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NetBSD/sys/kern/sys_pipe.c

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/* $NetBSD: sys_pipe.c,v 1.84 2007/03/26 22:52:44 hubertf Exp $ */
/*-
* Copyright (c) 2003, 2007 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Paul Kranenburg, and by Andrew Doran.
*
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* 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.
*
* $FreeBSD: src/sys/kern/sys_pipe.c,v 1.95 2002/03/09 22:06:31 alfred Exp $
*/
/*
* 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.
*
* Adaption for NetBSD UVM, including uvm_loan() based direct write, was
* written by Jaromir Dolecek.
*/
/*
* 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 mapped read-only into the kernel address space
* using the UVM page loan facility from where the receiving process can copy
* the data directly from the pages in the sending process.
*
* 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. PIPE_SIZE is constrained by the
* amount of kernel virtual memory.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.84 2007/03/26 22:52:44 hubertf Exp $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/filio.h>
#include <sys/kernel.h>
#include <sys/ttycom.h>
#include <sys/stat.h>
#include <sys/malloc.h>
#include <sys/poll.h>
#include <sys/signalvar.h>
#include <sys/vnode.h>
#include <sys/uio.h>
#include <sys/lock.h>
#include <sys/select.h>
#include <sys/mount.h>
#include <sys/syscallargs.h>
#include <uvm/uvm.h>
#include <sys/sysctl.h>
#include <sys/kauth.h>
#include <sys/pipe.h>
/*
* Use this define if you want to disable *fancy* VM things. Expect an
* approx 30% decrease in transfer rate.
*/
/* #define PIPE_NODIRECT */
/*
* interfaces to the outside world
*/
static int pipe_read(struct file *fp, off_t *offset, struct uio *uio,
kauth_cred_t cred, int flags);
static int pipe_write(struct file *fp, off_t *offset, struct uio *uio,
kauth_cred_t cred, int flags);
static int pipe_close(struct file *fp, struct lwp *l);
static int pipe_poll(struct file *fp, int events, struct lwp *l);
static int pipe_kqfilter(struct file *fp, struct knote *kn);
static int pipe_stat(struct file *fp, struct stat *sb, struct lwp *l);
static int pipe_ioctl(struct file *fp, u_long cmd, void *data,
struct lwp *l);
static const struct fileops pipeops = {
pipe_read, pipe_write, pipe_ioctl, fnullop_fcntl, pipe_poll,
pipe_stat, pipe_close, pipe_kqfilter
};
/*
* 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)
/*
* Maximum amount of kva for pipes -- this is kind-of a soft limit, but
* is there so that on large systems, we don't exhaust it.
*/
#define MAXPIPEKVA (8*1024*1024)
static int maxpipekva = MAXPIPEKVA;
/*
* Limit for direct transfers, we cannot, of course limit
* the amount of kva for pipes in general though.
*/
#define LIMITPIPEKVA (16*1024*1024)
static int limitpipekva = LIMITPIPEKVA;
/*
* Limit the number of "big" pipes
*/
#define LIMITBIGPIPES 32
static int maxbigpipes = LIMITBIGPIPES;
static int nbigpipe = 0;
/*
* Amount of KVA consumed by pipe buffers.
*/
static int amountpipekva = 0;
MALLOC_DEFINE(M_PIPE, "pipe", "Pipe structures");
static void pipeclose(struct file *fp, struct pipe *pipe);
static void pipe_free_kmem(struct pipe *pipe);
static int pipe_create(struct pipe **pipep, int allockva);
static int pipelock(struct pipe *pipe, int catch);
static inline void pipeunlock(struct pipe *pipe);
static void pipeselwakeup(struct pipe *pipe, struct pipe *sigp, int code);
#ifndef PIPE_NODIRECT
static int pipe_direct_write(struct file *fp, struct pipe *wpipe,
struct uio *uio);
#endif
static int pipespace(struct pipe *pipe, int size);
#ifndef PIPE_NODIRECT
static int pipe_loan_alloc(struct pipe *, int);
static void pipe_loan_free(struct pipe *);
#endif /* PIPE_NODIRECT */
static POOL_INIT(pipe_pool, sizeof(struct pipe), 0, 0, 0, "pipepl",
&pool_allocator_nointr, IPL_NONE);
static krwlock_t pipe_peer_lock;
void
pipe_init(void)
{
rw_init(&pipe_peer_lock);
}
/*
* The pipe system call for the DTYPE_PIPE type of pipes
*/
/* ARGSUSED */
int
sys_pipe(struct lwp *l, void *v, register_t *retval)
{
struct file *rf, *wf;
struct pipe *rpipe, *wpipe;
int fd, error;
rpipe = wpipe = NULL;
if (pipe_create(&rpipe, 1) || pipe_create(&wpipe, 0)) {
pipeclose(NULL, rpipe);
pipeclose(NULL, wpipe);
return (ENFILE);
}
/*
* Note: the file structure returned from falloc() is marked
* as 'larval' initially. Unless we mark it as 'mature' by
* FILE_SET_MATURE(), any attempt to do anything with it would
* return EBADF, including e.g. dup(2) or close(2). This avoids
* file descriptor races if we block in the second falloc().
*/
error = falloc(l, &rf, &fd);
if (error)
goto free2;
retval[0] = fd;
rf->f_flag = FREAD;
rf->f_type = DTYPE_PIPE;
rf->f_data = (void *)rpipe;
rf->f_ops = &pipeops;
error = falloc(l, &wf, &fd);
if (error)
goto free3;
retval[1] = fd;
wf->f_flag = FWRITE;
wf->f_type = DTYPE_PIPE;
wf->f_data = (void *)wpipe;
wf->f_ops = &pipeops;
rpipe->pipe_peer = wpipe;
wpipe->pipe_peer = rpipe;
FILE_SET_MATURE(rf);
FILE_SET_MATURE(wf);
FILE_UNUSE(rf, l);
FILE_UNUSE(wf, l);
return (0);
free3:
FILE_UNUSE(rf, l);
ffree(rf);
fdremove(l->l_proc->p_fd, retval[0]);
free2:
pipeclose(NULL, wpipe);
pipeclose(NULL, rpipe);
return (error);
}
/*
* 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(struct pipe *pipe, int size)
{
void *buffer;
/*
* Allocate pageable virtual address space. Physical memory is
* allocated on demand.
*/
buffer = (void *) uvm_km_alloc(kernel_map, round_page(size), 0,
UVM_KMF_PAGEABLE);
if (buffer == NULL)
return (ENOMEM);
/* free old resources if we're resizing */
pipe_free_kmem(pipe);
pipe->pipe_buffer.buffer = buffer;
pipe->pipe_buffer.size = size;
pipe->pipe_buffer.in = 0;
pipe->pipe_buffer.out = 0;
pipe->pipe_buffer.cnt = 0;
amountpipekva += pipe->pipe_buffer.size;
return (0);
}
/*
* Initialize and allocate VM and memory for pipe.
*/
static int
pipe_create(struct pipe **pipep, int allockva)
{
struct pipe *pipe;
int error;
pipe = *pipep = pool_get(&pipe_pool, PR_WAITOK);
/* Initialize */
memset(pipe, 0, sizeof(struct pipe));
pipe->pipe_state = PIPE_SIGNALR;
getmicrotime(&pipe->pipe_ctime);
pipe->pipe_atime = pipe->pipe_ctime;
pipe->pipe_mtime = pipe->pipe_ctime;
mutex_init(&pipe->pipe_lock, MUTEX_DEFAULT, IPL_NONE);
cv_init(&pipe->pipe_cv, "pipe");
cv_init(&pipe->pipe_lkcv, "pipelk");
if (allockva && (error = pipespace(pipe, PIPE_SIZE)))
return (error);
return (0);
}
/*
* Lock a pipe for I/O, blocking other access
* Called with pipe spin lock held.
* Return with pipe spin lock released on success.
*/
static int
pipelock(struct pipe *pipe, int catch)
{
int error;
KASSERT(mutex_owned(&pipe->pipe_lock));
while (pipe->pipe_state & PIPE_LOCKFL) {
pipe->pipe_state |= PIPE_LWANT;
if (catch) {
error = cv_wait_sig(&pipe->pipe_lkcv,
&pipe->pipe_lock);
if (error != 0)
return error;
} else
cv_wait(&pipe->pipe_lkcv, &pipe->pipe_lock);
}
pipe->pipe_state |= PIPE_LOCKFL;
mutex_exit(&pipe->pipe_lock);
return 0;
}
/*
* unlock a pipe I/O lock
*/
static inline void
pipeunlock(struct pipe *pipe)
{
KASSERT(pipe->pipe_state & PIPE_LOCKFL);
pipe->pipe_state &= ~PIPE_LOCKFL;
if (pipe->pipe_state & PIPE_LWANT) {
pipe->pipe_state &= ~PIPE_LWANT;
cv_broadcast(&pipe->pipe_lkcv);
}
}
/*
* Select/poll wakup. This also sends SIGIO to peer connected to
* 'sigpipe' side of pipe.
*/
static void
pipeselwakeup(struct pipe *selp, struct pipe *sigp, int code)
{
int band;
selnotify(&selp->pipe_sel, NOTE_SUBMIT);
if (sigp == NULL || (sigp->pipe_state & PIPE_ASYNC) == 0)
return;
switch (code) {
case POLL_IN:
band = POLLIN|POLLRDNORM;
break;
case POLL_OUT:
band = POLLOUT|POLLWRNORM;
break;
case POLL_HUP:
band = POLLHUP;
break;
#if POLL_HUP != POLL_ERR
case POLL_ERR:
band = POLLERR;
break;
#endif
default:
band = 0;
#ifdef DIAGNOSTIC
printf("bad siginfo code %d in pipe notification.\n", code);
#endif
break;
}
fownsignal(sigp->pipe_pgid, SIGIO, code, band, selp);
}
/* ARGSUSED */
static int
pipe_read(struct file *fp, off_t *offset, struct uio *uio, kauth_cred_t cred,
int flags)
{
struct pipe *rpipe = (struct pipe *) fp->f_data;
struct pipebuf *bp = &rpipe->pipe_buffer;
int error;
size_t nread = 0;
size_t size;
size_t ocnt;
mutex_enter(&rpipe->pipe_lock);
++rpipe->pipe_busy;
ocnt = bp->cnt;
again:
error = pipelock(rpipe, 1);
if (error)
goto unlocked_error;
while (uio->uio_resid) {
/*
* normal pipe buffer receive
*/
if (bp->cnt > 0) {
size = bp->size - bp->out;
if (size > bp->cnt)
size = bp->cnt;
if (size > uio->uio_resid)
size = uio->uio_resid;
error = uiomove((char *)bp->buffer + bp->out, size, uio);
if (error)
break;
bp->out += size;
if (bp->out >= bp->size)
bp->out = 0;
bp->cnt -= size;
/*
* If there is no more to read in the pipe, reset
* its pointers to the beginning. This improves
* cache hit stats.
*/
if (bp->cnt == 0) {
bp->in = 0;
bp->out = 0;
}
nread += size;
#ifndef PIPE_NODIRECT
} else if ((rpipe->pipe_state & PIPE_DIRECTR) != 0) {
/*
* Direct copy, bypassing a kernel buffer.
*/
void * va;
KASSERT(rpipe->pipe_state & PIPE_DIRECTW);
size = rpipe->pipe_map.cnt;
if (size > uio->uio_resid)
size = uio->uio_resid;
va = (char *)rpipe->pipe_map.kva + rpipe->pipe_map.pos;
error = uiomove(va, size, uio);
if (error)
break;
nread += size;
rpipe->pipe_map.pos += size;
rpipe->pipe_map.cnt -= size;
if (rpipe->pipe_map.cnt == 0) {
mutex_enter(&rpipe->pipe_lock);
rpipe->pipe_state &= ~PIPE_DIRECTR;
cv_broadcast(&rpipe->pipe_cv);
mutex_exit(&rpipe->pipe_lock);
}
#endif
} else {
/*
* Break if some data was read.
*/
if (nread > 0)
break;
mutex_enter(&rpipe->pipe_lock);
/*
* detect EOF condition
* read returns 0 on EOF, no need to set error
*/
if (rpipe->pipe_state & PIPE_EOF) {
mutex_exit(&rpipe->pipe_lock);
break;
}
/*
* don't block on non-blocking I/O
*/
if (fp->f_flag & FNONBLOCK) {
mutex_exit(&rpipe->pipe_lock);
error = EAGAIN;
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);
/*
* The PIPE_DIRECTR flag is not under the control
* of the long-term lock (see pipe_direct_write()),
* so re-check now while holding the spin lock.
*/
if ((rpipe->pipe_state & PIPE_DIRECTR) != 0)
goto again;
/*
* We want to read more, wake up select/poll.
*/
pipeselwakeup(rpipe, rpipe->pipe_peer, POLL_IN);
/*
* If the "write-side" is blocked, wake it up now.
*/
if (rpipe->pipe_state & PIPE_WANTW) {
rpipe->pipe_state &= ~PIPE_WANTW;
cv_broadcast(&rpipe->pipe_cv);
}
/* Now wait until the pipe is filled */
rpipe->pipe_state |= PIPE_WANTR;
error = cv_wait_sig(&rpipe->pipe_cv,
&rpipe->pipe_lock);
if (error != 0)
goto unlocked_error;
goto again;
}
}
if (error == 0)
getmicrotime(&rpipe->pipe_atime);
mutex_enter(&rpipe->pipe_lock);
pipeunlock(rpipe);
unlocked_error:
--rpipe->pipe_busy;
/*
* PIPE_WANTCLOSE processing only makes sense if pipe_busy is 0.
*/
if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANTCLOSE)) {
rpipe->pipe_state &= ~(PIPE_WANTCLOSE|PIPE_WANTW);
cv_broadcast(&rpipe->pipe_cv);
} else if (bp->cnt < MINPIPESIZE) {
/*
* Handle write blocking hysteresis.
*/
if (rpipe->pipe_state & PIPE_WANTW) {
rpipe->pipe_state &= ~PIPE_WANTW;
cv_broadcast(&rpipe->pipe_cv);
}
}
/*
* If anything was read off the buffer, signal to the writer it's
* possible to write more data. Also send signal if we are here for the
* first time after last write.
*/
if ((bp->size - bp->cnt) >= PIPE_BUF
&& (ocnt != bp->cnt || (rpipe->pipe_state & PIPE_SIGNALR))) {
pipeselwakeup(rpipe, rpipe->pipe_peer, POLL_OUT);
rpipe->pipe_state &= ~PIPE_SIGNALR;
}
mutex_exit(&rpipe->pipe_lock);
return (error);
}
#ifndef PIPE_NODIRECT
/*
* Allocate structure for loan transfer.
*/
static int
pipe_loan_alloc(struct pipe *wpipe, int npages)
{
vsize_t len;
len = (vsize_t)npages << PAGE_SHIFT;
wpipe->pipe_map.kva = uvm_km_alloc(kernel_map, len, 0,
UVM_KMF_VAONLY | UVM_KMF_WAITVA);
if (wpipe->pipe_map.kva == 0)
return (ENOMEM);
amountpipekva += len;
wpipe->pipe_map.npages = npages;
wpipe->pipe_map.pgs = malloc(npages * sizeof(struct vm_page *), M_PIPE,
M_WAITOK);
return (0);
}
/*
* Free resources allocated for loan transfer.
*/
static void
pipe_loan_free(struct pipe *wpipe)
{
vsize_t len;
len = (vsize_t)wpipe->pipe_map.npages << PAGE_SHIFT;
uvm_km_free(kernel_map, wpipe->pipe_map.kva, len, UVM_KMF_VAONLY);
wpipe->pipe_map.kva = 0;
amountpipekva -= len;
free(wpipe->pipe_map.pgs, M_PIPE);
wpipe->pipe_map.pgs = NULL;
}
/*
* NetBSD direct write, using uvm_loan() mechanism.
* 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.
*
* Called with the long-term pipe lock held.
*/
static int
pipe_direct_write(struct file *fp, struct pipe *wpipe, struct uio *uio)
{
int error, npages, j;
struct vm_page **pgs;
vaddr_t bbase, kva, base, bend;
vsize_t blen, bcnt;
voff_t bpos;
KASSERT(wpipe->pipe_map.cnt == 0);
/*
* Handle first PIPE_CHUNK_SIZE bytes of buffer. Deal with buffers
* not aligned to PAGE_SIZE.
*/
bbase = (vaddr_t)uio->uio_iov->iov_base;
base = trunc_page(bbase);
bend = round_page(bbase + uio->uio_iov->iov_len);
blen = bend - base;
bpos = bbase - base;
if (blen > PIPE_DIRECT_CHUNK) {
blen = PIPE_DIRECT_CHUNK;
bend = base + blen;
bcnt = PIPE_DIRECT_CHUNK - bpos;
} else {
bcnt = uio->uio_iov->iov_len;
}
npages = blen >> PAGE_SHIFT;
/*
* Free the old kva if we need more pages than we have
* allocated.
*/
if (wpipe->pipe_map.kva != 0 && npages > wpipe->pipe_map.npages)
pipe_loan_free(wpipe);
/* Allocate new kva. */
if (wpipe->pipe_map.kva == 0) {
error = pipe_loan_alloc(wpipe, npages);
if (error)
return (error);
}
/* Loan the write buffer memory from writer process */
pgs = wpipe->pipe_map.pgs;
error = uvm_loan(&uio->uio_vmspace->vm_map, base, blen,
pgs, UVM_LOAN_TOPAGE);
if (error) {
pipe_loan_free(wpipe);
return (ENOMEM); /* so that caller fallback to ordinary write */
}
/* Enter the loaned pages to kva */
kva = wpipe->pipe_map.kva;
for (j = 0; j < npages; j++, kva += PAGE_SIZE) {
pmap_kenter_pa(kva, VM_PAGE_TO_PHYS(pgs[j]), VM_PROT_READ);
}
pmap_update(pmap_kernel());
/* Now we can put the pipe in direct write mode */
wpipe->pipe_map.pos = bpos;
wpipe->pipe_map.cnt = bcnt;
wpipe->pipe_state |= PIPE_DIRECTW;
/*
* But before we can let someone do a direct read,
* we have to wait until the pipe is drained.
*/
/* Relase the pipe lock while we wait */
mutex_enter(&wpipe->pipe_lock);
pipeunlock(wpipe);
while (error == 0 && wpipe->pipe_buffer.cnt > 0) {
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
cv_broadcast(&wpipe->pipe_cv);
}
wpipe->pipe_state |= PIPE_WANTW;
error = cv_wait_sig(&wpipe->pipe_cv, &wpipe->pipe_lock);
if (error == 0 && wpipe->pipe_state & PIPE_EOF)
error = EPIPE;
}
/* Pipe is drained; next read will off the direct buffer */
wpipe->pipe_state |= PIPE_DIRECTR;
/* Wait until the reader is done */
while (error == 0 && (wpipe->pipe_state & PIPE_DIRECTR)) {
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
cv_broadcast(&wpipe->pipe_cv);
}
pipeselwakeup(wpipe, wpipe, POLL_IN);
error = cv_wait_sig(&wpipe->pipe_cv, &wpipe->pipe_lock);
if (error == 0 && wpipe->pipe_state & PIPE_EOF)
error = EPIPE;
}
/* Take pipe out of direct write mode */
wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTR);
/* Acquire the pipe lock and cleanup */
(void)pipelock(wpipe, 0);
if (pgs != NULL) {
pmap_kremove(wpipe->pipe_map.kva, blen);
uvm_unloan(pgs, npages, UVM_LOAN_TOPAGE);
}
if (error || amountpipekva > maxpipekva)
pipe_loan_free(wpipe);
if (error) {
pipeselwakeup(wpipe, wpipe, POLL_ERR);
/*
* If nothing was read from what we offered, return error
* straight on. Otherwise update uio resid first. Caller
* will deal with the error condition, returning short
* write, error, or restarting the write(2) as appropriate.
*/
if (wpipe->pipe_map.cnt == bcnt) {
wpipe->pipe_map.cnt = 0;
cv_broadcast(&wpipe->pipe_cv);
return (error);
}
bcnt -= wpipe->pipe_map.cnt;
}
uio->uio_resid -= bcnt;
/* uio_offset not updated, not set/used for write(2) */
uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + bcnt;
uio->uio_iov->iov_len -= bcnt;
if (uio->uio_iov->iov_len == 0) {
uio->uio_iov++;
uio->uio_iovcnt--;
}
wpipe->pipe_map.cnt = 0;
return (error);
}
#endif /* !PIPE_NODIRECT */
static int
pipe_write(struct file *fp, off_t *offset, struct uio *uio, kauth_cred_t cred,
int flags)
{
struct pipe *wpipe, *rpipe;
struct pipebuf *bp;
int error;
/* We want to write to our peer */
rpipe = (struct pipe *) fp->f_data;
retry:
error = 0;
mutex_enter(&rpipe->pipe_lock);
wpipe = rpipe->pipe_peer;
/*
* Detect loss of pipe read side, issue SIGPIPE if lost.
*/
if (wpipe == NULL)
error = EPIPE;
else if (mutex_tryenter(&wpipe->pipe_lock) == 0) {
/* Deal with race for peer */
mutex_exit(&rpipe->pipe_lock);
goto retry;
} else if ((wpipe->pipe_state & PIPE_EOF) != 0) {
mutex_exit(&wpipe->pipe_lock);
error = EPIPE;
}
mutex_exit(&rpipe->pipe_lock);
if (error != 0)
return (error);
++wpipe->pipe_busy;
/* Aquire the long-term pipe lock */
if ((error = pipelock(wpipe,1)) != 0) {
--wpipe->pipe_busy;
if (wpipe->pipe_busy == 0
&& (wpipe->pipe_state & PIPE_WANTCLOSE)) {
wpipe->pipe_state &= ~(PIPE_WANTCLOSE | PIPE_WANTR);
cv_broadcast(&wpipe->pipe_cv);
}
mutex_exit(&wpipe->pipe_lock);
return (error);
}
bp = &wpipe->pipe_buffer;
/*
* If it is advantageous to resize the pipe buffer, do so.
*/
if ((uio->uio_resid > PIPE_SIZE) &&
(nbigpipe < maxbigpipes) &&
#ifndef PIPE_NODIRECT
(wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
#endif
(bp->size <= PIPE_SIZE) && (bp->cnt == 0)) {
if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
nbigpipe++;
}
while (uio->uio_resid) {
size_t space;
#ifndef PIPE_NODIRECT
/*
* Pipe buffered writes cannot be coincidental with
* direct writes. Also, only one direct write can be
* in progress at any one time. We wait until the currently
* executing direct write is completed before continuing.
*
* We break out if a signal occurs or the reader goes away.
*/
while (error == 0 && wpipe->pipe_state & PIPE_DIRECTW) {
mutex_enter(&wpipe->pipe_lock);
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
cv_broadcast(&wpipe->pipe_cv);
}
pipeunlock(wpipe);
error = cv_wait_sig(&wpipe->pipe_cv,
&wpipe->pipe_lock);
(void)pipelock(wpipe, 0);
if (wpipe->pipe_state & PIPE_EOF)
error = EPIPE;
}
if (error)
break;
/*
* 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 &&
(wpipe->pipe_map.kva || (amountpipekva < limitpipekva))) {
error = pipe_direct_write(fp, wpipe, uio);
/*
* Break out if error occurred, unless it's ENOMEM.
* ENOMEM means we failed to allocate some resources
* for direct write, so we just fallback to ordinary
* write. If the direct write was successful,
* process rest of data via ordinary write.
*/
if (error == 0)
continue;
if (error != ENOMEM)
break;
}
#endif /* PIPE_NODIRECT */
space = bp->size - bp->cnt;
/* Writes of size <= PIPE_BUF must be atomic. */
if ((space < uio->uio_resid) && (uio->uio_resid <= PIPE_BUF))
space = 0;
if (space > 0) {
int size; /* Transfer size */
int segsize; /* first segment to transfer */
/*
* 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 = bp->size - bp->in;
if (segsize > size)
segsize = size;
/* Transfer first segment */
error = uiomove((char *)bp->buffer + bp->in, segsize,
uio);
if (error == 0 && segsize < size) {
/*
* Transfer remaining part now, to
* support atomic writes. Wraparound
* happened.
*/
#ifdef DEBUG
if (bp->in + segsize != bp->size)
panic("Expected pipe buffer wraparound disappeared");
#endif
error = uiomove(bp->buffer,
size - segsize, uio);
}
if (error)
break;
bp->in += size;
if (bp->in >= bp->size) {
#ifdef DEBUG
if (bp->in != size - segsize + bp->size)
panic("Expected wraparound bad");
#endif
bp->in = size - segsize;
}
bp->cnt += size;
#ifdef DEBUG
if (bp->cnt > bp->size)
panic("Pipe buffer overflow");
#endif
} else {
/*
* If the "read-side" has been blocked, wake it up now.
*/
mutex_enter(&wpipe->pipe_lock);
if (wpipe->pipe_state & PIPE_WANTR) {
wpipe->pipe_state &= ~PIPE_WANTR;
cv_broadcast(&wpipe->pipe_cv);
}
mutex_exit(&wpipe->pipe_lock);
/*
* 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.
*/
if (bp->cnt)
pipeselwakeup(wpipe, wpipe, POLL_OUT);
mutex_enter(&wpipe->pipe_lock);
pipeunlock(wpipe);
wpipe->pipe_state |= PIPE_WANTW;
error = cv_wait_sig(&wpipe->pipe_cv,
&wpipe->pipe_lock);
(void)pipelock(wpipe, 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;
}
}
}
mutex_enter(&wpipe->pipe_lock);
--wpipe->pipe_busy;
if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANTCLOSE)) {
wpipe->pipe_state &= ~(PIPE_WANTCLOSE | PIPE_WANTR);
cv_broadcast(&wpipe->pipe_cv);
} else if (bp->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;
cv_broadcast(&wpipe->pipe_cv);
}
}
/*
* Don't return EPIPE if I/O was successful
*/
if (error == EPIPE && bp->cnt == 0 && uio->uio_resid == 0)
error = 0;
if (error == 0)
getmicrotime(&wpipe->pipe_mtime);
/*
* We have something to offer, wake up select/poll.
* wpipe->pipe_map.cnt is always 0 in this point (direct write
* is only done synchronously), so check only wpipe->pipe_buffer.cnt
*/
if (bp->cnt)
pipeselwakeup(wpipe, wpipe, POLL_OUT);
/*
* Arrange for next read(2) to do a signal.
*/
wpipe->pipe_state |= PIPE_SIGNALR;
pipeunlock(wpipe);
mutex_exit(&wpipe->pipe_lock);
return (error);
}
/*
* we implement a very minimal set of ioctls for compatibility with sockets.
*/
int
pipe_ioctl(struct file *fp, u_long cmd, void *data, struct lwp *l)
{
struct pipe *pipe = (struct pipe *)fp->f_data;
struct proc *p = l->l_proc;
switch (cmd) {
case FIONBIO:
return (0);
case FIOASYNC:
mutex_enter(&pipe->pipe_lock);
if (*(int *)data) {
pipe->pipe_state |= PIPE_ASYNC;
} else {
pipe->pipe_state &= ~PIPE_ASYNC;
}
mutex_exit(&pipe->pipe_lock);
return (0);
case FIONREAD:
mutex_enter(&pipe->pipe_lock);
#ifndef PIPE_NODIRECT
if (pipe->pipe_state & PIPE_DIRECTW)
*(int *)data = pipe->pipe_map.cnt;
else
#endif
*(int *)data = pipe->pipe_buffer.cnt;
mutex_exit(&pipe->pipe_lock);
return (0);
case FIONWRITE:
/* Look at other side */
rw_enter(&pipe_peer_lock, RW_READER);
pipe = pipe->pipe_peer;
mutex_enter(&pipe->pipe_lock);
#ifndef PIPE_NODIRECT
if (pipe->pipe_state & PIPE_DIRECTW)
*(int *)data = pipe->pipe_map.cnt;
else
#endif
*(int *)data = pipe->pipe_buffer.cnt;
mutex_exit(&pipe->pipe_lock);
rw_exit(&pipe_peer_lock);
return (0);
case FIONSPACE:
/* Look at other side */
rw_enter(&pipe_peer_lock, RW_READER);
pipe = pipe->pipe_peer;
mutex_enter(&pipe->pipe_lock);
#ifndef PIPE_NODIRECT
/*
* If we're in direct-mode, we don't really have a
* send queue, and any other write will block. Thus
* zero seems like the best answer.
*/
if (pipe->pipe_state & PIPE_DIRECTW)
*(int *)data = 0;
else
#endif
*(int *)data = pipe->pipe_buffer.size -
pipe->pipe_buffer.cnt;
mutex_exit(&pipe->pipe_lock);
rw_exit(&pipe_peer_lock);
return (0);
case TIOCSPGRP:
case FIOSETOWN:
return fsetown(p, &pipe->pipe_pgid, cmd, data);
case TIOCGPGRP:
case FIOGETOWN:
return fgetown(p, pipe->pipe_pgid, cmd, data);
}
return (EPASSTHROUGH);
}
int
pipe_poll(struct file *fp, int events, struct lwp *l)
{
struct pipe *rpipe = (struct pipe *)fp->f_data;
struct pipe *wpipe;
int eof = 0;
int revents = 0;
retry:
mutex_enter(&rpipe->pipe_lock);
wpipe = rpipe->pipe_peer;
if (wpipe != NULL && mutex_tryenter(&wpipe->pipe_lock) == 0) {
/* Deal with race for peer */
mutex_exit(&rpipe->pipe_lock);
goto retry;
}
if (events & (POLLIN | POLLRDNORM))
if ((rpipe->pipe_buffer.cnt > 0) ||
#ifndef PIPE_NODIRECT
(rpipe->pipe_state & PIPE_DIRECTR) ||
#endif
(rpipe->pipe_state & PIPE_EOF))
revents |= events & (POLLIN | POLLRDNORM);
eof |= (rpipe->pipe_state & PIPE_EOF);
mutex_exit(&rpipe->pipe_lock);
if (wpipe == NULL)
revents |= events & (POLLOUT | POLLWRNORM);
else {
if (events & (POLLOUT | POLLWRNORM))
if ((wpipe->pipe_state & PIPE_EOF) || (
#ifndef PIPE_NODIRECT
(wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
#endif
(wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
revents |= events & (POLLOUT | POLLWRNORM);
eof |= (wpipe->pipe_state & PIPE_EOF);
mutex_exit(&wpipe->pipe_lock);
}
if (wpipe == NULL || eof)
revents |= POLLHUP;
if (revents == 0) {
if (events & (POLLIN | POLLRDNORM))
selrecord(l, &rpipe->pipe_sel);
if (events & (POLLOUT | POLLWRNORM))
selrecord(l, &wpipe->pipe_sel);
}
return (revents);
}
static int
pipe_stat(struct file *fp, struct stat *ub, struct lwp *l)
{
struct pipe *pipe = (struct pipe *)fp->f_data;
rw_enter(&pipe_peer_lock, RW_READER);
memset((void *)ub, 0, sizeof(*ub));
ub->st_mode = S_IFIFO | S_IRUSR | S_IWUSR;
ub->st_blksize = pipe->pipe_buffer.size;
if (ub->st_blksize == 0 && pipe->pipe_peer)
ub->st_blksize = pipe->pipe_peer->pipe_buffer.size;
ub->st_size = pipe->pipe_buffer.cnt;
ub->st_blocks = (ub->st_size) ? 1 : 0;
TIMEVAL_TO_TIMESPEC(&pipe->pipe_atime, &ub->st_atimespec);
TIMEVAL_TO_TIMESPEC(&pipe->pipe_mtime, &ub->st_mtimespec);
TIMEVAL_TO_TIMESPEC(&pipe->pipe_ctime, &ub->st_ctimespec);
ub->st_uid = kauth_cred_geteuid(fp->f_cred);
ub->st_gid = kauth_cred_getegid(fp->f_cred);
rw_exit(&pipe_peer_lock);
/*
* 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(struct file *fp, struct lwp *l)
{
struct pipe *pipe = (struct pipe *)fp->f_data;
fp->f_data = NULL;
pipeclose(fp, pipe);
return (0);
}
static void
pipe_free_kmem(struct pipe *pipe)
{
if (pipe->pipe_buffer.buffer != NULL) {
if (pipe->pipe_buffer.size > PIPE_SIZE)
--nbigpipe;
amountpipekva -= pipe->pipe_buffer.size;
uvm_km_free(kernel_map,
(vaddr_t)pipe->pipe_buffer.buffer,
pipe->pipe_buffer.size, UVM_KMF_PAGEABLE);
pipe->pipe_buffer.buffer = NULL;
}
#ifndef PIPE_NODIRECT
if (pipe->pipe_map.kva != 0) {
pipe_loan_free(pipe);
pipe->pipe_map.cnt = 0;
pipe->pipe_map.kva = 0;
pipe->pipe_map.pos = 0;
pipe->pipe_map.npages = 0;
}
#endif /* !PIPE_NODIRECT */
}
/*
* shutdown the pipe
*/
static void
pipeclose(struct file *fp, struct pipe *pipe)
{
struct pipe *ppipe;
if (pipe == NULL)
return;
retry:
rw_enter(&pipe_peer_lock, RW_WRITER);
mutex_enter(&pipe->pipe_lock);
pipeselwakeup(pipe, pipe, POLL_HUP);
/*
* If the other side is blocked, wake it up saying that
* we want to close it down.
*/
pipe->pipe_state |= PIPE_EOF;
if (pipe->pipe_busy) {
rw_exit(&pipe_peer_lock);
while (pipe->pipe_busy) {
cv_broadcast(&pipe->pipe_cv);
pipe->pipe_state |= PIPE_WANTCLOSE;
cv_wait_sig(&pipe->pipe_cv, &pipe->pipe_lock);
}
if (!rw_tryenter(&pipe_peer_lock, RW_READER)) {
mutex_exit(&pipe->pipe_lock);
goto retry;
}
}
/*
* Disconnect from peer
*/
if ((ppipe = pipe->pipe_peer) != NULL) {
/* Deal with race for peer */
if (mutex_tryenter(&ppipe->pipe_lock) == 0) {
mutex_exit(&pipe->pipe_lock);
rw_exit(&pipe_peer_lock);
goto retry;
}
pipeselwakeup(ppipe, ppipe, POLL_HUP);
ppipe->pipe_state |= PIPE_EOF;
cv_broadcast(&ppipe->pipe_cv);
ppipe->pipe_peer = NULL;
mutex_exit(&ppipe->pipe_lock);
}
KASSERT((pipe->pipe_state & PIPE_LOCKFL) == 0);
mutex_exit(&pipe->pipe_lock);
rw_exit(&pipe_peer_lock);
/*
* free resources
*/
pipe_free_kmem(pipe);
mutex_destroy(&pipe->pipe_lock);
cv_destroy(&pipe->pipe_cv);
cv_destroy(&pipe->pipe_lkcv);
pool_put(&pipe_pool, pipe);
}
static void
filt_pipedetach(struct knote *kn)
{
struct pipe *pipe = (struct pipe *)kn->kn_fp->f_data;
rw_enter(&pipe_peer_lock, RW_READER);
switch(kn->kn_filter) {
case EVFILT_WRITE:
/* need the peer structure, not our own */
pipe = pipe->pipe_peer;
/* if reader end already closed, just return */
if (pipe == NULL) {
rw_exit(&pipe_peer_lock);
return;
}
break;
default:
/* nothing to do */
break;
}
#ifdef DIAGNOSTIC
if (kn->kn_hook != pipe)
panic("filt_pipedetach: inconsistent knote");
#endif
mutex_enter(&pipe->pipe_lock);
SLIST_REMOVE(&pipe->pipe_sel.sel_klist, kn, knote, kn_selnext);
mutex_exit(&pipe->pipe_lock);
rw_exit(&pipe_peer_lock);
}
/*ARGSUSED*/
static int
filt_piperead(struct knote *kn, long hint)
{
struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
struct pipe *wpipe;
if ((hint & NOTE_SUBMIT) == 0) {
rw_enter(&pipe_peer_lock, RW_READER);
mutex_enter(&rpipe->pipe_lock);
}
wpipe = rpipe->pipe_peer;
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;
if ((hint & NOTE_SUBMIT) == 0) {
mutex_exit(&rpipe->pipe_lock);
rw_exit(&pipe_peer_lock);
}
return (1);
}
if ((hint & NOTE_SUBMIT) == 0) {
mutex_exit(&rpipe->pipe_lock);
rw_exit(&pipe_peer_lock);
}
return (kn->kn_data > 0);
}
/*ARGSUSED*/
static int
filt_pipewrite(struct knote *kn, long hint)
{
struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
struct pipe *wpipe;
if ((hint & NOTE_SUBMIT) == 0) {
rw_enter(&pipe_peer_lock, RW_READER);
mutex_enter(&rpipe->pipe_lock);
}
wpipe = rpipe->pipe_peer;
if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
kn->kn_data = 0;
kn->kn_flags |= EV_EOF;
if ((hint & NOTE_SUBMIT) == 0) {
mutex_exit(&rpipe->pipe_lock);
rw_exit(&pipe_peer_lock);
}
return (1);
}
kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
if (wpipe->pipe_state & PIPE_DIRECTW)
kn->kn_data = 0;
if ((hint & NOTE_SUBMIT) == 0) {
mutex_exit(&rpipe->pipe_lock);
rw_exit(&pipe_peer_lock);
}
return (kn->kn_data >= PIPE_BUF);
}
static const struct filterops pipe_rfiltops =
{ 1, NULL, filt_pipedetach, filt_piperead };
static const struct filterops pipe_wfiltops =
{ 1, NULL, filt_pipedetach, filt_pipewrite };
/*ARGSUSED*/
static int
pipe_kqfilter(struct file *fp, struct knote *kn)
{
struct pipe *pipe;
rw_enter(&pipe_peer_lock, RW_READER);
pipe = (struct pipe *)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;
pipe = pipe->pipe_peer;
if (pipe == NULL) {
/* other end of pipe has been closed */
rw_exit(&pipe_peer_lock);
return (EBADF);
}
break;
default:
rw_exit(&pipe_peer_lock);
return (1);
}
kn->kn_hook = pipe;
mutex_enter(&pipe->pipe_lock);
SLIST_INSERT_HEAD(&pipe->pipe_sel.sel_klist, kn, kn_selnext);
mutex_exit(&pipe->pipe_lock);
rw_exit(&pipe_peer_lock);
return (0);
}
/*
* Handle pipe sysctls.
*/
SYSCTL_SETUP(sysctl_kern_pipe_setup, "sysctl kern.pipe subtree setup")
{
sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "kern", NULL,
NULL, 0, NULL, 0,
CTL_KERN, CTL_EOL);
sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "pipe",
SYSCTL_DESCR("Pipe settings"),
NULL, 0, NULL, 0,
CTL_KERN, KERN_PIPE, CTL_EOL);
sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
CTLTYPE_INT, "maxkvasz",
SYSCTL_DESCR("Maximum amount of kernel memory to be "
"used for pipes"),
NULL, 0, &maxpipekva, 0,
CTL_KERN, KERN_PIPE, KERN_PIPE_MAXKVASZ, CTL_EOL);
sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
CTLTYPE_INT, "maxloankvasz",
SYSCTL_DESCR("Limit for direct transfers via page loan"),
NULL, 0, &limitpipekva, 0,
CTL_KERN, KERN_PIPE, KERN_PIPE_LIMITKVA, CTL_EOL);
sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
CTLTYPE_INT, "maxbigpipes",
SYSCTL_DESCR("Maximum number of \"big\" pipes"),
NULL, 0, &maxbigpipes, 0,
CTL_KERN, KERN_PIPE, KERN_PIPE_MAXBIGPIPES, CTL_EOL);
sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT,
CTLTYPE_INT, "nbigpipes",
SYSCTL_DESCR("Number of \"big\" pipes"),
NULL, 0, &nbigpipe, 0,
CTL_KERN, KERN_PIPE, KERN_PIPE_NBIGPIPES, CTL_EOL);
sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT,
CTLTYPE_INT, "kvasize",
SYSCTL_DESCR("Amount of kernel memory consumed by pipe "
"buffers"),
NULL, 0, &amountpipekva, 0,
CTL_KERN, KERN_PIPE, KERN_PIPE_KVASIZE, CTL_EOL);
}
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