_sess *sess)
+{
+	cancel_delayed_work_sync(&sess->hb_dwork);
+	sess->hb_missed_cnt = 0;
+	sess->hb_missed_max = 0;
+}
+EXPORT_SYMBOL_GPL(rtrs_stop_hb);
+
+static int rtrs_str_gid_to_sockaddr(const char *addr, size_t len,
+				     short port, struct sockaddr_storage *dst)
+{
+	struct sockaddr_ib *dst_ib = (struct sockaddr_ib *)dst;
+	int ret;
+
+	/*
+	 * We can use some of the I6 functions since GID is a valid
+	 * IPv6 address format
+	 */
+	ret = in6_pton(addr, len, dst_ib->sib_addr.sib_raw, '\0', NULL);
+	if (ret == 0)
+		return -EINVAL;
+
+	dst_ib->sib_family = AF_IB;
+	/*
+	 * Use the same TCP server port number as the IB service ID
+	 * on the IB port space range
+	 */
+	dst_ib->sib_sid = cpu_to_be64(RDMA_IB_IP_PS_IB | port);
+	dst_ib->sib_sid_mask = cpu_to_be64(0xffffffffffffffffULL);
+	dst_ib->sib_pkey = cpu_to_be16(0xffff);
+
+	return 0;
+}
+
+/**
+ * rtrs_str_to_sockaddr() - Convert rtrs address string to sockaddr
+ * @addr:	String representation of an addr (IPv4, IPv6 or IB GID):
+ *              - "ip:192.168.1.1"
+ *              - "ip:fe80::200:5aee:feaa:20a2"
+ *              - "gid:fe80::200:5aee:feaa:20a2"
+ * @len:        String address length
+ * @port:	Destination port
+ * @dst:	Destination sockaddr structure
+ *
+ * Returns 0 if conversion successful. Non-zero on error.
+ */
+static int rtrs_str_to_sockaddr(const char *addr, size_t len,
+				 short port, struct sockaddr_storage *dst)
+{
+	if (strncmp(addr, "gid:", 4) == 0) {
+		return rtrs_str_gid_to_sockaddr(addr + 4, len - 4, port, dst);
+	} else if (strncmp(addr, "ip:", 3) == 0) {
+		char port_str[8];
+		char *cpy;
+		int err;
+
+		snprintf(port_str, sizeof(port_str), "%u", port);
+		cpy = kstrndup(addr + 3, len - 3, GFP_KERNEL);
+		err = cpy ? inet_pton_with_scope(&init_net, AF_UNSPEC,
+						 cpy, port_str, dst) : -ENOMEM;
+		kfree(cpy);
+
+		return err;
+	}
+	return -EPROTONOSUPPORT;
+}
+
+int sockaddr_to_str(const struct sockaddr *addr, char *buf, size_t len)
+{
+	int cnt;
+
+	switch (addr->sa_family) {
+	case AF_IB:
+		cnt = scnprintf(buf, len, "gid:%pI6",
+			&((struct sockaddr_ib *)addr)->sib_addr.sib_raw);
+		return cnt;
+	case AF_INET:
+		cnt = scnprintf(buf, len, "ip:%pI4",
+			&((struct sockaddr_in *)addr)->sin_addr);
+		return cnt;
+	case AF_INET6:
+		cnt = scnprintf(buf, len, "ip:%pI6c",
+			  &((struct sockaddr_in6 *)addr)->sin6_addr);
+		return cnt;
+	}
+	cnt = scnprintf(buf, len, "<invalid address family>");
+	pr_err("Invalid address family\n");
+	return cnt;
+}
+EXPORT_SYMBOL(sockaddr_to_str);
+
+int rtrs_addr_to_sockaddr(const char *str, size_t len, short port,
+			   struct rtrs_addr *addr)
+{
+	const char *d;
+	int ret;
+
+	d = strchr(str, ',');
+	if (!d)
+		d = strchr(str, '@');
+	if (d) {
+		if (rtrs_str_to_sockaddr(str, d - str, 0, addr->src))
+			return -EINVAL;
+		d += 1;
+		len -= d - str;
+		str  = d;
+
+	} else {
+		addr->src = NULL;
+	}
+	ret = rtrs_str_to_sockaddr(str, len, port, addr->dst);
+
+	return ret;
+}
+EXPORT_SYMBOL(rtrs_addr_to_sockaddr);
+
+void rtrs_ib_dev_pool_init(enum ib_pd_flags pd_flags,
+			    struct rtrs_ib_dev_pool *pool)
+{
+	WARN_ON(pool->ops && (!pool->ops->alloc ^ !pool->ops->free));
+	INIT_LIST_HEAD(&pool->list);
+	mutex_init(&pool->mutex);
+	pool->pd_flags = pd_flags;
+}
+EXPORT_SYMBOL(rtrs_ib_dev_pool_init);
+
+void rtrs_ib_dev_pool_deinit(struct rtrs_ib_dev_pool *pool)
+{
+	WARN_ON(!list_empty(&pool->list));
+}
+EXPORT_SYMBOL(rtrs_ib_dev_pool_deinit);
+
+static void dev_free(struct kref *ref)
+{
+	struct rtrs_ib_dev_pool *pool;
+	struct rtrs_ib_dev *dev;
+
+	dev = container_of(ref, typeof(*dev), ref);
+	pool = dev->pool;
+
+	mutex_lock(&pool->mutex);
+	list_del(&dev->entry);
+	mutex_unlock(&pool->mutex);
+
+	if (pool->ops && pool->ops->deinit)
+		pool->ops->deinit(dev);
+
+	ib_dealloc_pd(dev->ib_pd);
+
+	if (pool->ops && pool->ops->free)
+		pool->ops->free(dev);
+	else
+		kfree(dev);
+}
+
+int rtrs_ib_dev_put(struct rtrs_ib_dev *dev)
+{
+	return kref_put(&dev->ref, dev_free);
+}
+EXPORT_SYMBOL(rtrs_ib_dev_put);
+
+static int rtrs_ib_dev_get(struct rtrs_ib_dev *dev)
+{
+	return kref_get_unless_zero(&dev->ref);
+}
+
+struct rtrs_ib_dev *
+rtrs_ib_dev_find_or_add(struct ib_device *ib_dev,
+			 struct rtrs_ib_dev_pool *pool)
+{
+	struct rtrs_ib_dev *dev;
+
+	mutex_lock(&pool->mutex);
+	list_for_each_entry(dev, &pool->list, entry) {
+		if (dev->ib_dev->node_guid == ib_dev->node_guid &&
+		    rtrs_ib_dev_get(dev))
+			goto out_unlock;
+	}
+	if (pool->ops && pool->ops->alloc)
+		dev = pool->ops->alloc();
+	else
+		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (IS_ERR_OR_NULL(dev))
+		goto out_err;
+
+	kref_init(&dev->ref);
+	dev->pool = pool;
+	dev->ib_dev = ib_dev;
+	dev->ib_pd = ib_alloc_pd(ib_dev, pool->pd_flags);
+	if (IS_ERR(dev->ib_pd))
+		goto out_free_dev;
+
+	if (pool->ops && pool->ops->init && pool->ops->init(dev))
+		goto out_free_pd;
+
+	list_add(&dev->entry, &pool->list);
+out_unlock:
+	mutex_unlock(&pool->mutex);
+	return dev;
+
+out_free_pd:
+	ib_dealloc_pd(dev->ib_pd);
+out_free_dev:
+	if (pool->ops && pool->ops->free)
+		pool->ops->free(dev);
+	else
+		kfree(dev);
+out_err:
+	mutex_unlock(&pool->mutex);
+	return NULL;
+}
+EXPORT_SYMBOL(rtrs_ib_dev_find_or_add);