freebsd-nq/sys/fs/fifofs/fifo_vnops.c
John-Mark Gurney ad3b9257c2 Add locking to the kqueue subsystem. This also makes the kqueue subsystem
a more complete subsystem, and removes the knowlege of how things are
implemented from the drivers.  Include locking around filter ops, so a
module like aio will know when not to be unloaded if there are outstanding
knotes using it's filter ops.

Currently, it uses the MTX_DUPOK even though it is not always safe to
aquire duplicate locks.  Witness currently doesn't support the ability
to discover if a dup lock is ok (in some cases).

Reviewed by:	green, rwatson (both earlier versions)
2004-08-15 06:24:42 +00:00

671 lines
17 KiB
C

/*
* Copyright (c) 1990, 1993, 1995
* The Regents of the University of California. All rights reserved.
*
* 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.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)fifo_vnops.c 8.10 (Berkeley) 5/27/95
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/event.h>
#include <sys/filio.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/malloc.h>
#include <sys/poll.h>
#include <sys/proc.h> /* XXXKSE */
#include <sys/signalvar.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sx.h>
#include <sys/systm.h>
#include <sys/un.h>
#include <sys/unistd.h>
#include <sys/vnode.h>
#include <fs/fifofs/fifo.h>
/*
* This structure is associated with the FIFO vnode and stores
* the state associated with the FIFO.
*/
struct fifoinfo {
struct socket *fi_readsock;
struct socket *fi_writesock;
long fi_readers;
long fi_writers;
};
static int fifo_print(struct vop_print_args *);
static int fifo_lookup(struct vop_lookup_args *);
static int fifo_open(struct vop_open_args *);
static int fifo_close(struct vop_close_args *);
static int fifo_read(struct vop_read_args *);
static int fifo_write(struct vop_write_args *);
static int fifo_ioctl(struct vop_ioctl_args *);
static int fifo_poll(struct vop_poll_args *);
static int fifo_kqfilter(struct vop_kqfilter_args *);
static int fifo_pathconf(struct vop_pathconf_args *);
static int fifo_advlock(struct vop_advlock_args *);
static void filt_fifordetach(struct knote *kn);
static int filt_fiforead(struct knote *kn, long hint);
static void filt_fifowdetach(struct knote *kn);
static int filt_fifowrite(struct knote *kn, long hint);
static struct filterops fiforead_filtops =
{ 1, NULL, filt_fifordetach, filt_fiforead };
static struct filterops fifowrite_filtops =
{ 1, NULL, filt_fifowdetach, filt_fifowrite };
vop_t **fifo_vnodeop_p;
static struct vnodeopv_entry_desc fifo_vnodeop_entries[] = {
{ &vop_default_desc, (vop_t *) vop_defaultop },
{ &vop_access_desc, (vop_t *) vop_ebadf },
{ &vop_advlock_desc, (vop_t *) fifo_advlock },
{ &vop_close_desc, (vop_t *) fifo_close },
{ &vop_create_desc, (vop_t *) vop_panic },
{ &vop_getattr_desc, (vop_t *) vop_ebadf },
{ &vop_getwritemount_desc, (vop_t *) vop_stdgetwritemount },
{ &vop_ioctl_desc, (vop_t *) fifo_ioctl },
{ &vop_kqfilter_desc, (vop_t *) fifo_kqfilter },
{ &vop_lease_desc, (vop_t *) vop_null },
{ &vop_link_desc, (vop_t *) vop_panic },
{ &vop_lookup_desc, (vop_t *) fifo_lookup },
{ &vop_mkdir_desc, (vop_t *) vop_panic },
{ &vop_mknod_desc, (vop_t *) vop_panic },
{ &vop_open_desc, (vop_t *) fifo_open },
{ &vop_pathconf_desc, (vop_t *) fifo_pathconf },
{ &vop_poll_desc, (vop_t *) fifo_poll },
{ &vop_print_desc, (vop_t *) fifo_print },
{ &vop_read_desc, (vop_t *) fifo_read },
{ &vop_readdir_desc, (vop_t *) vop_panic },
{ &vop_readlink_desc, (vop_t *) vop_panic },
{ &vop_reallocblks_desc, (vop_t *) vop_panic },
{ &vop_reclaim_desc, (vop_t *) vop_null },
{ &vop_remove_desc, (vop_t *) vop_panic },
{ &vop_rename_desc, (vop_t *) vop_panic },
{ &vop_rmdir_desc, (vop_t *) vop_panic },
{ &vop_setattr_desc, (vop_t *) vop_ebadf },
{ &vop_symlink_desc, (vop_t *) vop_panic },
{ &vop_write_desc, (vop_t *) fifo_write },
{ NULL, NULL }
};
static struct vnodeopv_desc fifo_vnodeop_opv_desc =
{ &fifo_vnodeop_p, fifo_vnodeop_entries };
VNODEOP_SET(fifo_vnodeop_opv_desc);
struct mtx fifo_mtx;
MTX_SYSINIT(fifo, &fifo_mtx, "fifo mutex", MTX_DEF);
int
fifo_vnoperate(ap)
struct vop_generic_args /* {
struct vnodeop_desc *a_desc;
<other random data follows, presumably>
} */ *ap;
{
return (VOCALL(fifo_vnodeop_p, ap->a_desc->vdesc_offset, ap));
}
/*
* Trivial lookup routine that always fails.
*/
/* ARGSUSED */
static int
fifo_lookup(ap)
struct vop_lookup_args /* {
struct vnode * a_dvp;
struct vnode ** a_vpp;
struct componentname * a_cnp;
} */ *ap;
{
*ap->a_vpp = NULL;
return (ENOTDIR);
}
/*
* Dispose of fifo resources.
*/
static void
fifo_cleanup(struct vnode *vp)
{
struct fifoinfo *fip = vp->v_fifoinfo;
ASSERT_VOP_LOCKED(vp, "fifo_cleanup");
if (fip->fi_readers == 0 && fip->fi_writers == 0) {
vp->v_fifoinfo = NULL;
(void)soclose(fip->fi_readsock);
(void)soclose(fip->fi_writesock);
FREE(fip, M_VNODE);
}
}
/*
* Open called to set up a new instance of a fifo or
* to find an active instance of a fifo.
*/
/* ARGSUSED */
static int
fifo_open(ap)
struct vop_open_args /* {
struct vnode *a_vp;
int a_mode;
struct ucred *a_cred;
struct thread *a_td;
} */ *ap;
{
struct vnode *vp = ap->a_vp;
struct fifoinfo *fip;
struct thread *td = ap->a_td;
struct ucred *cred = ap->a_cred;
struct socket *rso, *wso;
int error;
if ((fip = vp->v_fifoinfo) == NULL) {
MALLOC(fip, struct fifoinfo *, sizeof(*fip), M_VNODE, M_WAITOK);
error = socreate(AF_LOCAL, &rso, SOCK_STREAM, 0, cred, td);
if (error)
goto fail1;
fip->fi_readsock = rso;
error = socreate(AF_LOCAL, &wso, SOCK_STREAM, 0, cred, td);
if (error)
goto fail2;
fip->fi_writesock = wso;
error = uipc_connect2(wso, rso);
if (error) {
(void)soclose(wso);
fail2:
(void)soclose(rso);
fail1:
free(fip, M_VNODE);
return (error);
}
fip->fi_readers = fip->fi_writers = 0;
wso->so_snd.sb_lowat = PIPE_BUF;
SOCKBUF_LOCK(&rso->so_rcv);
rso->so_rcv.sb_state |= SBS_CANTRCVMORE;
SOCKBUF_UNLOCK(&rso->so_rcv);
vp->v_fifoinfo = fip;
}
/*
* General access to fi_readers and fi_writers is protected using
* the vnode lock.
*
* Protect the increment of fi_readers and fi_writers and the
* associated calls to wakeup() with the fifo mutex in addition
* to the vnode lock. This allows the vnode lock to be dropped
* for the msleep() calls below, and using the fifo mutex with
* msleep() prevents the wakeup from being missed.
*/
mtx_lock(&fifo_mtx);
if (ap->a_mode & FREAD) {
fip->fi_readers++;
if (fip->fi_readers == 1) {
SOCKBUF_LOCK(&fip->fi_writesock->so_snd);
fip->fi_writesock->so_snd.sb_state &= ~SBS_CANTSENDMORE;
SOCKBUF_UNLOCK(&fip->fi_writesock->so_snd);
if (fip->fi_writers > 0) {
wakeup(&fip->fi_writers);
sowwakeup(fip->fi_writesock);
}
}
}
if (ap->a_mode & FWRITE) {
if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
mtx_unlock(&fifo_mtx);
return (ENXIO);
}
fip->fi_writers++;
if (fip->fi_writers == 1) {
SOCKBUF_LOCK(&fip->fi_writesock->so_rcv);
fip->fi_readsock->so_rcv.sb_state &= ~SBS_CANTRCVMORE;
SOCKBUF_UNLOCK(&fip->fi_writesock->so_rcv);
if (fip->fi_readers > 0) {
wakeup(&fip->fi_readers);
sorwakeup(fip->fi_writesock);
}
}
}
if ((ap->a_mode & O_NONBLOCK) == 0) {
if ((ap->a_mode & FREAD) && fip->fi_writers == 0) {
VOP_UNLOCK(vp, 0, td);
error = msleep(&fip->fi_readers, &fifo_mtx,
PDROP | PCATCH | PSOCK, "fifoor", 0);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
if (error) {
fip->fi_readers--;
if (fip->fi_readers == 0) {
socantsendmore(fip->fi_writesock);
fifo_cleanup(vp);
}
return (error);
}
mtx_lock(&fifo_mtx);
/*
* We must have got woken up because we had a writer.
* That (and not still having one) is the condition
* that we must wait for.
*/
}
if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) {
VOP_UNLOCK(vp, 0, td);
error = msleep(&fip->fi_writers, &fifo_mtx,
PDROP | PCATCH | PSOCK, "fifoow", 0);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
if (error) {
fip->fi_writers--;
if (fip->fi_writers == 0) {
socantrcvmore(fip->fi_readsock);
fifo_cleanup(vp);
}
return (error);
}
/*
* We must have got woken up because we had
* a reader. That (and not still having one)
* is the condition that we must wait for.
*/
return (0);
}
}
mtx_unlock(&fifo_mtx);
return (0);
}
/*
* Vnode op for read
*/
/* ARGSUSED */
static int
fifo_read(ap)
struct vop_read_args /* {
struct vnode *a_vp;
struct uio *a_uio;
int a_ioflag;
struct ucred *a_cred;
} */ *ap;
{
struct uio *uio = ap->a_uio;
struct socket *rso = ap->a_vp->v_fifoinfo->fi_readsock;
struct thread *td = uio->uio_td;
int error, flags;
#ifdef DIAGNOSTIC
if (uio->uio_rw != UIO_READ)
panic("fifo_read mode");
#endif
if (uio->uio_resid == 0)
return (0);
VOP_UNLOCK(ap->a_vp, 0, td);
flags = (ap->a_ioflag & IO_NDELAY) ? MSG_NBIO : 0;
error = soreceive(rso, (struct sockaddr **)0, uio, (struct mbuf **)0,
(struct mbuf **)0, &flags);
vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY, td);
return (error);
}
/*
* Vnode op for write
*/
/* ARGSUSED */
static int
fifo_write(ap)
struct vop_write_args /* {
struct vnode *a_vp;
struct uio *a_uio;
int a_ioflag;
struct ucred *a_cred;
} */ *ap;
{
struct socket *wso = ap->a_vp->v_fifoinfo->fi_writesock;
struct thread *td = ap->a_uio->uio_td;
int error, flags;
#ifdef DIAGNOSTIC
if (ap->a_uio->uio_rw != UIO_WRITE)
panic("fifo_write mode");
#endif
VOP_UNLOCK(ap->a_vp, 0, td);
flags = (ap->a_ioflag & IO_NDELAY) ? MSG_NBIO : 0;
error = sosend(wso, (struct sockaddr *)0, ap->a_uio, 0,
(struct mbuf *)0, flags, td);
vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY, td);
return (error);
}
/*
* Device ioctl operation.
*/
/* ARGSUSED */
static int
fifo_ioctl(ap)
struct vop_ioctl_args /* {
struct vnode *a_vp;
u_long a_command;
caddr_t a_data;
int a_fflag;
struct ucred *a_cred;
struct thread *a_td;
} */ *ap;
{
struct file filetmp; /* Local, so need not be locked. */
int error;
if (ap->a_command == FIONBIO)
return (0);
if (ap->a_fflag & FREAD) {
filetmp.f_data = ap->a_vp->v_fifoinfo->fi_readsock;
filetmp.f_cred = ap->a_cred;
error = soo_ioctl(&filetmp, ap->a_command, ap->a_data,
ap->a_td->td_ucred, ap->a_td);
if (error)
return (error);
}
if (ap->a_fflag & FWRITE) {
filetmp.f_data = ap->a_vp->v_fifoinfo->fi_writesock;
filetmp.f_cred = ap->a_cred;
error = soo_ioctl(&filetmp, ap->a_command, ap->a_data,
ap->a_td->td_ucred, ap->a_td);
if (error)
return (error);
}
return (0);
}
/* ARGSUSED */
static int
fifo_kqfilter(ap)
struct vop_kqfilter_args /* {
struct vnode *a_vp;
struct knote *a_kn;
} */ *ap;
{
struct fifoinfo *fi = ap->a_vp->v_fifoinfo;
struct socket *so;
struct sockbuf *sb;
switch (ap->a_kn->kn_filter) {
case EVFILT_READ:
ap->a_kn->kn_fop = &fiforead_filtops;
so = fi->fi_readsock;
sb = &so->so_rcv;
break;
case EVFILT_WRITE:
ap->a_kn->kn_fop = &fifowrite_filtops;
so = fi->fi_writesock;
sb = &so->so_snd;
break;
default:
return (1);
}
ap->a_kn->kn_hook = (caddr_t)so;
SOCKBUF_LOCK(sb);
knlist_add(&sb->sb_sel.si_note, ap->a_kn, 1);
sb->sb_flags |= SB_KNOTE;
SOCKBUF_UNLOCK(sb);
return (0);
}
static void
filt_fifordetach(struct knote *kn)
{
struct socket *so = (struct socket *)kn->kn_hook;
SOCKBUF_LOCK(&so->so_rcv);
knlist_remove(&so->so_rcv.sb_sel.si_note, kn, 1);
if (knlist_empty(&so->so_rcv.sb_sel.si_note))
so->so_rcv.sb_flags &= ~SB_KNOTE;
SOCKBUF_UNLOCK(&so->so_rcv);
}
static int
filt_fiforead(struct knote *kn, long hint)
{
struct socket *so = (struct socket *)kn->kn_hook;
int need_lock, result;
need_lock = !SOCKBUF_OWNED(&so->so_rcv);
if (need_lock)
SOCKBUF_LOCK(&so->so_rcv);
kn->kn_data = so->so_rcv.sb_cc;
if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
kn->kn_flags |= EV_EOF;
result = 1;
} else {
kn->kn_flags &= ~EV_EOF;
result = (kn->kn_data > 0);
}
if (need_lock)
SOCKBUF_UNLOCK(&so->so_rcv);
return (result);
}
static void
filt_fifowdetach(struct knote *kn)
{
struct socket *so = (struct socket *)kn->kn_hook;
SOCKBUF_LOCK(&so->so_snd);
knlist_remove(&so->so_snd.sb_sel.si_note, kn, 1);
if (knlist_empty(&so->so_snd.sb_sel.si_note))
so->so_snd.sb_flags &= ~SB_KNOTE;
SOCKBUF_UNLOCK(&so->so_snd);
}
static int
filt_fifowrite(struct knote *kn, long hint)
{
struct socket *so = (struct socket *)kn->kn_hook;
int need_lock, result;
need_lock = !SOCKBUF_OWNED(&so->so_snd);
if (need_lock)
SOCKBUF_LOCK(&so->so_snd);
kn->kn_data = sbspace(&so->so_snd);
if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
kn->kn_flags |= EV_EOF;
result = 1;
} else {
kn->kn_flags &= ~EV_EOF;
result = (kn->kn_data >= so->so_snd.sb_lowat);
}
if (need_lock)
SOCKBUF_UNLOCK(&so->so_snd);
return (result);
}
/* ARGSUSED */
static int
fifo_poll(ap)
struct vop_poll_args /* {
struct vnode *a_vp;
int a_events;
struct ucred *a_cred;
struct thread *a_td;
} */ *ap;
{
struct file filetmp;
int events, revents = 0;
events = ap->a_events &
(POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
if (events) {
/*
* If POLLIN or POLLRDNORM is requested and POLLINIGNEOF is
* not, then convert the first two to the last one. This
* tells the socket poll function to ignore EOF so that we
* block if there is no writer (and no data). Callers can
* set POLLINIGNEOF to get non-blocking behavior.
*/
if (events & (POLLIN | POLLRDNORM) &&
!(events & POLLINIGNEOF)) {
events &= ~(POLLIN | POLLRDNORM);
events |= POLLINIGNEOF;
}
filetmp.f_data = ap->a_vp->v_fifoinfo->fi_readsock;
filetmp.f_cred = ap->a_cred;
if (filetmp.f_data)
revents |= soo_poll(&filetmp, events,
ap->a_td->td_ucred, ap->a_td);
/* Reverse the above conversion. */
if ((revents & POLLINIGNEOF) &&
!(ap->a_events & POLLINIGNEOF)) {
revents |= (ap->a_events & (POLLIN | POLLRDNORM));
revents &= ~POLLINIGNEOF;
}
}
events = ap->a_events & (POLLOUT | POLLWRNORM | POLLWRBAND);
if (events) {
filetmp.f_data = ap->a_vp->v_fifoinfo->fi_writesock;
filetmp.f_cred = ap->a_cred;
if (filetmp.f_data) {
revents |= soo_poll(&filetmp, events,
ap->a_td->td_ucred, ap->a_td);
}
}
return (revents);
}
/*
* Device close routine
*/
/* ARGSUSED */
static int
fifo_close(ap)
struct vop_close_args /* {
struct vnode *a_vp;
int a_fflag;
struct ucred *a_cred;
struct thread *a_td;
} */ *ap;
{
struct vnode *vp = ap->a_vp;
struct thread *td = ap->a_td;
struct fifoinfo *fip = vp->v_fifoinfo;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
if (ap->a_fflag & FREAD) {
fip->fi_readers--;
if (fip->fi_readers == 0)
socantsendmore(fip->fi_writesock);
}
if (ap->a_fflag & FWRITE) {
fip->fi_writers--;
if (fip->fi_writers == 0)
socantrcvmore(fip->fi_readsock);
}
fifo_cleanup(vp);
VOP_UNLOCK(vp, 0, td);
return (0);
}
/*
* Print out internal contents of a fifo vnode.
*/
int
fifo_printinfo(vp)
struct vnode *vp;
{
register struct fifoinfo *fip = vp->v_fifoinfo;
printf(", fifo with %ld readers and %ld writers",
fip->fi_readers, fip->fi_writers);
return (0);
}
/*
* Print out the contents of a fifo vnode.
*/
static int
fifo_print(ap)
struct vop_print_args /* {
struct vnode *a_vp;
} */ *ap;
{
fifo_printinfo(ap->a_vp);
printf("\n");
return (0);
}
/*
* Return POSIX pathconf information applicable to fifo's.
*/
static int
fifo_pathconf(ap)
struct vop_pathconf_args /* {
struct vnode *a_vp;
int a_name;
int *a_retval;
} */ *ap;
{
switch (ap->a_name) {
case _PC_LINK_MAX:
*ap->a_retval = LINK_MAX;
return (0);
case _PC_PIPE_BUF:
*ap->a_retval = PIPE_BUF;
return (0);
case _PC_CHOWN_RESTRICTED:
*ap->a_retval = 1;
return (0);
default:
return (EINVAL);
}
/* NOTREACHED */
}
/*
* Fifo advisory byte-level locks.
*/
/* ARGSUSED */
static int
fifo_advlock(ap)
struct vop_advlock_args /* {
struct vnode *a_vp;
caddr_t a_id;
int a_op;
struct flock *a_fl;
int a_flags;
} */ *ap;
{
return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL);
}