git: 2002e0712320 - stable/15 - kqueuex(2): add KQUEUE_CPONFORK
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Date: Sat, 01 Nov 2025 00:45:07 UTC
The branch stable/15 has been updated by kib:
URL: https://cgit.FreeBSD.org/src/commit/?id=2002e07123202a0b86f7220a78786eec71c61070
commit 2002e07123202a0b86f7220a78786eec71c61070
Author: Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2025-08-19 04:34:04 +0000
Commit: Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2025-11-01 00:43:14 +0000
kqueuex(2): add KQUEUE_CPONFORK
(cherry picked from commit b11289f87123f8ae06fc70bc70d26a25d4356a65)
---
sys/compat/linux/linux_event.c | 2 +-
sys/kern/kern_event.c | 174 ++++++++++++++++++++++++++++++++++++++---
sys/sys/event.h | 2 +
sys/sys/eventvar.h | 2 +
sys/sys/syscallsubr.h | 3 +-
5 files changed, 168 insertions(+), 15 deletions(-)
diff --git a/sys/compat/linux/linux_event.c b/sys/compat/linux/linux_event.c
index e88791659f1f..fc3ef7c3e90a 100644
--- a/sys/compat/linux/linux_event.c
+++ b/sys/compat/linux/linux_event.c
@@ -104,7 +104,7 @@ static int
epoll_create_common(struct thread *td, int flags)
{
- return (kern_kqueue(td, flags, NULL));
+ return (kern_kqueue(td, flags, false, NULL));
}
#ifdef LINUX_LEGACY_SYSCALLS
diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c
index 59d3e39aef93..7a6c395df86f 100644
--- a/sys/kern/kern_event.c
+++ b/sys/kern/kern_event.c
@@ -134,6 +134,7 @@ static fo_kqfilter_t kqueue_kqfilter;
static fo_stat_t kqueue_stat;
static fo_close_t kqueue_close;
static fo_fill_kinfo_t kqueue_fill_kinfo;
+static fo_fork_t kqueue_fork;
static const struct fileops kqueueops = {
.fo_read = invfo_rdwr,
@@ -148,7 +149,9 @@ static const struct fileops kqueueops = {
.fo_chown = invfo_chown,
.fo_sendfile = invfo_sendfile,
.fo_cmp = file_kcmp_generic,
+ .fo_fork = kqueue_fork,
.fo_fill_kinfo = kqueue_fill_kinfo,
+ .fo_flags = DFLAG_FORK,
};
static int knote_attach(struct knote *kn, struct kqueue *kq);
@@ -1151,7 +1154,7 @@ int
sys_kqueue(struct thread *td, struct kqueue_args *uap)
{
- return (kern_kqueue(td, 0, NULL));
+ return (kern_kqueue(td, 0, false, NULL));
}
int
@@ -1159,27 +1162,30 @@ sys_kqueuex(struct thread *td, struct kqueuex_args *uap)
{
int flags;
- if ((uap->flags & ~(KQUEUE_CLOEXEC)) != 0)
+ if ((uap->flags & ~(KQUEUE_CLOEXEC | KQUEUE_CPONFORK)) != 0)
return (EINVAL);
flags = 0;
if ((uap->flags & KQUEUE_CLOEXEC) != 0)
flags |= O_CLOEXEC;
- return (kern_kqueue(td, flags, NULL));
+ return (kern_kqueue(td, flags, (uap->flags & KQUEUE_CPONFORK) != 0,
+ NULL));
}
static void
-kqueue_init(struct kqueue *kq)
+kqueue_init(struct kqueue *kq, bool cponfork)
{
mtx_init(&kq->kq_lock, "kqueue", NULL, MTX_DEF | MTX_DUPOK);
TAILQ_INIT(&kq->kq_head);
knlist_init_mtx(&kq->kq_sel.si_note, &kq->kq_lock);
TASK_INIT(&kq->kq_task, 0, kqueue_task, kq);
+ if (cponfork)
+ kq->kq_state |= KQ_CPONFORK;
}
static int
kern_kqueue_alloc(struct thread *td, struct filedesc *fdp, int *fdip,
- struct file **fpp, int flags, struct filecaps *fcaps,
+ struct file **fpp, int flags, struct filecaps *fcaps, bool cponfork,
struct kqueue **kqp)
{
struct ucred *cred;
@@ -1191,7 +1197,7 @@ kern_kqueue_alloc(struct thread *td, struct filedesc *fdp, int *fdip,
return (ENOMEM);
error = fdip != NULL ? falloc_caps(td, fpp, fdip, flags, fcaps) :
- _falloc_noinstall(td, fpp, 2);
+ _falloc_noinstall(td, fpp, 1);
if (error != 0) {
chgkqcnt(cred->cr_ruidinfo, -1, 0);
return (error);
@@ -1199,31 +1205,33 @@ kern_kqueue_alloc(struct thread *td, struct filedesc *fdp, int *fdip,
/* An extra reference on `fp' has been held for us by falloc(). */
kq = malloc(sizeof(*kq), M_KQUEUE, M_WAITOK | M_ZERO);
- kqueue_init(kq);
+ kqueue_init(kq, cponfork);
kq->kq_fdp = fdp;
kq->kq_cred = crhold(cred);
- FILEDESC_XLOCK(fdp);
+ if (fdip != NULL)
+ FILEDESC_XLOCK(fdp);
TAILQ_INSERT_HEAD(&fdp->fd_kqlist, kq, kq_list);
- FILEDESC_XUNLOCK(fdp);
+ if (fdip != NULL)
+ FILEDESC_XUNLOCK(fdp);
+ finit(*fpp, FREAD | FWRITE, DTYPE_KQUEUE, kq, &kqueueops);
*kqp = kq;
return (0);
}
int
-kern_kqueue(struct thread *td, int flags, struct filecaps *fcaps)
+kern_kqueue(struct thread *td, int flags, bool cponfork, struct filecaps *fcaps)
{
struct kqueue *kq;
struct file *fp;
int fd, error;
error = kern_kqueue_alloc(td, td->td_proc->p_fd, &fd, &fp, flags,
- fcaps, &kq);
+ fcaps, cponfork, &kq);
if (error != 0)
return (error);
- finit(fp, FREAD | FWRITE, DTYPE_KQUEUE, kq, &kqueueops);
fdrop(fp, td);
td->td_retval[0] = fd;
@@ -1504,7 +1512,7 @@ kern_kevent_anonymous(struct thread *td, int nevents,
struct kqueue kq = {};
int error;
- kqueue_init(&kq);
+ kqueue_init(&kq, false);
kq.kq_refcnt = 1;
error = kqueue_kevent(&kq, td, nevents, nevents, k_ops, NULL);
kqueue_drain(&kq, td);
@@ -2958,6 +2966,146 @@ noacquire:
return (error);
}
+static int
+kqueue_fork_alloc(struct filedesc *fdp, struct file *fp, struct file **fp1,
+ struct thread *td)
+{
+ struct kqueue *kq, *kq1;
+ int error;
+
+ MPASS(fp->f_type == DTYPE_KQUEUE);
+ kq = fp->f_data;
+ if ((kq->kq_state & KQ_CPONFORK) == 0)
+ return (EOPNOTSUPP);
+ error = kqueue_acquire_ref(kq);
+ if (error != 0)
+ return (error);
+ error = kern_kqueue_alloc(td, fdp, NULL, fp1, 0, NULL, true, &kq1);
+ if (error == 0) {
+ kq1->kq_forksrc = kq;
+ (*fp1)->f_flag = fp->f_flag & (FREAD | FWRITE | FEXEC |
+ O_CLOEXEC | O_CLOFORK);
+ } else {
+ kqueue_release(kq, 0);
+ }
+ return (error);
+}
+
+static void
+kqueue_fork_copy_knote(struct kqueue *kq1, struct knote *kn, struct proc *p1,
+ struct filedesc *fdp)
+{
+ struct knote *kn1;
+ const struct filterops *fop;
+ int error;
+
+ fop = kn->kn_fop;
+ if (fop->f_copy == NULL || (fop->f_isfd &&
+ fdp->fd_files->fdt_ofiles[kn->kn_kevent.ident].fde_file == NULL))
+ return;
+ error = kqueue_expand(kq1, fop, kn->kn_kevent.ident, M_WAITOK);
+ if (error != 0)
+ return;
+
+ kn1 = knote_alloc(M_WAITOK);
+ *kn1 = *kn;
+ kn1->kn_status |= KN_DETACHED;
+ kn1->kn_status &= ~KN_QUEUED;
+ kn1->kn_kq = kq1;
+ error = fop->f_copy(kn1, p1);
+ if (error != 0) {
+ knote_free(kn1);
+ return;
+ }
+ (void)kqueue_fo_find(kn->kn_kevent.filter);
+ if (fop->f_isfd && !fhold(kn1->kn_fp)) {
+ fop->f_detach(kn1);
+ kqueue_fo_release(kn->kn_kevent.filter);
+ knote_free(kn1);
+ return;
+ }
+ if (kn->kn_knlist != NULL)
+ knlist_add(kn->kn_knlist, kn1, 0);
+ KQ_LOCK(kq1);
+ knote_attach(kn1, kq1);
+ kn1->kn_influx = 0;
+ if ((kn->kn_status & KN_QUEUED) != 0)
+ knote_enqueue(kn1);
+ KQ_UNLOCK(kq1);
+}
+
+static void
+kqueue_fork_copy_list(struct klist *knlist, struct knote *marker,
+ struct kqueue *kq, struct kqueue *kq1, struct proc *p1,
+ struct filedesc *fdp)
+{
+ struct knote *kn;
+
+ KQ_OWNED(kq);
+ kn = SLIST_FIRST(knlist);
+ while (kn != NULL) {
+ if ((kn->kn_status & KN_DETACHED) != 0 ||
+ (kn_in_flux(kn) && (kn->kn_status & KN_SCAN) == 0)) {
+ kn = SLIST_NEXT(kn, kn_link);
+ continue;
+ }
+ kn_enter_flux(kn);
+ SLIST_INSERT_AFTER(kn, marker, kn_link);
+ KQ_UNLOCK(kq);
+ kqueue_fork_copy_knote(kq1, kn, p1, fdp);
+ KQ_LOCK(kq);
+ kn_leave_flux(kn);
+ kn = SLIST_NEXT(marker, kn_link);
+ /* XXXKIB switch kn_link to LIST? */
+ SLIST_REMOVE(knlist, marker, knote, kn_link);
+ }
+}
+
+static int
+kqueue_fork_copy(struct filedesc *fdp, struct file *fp, struct file *fp1,
+ struct proc *p1, struct thread *td)
+{
+ struct kqueue *kq, *kq1;
+ struct knote *marker;
+ int error, i;
+
+ error = 0;
+ MPASS(fp == NULL);
+ MPASS(fp1->f_type == DTYPE_KQUEUE);
+
+ kq1 = fp1->f_data;
+ kq = kq1->kq_forksrc;
+ marker = knote_alloc(M_WAITOK);
+ marker->kn_status = KN_MARKER;
+
+ KQ_LOCK(kq);
+ for (i = 0; i < kq->kq_knlistsize; i++) {
+ kqueue_fork_copy_list(&kq->kq_knlist[i], marker, kq, kq1,
+ p1, fdp);
+ }
+ if (kq->kq_knhashmask != 0) {
+ for (i = 0; i <= kq->kq_knhashmask; i++) {
+ kqueue_fork_copy_list(&kq->kq_knhash[i], marker, kq,
+ kq1, p1, fdp);
+ }
+ }
+ kqueue_release(kq, 1);
+ kq1->kq_forksrc = NULL;
+ KQ_UNLOCK(kq);
+
+ knote_free(marker);
+ return (error);
+}
+
+static int
+kqueue_fork(struct filedesc *fdp, struct file *fp, struct file **fp1,
+ struct proc *p1, struct thread *td)
+{
+ if (*fp1 == NULL)
+ return (kqueue_fork_alloc(fdp, fp, fp1, td));
+ return (kqueue_fork_copy(fdp, fp, *fp1, p1, td));
+}
+
struct knote_status_export_bit {
int kn_status_bit;
int knt_status_bit;
diff --git a/sys/sys/event.h b/sys/sys/event.h
index 084eaafcbdc0..6e71445f03b0 100644
--- a/sys/sys/event.h
+++ b/sys/sys/event.h
@@ -228,6 +228,7 @@ struct freebsd11_kevent32 {
/* Flags for kqueuex(2) */
#define KQUEUE_CLOEXEC 0x00000001 /* close on exec */
+#define KQUEUE_CPONFORK 0x00000002 /* copy on fork */
struct knote;
SLIST_HEAD(klist, knote);
@@ -283,6 +284,7 @@ struct filterops {
void (*f_touch)(struct knote *kn, struct kevent *kev, u_long type);
int (*f_userdump)(struct proc *p, struct knote *kn,
struct kinfo_knote *kin);
+ int (*f_copy)(struct knote *kn, struct proc *p1);
};
/*
diff --git a/sys/sys/eventvar.h b/sys/sys/eventvar.h
index 7fec444447f9..7cb3269f1fdf 100644
--- a/sys/sys/eventvar.h
+++ b/sys/sys/eventvar.h
@@ -55,12 +55,14 @@ struct kqueue {
#define KQ_CLOSING 0x10
#define KQ_TASKSCHED 0x20 /* task scheduled */
#define KQ_TASKDRAIN 0x40 /* waiting for task to drain */
+#define KQ_CPONFORK 0x80
int kq_knlistsize; /* size of knlist */
struct klist *kq_knlist; /* list of knotes */
u_long kq_knhashmask; /* size of knhash */
struct klist *kq_knhash; /* hash table for knotes */
struct task kq_task;
struct ucred *kq_cred;
+ struct kqueue *kq_forksrc;
};
#endif /* !_SYS_EVENTVAR_H_ */
diff --git a/sys/sys/syscallsubr.h b/sys/sys/syscallsubr.h
index 8237165b84ce..d32690634059 100644
--- a/sys/sys/syscallsubr.h
+++ b/sys/sys/syscallsubr.h
@@ -211,7 +211,8 @@ int kern_kevent_fp(struct thread *td, struct file *fp, int nchanges,
int nevents, struct kevent_copyops *k_ops,
const struct timespec *timeout);
int kern_kill(struct thread *td, pid_t pid, int signum);
-int kern_kqueue(struct thread *td, int flags, struct filecaps *fcaps);
+int kern_kqueue(struct thread *td, int flags, bool cponfork,
+ struct filecaps *fcaps);
int kern_kldload(struct thread *td, const char *file, int *fileid);
int kern_kldstat(struct thread *td, int fileid, struct kld_file_stat *stat);
int kern_kldunload(struct thread *td, int fileid, int flags);