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userdbd: rework to use sd_event_add_child() instead of manual SIGCHLD

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Let's modernize userdbd furzer, and use the common child handling we
nowadays have in sd-event, instead of rolling our own.

This also means we'll start using pidfds where we can.
This commit is contained in:
Lennart Poettering 2023-03-15 15:46:54 +01:00
parent 755424e94f
commit 66a3869e7e
1 changed files with 32 additions and 50 deletions
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82
src/userdb/userdbd-manager.c
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@ -20,49 +20,27 @@
static int start_workers(Manager *m, bool explicit_request);
static int on_sigchld(sd_event_source *s, const struct signalfd_siginfo *si, void *userdata) {
static int on_worker_exit(sd_event_source *s, const siginfo_t *si, void *userdata) {
Manager *m = ASSERT_PTR(userdata);
assert(s);
for (;;) {
siginfo_t siginfo = {};
bool removed = false;
assert_se(!set_remove(m->workers_dynamic, s) != !set_remove(m->workers_fixed, s));
sd_event_source_disable_unref(s);
if (waitid(P_ALL, 0, &siginfo, WNOHANG|WEXITED) < 0) {
if (errno == ECHILD)
break;
log_warning_errno(errno, "Failed to invoke waitid(): %m");
break;
}
if (siginfo.si_pid == 0)
break;
if (set_remove(m->workers_dynamic, PID_TO_PTR(siginfo.si_pid)))
removed = true;
if (set_remove(m->workers_fixed, PID_TO_PTR(siginfo.si_pid)))
removed = true;
if (!removed) {
log_warning("Weird, got SIGCHLD for unknown child " PID_FMT ", ignoring.", siginfo.si_pid);
continue;
}
if (siginfo.si_code == CLD_EXITED) {
if (siginfo.si_status == EXIT_SUCCESS)
log_debug("Worker " PID_FMT " exited successfully.", siginfo.si_pid);
else
log_warning("Worker " PID_FMT " died with a failure exit status %i, ignoring.", siginfo.si_pid, siginfo.si_status);
} else if (siginfo.si_code == CLD_KILLED)
log_warning("Worker " PID_FMT " was killed by signal %s, ignoring.", siginfo.si_pid, signal_to_string(siginfo.si_status));
else if (siginfo.si_code == CLD_DUMPED)
log_warning("Worker " PID_FMT " dumped core by signal %s, ignoring.", siginfo.si_pid, signal_to_string(siginfo.si_status));
if (si->si_code == CLD_EXITED) {
if (si->si_status == EXIT_SUCCESS)
log_debug("Worker " PID_FMT " exited successfully.", si->si_pid);
else
log_warning("Can't handle SIGCHLD of this type");
}
log_warning("Worker " PID_FMT " died with a failure exit status %i, ignoring.", si->si_pid, si->si_status);
} else if (si->si_code == CLD_KILLED)
log_warning("Worker " PID_FMT " was killed by signal %s, ignoring.", si->si_pid, signal_to_string(si->si_status));
else if (si->si_code == CLD_DUMPED)
log_warning("Worker " PID_FMT " dumped core by signal %s, ignoring.", si->si_pid, signal_to_string(si->si_status));
else
log_warning("Can't handle SIGCHLD of this type");
(void) start_workers(m, false); /* Fill up workers again if we fell below the low watermark */
(void) start_workers(m, /* explicit_request= */ false); /* Fill up workers again if we fell below the low watermark */
return 0;
}
@ -75,6 +53,13 @@ static int on_sigusr2(sd_event_source *s, const struct signalfd_siginfo *si, voi
return 0;
}
DEFINE_HASH_OPS_WITH_KEY_DESTRUCTOR(
event_source_hash_ops,
sd_event_source,
(void (*)(const sd_event_source*, struct siphash*)) trivial_hash_func,
(int (*)(const sd_event_source*, const sd_event_source*)) trivial_compare_func,
sd_event_source_disable_unref);
int manager_new(Manager **ret) {
_cleanup_(manager_freep) Manager *m = NULL;
int r;
@ -111,20 +96,10 @@ int manager_new(Manager **ret) {
if (r < 0)
log_debug_errno(r, "Failed to enable watchdog handling, ignoring: %m");
m->workers_fixed = set_new(NULL);
m->workers_dynamic = set_new(NULL);
if (!m->workers_fixed || !m->workers_dynamic)
return -ENOMEM;
r = sd_event_add_signal(m->event, NULL, SIGUSR2|SD_EVENT_SIGNAL_PROCMASK, on_sigusr2, m);
if (r < 0)
return r;
r = sd_event_add_signal(m->event, NULL, SIGCHLD|SD_EVENT_SIGNAL_PROCMASK, on_sigchld, m);
if (r < 0)
return r;
*ret = TAKE_PTR(m);
return 0;
}
@ -148,6 +123,7 @@ static size_t manager_current_workers(Manager *m) {
}
static int start_one_worker(Manager *m) {
_cleanup_(sd_event_source_disable_unrefp) sd_event_source *source = NULL;
bool fixed;
pid_t pid;
int r;
@ -208,13 +184,19 @@ static int start_one_worker(Manager *m) {
_exit(EXIT_FAILURE);
}
if (fixed)
r = set_put(m->workers_fixed, PID_TO_PTR(pid));
else
r = set_put(m->workers_dynamic, PID_TO_PTR(pid));
r = sd_event_add_child(m->event, &source, pid, WEXITED, on_worker_exit, m);
if (r < 0)
return log_error_errno(r, "Failed to watch child " PID_FMT ": %m", pid);
r = set_ensure_put(
fixed ? &m->workers_fixed : &m->workers_dynamic,
&event_source_hash_ops,
source);
if (r < 0)
return log_error_errno(r, "Failed to add child process to set: %m");
TAKE_PTR(source);
return 0;
}