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kqueue: EVFILT_USER fixes
On Sun, May 18, 2025 at 05:21:14PM +0000, Visa Hankala wrote:
> The EVFILT_USER implementation does not quite align with FreeBSD.
> One difference is that FreeBSD updates the `data' and `udata' fields
> when a user event is triggered. FreeBSD also preserves `fflags' when
> the event is "untriggered". The diff below fixes these.
>
> In addition, use kn_sfflags and kn_sdata instead of kn_fflags and
> kn_data to make the implementation a bit more similar to FreeBSD.
>
> OK?
>
FreeBSD and NetBSD clean `kn_data' and `kn_fflag' if EV_CLEAR flag is
set. Shouldn't you do the same?
case EVENT_REGISTER:
kn->kn_sdata = kev->data;
if (kev->flags & EV_CLEAR) {
kn->kn_hookid = 0;
kn->kn_data = 0;
kn->kn_fflags = 0;
}
break;
case EVENT_PROCESS:
*kev = kn->kn_kevent;
kev->fflags = kn->kn_sfflags;
kev->data = kn->kn_sdata;
if (kn->kn_flags & EV_CLEAR) {
kn->kn_hookid = 0;
kn->kn_data = 0;
kn->kn_fflags = 0;
}
> Index: sys/kern/kern_event.c
> ===================================================================
> RCS file: src/sys/kern/kern_event.c,v
> retrieving revision 1.204
> diff -u -p -r1.204 kern_event.c
> --- sys/kern/kern_event.c 15 May 2025 19:56:08 -0000 1.204
> +++ sys/kern/kern_event.c 18 May 2025 17:17:04 -0000
> @@ -809,8 +809,6 @@ filt_userattach(struct knote *kn)
> }
>
> kn->kn_ptr.p_useract = ((kn->kn_sfflags & NOTE_TRIGGER) != 0);
> - kn->kn_fflags = kn->kn_sfflags & NOTE_FFLAGSMASK;
> - kn->kn_data = kn->kn_sdata;
>
> return (0);
> }
> @@ -837,29 +835,25 @@ filt_usermodify(struct kevent *kev, stru
> case NOTE_FFNOP:
> break;
> case NOTE_FFAND:
> - kn->kn_fflags &= fflags;
> + kn->kn_sfflags &= fflags;
> break;
> case NOTE_FFOR:
> - kn->kn_fflags |= fflags;
> + kn->kn_sfflags |= fflags;
> break;
> case NOTE_FFCOPY:
> - kn->kn_fflags = fflags;
> + kn->kn_sfflags = fflags;
> break;
> default:
> /* ignored, should not happen */
> break;
> }
>
> - if (kev->flags & EV_ADD) {
> - kn->kn_data = kev->data;
> - kn->kn_udata = kev->udata;
> - }
> + kn->kn_sdata = kev->data;
> + kn->kn_udata = kev->udata;
>
> /* Allow clearing of an activated event. */
> - if (kev->flags & EV_CLEAR) {
> + if (kev->flags & EV_CLEAR)
> kn->kn_ptr.p_useract = 0;
> - kn->kn_data = 0;
> - }
>
> return (kn->kn_ptr.p_useract);
> }
> @@ -872,11 +866,10 @@ filt_userprocess(struct knote *kn, struc
> active = kn->kn_ptr.p_useract;
> if (active && kev != NULL) {
> *kev = kn->kn_kevent;
> - if (kn->kn_flags & EV_CLEAR) {
> + kev->fflags = kn->kn_sfflags & NOTE_FFLAGSMASK;
> + kev->data = kn->kn_sdata;
> + if (kn->kn_flags & EV_CLEAR)
> kn->kn_ptr.p_useract = 0;
> - kn->kn_fflags = 0;
> - kn->kn_data = 0;
> - }
> }
>
> return (active);
> Index: regress/sys/kern/kqueue/kqueue-user.c
> ===================================================================
> RCS file: src/regress/sys/kern/kqueue/kqueue-user.c,v
> retrieving revision 1.1
> diff -u -p -r1.1 kqueue-user.c
> --- regress/sys/kern/kqueue/kqueue-user.c 10 May 2025 09:44:39 -0000 1.1
> +++ regress/sys/kern/kqueue/kqueue-user.c 18 May 2025 17:17:04 -0000
> @@ -44,10 +44,7 @@ do_user(void)
> n = kevent(kq, NULL, 0, kev, 2, &ts);
> ASSX(n == 0);
>
> - /*
> - * Activate the event.
> - * Fields `data' and `udata' do not get updated without EV_ADD.
> - */
> + /* Activate the event. This updates `data' and `udata'. */
> EV_SET(&kev[0], 1, EVFILT_USER, 0, NOTE_TRIGGER | NOTE_FFNOP,
> 123, &dummy);
> n = kevent(kq, kev, 1, NULL, 0, NULL);
> @@ -58,20 +55,6 @@ do_user(void)
> ASSX(n == 1);
> ASSX(kev[0].ident == 1);
> ASSX(kev[0].fflags == NOTE_FFLAGSMASK);
> - ASSX(kev[0].data == 0);
> - ASSX(kev[0].udata == NULL);
> -
> - /* Activate the event. Update `data' and `udata'. */
> - EV_SET(&kev[0], 1, EVFILT_USER, EV_ADD, NOTE_TRIGGER | NOTE_FFNOP,
> - 123, &dummy);
> - n = kevent(kq, kev, 1, NULL, 0, NULL);
> - ASSX(n == 0);
> -
> - /* Check active events. */
> - n = kevent(kq, NULL, 0, kev, 2, &ts);
> - ASSX(n == 1);
> - ASSX(kev[0].ident == 1);
> - ASSX(kev[0].fflags == NOTE_FFLAGSMASK);
> ASSX(kev[0].data == 123);
> ASSX(kev[0].udata == &dummy);
>
> @@ -122,8 +105,8 @@ do_user(void)
> ASSX(n == 1);
> ASSX(kev[0].ident == 2);
> ASSX(kev[0].fflags == 0x11);
> - ASSX(kev[0].data == 42);
> - ASSX(kev[0].udata == &dummy);
> + ASSX(kev[0].data == 24);
> + ASSX(kev[0].udata == &dummy2);
>
> n = kevent(kq, NULL, 0, kev, 2, &ts);
> ASSX(n == 0);
> @@ -132,9 +115,9 @@ do_user(void)
> n = kevent(kq, kev, 1, kev, 2, &ts);
> ASSX(n == 1);
> ASSX(kev[0].ident == 2);
> - ASSX(kev[0].fflags == 0);
> - ASSX(kev[0].data == 0);
> - ASSX(kev[0].udata == &dummy);
> + ASSX(kev[0].fflags == 0x11);
> + ASSX(kev[0].data == 9);
> + ASSX(kev[0].udata == &dummy2);
>
> EV_SET(&kev[0], 2, EVFILT_USER, EV_DELETE, 0, 0, NULL);
> n = kevent(kq, kev, 1, kev, 2, &ts);
> @@ -154,7 +137,7 @@ do_user(void)
> ASSX(kev[0].ident == 1);
> ASSX(kev[0].fflags == 0x0faaf0);
> ASSX(kev[0].data == 0);
> - ASSX(kev[0].udata == &dummy);
> + ASSX(kev[0].udata == NULL);
>
> /* Test event limit. */
> for (i = 0;; i++) {
>
kqueue: EVFILT_USER fixes