RE: [PATCH iproute2-next 2/2] vdpa: Add vdpa tool

[Parav Pandit <parav@nvidia.com>]

> From: David Ahern <dsahern@gmail.com>
> Sent: Tuesday, January 26, 2021 9:53 AM
> 
> Looks fine. A few comments below around code re-use.
> 
> On 1/22/21 4:26 AM, Parav Pandit wrote:
> > diff --git a/vdpa/vdpa.c b/vdpa/vdpa.c new file mode 100644 index
> > 00000000..942524b7
> > --- /dev/null
> > +++ b/vdpa/vdpa.c
> > @@ -0,0 +1,828 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +
> > +#include <stdio.h>
> > +#include <getopt.h>
> > +#include <errno.h>
> > +#include <linux/genetlink.h>
> > +#include <linux/vdpa.h>
> > +#include <linux/virtio_ids.h>
> > +#include <linux/netlink.h>
> > +#include <libmnl/libmnl.h>
> > +#include "mnl_utils.h"
> > +
> > +#include "version.h"
> > +#include "json_print.h"
> > +#include "utils.h"
> > +
> > +static int g_indent_level;
> > +
> > +#define INDENT_STR_STEP 2
> > +#define INDENT_STR_MAXLEN 32
> > +static char g_indent_str[INDENT_STR_MAXLEN + 1] = "";
> 
> The indent code has a lot of parallels with devlink -- including helpers below
> around indent_inc and _dec. Please take a look at how to refactor and re-
> use.
> 
Ok. Devlink has some more convoluted code with next line etc.
But I will see if I can consolidate without changing the devlink's flow/logic.

> > +
> > +struct vdpa_socket {
> > +	struct mnl_socket *nl;
> > +	char *buf;
> > +	uint32_t family;
> > +	unsigned int seq;
> > +};
> > +
> > +static int vdpa_socket_sndrcv(struct vdpa_socket *nlg, const struct
> nlmsghdr *nlh,
> > +			      mnl_cb_t data_cb, void *data) {
> > +	int err;
> > +
> > +	err = mnl_socket_sendto(nlg->nl, nlh, nlh->nlmsg_len);
> > +	if (err < 0) {
> > +		perror("Failed to send data");
> > +		return -errno;
> > +	}
> > +
> > +	err = mnlu_socket_recv_run(nlg->nl, nlh->nlmsg_seq, nlg->buf,
> MNL_SOCKET_BUFFER_SIZE,
> > +				   data_cb, data);
> > +	if (err < 0) {
> > +		fprintf(stderr, "vdpa answers: %s\n", strerror(errno));
> > +		return -errno;
> > +	}
> > +	return 0;
> > +}
> > +
> > +static int get_family_id_attr_cb(const struct nlattr *attr, void
> > +*data) {
> > +	int type = mnl_attr_get_type(attr);
> > +	const struct nlattr **tb = data;
> > +
> > +	if (mnl_attr_type_valid(attr, CTRL_ATTR_MAX) < 0)
> > +		return MNL_CB_ERROR;
> > +
> > +	if (type == CTRL_ATTR_FAMILY_ID &&
> > +	    mnl_attr_validate(attr, MNL_TYPE_U16) < 0)
> > +		return MNL_CB_ERROR;
> > +	tb[type] = attr;
> > +	return MNL_CB_OK;
> > +}
> > +
> > +static int get_family_id_cb(const struct nlmsghdr *nlh, void *data) {
> > +	struct genlmsghdr *genl = mnl_nlmsg_get_payload(nlh);
> > +	struct nlattr *tb[CTRL_ATTR_MAX + 1] = {};
> > +	uint32_t *p_id = data;
> > +
> > +	mnl_attr_parse(nlh, sizeof(*genl), get_family_id_attr_cb, tb);
> > +	if (!tb[CTRL_ATTR_FAMILY_ID])
> > +		return MNL_CB_ERROR;
> > +	*p_id = mnl_attr_get_u16(tb[CTRL_ATTR_FAMILY_ID]);
> > +	return MNL_CB_OK;
> > +}
> > +
> > +static int family_get(struct vdpa_socket *nlg) {
> > +	struct genlmsghdr hdr = {};
> > +	struct nlmsghdr *nlh;
> > +	int err;
> > +
> > +	hdr.cmd = CTRL_CMD_GETFAMILY;
> > +	hdr.version = 0x1;
> > +
> > +	nlh = mnlu_msg_prepare(nlg->buf, GENL_ID_CTRL,
> > +			       NLM_F_REQUEST | NLM_F_ACK,
> > +			       &hdr, sizeof(hdr));
> > +
> > +	mnl_attr_put_strz(nlh, CTRL_ATTR_FAMILY_NAME,
> VDPA_GENL_NAME);
> > +
> > +	err = mnl_socket_sendto(nlg->nl, nlh, nlh->nlmsg_len);
> > +	if (err < 0)
> > +		return err;
> > +
> > +	err = mnlu_socket_recv_run(nlg->nl, nlh->nlmsg_seq, nlg->buf,
> > +				   MNL_SOCKET_BUFFER_SIZE,
> > +				   get_family_id_cb, &nlg->family);
> > +	return err;
> > +}
> > +
> > +static int vdpa_socket_open(struct vdpa_socket *nlg) {
> > +	int err;
> > +
> > +	nlg->buf = malloc(MNL_SOCKET_BUFFER_SIZE);
> > +	if (!nlg->buf)
> > +		goto err_buf_alloc;
> > +
> > +	nlg->nl = mnlu_socket_open(NETLINK_GENERIC);
> > +	if (!nlg->nl)
> > +		goto err_socket_open;
> > +
> > +	err = family_get(nlg);
> > +	if (err)
> > +		goto err_socket;
> > +
> > +	return 0;
> > +
> > +err_socket:
> > +	mnl_socket_close(nlg->nl);
> > +err_socket_open:
> > +	free(nlg->buf);
> > +err_buf_alloc:
> > +	return -1;
> > +}
> 
> The above 4 functions duplicate a lot of devlink functionality. Please create a
> helper in lib/mnl_utils.c that can be used in both.
> 
Will do.

> > +
> > +static unsigned int strslashcount(char *str) {
> > +	unsigned int count = 0;
> > +	char *pos = str;
> > +
> > +	while ((pos = strchr(pos, '/'))) {
> > +		count++;
> > +		pos++;
> > +	}
> > +	return count;
> > +}
> 
> you could make that a generic function (e.g., str_char_count) by passing '/' as
> an input.
> 
Yes.

> > +
> > +static int strslashrsplit(char *str, const char **before, const char
> > +**after) {
> > +	char *slash;
> > +
> > +	slash = strrchr(str, '/');
> > +	if (!slash)
> > +		return -EINVAL;
> > +	*slash = '\0';
> > +	*before = str;
> > +	*after = slash + 1;
> > +	return 0;
> > +}
> 
> similarly here. If you start with things like this in lib/utils you make it easier for
> follow on users to find.
> 
Will do.
Thanks for the review.
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