svn commit: r257759 - in stable/9/sys: kern sys

[John Baldwin]

Author: jhb
Date: Wed Nov  6 19:33:25 2013
New Revision: 257759
URL: http://svnweb.freebsd.org/changeset/base/257759

Log:
  MFC 254072:
  Don't emit a spurious EVFILT_PROC event with no fflags set on process exit
  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.

Modified:
  stable/9/sys/kern/kern_event.c
  stable/9/sys/sys/event.h
Directory Properties:
  stable/9/sys/   (props changed)
  stable/9/sys/sys/   (props changed)

Modified: stable/9/sys/kern/kern_event.c
==============================================================================
--- stable/9/sys/kern/kern_event.c	Wed Nov  6 19:18:39 2013	(r257758)
+++ stable/9/sys/kern/kern_event.c	Wed Nov  6 19:33:25 2013	(r257759)
@@ -429,8 +429,11 @@ 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);
 	}
 
@@ -1436,7 +1439,21 @@ start:
 		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--;

Modified: stable/9/sys/sys/event.h
==============================================================================
--- stable/9/sys/sys/event.h	Wed Nov  6 19:18:39 2013	(r257758)
+++ stable/9/sys/sys/event.h	Wed Nov  6 19:33:25 2013	(r257759)
@@ -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 */