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core: enforce that scope units can be started only once 

Scope units are populated from PIDs specified by the bus client. We do
that when a scope is started. We really shouldn't allow scopes to be
started multiple times, as the PIDs then might be heavily out of date.
Moreover, clients should have the guarantee that any scope they allocate
has a clear runtime cycle which is not repetitive.
This commit is contained in:
Lennart Poettering 2018-04-27 20:35:10 +02:00
parent d1a1f0aaf0
commit d4fd1cf208
6 changed files with 34 additions and 11 deletions
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6
src/core/job.c
View File

@ -612,6 +612,8 @@ int job_run_and_invalidate(Job *j) {
r = job_finish_and_invalidate(j, JOB_UNSUPPORTED, true, false);
else if (r == -ENOLINK)
r = job_finish_and_invalidate(j, JOB_DEPENDENCY, true, false);
else if (r == -ESTALE)
r = job_finish_and_invalidate(j, JOB_ONCE, true, false);
else if (r == -EAGAIN)
job_set_state(j, JOB_WAITING);
else if (r < 0)
@ -631,6 +633,7 @@ _pure_ static const char *job_get_status_message_format(Unit *u, JobType t, JobR
[JOB_ASSERT] = "Assertion failed for %s.",
[JOB_UNSUPPORTED] = "Starting of %s not supported.",
[JOB_COLLECTED] = "Unnecessary job for %s was removed.",
[JOB_ONCE] = "Unit %s has been started before and cannot be started again."
};
static const char *const generic_finished_stop_job[_JOB_RESULT_MAX] = {
[JOB_DONE] = "Stopped %s.",
@ -690,6 +693,7 @@ static const struct {
[JOB_ASSERT] = { ANSI_HIGHLIGHT_YELLOW, "ASSERT" },
[JOB_UNSUPPORTED] = { ANSI_HIGHLIGHT_YELLOW, "UNSUPP" },
/* JOB_COLLECTED */
[JOB_ONCE] = { ANSI_HIGHLIGHT_RED, " ONCE " },
};
static void job_print_status_message(Unit *u, JobType t, JobResult result) {
@ -747,6 +751,7 @@ static void job_log_status_message(Unit *u, JobType t, JobResult result) {
[JOB_ASSERT] = LOG_WARNING,
[JOB_UNSUPPORTED] = LOG_WARNING,
[JOB_COLLECTED] = LOG_INFO,
[JOB_ONCE] = LOG_ERR,
};
assert(u);
@ -1523,6 +1528,7 @@ static const char* const job_result_table[_JOB_RESULT_MAX] = {
[JOB_ASSERT] = "assert",
[JOB_UNSUPPORTED] = "unsupported",
[JOB_COLLECTED] = "collected",
[JOB_ONCE] = "once",
};
DEFINE_STRING_TABLE_LOOKUP(job_result, JobResult);

1
src/core/job.h
View File

@ -96,6 +96,7 @@ enum JobResult {
JOB_ASSERT, /* Couldn't start a unit, because an assert didn't hold */
JOB_UNSUPPORTED, /* Couldn't start a unit, because the unit type is not supported on the system */
JOB_COLLECTED, /* Job was garbage collected, since nothing needed it anymore */
JOB_ONCE, /* Unit was started before, and hence can't be started again */
_JOB_RESULT_MAX,
_JOB_RESULT_INVALID = -1
};

1
src/core/scope.c
View File

@ -587,6 +587,7 @@ const UnitVTable scope_vtable = {
.can_transient = true,
.can_delegate = true,
.once_only = true,
.init = scope_init,
.load = scope_load,

9
src/core/unit.c
View File

@ -1753,6 +1753,7 @@ static bool unit_verify_deps(Unit *u) {
* -EINVAL: Unit not loaded
* -EOPNOTSUPP: Unit type not supported
* -ENOLINK: The necessary dependencies are not fulfilled.
* -ESTALE: This unit has been started before and can't be started a second time
*/
int unit_start(Unit *u) {
UnitActiveState state;
@ -1772,6 +1773,10 @@ int unit_start(Unit *u) {
if (u->load_state != UNIT_LOADED)
return -EINVAL;
/* Refuse starting scope units more than once */
if (UNIT_VTABLE(u)->once_only && dual_timestamp_is_set(&u->inactive_enter_timestamp))
return -ESTALE;
/* If the conditions failed, don't do anything at all. If we
* already are activating this call might still be useful to
* speed up activation in case there is some hold-off time,
@ -1835,6 +1840,10 @@ bool unit_can_start(Unit *u) {
if (!unit_supported(u))
return false;
/* Scope units may be started only once */
if (UNIT_VTABLE(u)->once_only && dual_timestamp_is_set(&u->inactive_exit_timestamp))
return false;
return !!UNIT_VTABLE(u)->start;
}

3
src/core/unit.h
View File

@ -561,6 +561,9 @@ struct UnitVTable {
/* True if cgroup delegation is permissible */
bool can_delegate:1;
/* True if units of this type shall be startable only once and then never again */
bool once_only:1;
/* True if queued jobs of this type should be GC'ed if no other job needs them anymore */
bool gc_jobs:1;
};

25
src/shared/bus-unit-util.c
View File

@ -1900,8 +1900,6 @@ finish:
}
static int check_wait_response(BusWaitForJobs *d, bool quiet, const char* const* extra_args) {
int r = 0;
assert(d->result);
if (!quiet) {
@ -1919,6 +1917,8 @@ static int check_wait_response(BusWaitForJobs *d, bool quiet, const char* const*
log_error("Operation on or unit type of %s not supported on this system.", strna(d->name));
else if (streq(d->result, "collected"))
log_error("Queued job for %s was garbage collected.", strna(d->name));
else if (streq(d->result, "once"))
log_error("Unit %s was started already once and can't be started again.", strna(d->name));
else if (!STR_IN_SET(d->result, "done", "skipped")) {
if (d->name) {
_cleanup_free_ char *result = NULL;
@ -1935,21 +1935,24 @@ static int check_wait_response(BusWaitForJobs *d, bool quiet, const char* const*
}
if (STR_IN_SET(d->result, "canceled", "collected"))
r = -ECANCELED;
return -ECANCELED;
else if (streq(d->result, "timeout"))
r = -ETIME;
return -ETIME;
else if (streq(d->result, "dependency"))
r = -EIO;
return -EIO;
else if (streq(d->result, "invalid"))
r = -ENOEXEC;
return -ENOEXEC;
else if (streq(d->result, "assert"))
r = -EPROTO;
return -EPROTO;
else if (streq(d->result, "unsupported"))
r = -EOPNOTSUPP;
else if (!STR_IN_SET(d->result, "done", "skipped"))
r = -EIO;
return -EOPNOTSUPP;
else if (streq(d->result, "once"))
return -ESTALE;
else if (STR_IN_SET(d->result, "done", "skipped"))
return 0;
return r;
log_debug("Unexpected job result, assuming server side newer than us: %s", d->result);
return -EIO;
}
int bus_wait_for_jobs(BusWaitForJobs *d, bool quiet, const char* const* extra_args) {