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Merge pull request #15592 from kennylevinsen/fdpoll-standalone

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Introduce FDPOLL=0
This commit is contained in:
Lennart Poettering 2020-04-30 22:32:28 +02:00 committed by GitHub
commit a8332698d7
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3 changed files with 53 additions and 33 deletions
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14
man/sd_notify.xml
View File

@ -219,8 +219,8 @@
in a <citerefentry><refentrytitle>memfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry> memory
file descriptor. Note that the service manager will accept messages for a service only if its
<varname>FileDescriptorStoreMax=</varname> setting is non-zero (defaults to zero, see
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>). If file
descriptors sent are pollable (see
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>). If
<varname>FDPOLL=0</varname> is not set and the file descriptors sent are pollable (see
<citerefentry><refentrytitle>epoll_ctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>), then any
<constant>EPOLLHUP</constant> or <constant>EPOLLERR</constant> event seen on them will result in their
automatic removal from the store. Multiple arrays of file descriptors may be sent in separate messages, in
@ -251,6 +251,16 @@
submitted name does not follow these restrictions, it is ignored.</para></listitem>
</varlistentry>
<varlistentry>
<term>FDPOLL=0</term>
<listitem><para>When used in combination with <varname>FDSTORE=1</varname>, disables polling of the stored
file descriptors regardless of whether or not they are pollable. As this option disables automatic cleanup
of the stored file descriptors on EPOLLERR and EPOLLHUP, care must be taken to ensure proper manual cleanup.
Use of this option is not generally recommended except for when automatic cleanup has unwanted behavior such
as prematurely discarding file descriptors from the store.</para></listitem>
</varlistentry>
</variablelist>
<para>It is recommended to prefix variable names that are not

71
src/core/service.c
View File

@ -423,7 +423,7 @@ static int on_fd_store_io(sd_event_source *e, int fd, uint32_t revents, void *us
return 0;
}
static int service_add_fd_store(Service *s, int fd, const char *name) {
static int service_add_fd_store(Service *s, int fd, const char *name, bool do_poll) {
ServiceFDStore *fs;
int r;
@ -453,19 +453,22 @@ static int service_add_fd_store(Service *s, int fd, const char *name) {
fs->fd = fd;
fs->service = s;
fs->do_poll = do_poll;
fs->fdname = strdup(name ?: "stored");
if (!fs->fdname) {
free(fs);
return -ENOMEM;
}
r = sd_event_add_io(UNIT(s)->manager->event, &fs->event_source, fd, 0, on_fd_store_io, fs);
if (r < 0 && r != -EPERM) { /* EPERM indicates fds that aren't pollable, which is OK */
free(fs->fdname);
free(fs);
return r;
} else if (r >= 0)
(void) sd_event_source_set_description(fs->event_source, "service-fd-store");
if (do_poll) {
r = sd_event_add_io(UNIT(s)->manager->event, &fs->event_source, fd, 0, on_fd_store_io, fs);
if (r < 0 && r != -EPERM) { /* EPERM indicates fds that aren't pollable, which is OK */
free(fs->fdname);
free(fs);
return r;
} else if (r >= 0)
(void) sd_event_source_set_description(fs->event_source, "service-fd-store");
}
LIST_PREPEND(fd_store, s->fd_store, fs);
s->n_fd_store++;
@ -473,7 +476,7 @@ static int service_add_fd_store(Service *s, int fd, const char *name) {
return 1; /* fd newly stored */
}
static int service_add_fd_store_set(Service *s, FDSet *fds, const char *name) {
static int service_add_fd_store_set(Service *s, FDSet *fds, const char *name, bool do_poll) {
int r;
assert(s);
@ -485,7 +488,7 @@ static int service_add_fd_store_set(Service *s, FDSet *fds, const char *name) {
if (fd < 0)
break;
r = service_add_fd_store(s, fd, name);
r = service_add_fd_store(s, fd, name, do_poll);
if (r == -EXFULL)
return log_unit_warning_errno(UNIT(s), r,
"Cannot store more fds than FileDescriptorStoreMax=%u, closing remaining.",
@ -2715,7 +2718,7 @@ static int service_serialize(Unit *u, FILE *f, FDSet *fds) {
if (!c)
return log_oom();
(void) serialize_item_format(f, "fd-store-fd", "%i %s", copy, c);
(void) serialize_item_format(f, "fd-store-fd", "%i \"%s\" %i", copy, c, fs->do_poll);
}
if (s->main_exec_status.pid > 0) {
@ -2944,30 +2947,36 @@ static int service_deserialize_item(Unit *u, const char *key, const char *value,
s->socket_fd = fdset_remove(fds, fd);
}
} else if (streq(key, "fd-store-fd")) {
const char *fdv;
size_t pf;
_cleanup_free_ char *fdv = NULL, *fdn = NULL, *fdp = NULL;
int fd;
int do_poll;
pf = strcspn(value, WHITESPACE);
fdv = strndupa(value, pf);
if (safe_atoi(fdv, &fd) < 0 || fd < 0 || !fdset_contains(fds, fd))
r = extract_first_word(&value, &fdv, NULL, 0);
if (r <= 0 || safe_atoi(fdv, &fd) < 0 || fd < 0 || !fdset_contains(fds, fd)) {
log_unit_debug(u, "Failed to parse fd-store-fd value: %s", value);
else {
_cleanup_free_ char *t = NULL;
const char *fdn;
fdn = value + pf;
fdn += strspn(fdn, WHITESPACE);
(void) cunescape(fdn, 0, &t);
r = service_add_fd_store(s, fd, t);
if (r < 0)
log_unit_error_errno(u, r, "Failed to add fd to store: %m");
else
fdset_remove(fds, fd);
return 0;
}
r = extract_first_word(&value, &fdn, NULL, EXTRACT_CUNESCAPE | EXTRACT_UNQUOTE);
if (r <= 0) {
log_unit_debug_errno(u, r, "Failed to parse fd-store-fd value \"%s\": %m", value);
return 0;
}
r = extract_first_word(&value, &fdp, NULL, 0);
if (r == 0) {
/* If the value is not present, we assume the default */
do_poll = 1;
} else if (r < 0 || safe_atoi(fdp, &do_poll) < 0) {
log_unit_debug_errno(u, r, "Failed to parse fd-store-fd value \"%s\": %m", value);
return 0;
}
r = service_add_fd_store(s, fd, fdn, do_poll);
if (r < 0)
log_unit_error_errno(u, r, "Failed to add fd to store: %m");
else
fdset_remove(fds, fd);
} else if (streq(key, "main-exec-status-pid")) {
pid_t pid;
@ -4068,7 +4077,7 @@ static void service_notify_message(
name = NULL;
}
(void) service_add_fd_store_set(s, fds, name);
(void) service_add_fd_store_set(s, fds, name, !strv_contains(tags, "FDPOLL=0"));
}
/* Notify clients about changed status or main pid */

1
src/core/service.h
View File

@ -80,6 +80,7 @@ struct ServiceFDStore {
int fd;
char *fdname;
sd_event_source *event_source;
bool do_poll;
LIST_FIELDS(ServiceFDStore, fd_store);
};