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authorLennart Poettering <lennart@poettering.net>2014-02-07 11:58:25 +0100
committerLennart Poettering <lennart@poettering.net>2014-02-07 15:14:36 +0100
commit5ba6985b6c8ef85a8bcfeb1b65239c863436e75b (patch)
treed6e881b385efc01d14e13cb8555beb67cae7a61b
parent8190da36f71a887945297cd65d6426c78b466a50 (diff)
core: allow PIDs to be watched by two units at the same time
In some cases it is interesting to map a PID to two units at the same time. For example, when a user logs in via a getty, which is reexeced to /sbin/login that binary will be explicitly referenced as main pid of the getty service, as well as implicitly referenced as part of the session scope.
-rw-r--r--src/core/manager.c120
-rw-r--r--src/core/manager.h9
-rw-r--r--src/core/unit.c28
3 files changed, 102 insertions, 55 deletions
diff --git a/src/core/manager.c b/src/core/manager.c
index c0bcc79f00..b58b98c137 100644
--- a/src/core/manager.c
+++ b/src/core/manager.c
@@ -447,10 +447,6 @@ int manager_new(SystemdRunningAs running_as, Manager **_m) {
if (r < 0)
goto fail;
- r = hashmap_ensure_allocated(&m->watch_pids, trivial_hash_func, trivial_compare_func);
- if (r < 0)
- goto fail;
-
r = hashmap_ensure_allocated(&m->watch_bus, string_hash_func, string_compare_func);
if (r < 0)
goto fail;
@@ -778,7 +774,8 @@ void manager_free(Manager *m) {
hashmap_free(m->units);
hashmap_free(m->jobs);
- hashmap_free(m->watch_pids);
+ hashmap_free(m->watch_pids1);
+ hashmap_free(m->watch_pids2);
hashmap_free(m->watch_bus);
sd_event_source_unref(m->signal_event_source);
@@ -1319,6 +1316,26 @@ static unsigned manager_dispatch_dbus_queue(Manager *m) {
return n;
}
+static void manager_invoke_notify_message(Manager *m, Unit *u, pid_t pid, char *buf, size_t n) {
+ _cleanup_strv_free_ char **tags = NULL;
+
+ assert(m);
+ assert(u);
+ assert(buf);
+ assert(n > 0);
+
+ tags = strv_split(buf, "\n\r");
+ if (!tags) {
+ log_oom();
+ return;
+ }
+
+ log_debug_unit(u->id, "Got notification message for unit %s", u->id);
+
+ if (UNIT_VTABLE(u)->notify_message)
+ UNIT_VTABLE(u)->notify_message(u, pid, tags);
+}
+
static int manager_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t revents, void *userdata) {
Manager *m = userdata;
ssize_t n;
@@ -1337,6 +1354,7 @@ static int manager_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t
.iov_base = buf,
.iov_len = sizeof(buf)-1,
};
+ bool found = false;
union {
struct cmsghdr cmsghdr;
@@ -1351,7 +1369,6 @@ static int manager_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t
};
struct ucred *ucred;
Unit *u;
- _cleanup_strv_free_ char **tags = NULL;
n = recvmsg(m->notify_fd, &msghdr, MSG_DONTWAIT);
if (n <= 0) {
@@ -1374,36 +1391,50 @@ static int manager_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t
ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
- u = hashmap_get(m->watch_pids, LONG_TO_PTR(ucred->pid));
- if (!u) {
- u = manager_get_unit_by_pid(m, ucred->pid);
- if (!u) {
- log_warning("Cannot find unit for notify message of PID "PID_FMT".", ucred->pid);
- continue;
- }
- }
-
assert((size_t) n < sizeof(buf));
buf[n] = 0;
- tags = strv_split(buf, "\n\r");
- if (!tags)
- return log_oom();
- log_debug_unit(u->id, "Got notification message for unit %s", u->id);
+ u = manager_get_unit_by_pid(m, ucred->pid);
+ if (u) {
+ manager_invoke_notify_message(m, u, ucred->pid, buf, n);
+ found = true;
+ }
+
+ u = hashmap_get(m->watch_pids1, LONG_TO_PTR(ucred->pid));
+ if (u) {
+ manager_invoke_notify_message(m, u, ucred->pid, buf, n);
+ found = true;
+ }
+
+ u = hashmap_get(m->watch_pids2, LONG_TO_PTR(ucred->pid));
+ if (u) {
+ manager_invoke_notify_message(m, u, ucred->pid, buf, n);
+ found = true;
+ }
- if (UNIT_VTABLE(u)->notify_message)
- UNIT_VTABLE(u)->notify_message(u, ucred->pid, tags);
+ if (!found)
+ log_warning("Cannot find unit for notify message of PID "PID_FMT".", ucred->pid);
}
return 0;
}
+static void invoke_sigchld_event(Manager *m, Unit *u, siginfo_t *si) {
+ assert(m);
+ assert(u);
+ assert(si);
+
+ log_debug_unit(u->id, "Child "PID_FMT" belongs to %s", si->si_pid, u->id);
+
+ unit_unwatch_pid(u, si->si_pid);
+ UNIT_VTABLE(u)->sigchld_event(u, si->si_pid, si->si_code, si->si_status);
+}
+
static int manager_dispatch_sigchld(Manager *m) {
assert(m);
for (;;) {
siginfo_t si = {};
- Unit *u;
/* First we call waitd() for a PID and do not reap the
* zombie. That way we can still access /proc/$PID for
@@ -1424,15 +1455,30 @@ static int manager_dispatch_sigchld(Manager *m) {
if (si.si_code == CLD_EXITED || si.si_code == CLD_KILLED || si.si_code == CLD_DUMPED) {
_cleanup_free_ char *name = NULL;
+ Unit *u;
get_process_comm(si.si_pid, &name);
- log_debug("Got SIGCHLD for process "PID_FMT" (%s)", si.si_pid, strna(name));
- }
- /* And now figure out the unit this belongs to */
- u = hashmap_get(m->watch_pids, LONG_TO_PTR(si.si_pid));
- if (!u)
+ log_debug("Child "PID_FMT" (%s) died (code=%s, status=%i/%s)",
+ si.si_pid, strna(name),
+ sigchld_code_to_string(si.si_code),
+ si.si_status,
+ strna(si.si_code == CLD_EXITED
+ ? exit_status_to_string(si.si_status, EXIT_STATUS_FULL)
+ : signal_to_string(si.si_status)));
+
+ /* And now figure out the unit this belongs
+ * to, it might be multiple... */
u = manager_get_unit_by_pid(m, si.si_pid);
+ if (u)
+ invoke_sigchld_event(m, u, &si);
+ u = hashmap_get(m->watch_pids1, LONG_TO_PTR(si.si_pid));
+ if (u)
+ invoke_sigchld_event(m, u, &si);
+ u = hashmap_get(m->watch_pids2, LONG_TO_PTR(si.si_pid));
+ if (u)
+ invoke_sigchld_event(m, u, &si);
+ }
/* And now, we actually reap the zombie. */
if (waitid(P_PID, si.si_pid, &si, WEXITED) < 0) {
@@ -1441,26 +1487,6 @@ static int manager_dispatch_sigchld(Manager *m) {
return -errno;
}
-
- if (si.si_code != CLD_EXITED && si.si_code != CLD_KILLED && si.si_code != CLD_DUMPED)
- continue;
-
- log_debug("Child %lu died (code=%s, status=%i/%s)",
- (long unsigned) si.si_pid,
- sigchld_code_to_string(si.si_code),
- si.si_status,
- strna(si.si_code == CLD_EXITED
- ? exit_status_to_string(si.si_status, EXIT_STATUS_FULL)
- : signal_to_string(si.si_status)));
-
- if (!u)
- continue;
-
- log_debug_unit(u->id,
- "Child %lu belongs to %s", (long unsigned) si.si_pid, u->id);
-
- unit_unwatch_pid(u, si.si_pid);
- UNIT_VTABLE(u)->sigchld_event(u, si.si_pid, si.si_code, si.si_status);
}
return 0;
diff --git a/src/core/manager.h b/src/core/manager.h
index 358aba7ff9..948ea98a45 100644
--- a/src/core/manager.h
+++ b/src/core/manager.h
@@ -96,7 +96,14 @@ struct Manager {
sd_event *event;
- Hashmap *watch_pids; /* pid => Unit object n:1 */
+ /* We use two hash tables here, since the same PID might be
+ * watched by two different units: once the unit that forked
+ * it off, and possibly a different unit to which it was
+ * joined as cgroup member. Since we know that it is either
+ * one or two units for each PID we just use to hashmaps
+ * here. */
+ Hashmap *watch_pids1; /* pid => Unit object n:1 */
+ Hashmap *watch_pids2; /* pid => Unit object n:1 */
sd_event_source *run_queue_event_source;
diff --git a/src/core/unit.c b/src/core/unit.c
index 6e1c112124..b0bb0260bc 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -1704,16 +1704,27 @@ int unit_watch_pid(Unit *u, pid_t pid) {
assert(u);
assert(pid >= 1);
+ /* Watch a specific PID. We only support one or two units
+ * watching each PID for now, not more. */
+
+ r = hashmap_ensure_allocated(&u->manager->watch_pids1, trivial_hash_func, trivial_compare_func);
+ if (r < 0)
+ return r;
+
r = set_ensure_allocated(&u->pids, trivial_hash_func, trivial_compare_func);
if (r < 0)
return r;
- /* Watch a specific PID. We only support one unit watching
- * each PID for now. */
+ r = hashmap_put(u->manager->watch_pids1, LONG_TO_PTR(pid), u);
+ if (r == -EEXIST) {
+ r = hashmap_ensure_allocated(&u->manager->watch_pids2, trivial_hash_func, trivial_compare_func);
+ if (r < 0)
+ return r;
- r = set_put(u->pids, LONG_TO_PTR(pid));
+ r = hashmap_put(u->manager->watch_pids2, LONG_TO_PTR(pid), u);
+ }
- q = hashmap_put(u->manager->watch_pids, LONG_TO_PTR(pid), u);
+ q = set_put(u->pids, LONG_TO_PTR(pid));
if (q < 0)
return q;
@@ -1724,7 +1735,8 @@ void unit_unwatch_pid(Unit *u, pid_t pid) {
assert(u);
assert(pid >= 1);
- hashmap_remove_value(u->manager->watch_pids, LONG_TO_PTR(pid), u);
+ hashmap_remove_value(u->manager->watch_pids1, LONG_TO_PTR(pid), u);
+ hashmap_remove_value(u->manager->watch_pids2, LONG_TO_PTR(pid), u);
set_remove(u->pids, LONG_TO_PTR(pid));
}
@@ -1797,8 +1809,10 @@ void unit_unwatch_all_pids(Unit *u) {
assert(u);
- SET_FOREACH(e, u->pids, i)
- hashmap_remove_value(u->manager->watch_pids, e, u);
+ SET_FOREACH(e, u->pids, i) {
+ hashmap_remove_value(u->manager->watch_pids1, e, u);
+ hashmap_remove_value(u->manager->watch_pids2, e, u);
+ }
set_free(u->pids);
u->pids = NULL;