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Don't emit a spurious EVFILT_PROC event with no fflags set on process exit

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if NOTE_EXIT is not being monitored.  The rationale is that a listener
should only get an event for exit() if they registered interest via
NOTE_EXIT.  This matches the behavior on OS X.
- Don't save the exit status on process exit unless NOTE_EXIT is being
  monitored.
- Add an internal EV_DROP flag that requests kqueue_scan() to free the
  knote without signalling it to userland and use this when a process
  exits but the fflags in the knote is zero.

Reviewed by:	jmg
MFC after:	1 month
This commit is contained in:
John Baldwin 2013-08-07 19:56:35 +00:00
parent 449c2e92c9
commit 5b596f0f5f
2 changed files with 20 additions and 2 deletions
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21
sys/kern/kern_event.c
View File

@ -431,8 +431,11 @@ filt_proc(struct knote *kn, long hint)
if (!(kn->kn_status & KN_DETACHED))
knlist_remove_inevent(&p->p_klist, kn);
kn->kn_flags |= (EV_EOF | EV_ONESHOT);
kn->kn_data = p->p_xstat;
kn->kn_ptr.p_proc = NULL;
if (kn->kn_fflags & NOTE_EXIT)
kn->kn_data = p->p_xstat;
if (kn->kn_fflags == 0)
kn->kn_flags |= EV_DROP;
return (1);
}
@ -1410,7 +1413,21 @@ retry:
KASSERT((kn->kn_status & KN_INFLUX) == 0,
("KN_INFLUX set when not suppose to be"));
if ((kn->kn_flags & EV_ONESHOT) == EV_ONESHOT) {
if ((kn->kn_flags & EV_DROP) == EV_DROP) {
kn->kn_status &= ~KN_QUEUED;
kn->kn_status |= KN_INFLUX;
kq->kq_count--;
KQ_UNLOCK(kq);
/*
* We don't need to lock the list since we've marked
* it _INFLUX.
*/
if (!(kn->kn_status & KN_DETACHED))
kn->kn_fop->f_detach(kn);
knote_drop(kn, td);
KQ_LOCK(kq);
continue;
} else if ((kn->kn_flags & EV_ONESHOT) == EV_ONESHOT) {
kn->kn_status &= ~KN_QUEUED;
kn->kn_status |= KN_INFLUX;
kq->kq_count--;

1
sys/sys/event.h
View File

@ -76,6 +76,7 @@ struct kevent {
#define EV_DISPATCH 0x0080 /* disable event after reporting */
#define EV_SYSFLAGS 0xF000 /* reserved by system */
#define EV_DROP 0x1000 /* note should be dropped */
#define EV_FLAG1 0x2000 /* filter-specific flag */
/* returned values */