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Systemd/src/udev/udevadm-trigger.c
Mao 792cc203a6 udevadm: allow trigger command to be synchronous 
There are cases that we want to trigger and settle only specific
commands. For example, let's say at boot time we want to make sure all
the graphics devices are working correctly because it's critical for
booting, but not the USB subsystem (we'll trigger USB events later). So
we do:

  udevadm trigger --action="add" --subsystem-match="graphics"
  udevadm settle

However, we cannot block the kernel from emitting kernel events from
discovering USB devices. So if any of the USB kernel event was emitted
before the settle command, the settle command would still wait for the
entire queue to complete. And if the USB event takes a long time to be
processed, the system slows down.

The new `settle` option allows the `trigger` command to wait for only
the triggered events, and effectively solves this problem.
2018-02-09 11:59:03 +01:00

373 lines
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/* SPDX-License-Identifier: GPL-2.0+ */
/*
* Copyright (C) 2008-2009 Kay Sievers <kay@vrfy.org>
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "fd-util.h"
#include "set.h"
#include "string-util.h"
#include "udev-util.h"
#include "udev.h"
#include "udevadm-util.h"
#include "util.h"
static int verbose;
static int dry_run;
static void exec_list(struct udev_enumerate *udev_enumerate, const char *action, Set *settle_set) {
struct udev_list_entry *entry;
udev_list_entry_foreach(entry, udev_enumerate_get_list_entry(udev_enumerate)) {
char filename[UTIL_PATH_SIZE];
const char *syspath;
int fd;
syspath = udev_list_entry_get_name(entry);
if (verbose)
printf("%s\n", syspath);
if (dry_run)
continue;
strscpyl(filename, sizeof(filename), syspath, "/uevent", NULL);
fd = open(filename, O_WRONLY|O_CLOEXEC);
if (fd < 0)
continue;
if (settle_set != NULL)
set_put_strdup(settle_set, syspath);
if (write(fd, action, strlen(action)) < 0)
log_debug_errno(errno, "error writing '%s' to '%s': %m", action, filename);
close(fd);
}
}
static const char *keyval(const char *str, const char **val, char *buf, size_t size) {
char *pos;
strscpy(buf, size,str);
pos = strchr(buf, '=');
if (pos != NULL) {
pos[0] = 0;
pos++;
}
*val = pos;
return buf;
}
static void help(void) {
printf("%s trigger [OPTIONS] DEVPATH\n\n"
"Request events from the kernel.\n\n"
" -h --help Show this help\n"
" -V --version Show package version\n"
" -v --verbose Print the list of devices while running\n"
" -n --dry-run Do not actually trigger the events\n"
" -t --type= Type of events to trigger\n"
" devices sysfs devices (default)\n"
" subsystems sysfs subsystems and drivers\n"
" -c --action=ACTION Event action value, default is \"change\"\n"
" -s --subsystem-match=SUBSYSTEM Trigger devices from a matching subsystem\n"
" -S --subsystem-nomatch=SUBSYSTEM Exclude devices from a matching subsystem\n"
" -a --attr-match=FILE[=VALUE] Trigger devices with a matching attribute\n"
" -A --attr-nomatch=FILE[=VALUE] Exclude devices with a matching attribute\n"
" -p --property-match=KEY=VALUE Trigger devices with a matching property\n"
" -g --tag-match=KEY=VALUE Trigger devices with a matching property\n"
" -y --sysname-match=NAME Trigger devices with this /sys path\n"
" --name-match=NAME Trigger devices with this /dev name\n"
" -b --parent-match=NAME Trigger devices with that parent device\n"
" -w --settle Wait for the triggered events to complete\n"
, program_invocation_short_name);
}
static int adm_trigger(struct udev *udev, int argc, char *argv[]) {
enum {
ARG_NAME = 0x100,
};
static const struct option options[] = {
{ "verbose", no_argument, NULL, 'v' },
{ "dry-run", no_argument, NULL, 'n' },
{ "type", required_argument, NULL, 't' },
{ "action", required_argument, NULL, 'c' },
{ "subsystem-match", required_argument, NULL, 's' },
{ "subsystem-nomatch", required_argument, NULL, 'S' },
{ "attr-match", required_argument, NULL, 'a' },
{ "attr-nomatch", required_argument, NULL, 'A' },
{ "property-match", required_argument, NULL, 'p' },
{ "tag-match", required_argument, NULL, 'g' },
{ "sysname-match", required_argument, NULL, 'y' },
{ "name-match", required_argument, NULL, ARG_NAME },
{ "parent-match", required_argument, NULL, 'b' },
{ "settle", no_argument, NULL, 'w' },
{ "version", no_argument, NULL, 'V' },
{ "help", no_argument, NULL, 'h' },
{}
};
enum {
TYPE_DEVICES,
TYPE_SUBSYSTEMS,
} device_type = TYPE_DEVICES;
const char *action = "change";
_cleanup_udev_enumerate_unref_ struct udev_enumerate *udev_enumerate = NULL;
_cleanup_udev_monitor_unref_ struct udev_monitor *udev_monitor = NULL;
_cleanup_close_ int fd_ep = -1;
int fd_udev = -1;
struct epoll_event ep_udev;
bool settle = false;
_cleanup_set_free_free_ Set *settle_set = NULL;
int c, r;
udev_enumerate = udev_enumerate_new(udev);
if (udev_enumerate == NULL)
return 1;
while ((c = getopt_long(argc, argv, "vnt:c:s:S:a:A:p:g:y:b:wVh", options, NULL)) >= 0) {
const char *key;
const char *val;
char buf[UTIL_PATH_SIZE];
switch (c) {
case 'v':
verbose = 1;
break;
case 'n':
dry_run = 1;
break;
case 't':
if (streq(optarg, "devices"))
device_type = TYPE_DEVICES;
else if (streq(optarg, "subsystems"))
device_type = TYPE_SUBSYSTEMS;
else {
log_error("unknown type --type=%s", optarg);
return 2;
}
break;
case 'c':
if (!STR_IN_SET(optarg, "add", "remove", "change")) {
log_error("unknown action '%s'", optarg);
return 2;
} else
action = optarg;
break;
case 's':
r = udev_enumerate_add_match_subsystem(udev_enumerate, optarg);
if (r < 0) {
log_error_errno(r, "could not add subsystem match '%s': %m", optarg);
return 2;
}
break;
case 'S':
r = udev_enumerate_add_nomatch_subsystem(udev_enumerate, optarg);
if (r < 0) {
log_error_errno(r, "could not add negative subsystem match '%s': %m", optarg);
return 2;
}
break;
case 'a':
key = keyval(optarg, &val, buf, sizeof(buf));
r = udev_enumerate_add_match_sysattr(udev_enumerate, key, val);
if (r < 0) {
log_error_errno(r, "could not add sysattr match '%s=%s': %m", key, val);
return 2;
}
break;
case 'A':
key = keyval(optarg, &val, buf, sizeof(buf));
r = udev_enumerate_add_nomatch_sysattr(udev_enumerate, key, val);
if (r < 0) {
log_error_errno(r, "could not add negative sysattr match '%s=%s': %m", key, val);
return 2;
}
break;
case 'p':
key = keyval(optarg, &val, buf, sizeof(buf));
r = udev_enumerate_add_match_property(udev_enumerate, key, val);
if (r < 0) {
log_error_errno(r, "could not add property match '%s=%s': %m", key, val);
return 2;
}
break;
case 'g':
r = udev_enumerate_add_match_tag(udev_enumerate, optarg);
if (r < 0) {
log_error_errno(r, "could not add tag match '%s': %m", optarg);
return 2;
}
break;
case 'y':
r = udev_enumerate_add_match_sysname(udev_enumerate, optarg);
if (r < 0) {
log_error_errno(r, "could not add sysname match '%s': %m", optarg);
return 2;
}
break;
case 'b': {
_cleanup_udev_device_unref_ struct udev_device *dev;
dev = find_device(udev, optarg, "/sys");
if (dev == NULL) {
log_error("unable to open the device '%s'", optarg);
return 2;
}
r = udev_enumerate_add_match_parent(udev_enumerate, dev);
if (r < 0) {
log_error_errno(r, "could not add parent match '%s': %m", optarg);
return 2;
}
break;
}
case 'w':
settle = true;
break;
case ARG_NAME: {
_cleanup_udev_device_unref_ struct udev_device *dev;
dev = find_device(udev, optarg, "/dev/");
if (dev == NULL) {
log_error("unable to open the device '%s'", optarg);
return 2;
}
r = udev_enumerate_add_match_parent(udev_enumerate, dev);
if (r < 0) {
log_error_errno(r, "could not add parent match '%s': %m", optarg);
return 2;
}
break;
}
case 'V':
print_version();
return 0;
case 'h':
help();
return 0;
case '?':
return 1;
default:
assert_not_reached("Unknown option");
}
}
for (; optind < argc; optind++) {
_cleanup_udev_device_unref_ struct udev_device *dev;
dev = find_device(udev, argv[optind], NULL);
if (dev == NULL) {
log_error("unable to open the device '%s'", argv[optind]);
return 2;
}
r = udev_enumerate_add_match_parent(udev_enumerate, dev);
if (r < 0) {
log_error_errno(r, "could not add tag match '%s': %m", optarg);
return 2;
}
}
if (settle) {
fd_ep = epoll_create1(EPOLL_CLOEXEC);
if (fd_ep < 0) {
log_error_errno(errno, "error creating epoll fd: %m");
return 1;
}
udev_monitor = udev_monitor_new_from_netlink(udev, "udev");
if (udev_monitor == NULL) {
log_error("error: unable to create netlink socket");
return 3;
}
fd_udev = udev_monitor_get_fd(udev_monitor);
if (udev_monitor_enable_receiving(udev_monitor) < 0) {
log_error("error: unable to subscribe to udev events");
return 4;
}
ep_udev = (struct epoll_event) { .events = EPOLLIN, .data.fd = fd_udev };
if (epoll_ctl(fd_ep, EPOLL_CTL_ADD, fd_udev, &ep_udev) < 0) {
log_error_errno(errno, "fail to add fd to epoll: %m");
return 5;
}
settle_set = set_new(&string_hash_ops);
if (settle_set == NULL) {
log_oom();
return 1;
}
}
switch (device_type) {
case TYPE_SUBSYSTEMS:
udev_enumerate_scan_subsystems(udev_enumerate);
break;
case TYPE_DEVICES:
udev_enumerate_scan_devices(udev_enumerate);
break;
default:
assert_not_reached("device_type");
}
exec_list(udev_enumerate, action, settle_set);
while (!set_isempty(settle_set)) {
int fdcount;
struct epoll_event ev[4];
int i;
fdcount = epoll_wait(fd_ep, ev, ELEMENTSOF(ev), -1);
if (fdcount < 0) {
if (errno != EINTR)
log_error_errno(errno, "error receiving uevent message: %m");
continue;
}
for (i = 0; i < fdcount; i++) {
if (ev[i].data.fd == fd_udev && ev[i].events & EPOLLIN) {
_cleanup_udev_device_unref_ struct udev_device *device;
const char *syspath = NULL;
device = udev_monitor_receive_device(udev_monitor);
if (device == NULL)
continue;
syspath = udev_device_get_syspath(device);
if (verbose)
printf("settle %s\n", syspath);
if (!set_remove(settle_set, syspath))
log_debug("Got epoll event on syspath %s not present in syspath set", syspath);
}
}
}
return 0;
}
const struct udevadm_cmd udevadm_trigger = {
.name = "trigger",
.cmd = adm_trigger,
.help = "Request events from the kernel",
};
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