/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2014 Dmitry Chagin <dchagin@FreeBSD.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/types.h>
#include <sys/user.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/filio.h>
#include <sys/stat.h>
#include <sys/errno.h>
#include <sys/event.h>
#include <sys/poll.h>
#include <sys/proc.h>
#include <sys/uio.h>
#include <sys/selinfo.h>
#include <sys/eventfd.h>
#include <security/audit/audit.h>
_Static_assert(EFD_CLOEXEC == O_CLOEXEC, "Mismatched EFD_CLOEXEC");
_Static_assert(EFD_NONBLOCK == O_NONBLOCK, "Mismatched EFD_NONBLOCK");
MALLOC_DEFINE(M_EVENTFD, "eventfd", "eventfd structures");
static fo_rdwr_t eventfd_read;
static fo_rdwr_t eventfd_write;
static fo_ioctl_t eventfd_ioctl;
static fo_poll_t eventfd_poll;
static fo_kqfilter_t eventfd_kqfilter;
static fo_stat_t eventfd_stat;
static fo_close_t eventfd_close;
static fo_fill_kinfo_t eventfd_fill_kinfo;
static struct fileops eventfdops = {
.fo_read = eventfd_read,
.fo_write = eventfd_write,
.fo_truncate = invfo_truncate,
.fo_ioctl = eventfd_ioctl,
.fo_poll = eventfd_poll,
.fo_kqfilter = eventfd_kqfilter,
.fo_stat = eventfd_stat,
.fo_close = eventfd_close,
.fo_chmod = invfo_chmod,
.fo_chown = invfo_chown,
.fo_sendfile = invfo_sendfile,
.fo_fill_kinfo = eventfd_fill_kinfo,
.fo_flags = DFLAG_PASSABLE
};
static void filt_eventfddetach(struct knote *kn);
static int filt_eventfdread(struct knote *kn, long hint);
static int filt_eventfdwrite(struct knote *kn, long hint);
static struct filterops eventfd_rfiltops = {
.f_isfd = 1,
.f_detach = filt_eventfddetach,
.f_event = filt_eventfdread
};
static struct filterops eventfd_wfiltops = {
.f_isfd = 1,
.f_detach = filt_eventfddetach,
.f_event = filt_eventfdwrite
};
struct eventfd {
eventfd_t efd_count;
uint32_t efd_flags;
struct selinfo efd_sel;
struct mtx efd_lock;
};
int
eventfd_create_file(struct thread *td, struct file *fp, uint32_t initval,
int flags)
{
struct eventfd *efd;
int fflags;
AUDIT_ARG_FFLAGS(flags);
AUDIT_ARG_VALUE(initval);
efd = malloc(sizeof(*efd), M_EVENTFD, M_WAITOK | M_ZERO);
efd->efd_flags = flags;
efd->efd_count = initval;
mtx_init(&efd->efd_lock, "eventfd", NULL, MTX_DEF);
knlist_init_mtx(&efd->efd_sel.si_note, &efd->efd_lock);
fflags = FREAD | FWRITE;
if ((flags & EFD_NONBLOCK) != 0)
fflags |= FNONBLOCK;
finit(fp, fflags, DTYPE_EVENTFD, efd, &eventfdops);
return (0);
}
static int
eventfd_close(struct file *fp, struct thread *td)
{
struct eventfd *efd;
efd = fp->f_data;
seldrain(&efd->efd_sel);
knlist_destroy(&efd->efd_sel.si_note);
mtx_destroy(&efd->efd_lock);
free(efd, M_EVENTFD);
return (0);
}
static int
eventfd_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
int flags, struct thread *td)
{
struct eventfd *efd;
eventfd_t count;
int error;
if (uio->uio_resid < sizeof(eventfd_t))
return (EINVAL);
error = 0;
efd = fp->f_data;
mtx_lock(&efd->efd_lock);
while (error == 0 && efd->efd_count == 0) {
if ((fp->f_flag & FNONBLOCK) != 0) {
mtx_unlock(&efd->efd_lock);
return (EAGAIN);
}
error = mtx_sleep(&efd->efd_count, &efd->efd_lock, PCATCH,
"efdrd", 0);
}
if (error == 0) {
MPASS(efd->efd_count > 0);
if ((efd->efd_flags & EFD_SEMAPHORE) != 0) {
count = 1;
--efd->efd_count;
} else {
count = efd->efd_count;
efd->efd_count = 0;
}
KNOTE_LOCKED(&efd->efd_sel.si_note, 0);
selwakeup(&efd->efd_sel);
wakeup(&efd->efd_count);
mtx_unlock(&efd->efd_lock);
error = uiomove(&count, sizeof(eventfd_t), uio);
} else
mtx_unlock(&efd->efd_lock);
return (error);
}
static int
eventfd_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
int flags, struct thread *td)
{
struct eventfd *efd;
eventfd_t count;
int error;
if (uio->uio_resid < sizeof(eventfd_t))
return (EINVAL);
error = uiomove(&count, sizeof(eventfd_t), uio);
if (error != 0)
return (error);
if (count == UINT64_MAX)
return (EINVAL);
efd = fp->f_data;
mtx_lock(&efd->efd_lock);
retry:
if (UINT64_MAX - efd->efd_count <= count) {
if ((fp->f_flag & FNONBLOCK) != 0) {
mtx_unlock(&efd->efd_lock);
/* Do not not return the number of bytes written */
uio->uio_resid += sizeof(eventfd_t);
return (EAGAIN);
}
error = mtx_sleep(&efd->efd_count, &efd->efd_lock,
PCATCH, "efdwr", 0);
if (error == 0)
goto retry;
}
if (error == 0) {
MPASS(UINT64_MAX - efd->efd_count > count);
efd->efd_count += count;
KNOTE_LOCKED(&efd->efd_sel.si_note, 0);
selwakeup(&efd->efd_sel);
wakeup(&efd->efd_count);
}
mtx_unlock(&efd->efd_lock);
return (error);
}
static int
eventfd_poll(struct file *fp, int events, struct ucred *active_cred,
struct thread *td)
{
struct eventfd *efd;
int revents;
efd = fp->f_data;
revents = 0;
mtx_lock(&efd->efd_lock);
if ((events & (POLLIN | POLLRDNORM)) != 0 && efd->efd_count > 0)
revents |= events & (POLLIN | POLLRDNORM);
if ((events & (POLLOUT | POLLWRNORM)) != 0 && UINT64_MAX - 1 >
efd->efd_count)
revents |= events & (POLLOUT | POLLWRNORM);
if (revents == 0)
selrecord(td, &efd->efd_sel);
mtx_unlock(&efd->efd_lock);
return (revents);
}
static int
eventfd_kqfilter(struct file *fp, struct knote *kn)
{
struct eventfd *efd = fp->f_data;
mtx_lock(&efd->efd_lock);
switch (kn->kn_filter) {
case EVFILT_READ:
kn->kn_fop = &eventfd_rfiltops;
break;
case EVFILT_WRITE:
kn->kn_fop = &eventfd_wfiltops;
break;
default:
mtx_unlock(&efd->efd_lock);
return (EINVAL);
}
kn->kn_hook = efd;
knlist_add(&efd->efd_sel.si_note, kn, 1);
mtx_unlock(&efd->efd_lock);
return (0);
}
static void
filt_eventfddetach(struct knote *kn)
{
struct eventfd *efd = kn->kn_hook;
mtx_lock(&efd->efd_lock);
knlist_remove(&efd->efd_sel.si_note, kn, 1);
mtx_unlock(&efd->efd_lock);
}
static int
filt_eventfdread(struct knote *kn, long hint)
{
struct eventfd *efd = kn->kn_hook;
int ret;
mtx_assert(&efd->efd_lock, MA_OWNED);
kn->kn_data = (int64_t)efd->efd_count;
ret = efd->efd_count > 0;
return (ret);
}
static int
filt_eventfdwrite(struct knote *kn, long hint)
{
struct eventfd *efd = kn->kn_hook;
int ret;
mtx_assert(&efd->efd_lock, MA_OWNED);
kn->kn_data = (int64_t)(UINT64_MAX - 1 - efd->efd_count);
ret = UINT64_MAX - 1 > efd->efd_count;
return (ret);
}
static int
eventfd_ioctl(struct file *fp, u_long cmd, void *data,
struct ucred *active_cred, struct thread *td)
{
switch (cmd) {
case FIONBIO:
case FIOASYNC:
return (0);
}
return (ENOTTY);
}
static int
eventfd_stat(struct file *fp, struct stat *st, struct ucred *active_cred,
struct thread *td)
{
bzero((void *)st, sizeof *st);
st->st_mode = S_IFIFO;
return (0);
}
static int
eventfd_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
{
struct eventfd *efd = fp->f_data;
kif->kf_type = KF_TYPE_EVENTFD;
mtx_lock(&efd->efd_lock);
kif->kf_un.kf_eventfd.kf_eventfd_value = efd->efd_count;
kif->kf_un.kf_eventfd.kf_eventfd_flags = efd->efd_flags;
kif->kf_un.kf_eventfd.kf_eventfd_addr = (uintptr_t)efd;
mtx_unlock(&efd->efd_lock);
return (0);
}
