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https://github.com/torvalds/linux.git
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0a2418c327
Extract the duplicated generic netlink boilerplate (netlink_open,
send_request, get_family_id, and NLA walker macros) from cgroupstats.c and
taskstats_fill_stats_tgid.c into a shared netlink_helper.{h,c}.
Link: https://lore.kernel.org/a2adf27308b5cd90d50b59e8519b87da49486bee.1783876192.git.cyyzero16@gmail.com
Signed-off-by: Yiyang Chen <cyyzero16@gmail.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Balbir Singh <balbirs@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
117 lines
2.5 KiB
C
117 lines
2.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <errno.h>
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#include <stdint.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <sys/time.h>
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#include <unistd.h>
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#include <linux/genetlink.h>
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#include "netlink_helper.h"
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int netlink_open(void)
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{
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struct timeval tv = { .tv_sec = ACCT_RCV_TIMEOUT_SEC };
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struct sockaddr_nl addr = {
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.nl_family = AF_NETLINK,
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.nl_pid = getpid(),
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};
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int fd;
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fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
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if (fd < 0)
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return -errno;
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if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0) {
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int err = -errno;
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close(fd);
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return err;
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}
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if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
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int err = -errno;
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close(fd);
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return err;
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}
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return fd;
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}
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int send_request(int fd, void *buf, size_t len)
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{
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struct sockaddr_nl addr = {
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.nl_family = AF_NETLINK,
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};
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if (sendto(fd, buf, len, 0, (struct sockaddr *)&addr, sizeof(addr)) < 0)
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return -errno;
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return 0;
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}
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/*
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* Resolve the generic netlink family ID for @name.
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* Returns the family ID (>= 0) on success, negative errno on failure.
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*/
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int get_family_id(int fd, const char *name)
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{
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struct {
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struct nlmsghdr nlh;
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struct genlmsghdr genl;
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char buf[256];
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} req = { 0 };
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char resp[8192];
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struct nlmsghdr *nlh;
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struct genlmsghdr *genl;
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struct nlattr *na;
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int len;
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int rem;
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int ret;
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req.nlh.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
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req.nlh.nlmsg_type = GENL_ID_CTRL;
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req.nlh.nlmsg_flags = NLM_F_REQUEST;
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req.nlh.nlmsg_seq = 1;
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req.nlh.nlmsg_pid = getpid();
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req.genl.cmd = CTRL_CMD_GETFAMILY;
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req.genl.version = 1;
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na = (struct nlattr *)((char *)&req + NLMSG_ALIGN(req.nlh.nlmsg_len));
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na->nla_type = CTRL_ATTR_FAMILY_NAME;
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na->nla_len = NLA_HDRLEN + strlen(name) + 1;
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memcpy(nla_data(na), name, strlen(name) + 1);
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req.nlh.nlmsg_len = NLMSG_ALIGN(req.nlh.nlmsg_len) + NLA_ALIGN(na->nla_len);
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ret = send_request(fd, &req, req.nlh.nlmsg_len);
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if (ret)
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return ret;
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len = recv(fd, resp, sizeof(resp), 0);
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if (len < 0)
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return -errno;
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for (nlh = (struct nlmsghdr *)resp; NLMSG_OK(nlh, len);
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nlh = NLMSG_NEXT(nlh, len)) {
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if (nlh->nlmsg_type == NLMSG_ERROR) {
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struct nlmsgerr *err = NLMSG_DATA(nlh);
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return err->error ? err->error : -ENOENT;
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}
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genl = (struct genlmsghdr *)NLMSG_DATA(nlh);
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rem = nlh->nlmsg_len - NLMSG_HDRLEN - GENL_HDRLEN;
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na = (struct nlattr *)((char *)genl + GENL_HDRLEN);
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while (nla_ok(na, rem)) {
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if (na->nla_type == CTRL_ATTR_FAMILY_ID)
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return *(uint16_t *)nla_data(na);
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na = nla_next(na, &rem);
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}
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}
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return -ENOENT;
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}
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