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thread_pthread.c (ubf_timer_disarm): ignore EINVAL iff timer is dead

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The following race may happen if ubf_timer_destroy calls
timer_delete before ubf_timer_disarm gets called from
a different thread.  Consider the following timelines:

  ubf_timer_destroy                    | ubf_timer_disarm
  -------------------------------------+-----------------------------
                                       | CAS(ARM => DISARM)
  CAS(DISARM => DEAD)                  |
  timer_delete                         |
                                       | timer_settime(disarm)

Another option may be to add an intermediate "RTIMER_DISARMING"
state to the transition, but I figure the EINVAL check is
simpler and less intrusive code-wise.

cf. http://ci.rvm.jp/results/trunk-iseq_binary@silicon-docker/1545794

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66457 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
normal 2018-12-20 00:07:19 +00:00
parent cb3393add5
commit 0b38221d4e
1 changed files with 12 additions and 2 deletions
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14
thread_pthread.c
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@ -1769,8 +1769,18 @@ ubf_timer_disarm(void)
case RTIMER_DISARM: return; /* likely */
case RTIMER_ARMING: return; /* ubf_timer_arm will disarm itself */
case RTIMER_ARMED:
if (timer_settime(timer_posix.timerid, 0, &zero, 0))
rb_bug_errno("timer_settime (disarm)", errno);
if (timer_settime(timer_posix.timerid, 0, &zero, 0)) {
int err = errno;
if (err == EINVAL) {
prev = ATOMIC_CAS(timer_posix.state, RTIMER_DISARM, RTIMER_DISARM);
/* main thread may have killed the timer */
if (prev == RTIMER_DEAD) return;
rb_bug_errno("timer_settime (disarm)", err);
}
}
return;
case RTIMER_DEAD: return; /* stay dead */
default: