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dcb: Generalize dcb_get_attribute()

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The function dcb_get_attribute() assumes that the caller knows the exact
size of the looked-for payload. It also assumes that the response comes
wrapped in an DCB_ATTR_IEEE nest. The former assumption does not hold for
the IEEE APP table, which has variable size. The latter one does not hold
for DCBX, which is not IEEE-nested, and also for any CEE attributes, which
would come CEE-nested.

Factor out the payload extractor from the current dcb_get_attribute() code,
and put into a helper. Then rewrite dcb_get_attribute() compatibly in terms
of the new function. Introduce dcb_get_attribute_va() as a thin wrapper for
IEEE-nested access, and dcb_get_attribute_bare() for access to attributes
that are not nested.

Signed-off-by: Petr Machata <me@pmachata.org>
Signed-off-by: David Ahern <dsahern@kernel.org>
This commit is contained in:
Petr Machata 2021-01-02 01:03:38 +01:00 committed by David Ahern
parent 69290c32dc
commit e59876ff55
2 changed files with 68 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

79
dcb/dcb.c
View File

@ -59,25 +59,19 @@ static void dcb_free(struct dcb *dcb)
struct dcb_get_attribute {
struct dcb *dcb;
int attr;
void *data;
size_t data_len;
void *payload;
__u16 payload_len;
};
static int dcb_get_attribute_attr_ieee_cb(const struct nlattr *attr, void *data)
{
struct dcb_get_attribute *ga = data;
uint16_t len;
if (mnl_attr_get_type(attr) != ga->attr)
return MNL_CB_OK;
len = mnl_attr_get_payload_len(attr);
if (len != ga->data_len) {
fprintf(stderr, "Wrong len %d, expected %zd\n", len, ga->data_len);
return MNL_CB_ERROR;
}
memcpy(ga->data, mnl_attr_get_payload(attr), ga->data_len);
ga->payload = mnl_attr_get_payload(attr);
ga->payload_len = mnl_attr_get_payload_len(attr);
return MNL_CB_STOP;
}
@ -94,6 +88,16 @@ static int dcb_get_attribute_cb(const struct nlmsghdr *nlh, void *data)
return mnl_attr_parse(nlh, sizeof(struct dcbmsg), dcb_get_attribute_attr_cb, data);
}
static int dcb_get_attribute_bare_cb(const struct nlmsghdr *nlh, void *data)
{
/* Bare attributes (e.g. DCB_ATTR_DCBX) are not wrapped inside an IEEE
* container, so this does not have to go through unpacking in
* dcb_get_attribute_attr_cb().
*/
return mnl_attr_parse(nlh, sizeof(struct dcbmsg),
dcb_get_attribute_attr_ieee_cb, data);
}
struct dcb_set_attribute_response {
int response_attr;
};
@ -155,25 +159,70 @@ static struct nlmsghdr *dcb_prepare(struct dcb *dcb, const char *dev,
return nlh;
}
int dcb_get_attribute(struct dcb *dcb, const char *dev, int attr, void *data, size_t data_len)
static int __dcb_get_attribute(struct dcb *dcb, int command,
const char *dev, int attr,
void **payload_p, __u16 *payload_len_p,
int (*get_attribute_cb)(const struct nlmsghdr *nlh,
void *data))
{
struct dcb_get_attribute ga;
struct nlmsghdr *nlh;
int ret;
nlh = dcb_prepare(dcb, dev, RTM_GETDCB, DCB_CMD_IEEE_GET);
nlh = dcb_prepare(dcb, dev, RTM_GETDCB, command);
ga = (struct dcb_get_attribute) {
.dcb = dcb,
.attr = attr,
.data = data,
.data_len = data_len,
.payload = NULL,
};
ret = dcb_talk(dcb, nlh, dcb_get_attribute_cb, &ga);
ret = dcb_talk(dcb, nlh, get_attribute_cb, &ga);
if (ret) {
perror("Attribute read");
return ret;
}
if (ga.payload == NULL) {
perror("Attribute not found");
return -ENOENT;
}
*payload_p = ga.payload;
*payload_len_p = ga.payload_len;
return 0;
}
int dcb_get_attribute_va(struct dcb *dcb, const char *dev, int attr,
void **payload_p, __u16 *payload_len_p)
{
return __dcb_get_attribute(dcb, DCB_CMD_IEEE_GET, dev, attr,
payload_p, payload_len_p,
dcb_get_attribute_cb);
}
int dcb_get_attribute_bare(struct dcb *dcb, int cmd, const char *dev, int attr,
void **payload_p, __u16 *payload_len_p)
{
return __dcb_get_attribute(dcb, cmd, dev, attr,
payload_p, payload_len_p,
dcb_get_attribute_bare_cb);
}
int dcb_get_attribute(struct dcb *dcb, const char *dev, int attr, void *data, size_t data_len)
{
__u16 payload_len;
void *payload;
int ret;
ret = dcb_get_attribute_va(dcb, dev, attr, &payload, &payload_len);
if (ret)
return ret;
if (payload_len != data_len) {
fprintf(stderr, "Wrong len %d, expected %zd\n", payload_len, data_len);
return -EINVAL;
}
memcpy(data, payload, data_len);
return 0;
}

4
dcb/dcb.h
View File

@ -33,9 +33,13 @@ int dcb_get_attribute(struct dcb *dcb, const char *dev, int attr,
void *data, size_t data_len);
int dcb_set_attribute(struct dcb *dcb, const char *dev, int attr,
const void *data, size_t data_len);
int dcb_get_attribute_va(struct dcb *dcb, const char *dev, int attr,
void **payload_p, __u16 *payload_len_p);
int dcb_set_attribute_va(struct dcb *dcb, int command, const char *dev,
int (*cb)(struct dcb *dcb, struct nlmsghdr *nlh, void *data),
void *data);
int dcb_get_attribute_bare(struct dcb *dcb, int cmd, const char *dev, int attr,
void **payload_p, __u16 *payload_len_p);
int dcb_set_attribute_bare(struct dcb *dcb, int command, const char *dev,
int attr, const void *data, size_t data_len,
int response_attr);