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freebsd-dev/sys/kern/sys_pipe.c
Robert Watson 4795b82c13 Coalesce pipe allocations and frees. Previously, the pipe code 
would allocate two 'struct pipe's from the pipe zone, and malloc a
mutex.

- Create a new "struct pipepair" object holding the two 'struct
  pipe' instances, struct mutex, and struct label reference.  Pipe
  structures now have a back-pointer to the pipe pair, and a
  'pipe_present' flag to indicate whether the half has been
  closed.

- Perform mutex init/destroy in zone init/destroy, avoiding
  reallocating the mutex for each pipe.  Perform most pipe structure
  setup in zone constructor.

- VM memory mappings for pageable buffers are still done outside of
  the UMA zone.

- Change MAC API to speak 'struct pipepair' instead of 'struct pipe',
  update many policies.  MAC labels are also handled outside of the
  UMA zone for now.  Label-only policy modules don't have to be
  recompiled, but if a module is recompiled, its pipe entry points
  will need to be updated.  If a module actually reached into the
  pipe structures (unlikely), that would also need to be modified.

These changes substantially simplify failure handling in the pipe
code as there are many fewer possible failure modes.

On half-close, pipes no longer free the 'struct pipe' for the closed
half until a full-close takes place.  However, VM mapped buffers
are still released on half-close.

Some code refactoring is now possible to clean up some of the back
references, etc; this patch attempts not to change the structure
of most of the pipe implementation, only allocation/free code
paths, so as to avoid introducing bugs (hopefully).

This cuts about 8%-9% off the cost of sequential pipe allocation
and free in system call tests on UP and SMP in my micro-benchmarks.
May or may not make a difference in macro-benchmarks, but doing
less work is good.

Reviewed by:	juli, tjr
Testing help:	dwhite, fenestro, scottl, et al
2004-02-01 05:56:51 +00:00

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/*
* Copyright (c) 1996 John S. Dyson
* 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 immediately at the beginning of the file, without modification,
* 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.
* 3. Absolutely no warranty of function or purpose is made by the author
* John S. Dyson.
* 4. Modifications may be freely made to this file if the above conditions
* are met.
*/
/*
* This file contains a high-performance replacement for the socket-based
* pipes scheme originally used in FreeBSD/4.4Lite. It does not support
* all features of sockets, but does do everything that pipes normally
* do.
*/
/*
* This code has two modes of operation, a small write mode and a large
* write mode. The small write mode acts like conventional pipes with
* a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the
* "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT
* and PIPE_SIZE in size, it is fully mapped and wired into the kernel, and
* the receiving process can copy it directly from the pages in the sending
* process.
*
* If the sending process receives a signal, it is possible that it will
* go away, and certainly its address space can change, because control
* is returned back to the user-mode side. In that case, the pipe code
* arranges to copy the buffer supplied by the user process, to a pageable
* kernel buffer, and the receiving process will grab the data from the
* pageable kernel buffer. Since signals don't happen all that often,
* the copy operation is normally eliminated.
*
* The constant PIPE_MINDIRECT is chosen to make sure that buffering will
* happen for small transfers so that the system will not spend all of
* its time context switching.
*
* In order to limit the resource use of pipes, two sysctls exist:
*
* kern.ipc.maxpipekva - This is a hard limit on the amount of pageable
* address space available to us in pipe_map. Whenever the amount in use
* exceeds half of this value, all new pipes will be created with size
* SMALL_PIPE_SIZE, rather than PIPE_SIZE. Big pipe creation will be limited
* as well. This value is loader tunable only.
*
* kern.ipc.maxpipekvawired - This value limits the amount of memory that may
* be wired in order to facilitate direct copies using page flipping.
* Whenever this value is exceeded, pipes will fall back to using regular
* copies. This value is sysctl controllable at all times.
*
* These values are autotuned in subr_param.c.
*
* Memory usage may be monitored through the sysctls
* kern.ipc.pipes, kern.ipc.pipekva and kern.ipc.pipekvawired.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/filio.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mac.h>
#include <sys/mutex.h>
#include <sys/ttycom.h>
#include <sys/stat.h>
#include <sys/malloc.h>
#include <sys/poll.h>
#include <sys/selinfo.h>
#include <sys/signalvar.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/pipe.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/uio.h>
#include <sys/event.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_object.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/uma.h>
/*
* Use this define if you want to disable *fancy* VM things. Expect an
* approx 30% decrease in transfer rate. This could be useful for
* NetBSD or OpenBSD.
*/
/* #define PIPE_NODIRECT */
/*
* interfaces to the outside world
*/
static fo_rdwr_t pipe_read;
static fo_rdwr_t pipe_write;
static fo_ioctl_t pipe_ioctl;
static fo_poll_t pipe_poll;
static fo_kqfilter_t pipe_kqfilter;
static fo_stat_t pipe_stat;
static fo_close_t pipe_close;
static struct fileops pipeops = {
.fo_read = pipe_read,
.fo_write = pipe_write,
.fo_ioctl = pipe_ioctl,
.fo_poll = pipe_poll,
.fo_kqfilter = pipe_kqfilter,
.fo_stat = pipe_stat,
.fo_close = pipe_close,
.fo_flags = DFLAG_PASSABLE
};
static void filt_pipedetach(struct knote *kn);
static int filt_piperead(struct knote *kn, long hint);
static int filt_pipewrite(struct knote *kn, long hint);
static struct filterops pipe_rfiltops =
{ 1, NULL, filt_pipedetach, filt_piperead };
static struct filterops pipe_wfiltops =
{ 1, NULL, filt_pipedetach, filt_pipewrite };
/*
* Default pipe buffer size(s), this can be kind-of large now because pipe
* space is pageable. The pipe code will try to maintain locality of
* reference for performance reasons, so small amounts of outstanding I/O
* will not wipe the cache.
*/
#define MINPIPESIZE (PIPE_SIZE/3)
#define MAXPIPESIZE (2*PIPE_SIZE/3)
/*
* Limit the number of "big" pipes
*/
#define LIMITBIGPIPES 32
static int nbigpipe;
static int amountpipes;
static int amountpipekva;
static int amountpipekvawired;
SYSCTL_DECL(_kern_ipc);
SYSCTL_INT(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN,
&maxpipekva, 0, "Pipe KVA limit");
SYSCTL_INT(_kern_ipc, OID_AUTO, maxpipekvawired, CTLFLAG_RW,
&maxpipekvawired, 0, "Pipe KVA wired limit");
SYSCTL_INT(_kern_ipc, OID_AUTO, pipes, CTLFLAG_RD,
&amountpipes, 0, "Current # of pipes");
SYSCTL_INT(_kern_ipc, OID_AUTO, bigpipes, CTLFLAG_RD,
&nbigpipe, 0, "Current # of big pipes");
SYSCTL_INT(_kern_ipc, OID_AUTO, pipekva, CTLFLAG_RD,
&amountpipekva, 0, "Pipe KVA usage");
SYSCTL_INT(_kern_ipc, OID_AUTO, pipekvawired, CTLFLAG_RD,
&amountpipekvawired, 0, "Pipe wired KVA usage");
static void pipeinit(void *dummy __unused);
static void pipeclose(struct pipe *cpipe);
static void pipe_free_kmem(struct pipe *cpipe);
static int pipe_create(struct pipe *pipe);
static __inline int pipelock(struct pipe *cpipe, int catch);
static __inline void pipeunlock(struct pipe *cpipe);
static __inline void pipeselwakeup(struct pipe *cpipe);
#ifndef PIPE_NODIRECT
static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
static void pipe_destroy_write_buffer(struct pipe *wpipe);
static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
static void pipe_clone_write_buffer(struct pipe *wpipe);
#endif
static int pipespace(struct pipe *cpipe, int size);
static void pipe_zone_ctor(void *mem, int size, void *arg);
static void pipe_zone_dtor(void *mem, int size, void *arg);
static void pipe_zone_init(void *mem, int size);
static void pipe_zone_fini(void *mem, int size);
static uma_zone_t pipe_zone;
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
static void
pipeinit(void *dummy __unused)
{
pipe_zone = uma_zcreate("PIPE", sizeof(struct pipepair),
pipe_zone_ctor, pipe_zone_dtor, pipe_zone_init, pipe_zone_fini,
UMA_ALIGN_PTR, 0);
KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
}
static void
pipe_zone_ctor(void *mem, int size, void *arg)
{
struct pipepair *pp;
struct pipe *rpipe, *wpipe;
KASSERT(size == sizeof(*pp), ("pipe_zone_ctor: wrong size"));
pp = (struct pipepair *)mem;
/*
* We zero both pipe endpoints to make sure all the kmem pointers
* are NULL, flag fields are zero'd, etc. We timestamp both
* endpoints with the same time.
*/
rpipe = &pp->pp_rpipe;
bzero(rpipe, sizeof(*rpipe));
vfs_timestamp(&rpipe->pipe_ctime);
rpipe->pipe_atime = rpipe->pipe_mtime = rpipe->pipe_ctime;
wpipe = &pp->pp_wpipe;
bzero(wpipe, sizeof(*wpipe));
wpipe->pipe_ctime = rpipe->pipe_ctime;
wpipe->pipe_atime = wpipe->pipe_mtime = rpipe->pipe_ctime;
rpipe->pipe_peer = wpipe;
rpipe->pipe_pair = pp;
wpipe->pipe_peer = rpipe;
wpipe->pipe_pair = pp;
/*
* Mark both endpoints as present; they will later get free'd
* one at a time. When both are free'd, then the whole pair
* is released.
*/
rpipe->pipe_present = 1;
wpipe->pipe_present = 1;
/*
* Eventually, the MAC Framework may initialize the label
* in ctor or init, but for now we do it elswhere to avoid
* blocking in ctor or init.
*/
pp->pp_label = NULL;
}
static void
pipe_zone_dtor(void *mem, int size, void *arg)
{
struct pipepair *pp;
KASSERT(size == sizeof(*pp), ("pipe_zone_dtor: wrong size"));
pp = (struct pipepair *)mem;
}
static void
pipe_zone_init(void *mem, int size)
{
struct pipepair *pp;
KASSERT(size == sizeof(*pp), ("pipe_zone_init: wrong size"));
pp = (struct pipepair *)mem;
mtx_init(&pp->pp_mtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE);
}
static void
pipe_zone_fini(void *mem, int size)
{
struct pipepair *pp;
KASSERT(size == sizeof(*pp), ("pipe_zone_fini: wrong size"));
pp = (struct pipepair *)mem;
mtx_destroy(&pp->pp_mtx);
}
/*
* The pipe system call for the DTYPE_PIPE type of pipes. If we fail,
* let the zone pick up the pieces via pipeclose().
*/
/* ARGSUSED */
int
pipe(td, uap)
struct thread *td;
struct pipe_args /* {
int dummy;
} */ *uap;
{
struct filedesc *fdp = td->td_proc->p_fd;
struct file *rf, *wf;
struct pipepair *pp;
struct pipe *rpipe, *wpipe;
int fd, error;
pp = uma_zalloc(pipe_zone, M_WAITOK);
#ifdef MAC
/*
* struct pipe represents a pipe endpoint. The MAC label is shared
* between the connected endpoints. As a result mac_init_pipe() and
* mac_create_pipe() should only be called on one of the endpoints
* after they have been connected.
*/
mac_init_pipe(pp);
mac_create_pipe(td->td_ucred, pp);
#endif
rpipe = &pp->pp_rpipe;
wpipe = &pp->pp_wpipe;
if (pipe_create(rpipe) || pipe_create(wpipe)) {
pipeclose(rpipe);
pipeclose(wpipe);
return (ENFILE);
}
rpipe->pipe_state |= PIPE_DIRECTOK;
wpipe->pipe_state |= PIPE_DIRECTOK;
error = falloc(td, &rf, &fd);
if (error) {
pipeclose(rpipe);
pipeclose(wpipe);
return (error);
}
/* An extra reference on `rf' has been held for us by falloc(). */
td->td_retval[0] = fd;
/*
* Warning: once we've gotten past allocation of the fd for the
* read-side, we can only drop the read side via fdrop() in order
* to avoid races against processes which manage to dup() the read
* side while we are blocked trying to allocate the write side.
*/
FILE_LOCK(rf);
rf->f_flag = FREAD | FWRITE;
rf->f_type = DTYPE_PIPE;
rf->f_data = rpipe;
rf->f_ops = &pipeops;
FILE_UNLOCK(rf);
error = falloc(td, &wf, &fd);
if (error) {
FILEDESC_LOCK(fdp);
if (fdp->fd_ofiles[td->td_retval[0]] == rf) {
fdp->fd_ofiles[td->td_retval[0]] = NULL;
fdunused(fdp, td->td_retval[0]);
FILEDESC_UNLOCK(fdp);
fdrop(rf, td);
} else {
FILEDESC_UNLOCK(fdp);
}
fdrop(rf, td);
/* rpipe has been closed by fdrop(). */
pipeclose(wpipe);
return (error);
}
/* An extra reference on `wf' has been held for us by falloc(). */
FILE_LOCK(wf);
wf->f_flag = FREAD | FWRITE;
wf->f_type = DTYPE_PIPE;
wf->f_data = wpipe;
wf->f_ops = &pipeops;
FILE_UNLOCK(wf);
fdrop(wf, td);
td->td_retval[1] = fd;
fdrop(rf, td);
return (0);
}
/*
* Allocate kva for pipe circular buffer, the space is pageable
* This routine will 'realloc' the size of a pipe safely, if it fails
* it will retain the old buffer.
* If it fails it will return ENOMEM.
*/
static int
pipespace(cpipe, size)
struct pipe *cpipe;
int size;
{
caddr_t buffer;
int error;
static int curfail = 0;
static struct timeval lastfail;
KASSERT(!mtx_owned(PIPE_MTX(cpipe)), ("pipespace: pipe mutex locked"));
size = round_page(size);
/*
* XXX -- minor change needed here for NetBSD/OpenBSD VM systems.
*/
buffer = (caddr_t) vm_map_min(pipe_map);
/*
* The map entry is, by default, pageable.
* XXX -- minor change needed here for NetBSD/OpenBSD VM systems.
*/
error = vm_map_find(pipe_map, NULL, 0,
(vm_offset_t *) &buffer, size, 1,
VM_PROT_ALL, VM_PROT_ALL, 0);
if (error != KERN_SUCCESS) {
if (ppsratecheck(&lastfail, &curfail, 1))
printf("kern.ipc.maxpipekva exceeded; see tuning(7)\n");
return (ENOMEM);
}
/* free old resources if we're resizing */
pipe_free_kmem(cpipe);
cpipe->pipe_buffer.buffer = buffer;
cpipe->pipe_buffer.size = size;
cpipe->pipe_buffer.in = 0;
cpipe->pipe_buffer.out = 0;
cpipe->pipe_buffer.cnt = 0;
atomic_add_int(&amountpipes, 1);
atomic_add_int(&amountpipekva, cpipe->pipe_buffer.size);
return (0);
}
/*
* Initialize and allocate VM and memory for pipe. The structure
* will start out zero'd from the ctor, so we just manage the kmem.
*/
static int
pipe_create(pipe)
struct pipe *pipe;
{
int error;
/*
* Reduce to 1/4th pipe size if we're over our global max.
*/
if (amountpipekva > maxpipekva / 2)
error = pipespace(pipe, SMALL_PIPE_SIZE);
else
error = pipespace(pipe, PIPE_SIZE);
if (error)
return (error);
return (0);
}
/*
* lock a pipe for I/O, blocking other access
*/
static __inline int
pipelock(cpipe, catch)
struct pipe *cpipe;
int catch;
{
int error;
PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
while (cpipe->pipe_state & PIPE_LOCKFL) {
cpipe->pipe_state |= PIPE_LWANT;
error = msleep(cpipe, PIPE_MTX(cpipe),
catch ? (PRIBIO | PCATCH) : PRIBIO,
"pipelk", 0);
if (error != 0)
return (error);
}
cpipe->pipe_state |= PIPE_LOCKFL;
return (0);
}
/*
* unlock a pipe I/O lock
*/
static __inline void
pipeunlock(cpipe)
struct pipe *cpipe;
{
PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
cpipe->pipe_state &= ~PIPE_LOCKFL;
if (cpipe->pipe_state & PIPE_LWANT) {
cpipe->pipe_state &= ~PIPE_LWANT;
wakeup(cpipe);
}
}
static __inline void
pipeselwakeup(cpipe)
struct pipe *cpipe;
{
if (cpipe->pipe_state & PIPE_SEL) {
cpipe->pipe_state &= ~PIPE_SEL;
selwakeuppri(&cpipe->pipe_sel, PSOCK);
}
if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
KNOTE(&cpipe->pipe_sel.si_note, 0);
}
/* ARGSUSED */
static int
pipe_read(fp, uio, active_cred, flags, td)
struct file *fp;
struct uio *uio;
struct ucred *active_cred;
struct thread *td;
int flags;
{
struct pipe *rpipe = fp->f_data;
int error;
int nread = 0;
u_int size;
PIPE_LOCK(rpipe);
++rpipe->pipe_busy;
error = pipelock(rpipe, 1);
if (error)
goto unlocked_error;
#ifdef MAC
error = mac_check_pipe_read(active_cred, rpipe->pipe_pair);
if (error)
goto locked_error;
#endif
while (uio->uio_resid) {
/*
* normal pipe buffer receive
*/
if (rpipe->pipe_buffer.cnt > 0) {
size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
if (size > rpipe->pipe_buffer.cnt)
size = rpipe->pipe_buffer.cnt;
if (size > (u_int) uio->uio_resid)
size = (u_int) uio->uio_resid;
PIPE_UNLOCK(rpipe);
error = uiomove(
&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
size, uio);
PIPE_LOCK(rpipe);
if (error)
break;
rpipe->pipe_buffer.out += size;
if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
rpipe->pipe_buffer.out = 0;
rpipe->pipe_buffer.cnt -= size;
/*
* If there is no more to read in the pipe, reset
* its pointers to the beginning. This improves
* cache hit stats.
*/
if (rpipe->pipe_buffer.cnt == 0) {
rpipe->pipe_buffer.in = 0;
rpipe->pipe_buffer.out = 0;
}
nread += size;
#ifndef PIPE_NODIRECT
/*
* Direct copy, bypassing a kernel buffer.
*/
} else if ((size = rpipe->pipe_map.cnt) &&
(rpipe->pipe_state & PIPE_DIRECTW)) {
caddr_t va;
if (size > (u_int) uio->uio_resid)
size = (u_int) uio->uio_resid;
va = (caddr_t) rpipe->pipe_map.kva +
rpipe->pipe_map.pos;
PIPE_UNLOCK(rpipe);
error = uiomove(va, size, uio);
PIPE_LOCK(rpipe);
if (error)
break;
nread += size;
rpipe->pipe_map.pos += size;
rpipe->pipe_map.cnt -= size;
if (rpipe->pipe_map.cnt == 0) {
rpipe->pipe_state &= ~PIPE_DIRECTW;
wakeup(rpipe);
}
#endif
} else {
/*
* detect EOF condition
* read returns 0 on EOF, no need to set error
*/
if (rpipe->pipe_state & PIPE_EOF)
break;
/*
* If the "write-side" has been blocked, wake it up now.
*/
if (rpipe->pipe_state & PIPE_WANTW) {
rpipe->pipe_state &= ~PIPE_WANTW;
wakeup(rpipe);
}
/*
* Break if some data was read.
*/
if (nread > 0)
break;
/*
* Unlock the pipe buffer for our remaining processing.
* We will either break out with an error or we will
* sleep and relock to loop.
*/
pipeunlock(rpipe);
/*
* Handle non-blocking mode operation or
* wait for more data.
*/
if (fp->f_flag & FNONBLOCK) {
error = EAGAIN;
} else {
rpipe->pipe_state |= PIPE_WANTR;
if ((error = msleep(rpipe, PIPE_MTX(rpipe),
PRIBIO | PCATCH,
"piperd", 0)) == 0)
error = pipelock(rpipe, 1);
}
if (error)
goto unlocked_error;
}
}
#ifdef MAC
locked_error:
#endif
pipeunlock(rpipe);
/* XXX: should probably do this before getting any locks. */
if (error == 0)
vfs_timestamp(&rpipe->pipe_atime);
unlocked_error:
--rpipe->pipe_busy;
/*
* PIPE_WANT processing only makes sense if pipe_busy is 0.
*/
if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
wakeup(rpipe);
} else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
/*
* Handle write blocking hysteresis.
*/
if (rpipe->pipe_state & PIPE_WANTW) {
rpipe->pipe_state &= ~PIPE_WANTW;
wakeup(rpipe);
}
}
if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
pipeselwakeup(rpipe);
PIPE_UNLOCK(rpipe);
return (error);
}
#ifndef PIPE_NODIRECT
/*
* Map the sending processes' buffer into kernel space and wire it.
* This is similar to a physical write operation.
*/
static int
pipe_build_write_buffer(wpipe, uio)
struct pipe *wpipe;
struct uio *uio;
{
pmap_t pmap;
u_int size;
int i, j;
vm_offset_t addr, endaddr;
PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
size = (u_int) uio->uio_iov->iov_len;
if (size > wpipe->pipe_buffer.size)
size = wpipe->pipe_buffer.size;
pmap = vmspace_pmap(curproc->p_vmspace);
endaddr = round_page((vm_offset_t)uio->uio_iov->iov_base + size);
addr = trunc_page((vm_offset_t)uio->uio_iov->iov_base);
for (i = 0; addr < endaddr; addr += PAGE_SIZE, i++) {
/*
* vm_fault_quick() can sleep. Consequently,
* vm_page_lock_queue() and vm_page_unlock_queue()
* should not be performed outside of this loop.
*/
race:
if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0) {
vm_page_lock_queues();
for (j = 0; j < i; j++)
vm_page_unhold(wpipe->pipe_map.ms[j]);
vm_page_unlock_queues();
return (EFAULT);
}
wpipe->pipe_map.ms[i] = pmap_extract_and_hold(pmap, addr,
VM_PROT_READ);
if (wpipe->pipe_map.ms[i] == NULL)
goto race;
}
/*
* set up the control block
*/
wpipe->pipe_map.npages = i;
wpipe->pipe_map.pos =
((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
wpipe->pipe_map.cnt = size;
/*
* and map the buffer
*/
if (wpipe->pipe_map.kva == 0) {
/*
* We need to allocate space for an extra page because the
* address range might (will) span pages at times.
*/
wpipe->pipe_map.kva = kmem_alloc_nofault(kernel_map,
wpipe->pipe_buffer.size + PAGE_SIZE);
atomic_add_int(&amountpipekvawired,
wpipe->pipe_buffer.size + PAGE_SIZE);
}
pmap_qenter(wpipe->pipe_map.kva, wpipe->pipe_map.ms,
wpipe->pipe_map.npages);
/*
* and update the uio data
*/
uio->uio_iov->iov_len -= size;
uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
if (uio->uio_iov->iov_len == 0)
uio->uio_iov++;
uio->uio_resid -= size;
uio->uio_offset += size;
return (0);
}
/*
* unmap and unwire the process buffer
*/
static void
pipe_destroy_write_buffer(wpipe)
struct pipe *wpipe;
{
int i;
PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
if (wpipe->pipe_map.kva) {
pmap_qremove(wpipe->pipe_map.kva, wpipe->pipe_map.npages);
if (amountpipekvawired > maxpipekvawired / 2) {
/* Conserve address space */
vm_offset_t kva = wpipe->pipe_map.kva;
wpipe->pipe_map.kva = 0;
kmem_free(kernel_map, kva,
wpipe->pipe_buffer.size + PAGE_SIZE);
atomic_subtract_int(&amountpipekvawired,
wpipe->pipe_buffer.size + PAGE_SIZE);
}
}
vm_page_lock_queues();
for (i = 0; i < wpipe->pipe_map.npages; i++) {
vm_page_unhold(wpipe->pipe_map.ms[i]);
}
vm_page_unlock_queues();
wpipe->pipe_map.npages = 0;
}
/*
* In the case of a signal, the writing process might go away. This
* code copies the data into the circular buffer so that the source
* pages can be freed without loss of data.
*/
static void
pipe_clone_write_buffer(wpipe)
struct pipe *wpipe;
{
int size;
int pos;
PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
size = wpipe->pipe_map.cnt;
pos = wpipe->pipe_map.pos;
wpipe->pipe_buffer.in = size;
wpipe->pipe_buffer.out = 0;
wpipe->pipe_buffer.cnt = size;
wpipe->pipe_state &= ~PIPE_DIRECTW;
PIPE_UNLOCK(wpipe);
bcopy((caddr_t) wpipe->pipe_map.kva + pos,
wpipe->pipe_buffer.buffer, size);
pipe_destroy_write_buffer(wpipe);
PIPE_LOCK(wpipe);
}
/*
* This implements the pipe buffer write mechanism. Note that only
* a direct write OR a normal pipe write can be pending at any given time.
* If there are any characters in the pipe buffer, the direct write will
* be deferred until the receiving process grabs all of the bytes from
* the pipe buffer. Then the direct mapping write is set-up.
*/
static int
pipe_direct_write(wpipe, uio)
struct pipe *wpipe;
struct uio *uio;
{
int error;
retry:
PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
while (wpipe->pipe_state & PIPE_DIRECTW) {
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
wpipe->pipe_state |= PIPE_WANTW;
error = msleep(wpipe, PIPE_MTX(wpipe),
PRIBIO | PCATCH, "pipdww", 0);
if (error)
goto error1;
if (wpipe->pipe_state & PIPE_EOF) {
error = EPIPE;
goto error1;
}
}
wpipe->pipe_map.cnt = 0; /* transfer not ready yet */
if (wpipe->pipe_buffer.cnt > 0) {
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
wpipe->pipe_state |= PIPE_WANTW;
error = msleep(wpipe, PIPE_MTX(wpipe),
PRIBIO | PCATCH, "pipdwc", 0);
if (error)
goto error1;
if (wpipe->pipe_state & PIPE_EOF) {
error = EPIPE;
goto error1;
}
goto retry;
}
wpipe->pipe_state |= PIPE_DIRECTW;
pipelock(wpipe, 0);
PIPE_UNLOCK(wpipe);
error = pipe_build_write_buffer(wpipe, uio);
PIPE_LOCK(wpipe);
pipeunlock(wpipe);
if (error) {
wpipe->pipe_state &= ~PIPE_DIRECTW;
goto error1;
}
error = 0;
while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
if (wpipe->pipe_state & PIPE_EOF) {
pipelock(wpipe, 0);
PIPE_UNLOCK(wpipe);
pipe_destroy_write_buffer(wpipe);
PIPE_LOCK(wpipe);
pipeselwakeup(wpipe);
pipeunlock(wpipe);
error = EPIPE;
goto error1;
}
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
pipeselwakeup(wpipe);
error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
"pipdwt", 0);
}
pipelock(wpipe,0);
if (wpipe->pipe_state & PIPE_DIRECTW) {
/*
* this bit of trickery substitutes a kernel buffer for
* the process that might be going away.
*/
pipe_clone_write_buffer(wpipe);
} else {
PIPE_UNLOCK(wpipe);
pipe_destroy_write_buffer(wpipe);
PIPE_LOCK(wpipe);
}
pipeunlock(wpipe);
return (error);
error1:
wakeup(wpipe);
return (error);
}
#endif
static int
pipe_write(fp, uio, active_cred, flags, td)
struct file *fp;
struct uio *uio;
struct ucred *active_cred;
struct thread *td;
int flags;
{
int error = 0;
int orig_resid;
struct pipe *wpipe, *rpipe;
rpipe = fp->f_data;
wpipe = rpipe->pipe_peer;
PIPE_LOCK(rpipe);
/*
* detect loss of pipe read side, issue SIGPIPE if lost.
*/
if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
PIPE_UNLOCK(rpipe);
return (EPIPE);
}
#ifdef MAC
error = mac_check_pipe_write(active_cred, wpipe->pipe_pair);
if (error) {
PIPE_UNLOCK(rpipe);
return (error);
}
#endif
++wpipe->pipe_busy;
/*
* If it is advantageous to resize the pipe buffer, do
* so.
*/
if ((uio->uio_resid > PIPE_SIZE) &&
(amountpipekva < maxpipekva / 2) &&
(nbigpipe < LIMITBIGPIPES) &&
(wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
(wpipe->pipe_buffer.size <= PIPE_SIZE) &&
(wpipe->pipe_buffer.cnt == 0)) {
if ((error = pipelock(wpipe, 1)) == 0) {
PIPE_UNLOCK(wpipe);
if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
atomic_add_int(&nbigpipe, 1);
PIPE_LOCK(wpipe);
pipeunlock(wpipe);
}
}
/*
* If an early error occured unbusy and return, waking up any pending
* readers.
*/
if (error) {
--wpipe->pipe_busy;
if ((wpipe->pipe_busy == 0) &&
(wpipe->pipe_state & PIPE_WANT)) {
wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
wakeup(wpipe);
}
PIPE_UNLOCK(rpipe);
return(error);
}
orig_resid = uio->uio_resid;
while (uio->uio_resid) {
int space;
#ifndef PIPE_NODIRECT
/*
* If the transfer is large, we can gain performance if
* we do process-to-process copies directly.
* If the write is non-blocking, we don't use the
* direct write mechanism.
*
* The direct write mechanism will detect the reader going
* away on us.
*/
if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) &&
(fp->f_flag & FNONBLOCK) == 0 &&
amountpipekvawired + uio->uio_resid < maxpipekvawired) {
error = pipe_direct_write(wpipe, uio);
if (error)
break;
continue;
}
#endif
/*
* Pipe buffered writes cannot be coincidental with
* direct writes. We wait until the currently executing
* direct write is completed before we start filling the
* pipe buffer. We break out if a signal occurs or the
* reader goes away.
*/
retrywrite:
while (wpipe->pipe_state & PIPE_DIRECTW) {
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
"pipbww", 0);
if (wpipe->pipe_state & PIPE_EOF)
break;
if (error)
break;
}
if (wpipe->pipe_state & PIPE_EOF) {
error = EPIPE;
break;
}
space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
/* Writes of size <= PIPE_BUF must be atomic. */
if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
space = 0;
if (space > 0) {
if ((error = pipelock(wpipe,1)) == 0) {
int size; /* Transfer size */
int segsize; /* first segment to transfer */
/*
* It is possible for a direct write to
* slip in on us... handle it here...
*/
if (wpipe->pipe_state & PIPE_DIRECTW) {
pipeunlock(wpipe);
goto retrywrite;
}
/*
* If a process blocked in uiomove, our
* value for space might be bad.
*
* XXX will we be ok if the reader has gone
* away here?
*/
if (space > wpipe->pipe_buffer.size -
wpipe->pipe_buffer.cnt) {
pipeunlock(wpipe);
goto retrywrite;
}
/*
* Transfer size is minimum of uio transfer
* and free space in pipe buffer.
*/
if (space > uio->uio_resid)
size = uio->uio_resid;
else
size = space;
/*
* First segment to transfer is minimum of
* transfer size and contiguous space in
* pipe buffer. If first segment to transfer
* is less than the transfer size, we've got
* a wraparound in the buffer.
*/
segsize = wpipe->pipe_buffer.size -
wpipe->pipe_buffer.in;
if (segsize > size)
segsize = size;
/* Transfer first segment */
PIPE_UNLOCK(rpipe);
error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in],
segsize, uio);
PIPE_LOCK(rpipe);
if (error == 0 && segsize < size) {
/*
* Transfer remaining part now, to
* support atomic writes. Wraparound
* happened.
*/
if (wpipe->pipe_buffer.in + segsize !=
wpipe->pipe_buffer.size)
panic("Expected pipe buffer "
"wraparound disappeared");
PIPE_UNLOCK(rpipe);
error = uiomove(
&wpipe->pipe_buffer.buffer[0],
size - segsize, uio);
PIPE_LOCK(rpipe);
}
if (error == 0) {
wpipe->pipe_buffer.in += size;
if (wpipe->pipe_buffer.in >=
wpipe->pipe_buffer.size) {
if (wpipe->pipe_buffer.in !=
size - segsize +
wpipe->pipe_buffer.size)
panic("Expected "
"wraparound bad");
wpipe->pipe_buffer.in = size -
segsize;
}
wpipe->pipe_buffer.cnt += size;
if (wpipe->pipe_buffer.cnt >
wpipe->pipe_buffer.size)
panic("Pipe buffer overflow");
}
pipeunlock(wpipe);
}
if (error)
break;
} else {
/*
* If the "read-side" has been blocked, wake it up now.
*/
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
/*
* don't block on non-blocking I/O
*/
if (fp->f_flag & FNONBLOCK) {
error = EAGAIN;
break;
}
/*
* We have no more space and have something to offer,
* wake up select/poll.
*/
pipeselwakeup(wpipe);
wpipe->pipe_state |= PIPE_WANTW;
error = msleep(wpipe, PIPE_MTX(rpipe),
PRIBIO | PCATCH, "pipewr", 0);
if (error != 0)
break;
/*
* If read side wants to go away, we just issue a signal
* to ourselves.
*/
if (wpipe->pipe_state & PIPE_EOF) {
error = EPIPE;
break;
}
}
}
--wpipe->pipe_busy;
if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
wakeup(wpipe);
} else if (wpipe->pipe_buffer.cnt > 0) {
/*
* If we have put any characters in the buffer, we wake up
* the reader.
*/
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
wakeup(wpipe);
}
}
/*
* Don't return EPIPE if I/O was successful
*/
if ((wpipe->pipe_buffer.cnt == 0) &&
(uio->uio_resid == 0) &&
(error == EPIPE)) {
error = 0;
}
if (error == 0)
vfs_timestamp(&wpipe->pipe_mtime);
/*
* We have something to offer,
* wake up select/poll.
*/
if (wpipe->pipe_buffer.cnt)
pipeselwakeup(wpipe);
PIPE_UNLOCK(rpipe);
return (error);
}
/*
* we implement a very minimal set of ioctls for compatibility with sockets.
*/
static int
pipe_ioctl(fp, cmd, data, active_cred, td)
struct file *fp;
u_long cmd;
void *data;
struct ucred *active_cred;
struct thread *td;
{
struct pipe *mpipe = fp->f_data;
#ifdef MAC
int error;
#endif
PIPE_LOCK(mpipe);
#ifdef MAC
error = mac_check_pipe_ioctl(active_cred, mpipe->pipe_pair, cmd, data);
if (error) {
PIPE_UNLOCK(mpipe);
return (error);
}
#endif
switch (cmd) {
case FIONBIO:
PIPE_UNLOCK(mpipe);
return (0);
case FIOASYNC:
if (*(int *)data) {
mpipe->pipe_state |= PIPE_ASYNC;
} else {
mpipe->pipe_state &= ~PIPE_ASYNC;
}
PIPE_UNLOCK(mpipe);
return (0);
case FIONREAD:
if (mpipe->pipe_state & PIPE_DIRECTW)
*(int *)data = mpipe->pipe_map.cnt;
else
*(int *)data = mpipe->pipe_buffer.cnt;
PIPE_UNLOCK(mpipe);
return (0);
case FIOSETOWN:
PIPE_UNLOCK(mpipe);
return (fsetown(*(int *)data, &mpipe->pipe_sigio));
case FIOGETOWN:
PIPE_UNLOCK(mpipe);
*(int *)data = fgetown(&mpipe->pipe_sigio);
return (0);
/* This is deprecated, FIOSETOWN should be used instead. */
case TIOCSPGRP:
PIPE_UNLOCK(mpipe);
return (fsetown(-(*(int *)data), &mpipe->pipe_sigio));
/* This is deprecated, FIOGETOWN should be used instead. */
case TIOCGPGRP:
PIPE_UNLOCK(mpipe);
*(int *)data = -fgetown(&mpipe->pipe_sigio);
return (0);
}
PIPE_UNLOCK(mpipe);
return (ENOTTY);
}
static int
pipe_poll(fp, events, active_cred, td)
struct file *fp;
int events;
struct ucred *active_cred;
struct thread *td;
{
struct pipe *rpipe = fp->f_data;
struct pipe *wpipe;
int revents = 0;
#ifdef MAC
int error;
#endif
wpipe = rpipe->pipe_peer;
PIPE_LOCK(rpipe);
#ifdef MAC
error = mac_check_pipe_poll(active_cred, rpipe->pipe_pair);
if (error)
goto locked_error;
#endif
if (events & (POLLIN | POLLRDNORM))
if ((rpipe->pipe_state & PIPE_DIRECTW) ||
(rpipe->pipe_buffer.cnt > 0) ||
(rpipe->pipe_state & PIPE_EOF))
revents |= events & (POLLIN | POLLRDNORM);
if (events & (POLLOUT | POLLWRNORM))
if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) ||
(((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
(wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
revents |= events & (POLLOUT | POLLWRNORM);
if ((rpipe->pipe_state & PIPE_EOF) ||
(wpipe == NULL) ||
(wpipe->pipe_state & PIPE_EOF))
revents |= POLLHUP;
if (revents == 0) {
if (events & (POLLIN | POLLRDNORM)) {
selrecord(td, &rpipe->pipe_sel);
rpipe->pipe_state |= PIPE_SEL;
}
if (events & (POLLOUT | POLLWRNORM)) {
selrecord(td, &wpipe->pipe_sel);
wpipe->pipe_state |= PIPE_SEL;
}
}
#ifdef MAC
locked_error:
#endif
PIPE_UNLOCK(rpipe);
return (revents);
}
/*
* We shouldn't need locks here as we're doing a read and this should
* be a natural race.
*/
static int
pipe_stat(fp, ub, active_cred, td)
struct file *fp;
struct stat *ub;
struct ucred *active_cred;
struct thread *td;
{
struct pipe *pipe = fp->f_data;
#ifdef MAC
int error;
PIPE_LOCK(pipe);
error = mac_check_pipe_stat(active_cred, pipe->pipe_pair);
PIPE_UNLOCK(pipe);
if (error)
return (error);
#endif
bzero(ub, sizeof(*ub));
ub->st_mode = S_IFIFO;
ub->st_blksize = pipe->pipe_buffer.size;
ub->st_size = pipe->pipe_buffer.cnt;
ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
ub->st_atimespec = pipe->pipe_atime;
ub->st_mtimespec = pipe->pipe_mtime;
ub->st_ctimespec = pipe->pipe_ctime;
ub->st_uid = fp->f_cred->cr_uid;
ub->st_gid = fp->f_cred->cr_gid;
/*
* Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen.
* XXX (st_dev, st_ino) should be unique.
*/
return (0);
}
/* ARGSUSED */
static int
pipe_close(fp, td)
struct file *fp;
struct thread *td;
{
struct pipe *cpipe = fp->f_data;
fp->f_ops = &badfileops;
fp->f_data = NULL;
funsetown(&cpipe->pipe_sigio);
pipeclose(cpipe);
return (0);
}
static void
pipe_free_kmem(cpipe)
struct pipe *cpipe;
{
KASSERT(!mtx_owned(PIPE_MTX(cpipe)),
("pipe_free_kmem: pipe mutex locked"));
if (cpipe->pipe_buffer.buffer != NULL) {
if (cpipe->pipe_buffer.size > PIPE_SIZE)
atomic_subtract_int(&nbigpipe, 1);
atomic_subtract_int(&amountpipekva, cpipe->pipe_buffer.size);
atomic_subtract_int(&amountpipes, 1);
vm_map_remove(pipe_map,
(vm_offset_t)cpipe->pipe_buffer.buffer,
(vm_offset_t)cpipe->pipe_buffer.buffer + cpipe->pipe_buffer.size);
cpipe->pipe_buffer.buffer = NULL;
}
#ifndef PIPE_NODIRECT
if (cpipe->pipe_map.kva != 0) {
atomic_subtract_int(&amountpipekvawired,
cpipe->pipe_buffer.size + PAGE_SIZE);
kmem_free(kernel_map,
cpipe->pipe_map.kva,
cpipe->pipe_buffer.size + PAGE_SIZE);
cpipe->pipe_map.cnt = 0;
cpipe->pipe_map.kva = 0;
cpipe->pipe_map.pos = 0;
cpipe->pipe_map.npages = 0;
}
#endif
}
/*
* shutdown the pipe
*/
static void
pipeclose(cpipe)
struct pipe *cpipe;
{
struct pipepair *pp;
struct pipe *ppipe;
int hadpeer;
KASSERT(cpipe != NULL, ("pipeclose: cpipe == NULL"));
hadpeer = 0;
PIPE_LOCK(cpipe);
pp = cpipe->pipe_pair;
pipeselwakeup(cpipe);
/*
* If the other side is blocked, wake it up saying that
* we want to close it down.
*/
while (cpipe->pipe_busy) {
wakeup(cpipe);
cpipe->pipe_state |= PIPE_WANT | PIPE_EOF;
msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
}
/*
* Disconnect from peer, if any.
*/
ppipe = cpipe->pipe_peer;
if (ppipe->pipe_present != 0) {
hadpeer++;
pipeselwakeup(ppipe);
ppipe->pipe_state |= PIPE_EOF;
wakeup(ppipe);
KNOTE(&ppipe->pipe_sel.si_note, 0);
}
/*
* Mark this endpoint as free. Release kmem resources. We
* don't mark this endpoint as unused until we've finished
* doing that, or the pipe might disappear out from under
* us.
*/
PIPE_UNLOCK(cpipe);
pipe_free_kmem(cpipe);
PIPE_LOCK(cpipe);
cpipe->pipe_present = 0;
/*
* If both endpoints are now closed, release the memory for the
* pipe pair. If not, unlock.
*/
if (ppipe->pipe_present == 0) {
PIPE_UNLOCK(cpipe);
#ifdef MAC
mac_destroy_pipe(pp);
#endif
uma_zfree(pipe_zone, cpipe->pipe_pair);
} else
PIPE_UNLOCK(cpipe);
}
/*ARGSUSED*/
static int
pipe_kqfilter(struct file *fp, struct knote *kn)
{
struct pipe *cpipe;
cpipe = kn->kn_fp->f_data;
switch (kn->kn_filter) {
case EVFILT_READ:
kn->kn_fop = &pipe_rfiltops;
break;
case EVFILT_WRITE:
kn->kn_fop = &pipe_wfiltops;
cpipe = cpipe->pipe_peer;
if (cpipe == NULL)
/* other end of pipe has been closed */
return (EPIPE);
break;
default:
return (1);
}
PIPE_LOCK(cpipe);
SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
PIPE_UNLOCK(cpipe);
return (0);
}
static void
filt_pipedetach(struct knote *kn)
{
struct pipe *cpipe = (struct pipe *)kn->kn_fp->f_data;
if (kn->kn_filter == EVFILT_WRITE) {
if (cpipe->pipe_peer == NULL)
return;
cpipe = cpipe->pipe_peer;
}
PIPE_LOCK(cpipe);
SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
PIPE_UNLOCK(cpipe);
}
/*ARGSUSED*/
static int
filt_piperead(struct knote *kn, long hint)
{
struct pipe *rpipe = kn->kn_fp->f_data;
struct pipe *wpipe = rpipe->pipe_peer;
PIPE_LOCK(rpipe);
kn->kn_data = rpipe->pipe_buffer.cnt;
if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
kn->kn_data = rpipe->pipe_map.cnt;
if ((rpipe->pipe_state & PIPE_EOF) ||
(wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
kn->kn_flags |= EV_EOF;
PIPE_UNLOCK(rpipe);
return (1);
}
PIPE_UNLOCK(rpipe);
return (kn->kn_data > 0);
}
/*ARGSUSED*/
static int
filt_pipewrite(struct knote *kn, long hint)
{
struct pipe *rpipe = kn->kn_fp->f_data;
struct pipe *wpipe = rpipe->pipe_peer;
PIPE_LOCK(rpipe);
if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
kn->kn_data = 0;
kn->kn_flags |= EV_EOF;
PIPE_UNLOCK(rpipe);
return (1);
}
kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
if (wpipe->pipe_state & PIPE_DIRECTW)
kn->kn_data = 0;
PIPE_UNLOCK(rpipe);
return (kn->kn_data >= PIPE_BUF);
}
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