3a1e5dd8e6
framework allowing to set the suspension policy for the dynamic block. Extend the currently possible policies of stopping on interruptible sleeps and ignoring such sleeps by two more: do not suspend at interruptible sleeps, but interrupt them with either EINTR or ERESTART. Reviewed by: jilles Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 2 weeks Approved by: re (gjb)
388 lines
9.4 KiB
C
388 lines
9.4 KiB
C
/*-
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* Copyright (c) 1990, 1993, 1995
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* The Regents of the University of California.
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* Copyright (c) 2005 Robert N. M. Watson
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* Copyright (c) 2012 Giovanni Trematerra
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)fifo_vnops.c 8.10 (Berkeley) 5/27/95
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/event.h>
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#include <sys/file.h>
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#include <sys/filedesc.h>
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#include <sys/filio.h>
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#include <sys/fcntl.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/malloc.h>
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#include <sys/selinfo.h>
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#include <sys/pipe.h>
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#include <sys/proc.h>
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#include <sys/signalvar.h>
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#include <sys/sx.h>
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#include <sys/systm.h>
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#include <sys/un.h>
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#include <sys/unistd.h>
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#include <sys/vnode.h>
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/*
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* This structure is associated with the FIFO vnode and stores
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* the state associated with the FIFO.
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* Notes about locking:
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* - fi_pipe is invariant since init time.
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* - fi_readers and fi_writers are protected by the vnode lock.
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*/
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struct fifoinfo {
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struct pipe *fi_pipe;
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long fi_readers;
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long fi_writers;
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u_int fi_rgen;
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u_int fi_wgen;
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};
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static vop_print_t fifo_print;
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static vop_open_t fifo_open;
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static vop_close_t fifo_close;
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static vop_pathconf_t fifo_pathconf;
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static vop_advlock_t fifo_advlock;
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struct vop_vector fifo_specops = {
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.vop_default = &default_vnodeops,
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.vop_advlock = fifo_advlock,
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.vop_close = fifo_close,
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.vop_create = VOP_PANIC,
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.vop_getattr = VOP_EBADF,
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.vop_ioctl = VOP_PANIC,
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.vop_kqfilter = VOP_PANIC,
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.vop_link = VOP_PANIC,
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.vop_mkdir = VOP_PANIC,
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.vop_mknod = VOP_PANIC,
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.vop_open = fifo_open,
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.vop_pathconf = fifo_pathconf,
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.vop_print = fifo_print,
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.vop_read = VOP_PANIC,
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.vop_readdir = VOP_PANIC,
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.vop_readlink = VOP_PANIC,
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.vop_reallocblks = VOP_PANIC,
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.vop_reclaim = VOP_NULL,
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.vop_remove = VOP_PANIC,
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.vop_rename = VOP_PANIC,
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.vop_rmdir = VOP_PANIC,
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.vop_setattr = VOP_EBADF,
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.vop_symlink = VOP_PANIC,
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.vop_write = VOP_PANIC,
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};
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/*
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* Dispose of fifo resources.
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*/
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static void
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fifo_cleanup(struct vnode *vp)
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{
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struct fifoinfo *fip;
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ASSERT_VOP_ELOCKED(vp, "fifo_cleanup");
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fip = vp->v_fifoinfo;
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if (fip->fi_readers == 0 && fip->fi_writers == 0) {
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vp->v_fifoinfo = NULL;
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pipe_dtor(fip->fi_pipe);
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free(fip, M_VNODE);
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}
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}
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/*
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* Open called to set up a new instance of a fifo or
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* to find an active instance of a fifo.
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*/
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/* ARGSUSED */
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static int
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fifo_open(ap)
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struct vop_open_args /* {
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struct vnode *a_vp;
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int a_mode;
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struct ucred *a_cred;
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struct thread *a_td;
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struct file *a_fp;
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} */ *ap;
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{
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struct vnode *vp;
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struct file *fp;
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struct thread *td;
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struct fifoinfo *fip;
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struct pipe *fpipe;
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u_int gen;
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int error, stops_deferred;
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vp = ap->a_vp;
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fp = ap->a_fp;
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td = ap->a_td;
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ASSERT_VOP_ELOCKED(vp, "fifo_open");
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if (fp == NULL || (ap->a_mode & FEXEC) != 0)
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return (EINVAL);
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if ((fip = vp->v_fifoinfo) == NULL) {
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pipe_named_ctor(&fpipe, td);
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fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK);
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fip->fi_pipe = fpipe;
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fpipe->pipe_wgen = fip->fi_readers = fip->fi_writers = 0;
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KASSERT(vp->v_fifoinfo == NULL, ("fifo_open: v_fifoinfo race"));
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vp->v_fifoinfo = fip;
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}
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fpipe = fip->fi_pipe;
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KASSERT(fpipe != NULL, ("fifo_open: pipe is NULL"));
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/*
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* Use the pipe mutex here, in addition to the vnode lock,
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* in order to allow vnode lock dropping before msleep() calls
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* and still avoiding missed wakeups.
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*/
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PIPE_LOCK(fpipe);
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if (ap->a_mode & FREAD) {
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fip->fi_readers++;
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fip->fi_rgen++;
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if (fip->fi_readers == 1) {
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fpipe->pipe_state &= ~PIPE_EOF;
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if (fip->fi_writers > 0)
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wakeup(&fip->fi_writers);
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}
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fp->f_seqcount = fpipe->pipe_wgen - fip->fi_writers;
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}
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if (ap->a_mode & FWRITE) {
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if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
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PIPE_UNLOCK(fpipe);
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if (fip->fi_writers == 0)
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fifo_cleanup(vp);
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return (ENXIO);
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}
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fip->fi_writers++;
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fip->fi_wgen++;
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if (fip->fi_writers == 1) {
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fpipe->pipe_state &= ~PIPE_EOF;
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if (fip->fi_readers > 0)
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wakeup(&fip->fi_readers);
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}
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}
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if ((ap->a_mode & O_NONBLOCK) == 0) {
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if ((ap->a_mode & FREAD) && fip->fi_writers == 0) {
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gen = fip->fi_wgen;
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VOP_UNLOCK(vp, 0);
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stops_deferred = sigdeferstop(SIGDEFERSTOP_OFF);
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error = msleep(&fip->fi_readers, PIPE_MTX(fpipe),
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PDROP | PCATCH | PSOCK, "fifoor", 0);
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sigallowstop(stops_deferred);
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vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
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if (error != 0 && gen == fip->fi_wgen) {
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fip->fi_readers--;
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if (fip->fi_readers == 0) {
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PIPE_LOCK(fpipe);
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fpipe->pipe_state |= PIPE_EOF;
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if (fpipe->pipe_state & PIPE_WANTW)
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wakeup(fpipe);
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PIPE_UNLOCK(fpipe);
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fifo_cleanup(vp);
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}
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return (error);
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}
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PIPE_LOCK(fpipe);
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/*
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* We must have got woken up because we had a writer.
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* That (and not still having one) is the condition
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* that we must wait for.
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*/
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}
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if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) {
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gen = fip->fi_rgen;
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VOP_UNLOCK(vp, 0);
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stops_deferred = sigdeferstop(SIGDEFERSTOP_OFF);
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error = msleep(&fip->fi_writers, PIPE_MTX(fpipe),
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PDROP | PCATCH | PSOCK, "fifoow", 0);
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sigallowstop(stops_deferred);
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vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
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if (error != 0 && gen == fip->fi_rgen) {
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fip->fi_writers--;
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if (fip->fi_writers == 0) {
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PIPE_LOCK(fpipe);
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fpipe->pipe_state |= PIPE_EOF;
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if (fpipe->pipe_state & PIPE_WANTR)
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wakeup(fpipe);
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fpipe->pipe_wgen++;
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PIPE_UNLOCK(fpipe);
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fifo_cleanup(vp);
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}
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return (error);
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}
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/*
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* We must have got woken up because we had
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* a reader. That (and not still having one)
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* is the condition that we must wait for.
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*/
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PIPE_LOCK(fpipe);
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}
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}
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PIPE_UNLOCK(fpipe);
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KASSERT(fp != NULL, ("can't fifo/vnode bypass"));
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KASSERT(fp->f_ops == &badfileops, ("not badfileops in fifo_open"));
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finit(fp, fp->f_flag, DTYPE_FIFO, fpipe, &pipeops);
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return (0);
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}
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/*
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* Device close routine
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*/
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/* ARGSUSED */
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static int
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fifo_close(ap)
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struct vop_close_args /* {
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struct vnode *a_vp;
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int a_fflag;
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struct ucred *a_cred;
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struct thread *a_td;
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} */ *ap;
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{
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struct vnode *vp;
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struct fifoinfo *fip;
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struct pipe *cpipe;
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vp = ap->a_vp;
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fip = vp->v_fifoinfo;
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cpipe = fip->fi_pipe;
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ASSERT_VOP_ELOCKED(vp, "fifo_close");
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if (ap->a_fflag & FREAD) {
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fip->fi_readers--;
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if (fip->fi_readers == 0) {
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PIPE_LOCK(cpipe);
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cpipe->pipe_state |= PIPE_EOF;
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if ((cpipe->pipe_state & PIPE_WANTW)) {
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cpipe->pipe_state &= ~PIPE_WANTW;
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wakeup(cpipe);
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}
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pipeselwakeup(cpipe);
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PIPE_UNLOCK(cpipe);
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}
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}
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if (ap->a_fflag & FWRITE) {
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fip->fi_writers--;
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if (fip->fi_writers == 0) {
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PIPE_LOCK(cpipe);
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cpipe->pipe_state |= PIPE_EOF;
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if ((cpipe->pipe_state & PIPE_WANTR)) {
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cpipe->pipe_state &= ~PIPE_WANTR;
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wakeup(cpipe);
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}
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cpipe->pipe_wgen++;
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pipeselwakeup(cpipe);
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PIPE_UNLOCK(cpipe);
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}
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}
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fifo_cleanup(vp);
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return (0);
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}
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/*
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* Print out internal contents of a fifo vnode.
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*/
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int
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fifo_printinfo(vp)
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struct vnode *vp;
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{
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register struct fifoinfo *fip = vp->v_fifoinfo;
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if (fip == NULL){
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printf(", NULL v_fifoinfo");
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return (0);
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}
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printf(", fifo with %ld readers and %ld writers",
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fip->fi_readers, fip->fi_writers);
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return (0);
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}
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/*
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* Print out the contents of a fifo vnode.
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*/
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static int
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fifo_print(ap)
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struct vop_print_args /* {
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struct vnode *a_vp;
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} */ *ap;
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{
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printf(" ");
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fifo_printinfo(ap->a_vp);
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printf("\n");
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return (0);
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}
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/*
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* Return POSIX pathconf information applicable to fifo's.
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*/
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static int
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fifo_pathconf(ap)
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struct vop_pathconf_args /* {
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struct vnode *a_vp;
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int a_name;
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int *a_retval;
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} */ *ap;
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{
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switch (ap->a_name) {
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case _PC_LINK_MAX:
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*ap->a_retval = LINK_MAX;
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return (0);
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case _PC_PIPE_BUF:
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*ap->a_retval = PIPE_BUF;
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return (0);
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case _PC_CHOWN_RESTRICTED:
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*ap->a_retval = 1;
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return (0);
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default:
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return (EINVAL);
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}
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/* NOTREACHED */
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}
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/*
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* Fifo advisory byte-level locks.
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*/
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/* ARGSUSED */
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static int
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fifo_advlock(ap)
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struct vop_advlock_args /* {
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struct vnode *a_vp;
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caddr_t a_id;
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int a_op;
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struct flock *a_fl;
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int a_flags;
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} */ *ap;
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{
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return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL);
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}
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