The diff below has already been presented in August [0]. It is the first step at splitting the kqueue refactoring required for the poll and select rewrite.
This first iteration introduces the new API with only minimal changes. The only change in behavior is that the markers' `kn_filter' and `kn_status' are now initialized only once. Ok? [0] https://marc.info/?l=openbsd-tech&m=159740120705383&w=2 Index: kern/kern_event.c =================================================================== RCS file: /cvs/src/sys/kern/kern_event.c,v retrieving revision 1.142 diff -u -p -r1.142 kern_event.c --- kern/kern_event.c 12 Aug 2020 13:49:24 -0000 1.142 +++ kern/kern_event.c 7 Oct 2020 13:42:36 -0000 @@ -64,9 +64,6 @@ void KQREF(struct kqueue *); void KQRELE(struct kqueue *); int kqueue_sleep(struct kqueue *, struct timespec *); -int kqueue_scan(struct kqueue *kq, int maxevents, - struct kevent *ulistp, struct timespec *timeout, - struct kevent *kev, struct proc *p, int *retval); int kqueue_read(struct file *, struct uio *, int); int kqueue_write(struct file *, struct uio *, int); @@ -554,6 +551,7 @@ out: int sys_kevent(struct proc *p, void *v, register_t *retval) { + struct kqueue_scan_state scan; struct filedesc* fdp = p->p_fd; struct sys_kevent_args /* { syscallarg(int) fd; @@ -635,11 +633,12 @@ sys_kevent(struct proc *p, void *v, regi goto done; } - KQREF(kq); + kqueue_scan_setup(&scan, kq); FRELE(fp, p); - error = kqueue_scan(kq, SCARG(uap, nevents), SCARG(uap, eventlist), + error = kqueue_scan(&scan, SCARG(uap, nevents), SCARG(uap, eventlist), tsp, kev, p, &n); - KQRELE(kq); + kqueue_scan_finish(&scan); + *retval = n; return (error); @@ -895,11 +894,13 @@ kqueue_sleep(struct kqueue *kq, struct t } int -kqueue_scan(struct kqueue *kq, int maxevents, struct kevent *ulistp, - struct timespec *tsp, struct kevent *kev, struct proc *p, int *retval) +kqueue_scan(struct kqueue_scan_state *scan, int maxevents, + struct kevent *ulistp, struct timespec *tsp, struct kevent *kev, + struct proc *p, int *retval) { + struct kqueue *kq = scan->kqs_kq; struct kevent *kevp; - struct knote mend, mstart, *kn; + struct knote *kn; int s, count, nkev, error = 0; nkev = 0; @@ -909,9 +910,6 @@ kqueue_scan(struct kqueue *kq, int maxev if (count == 0) goto done; - memset(&mstart, 0, sizeof(mstart)); - memset(&mend, 0, sizeof(mend)); - retry: KASSERT(count == maxevents); KASSERT(nkev == 0); @@ -939,18 +937,16 @@ retry: goto done; } - mstart.kn_filter = EVFILT_MARKER; - mstart.kn_status = KN_PROCESSING; - TAILQ_INSERT_HEAD(&kq->kq_head, &mstart, kn_tqe); - mend.kn_filter = EVFILT_MARKER; - mend.kn_status = KN_PROCESSING; - TAILQ_INSERT_TAIL(&kq->kq_head, &mend, kn_tqe); + TAILQ_INSERT_TAIL(&kq->kq_head, &scan->kqs_end, kn_tqe); + TAILQ_INSERT_HEAD(&kq->kq_head, &scan->kqs_start, kn_tqe); while (count) { - kn = TAILQ_NEXT(&mstart, kn_tqe); + kn = TAILQ_NEXT(&scan->kqs_start, kn_tqe); if (kn->kn_filter == EVFILT_MARKER) { - if (kn == &mend) { - TAILQ_REMOVE(&kq->kq_head, &mend, kn_tqe); - TAILQ_REMOVE(&kq->kq_head, &mstart, kn_tqe); + if (kn == &scan->kqs_end) { + TAILQ_REMOVE(&kq->kq_head, &scan->kqs_end, + kn_tqe); + TAILQ_REMOVE(&kq->kq_head, &scan->kqs_start, + kn_tqe); splx(s); if (count == maxevents) goto retry; @@ -958,8 +954,9 @@ retry: } /* Move start marker past another thread's marker. */ - TAILQ_REMOVE(&kq->kq_head, &mstart, kn_tqe); - TAILQ_INSERT_AFTER(&kq->kq_head, kn, &mstart, kn_tqe); + TAILQ_REMOVE(&kq->kq_head, &scan->kqs_start, kn_tqe); + TAILQ_INSERT_AFTER(&kq->kq_head, kn, &scan->kqs_start, + kn_tqe); continue; } @@ -1029,8 +1026,8 @@ retry: break; } } - TAILQ_REMOVE(&kq->kq_head, &mend, kn_tqe); - TAILQ_REMOVE(&kq->kq_head, &mstart, kn_tqe); + TAILQ_REMOVE(&kq->kq_head, &scan->kqs_end, kn_tqe); + TAILQ_REMOVE(&kq->kq_head, &scan->kqs_start, kn_tqe); splx(s); done: if (nkev != 0) { @@ -1044,6 +1041,33 @@ done: *retval = maxevents - count; return (error); } + +void +kqueue_scan_setup(struct kqueue_scan_state *scan, struct kqueue *kq) +{ + memset(scan, 0, sizeof(*scan)); + + KQREF(kq); + scan->kqs_kq = kq; + scan->kqs_start.kn_filter = EVFILT_MARKER; + scan->kqs_start.kn_status = KN_PROCESSING; + scan->kqs_end.kn_filter = EVFILT_MARKER; + scan->kqs_end.kn_status = KN_PROCESSING; +} + +void +kqueue_scan_finish(struct kqueue_scan_state *scan) +{ + struct kqueue *kq = scan->kqs_kq; + + KASSERT(scan->kqs_start.kn_filter == EVFILT_MARKER); + KASSERT(scan->kqs_start.kn_status == KN_PROCESSING); + KASSERT(scan->kqs_end.kn_filter == EVFILT_MARKER); + KASSERT(scan->kqs_end.kn_status == KN_PROCESSING); + + KQRELE(kq); +} + /* * XXX Index: sys/event.h =================================================================== RCS file: /cvs/src/sys/sys/event.h,v retrieving revision 1.45 diff -u -p -r1.45 event.h --- sys/event.h 23 Aug 2020 07:05:29 -0000 1.45 +++ sys/event.h 7 Oct 2020 13:42:36 -0000 @@ -200,7 +200,14 @@ struct knote { #define kn_fp kn_ptr.p_fp }; +struct kqueue_scan_state { + struct kqueue *kqs_kq; /* kqueue of this scan */ + struct knote kqs_start; /* start marker */ + struct knote kqs_end; /* end marker */ +}; + struct proc; +struct timespec; extern const struct filterops sig_filtops; extern const struct filterops dead_filtops; @@ -212,6 +219,10 @@ extern void knote_fdclose(struct proc *p extern void knote_processexit(struct proc *); extern int kqueue_register(struct kqueue *kq, struct kevent *kev, struct proc *p); +int kqueue_scan(struct kqueue_scan_state *, int, struct kevent *, + struct timespec *, struct kevent *, struct proc *, int *); +extern void kqueue_scan_setup(struct kqueue_scan_state *, struct kqueue *); +extern void kqueue_scan_finish(struct kqueue_scan_state *); extern int filt_seltrue(struct knote *kn, long hint); extern int seltrue_kqfilter(dev_t, struct knote *); extern void klist_insert(struct klist *, struct knote *);
