[PATCH iproute2-next 0/4] Enrich rdma tool for net namespace commands

[PATCH iproute2-next 0/4] Enrich rdma tool for net namespace commands

[Parav Pandit]

RDMA subsystem can be running in either of the modes.
(a) Sharing RDMA devices among multiple net namespaces or
(b) Exclusive mode where RDMA device is bound to single net namespace 

This patch series adds
(1) query command to query rdma subsystem sharing mode
(2) set command to change rdma subsystem sharing mode
(3) assign rdma device to a net namespace

rdma tool examples:
(a) Query current rdma subsys net namespace sharing mode 
$ rdma sys show
netns shared

(b) Change rdma subsys mode to exclusive mode
$ rdma sys set netns exclusive

$ rdma sys show
netns exclusive

(c) Assign rdma device to a specific newly created net namespace
$ ip netns add foo
$ rdma dev set mlx5_1 netns foo 


Parav Pandit (4):
  rdma: Add an option to query,set net namespace sharing sys parameter
  rdma: Add man pages for rdma system commands
  rdma: Add an option to set net namespace of rdma device
  rdma: Add man page for rdma dev set netns command

 man/man8/rdma-dev.8    |  18 +++++-
 man/man8/rdma-system.8 |  82 +++++++++++++++++++++++
 man/man8/rdma.8        |   7 +-
 rdma/Makefile          |   2 +-
 rdma/dev.c             |  37 +++++++++++
 rdma/rdma.c            |   3 +-
 rdma/rdma.h            |   1 +
 rdma/sys.c             | 143 +++++++++++++++++++++++++++++++++++++++++
 rdma/utils.c           |   1 +
 9 files changed, 289 insertions(+), 5 deletions(-)
 create mode 100644 man/man8/rdma-system.8
 create mode 100644 rdma/sys.c

-- 
2.19.2

[PATCH iproute2-next 1/4] rdma: Add an option to query,set net namespace sharing sys parameter

[Parav Pandit]

Enrich rdma tool with an option to query rdma subsystem parameter
whether rdma devices are shared among multiple network namespaces
or exclusive to single network namespace.

rdma tool command examples and output.

$ rdma system show
netns shared

$ rdma system set netns exclusive

$ rdma system show
netns exclusive

Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
---
 rdma/Makefile |   2 +-
 rdma/rdma.c   |   3 +-
 rdma/rdma.h   |   1 +
 rdma/sys.c    | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++
 rdma/utils.c  |   1 +
 5 files changed, 148 insertions(+), 2 deletions(-)
 create mode 100644 rdma/sys.c

diff --git a/rdma/Makefile b/rdma/Makefile
index 6a424234..4847f27e 100644
--- a/rdma/Makefile
+++ b/rdma/Makefile
@@ -7,7 +7,7 @@ ifeq ($(HAVE_MNL),y)
 CFLAGS += -I./include/uapi/
 
 RDMA_OBJ = rdma.o utils.o dev.o link.o res.o res-pd.o res-mr.o res-cq.o \
-	   res-cmid.o res-qp.o
+	   res-cmid.o res-qp.o sys.o
 
 TARGETS += rdma
 endif
diff --git a/rdma/rdma.c b/rdma/rdma.c
index 676e03c2..e9f1b4bb 100644
--- a/rdma/rdma.c
+++ b/rdma/rdma.c
@@ -11,7 +11,7 @@ static void help(char *name)
 {
 	pr_out("Usage: %s [ OPTIONS ] OBJECT { COMMAND | help }\n"
 	       "       %s [ -f[orce] ] -b[atch] filename\n"
-	       "where  OBJECT := { dev | link | resource | help }\n"
+	       "where  OBJECT := { dev | link | resource | system | help }\n"
 	       "       OPTIONS := { -V[ersion] | -d[etails] | -j[son] | -p[retty]}\n", name, name);
 }
 
@@ -29,6 +29,7 @@ static int rd_cmd(struct rd *rd, int argc, char **argv)
 		{ "dev",	cmd_dev },
 		{ "link",	cmd_link },
 		{ "resource",	cmd_res },
+		{ "system",	cmd_sys },
 		{ 0 }
 	};
 
diff --git a/rdma/rdma.h b/rdma/rdma.h
index 9ed9e045..885a751e 100644
--- a/rdma/rdma.h
+++ b/rdma/rdma.h
@@ -93,6 +93,7 @@ char *rd_argv(struct rd *rd);
 int cmd_dev(struct rd *rd);
 int cmd_link(struct rd *rd);
 int cmd_res(struct rd *rd);
+int cmd_sys(struct rd *rd);
 int rd_exec_cmd(struct rd *rd, const struct rd_cmd *c, const char *str);
 int rd_exec_dev(struct rd *rd, int (*cb)(struct rd *rd));
 int rd_exec_require_dev(struct rd *rd, int (*cb)(struct rd *rd));
diff --git a/rdma/sys.c b/rdma/sys.c
new file mode 100644
index 00000000..78e5198f
--- /dev/null
+++ b/rdma/sys.c
@@ -0,0 +1,143 @@
+/*
+ * sys.c	RDMA tool
+ *
+ *              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.
+ */
+
+#include "rdma.h"
+
+static int sys_help(struct rd *rd)
+{
+	pr_out("Usage: %s system show [ netns ]\n", rd->filename);
+	pr_out("       %s system set netns { shared | exclusive }\n", rd->filename);
+	return 0;
+}
+
+static const char *netns_modes_str[] = {
+	"exclusive",
+	"shared",
+};
+
+static int sys_show_parse_cb(const struct nlmsghdr *nlh, void *data)
+{
+	struct nlattr *tb[RDMA_NLDEV_ATTR_MAX] = {};
+	struct rd *rd = data;
+
+	mnl_attr_parse(nlh, 0, rd_attr_cb, tb);
+
+	if (tb[RDMA_NLDEV_SYS_ATTR_NETNS_MODE]) {
+		const char *mode_str;
+		uint8_t netns_mode;
+
+		netns_mode =
+			mnl_attr_get_u8(tb[RDMA_NLDEV_SYS_ATTR_NETNS_MODE]);
+
+		if (netns_mode <= ARRAY_SIZE(netns_modes_str))
+			mode_str = netns_modes_str[netns_mode];
+		else
+			mode_str = "unknown";
+
+		if (rd->json_output)
+			jsonw_string_field(rd->jw, "netns", mode_str);
+		else
+			pr_out("netns %s\n", mode_str);
+	}
+	return MNL_CB_OK;
+}
+
+static int sys_show_no_args(struct rd *rd)
+{
+	uint32_t seq;
+	int ret;
+
+	rd_prepare_msg(rd, RDMA_NLDEV_CMD_SYS_GET,
+		       &seq, (NLM_F_REQUEST | NLM_F_ACK));
+	ret = rd_send_msg(rd);
+	if (ret)
+		return ret;
+
+	ret = rd_recv_msg(rd, sys_show_parse_cb, rd, seq);
+	return ret;
+}
+
+static int sys_show(struct rd *rd)
+{
+	const struct rd_cmd cmds[] = {
+		{ NULL,		sys_show_no_args},
+		{ "netns",	sys_show_no_args},
+		{ 0 }
+	};
+
+	return rd_exec_cmd(rd, cmds, "parameter");
+}
+
+static int sys_set_netns_cmd(struct rd *rd, bool enable)
+{
+	uint32_t seq;
+
+	rd_prepare_msg(rd, RDMA_NLDEV_CMD_SYS_SET,
+		       &seq, (NLM_F_REQUEST | NLM_F_ACK));
+	mnl_attr_put_u8(rd->nlh, RDMA_NLDEV_SYS_ATTR_NETNS_MODE, enable);
+
+	return rd_sendrecv_msg(rd, seq);
+}
+
+static bool sys_valid_netns_cmd(const char *cmd)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(netns_modes_str); i++) {
+		if (!strcmp(cmd, netns_modes_str[i]))
+			return true;
+	}
+	return false;
+}
+
+static int sys_set_netns_args(struct rd *rd)
+{
+	bool cmd;
+
+	if (rd_no_arg(rd) || !sys_valid_netns_cmd(rd_argv(rd))) {
+		pr_err("valid options are: { shared | exclusive }\n");
+		return -EINVAL;
+	}
+
+	cmd = (strcmp(rd_argv(rd), "shared") == 0) ? true : false;
+
+	return sys_set_netns_cmd(rd, cmd);
+}
+
+static int sys_set_help(struct rd *rd)
+{
+	pr_out("Usage: %s system set [PARAM] value\n", rd->filename);
+	pr_out("            system set netns { shared | exclusive }\n");
+	return 0;
+}
+
+static int sys_set(struct rd *rd)
+{
+	const struct rd_cmd cmds[] = {
+		{ NULL,			sys_set_help },
+		{ "help",		sys_set_help },
+		{ "netns",		sys_set_netns_args},
+		{ 0 }
+	};
+
+	return rd_exec_cmd(rd, cmds, "parameter");
+}
+
+int cmd_sys(struct rd *rd)
+{
+	const struct rd_cmd cmds[] = {
+		{ NULL,		sys_show },
+		{ "show",	sys_show },
+		{ "set",	sys_set },
+		{ "help",	sys_help },
+		{ 0 }
+	};
+
+	return rd_exec_cmd(rd, cmds, "system command");
+}
diff --git a/rdma/utils.c b/rdma/utils.c
index 11ed8a73..558d1c29 100644
--- a/rdma/utils.c
+++ b/rdma/utils.c
@@ -435,6 +435,7 @@ static const enum mnl_attr_data_type nldev_policy[RDMA_NLDEV_ATTR_MAX] = {
 	[RDMA_NLDEV_ATTR_DRIVER_U32] = MNL_TYPE_U32,
 	[RDMA_NLDEV_ATTR_DRIVER_S64] = MNL_TYPE_U64,
 	[RDMA_NLDEV_ATTR_DRIVER_U64] = MNL_TYPE_U64,
+	[RDMA_NLDEV_SYS_ATTR_NETNS_MODE] = MNL_TYPE_U8,
 };
 
 int rd_attr_check(const struct nlattr *attr, int *typep)
-- 
2.19.2

[PATCH iproute2-next 2/4] rdma: Add man pages for rdma system commands

[Parav Pandit]

Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
---
 man/man8/rdma-system.8 | 82 ++++++++++++++++++++++++++++++++++++++++++
 man/man8/rdma.8        |  7 +++-
 2 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 man/man8/rdma-system.8

diff --git a/man/man8/rdma-system.8 b/man/man8/rdma-system.8
new file mode 100644
index 00000000..a6873b52
--- /dev/null
+++ b/man/man8/rdma-system.8
@@ -0,0 +1,82 @@
+.TH RDMA\-SYSTEM 8 "06 Jul 2017" "iproute2" "Linux"
+.SH NAME
+rdma-system \- RDMA subsystem configuration
+.SH SYNOPSIS
+.sp
+.ad l
+.in +8
+.ti -8
+.B rdma
+.RI "[ " OPTIONS " ]"
+.B sys
+.RI  " { " COMMAND " | "
+.BR help " }"
+.sp
+
+.ti -8
+.IR OPTIONS " := { "
+\fB\-V\fR[\fIersion\fR] |
+\fB\-d\fR[\fIetails\fR] }
+
+.ti -8
+.B rdma system show
+
+.ti -8
+.B rdma system set
+.BR netns
+.BR NEWMODE
+
+.ti -8
+.B rdma system help
+
+.SH "DESCRIPTION"
+.SS rdma system set - set RDMA subsystem network namespace mode
+
+.SS rdma system show - display RDMA subsystem network namespace mode
+
+.PP
+.I "NEWMODE"
+- specifies the RDMA subsystem mode. Either exclusive or shared.
+When user wants to assign dedicated RDMA device to a particular
+network namespace, exclusive mode should be set before creating
+any network namespace. If there are active network namespaces and if
+one or more RDMA devices exist, changing mode from shared to
+exclusive returns error code EBUSY.
+
+When RDMA subsystem is in shared mode, RDMA device is accessible in
+all network namespace. When RDMA device isolation among multiple
+network namespaces is not needed, shared mode can be used.
+
+It is preferred to not change the subsystem mode when there is active
+RDMA traffic running, even though it is supported.
+
+.SH "EXAMPLES"
+.PP
+rdma system show
+.RS 4
+Shows the state of RDMA subsystem network namespace mode on the system.
+.RE
+.PP
+rdma system set netns exclusive
+.RS 4
+Sets the RDMA subsystem in network namespace exclusive mode. In this mode RDMA devices
+are visible only in single network namespace.
+.RE
+.PP
+rdma system set netns shared
+.RS 4
+Sets the RDMA subsystem in network namespace shared mode. In this mode RDMA devices
+are shared among network namespaces.
+.RE
+.PP
+
+.SH SEE ALSO
+.BR rdma (8),
+.BR rdma-link (8),
+.BR rdma-resource (8),
+.BR network_namespaces(7),
+.BR namespaces(7),
+.br
+
+.SH AUTHOR
+Parav Pandit <parav@mellanox.com>
diff --git a/man/man8/rdma.8 b/man/man8/rdma.8
index b2b5aef8..3ae33987 100644
--- a/man/man8/rdma.8
+++ b/man/man8/rdma.8
@@ -19,7 +19,7 @@ rdma \- RDMA tool
 
 .ti -8
 .IR OBJECT " := { "
-.BR dev " | " link " }"
+.BR dev " | " link " | " system " }"
 .sp
 
 .ti -8
@@ -70,6 +70,10 @@ Generate JSON output.
 .B link
 - RDMA port related.
 
+.TP
+.B sys
+- RDMA subsystem related.
+
 .PP
 The names of all objects may be written in full or
 abbreviated form, for example
@@ -107,6 +111,7 @@ Exit status is 0 if command was successful or a positive integer upon failure.
 .BR rdma-dev (8),
 .BR rdma-link (8),
 .BR rdma-resource (8),
+.BR rdma-system (8),
 .br
 
 .SH REPORTING BUGS
-- 
2.19.2

[PATCH iproute2-next 3/4] rdma: Add an option to set net namespace of rdma device

[Parav Pandit]

Enrich rdma tool with an option to set network namespace of RDMA
device. After successful execution of it, rdma device will
be accessible only in assigned network namespace.

rdma tool command examples and output.

First set netns mode to exclusive.

$ rdma system set netns exclusive

Now create network namespace and assign RDMA device to this
network namespace.

$ ip netns add foo
$ rdma dev set mlx5_1 netns foo

Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
---
 rdma/dev.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/rdma/dev.c b/rdma/dev.c
index 90483622..d28bf6b3 100644
--- a/rdma/dev.c
+++ b/rdma/dev.c
@@ -4,12 +4,14 @@
  * Authors:     Leon Romanovsky <leonro@mellanox.com>
  */
 
+#include <fcntl.h>
 #include "rdma.h"
 
 static int dev_help(struct rd *rd)
 {
 	pr_out("Usage: %s dev show [DEV]\n", rd->filename);
 	pr_out("       %s dev set [DEV] name DEVNAME\n", rd->filename);
+	pr_out("       %s dev set [DEV] netns NSNAME\n", rd->filename);
 	return 0;
 }
 
@@ -272,11 +274,46 @@ static int dev_set_name(struct rd *rd)
 	return rd_sendrecv_msg(rd, seq);
 }
 
+static int dev_set_netns(struct rd *rd)
+{
+	char *netns_path;
+	uint32_t seq;
+	int netns;
+	int ret;
+
+	if (rd_no_arg(rd)) {
+		pr_err("Please provide device name.\n");
+		return -EINVAL;
+	}
+
+	if (asprintf(&netns_path, "%s/%s", NETNS_RUN_DIR, rd_argv(rd)) < 0)
+		return -ENOMEM;
+
+	netns = open(netns_path, O_RDONLY | O_CLOEXEC);
+	if (netns < 0) {
+		fprintf(stderr, "Cannot open network namespace \"%s\": %s\n",
+			rd_argv(rd), strerror(errno));
+		ret = -EINVAL;
+		goto done;
+	}
+
+	rd_prepare_msg(rd, RDMA_NLDEV_CMD_SET,
+		       &seq, (NLM_F_REQUEST | NLM_F_ACK));
+	mnl_attr_put_u32(rd->nlh, RDMA_NLDEV_ATTR_DEV_INDEX, rd->dev_idx);
+	mnl_attr_put_u32(rd->nlh, RDMA_NLDEV_NET_NS_FD, netns);
+	ret = rd_sendrecv_msg(rd, seq);
+	close(netns);
+done:
+	free(netns_path);
+	return ret;
+}
+
 static int dev_one_set(struct rd *rd)
 {
 	const struct rd_cmd cmds[] = {
 		{ NULL,		dev_help},
 		{ "name",	dev_set_name},
+		{ "netns",	dev_set_netns},
 		{ 0 }
 	};
 
-- 
2.19.2

[PATCH iproute2-next 4/4] rdma: Add man page for rdma dev set netns command

[Parav Pandit]

Add man page to describe additional set netns command
for rdma device.

Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
---
 man/man8/rdma-dev.8 | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/man/man8/rdma-dev.8 b/man/man8/rdma-dev.8
index 069f4717..38e34b3b 100644
--- a/man/man8/rdma-dev.8
+++ b/man/man8/rdma-dev.8
@@ -28,13 +28,19 @@ rdma-dev \- RDMA device configuration
 .BR name
 .BR NEWNAME
 
+.ti -8
+.B rdma dev set
+.RI "[ " DEV " ]"
+.BR netns
+.BR NSNAME
+
 .ti -8
 .B rdma dev help
 
 .SH "DESCRIPTION"
-.SS rdma dev set - rename rdma device
+.SS rdma dev set - rename RDMA device or set network namespace
 
-.SS rdma dev show - display rdma device attributes
+.SS rdma dev show - display RDMA device attributes
 
 .PP
 .I "DEV"
@@ -58,11 +64,19 @@ rdma dev set mlx5_3 name rdma_0
 Renames the mlx5_3 device to rdma_0.
 .RE
 .PP
+rdma dev set mlx5_3 netns foo
+.RS 4
+Changes the network namespace of RDMA device to foo where foo is
+previously created using iproute2 ip command.
+.RE
+.PP
 
 .SH SEE ALSO
+.BR ip (8),
 .BR rdma (8),
 .BR rdma-link (8),
 .BR rdma-resource (8),
+.BR rdma-system (8),
 .br
 
 .SH AUTHOR
-- 
2.19.2

Re: [PATCH iproute2-next 1/4] rdma: Add an option to query,set net namespace sharing sys parameter

[David Ahern]

On 5/21/19 8:22 AM, Parav Pandit wrote:
> diff --git a/rdma/sys.c b/rdma/sys.c
> new file mode 100644
> index 00000000..78e5198f
> --- /dev/null
> +++ b/rdma/sys.c
> @@ -0,0 +1,143 @@
> +/*
> + * sys.c	RDMA tool
> + *
> + *              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.
> + */

Please use the SPDX line like the other rdma files.

> +
> +#include "rdma.h"
> +
> +static int sys_help(struct rd *rd)
> +{
> +	pr_out("Usage: %s system show [ netns ]\n", rd->filename);
> +	pr_out("       %s system set netns { shared | exclusive }\n", rd->filename);
> +	return 0;
> +}
> +
> +static const char *netns_modes_str[] = {
> +	"exclusive",
> +	"shared",
> +};
> +
> +static int sys_show_parse_cb(const struct nlmsghdr *nlh, void *data)
> +{
> +	struct nlattr *tb[RDMA_NLDEV_ATTR_MAX] = {};
> +	struct rd *rd = data;
> +
> +	mnl_attr_parse(nlh, 0, rd_attr_cb, tb);
> +
> +	if (tb[RDMA_NLDEV_SYS_ATTR_NETNS_MODE]) {
> +		const char *mode_str;
> +		uint8_t netns_mode;
> +
> +		netns_mode =
> +			mnl_attr_get_u8(tb[RDMA_NLDEV_SYS_ATTR_NETNS_MODE]);
> +
> +		if (netns_mode <= ARRAY_SIZE(netns_modes_str))
> +			mode_str = netns_modes_str[netns_mode];
> +		else
> +			mode_str = "unknown";
> +
> +		if (rd->json_output)
> +			jsonw_string_field(rd->jw, "netns", mode_str);
> +		else
> +			pr_out("netns %s\n", mode_str);
> +	}
> +	return MNL_CB_OK;
> +}
> +
> +static int sys_show_no_args(struct rd *rd)
> +{
> +	uint32_t seq;
> +	int ret;
> +
> +	rd_prepare_msg(rd, RDMA_NLDEV_CMD_SYS_GET,
> +		       &seq, (NLM_F_REQUEST | NLM_F_ACK));
> +	ret = rd_send_msg(rd);
> +	if (ret)
> +		return ret;
> +
> +	ret = rd_recv_msg(rd, sys_show_parse_cb, rd, seq);
> +	return ret;

since you are fixing the header, why not just
	return rd_recv_msg(rd, sys_show_parse_cb, rd, seq);

like the other functions?

RE: [PATCH iproute2-next 1/4] rdma: Add an option to query,set net namespace sharing sys parameter

[Parav Pandit]

Hi David,

> -----Original Message-----
> From: David Ahern <dsahern@gmail.com>
> Sent: Wednesday, May 29, 2019 9:43 PM
> To: Parav Pandit <parav@mellanox.com>
> Cc: netdev@vger.kernel.org; linux-rdma@vger.kernel.org;
> stephen@networkplumber.org; Leon Romanovsky <leonro@mellanox.com>
> Subject: Re: [PATCH iproute2-next 1/4] rdma: Add an option to query,set net
> namespace sharing sys parameter
> 
> On 5/21/19 8:22 AM, Parav Pandit wrote:
> > diff --git a/rdma/sys.c b/rdma/sys.c
> > new file mode 100644
> > index 00000000..78e5198f
> > --- /dev/null
> > +++ b/rdma/sys.c
> > @@ -0,0 +1,143 @@
> > +/*
> > + * sys.c	RDMA tool
> > + *
> > + *              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.
> > + */
> 
> Please use the SPDX line like the other rdma files.
> 
Sure. Yes.

> > +
> > +#include "rdma.h"
> > +
> > +static int sys_help(struct rd *rd)
> > +{
> > +	pr_out("Usage: %s system show [ netns ]\n", rd->filename);
> > +	pr_out("       %s system set netns { shared | exclusive }\n", rd-
> >filename);
> > +	return 0;
> > +}
> > +
> > +static const char *netns_modes_str[] = {
> > +	"exclusive",
> > +	"shared",
> > +};
> > +
> > +static int sys_show_parse_cb(const struct nlmsghdr *nlh, void *data)
> > +{
> > +	struct nlattr *tb[RDMA_NLDEV_ATTR_MAX] = {};
> > +	struct rd *rd = data;
> > +
> > +	mnl_attr_parse(nlh, 0, rd_attr_cb, tb);
> > +
> > +	if (tb[RDMA_NLDEV_SYS_ATTR_NETNS_MODE]) {
> > +		const char *mode_str;
> > +		uint8_t netns_mode;
> > +
> > +		netns_mode =
> > +
> 	mnl_attr_get_u8(tb[RDMA_NLDEV_SYS_ATTR_NETNS_MODE]);
> > +
> > +		if (netns_mode <= ARRAY_SIZE(netns_modes_str))
> > +			mode_str = netns_modes_str[netns_mode];
> > +		else
> > +			mode_str = "unknown";
> > +
> > +		if (rd->json_output)
> > +			jsonw_string_field(rd->jw, "netns", mode_str);
> > +		else
> > +			pr_out("netns %s\n", mode_str);
> > +	}
> > +	return MNL_CB_OK;
> > +}
> > +
> > +static int sys_show_no_args(struct rd *rd) {
> > +	uint32_t seq;
> > +	int ret;
> > +
> > +	rd_prepare_msg(rd, RDMA_NLDEV_CMD_SYS_GET,
> > +		       &seq, (NLM_F_REQUEST | NLM_F_ACK));
> > +	ret = rd_send_msg(rd);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = rd_recv_msg(rd, sys_show_parse_cb, rd, seq);
> > +	return ret;
> 
> since you are fixing the header, why not just
> 	return rd_recv_msg(rd, sys_show_parse_cb, rd, seq);
> 
> like the other functions?

Yep. Changed.
Sending v1.