The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/sys_pipe.c

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    1 /*      $NetBSD: sys_pipe.c,v 1.77 2006/11/01 10:17:59 yamt Exp $       */
    2 
    3 /*-
    4  * Copyright (c) 2003 The NetBSD Foundation, Inc.
    5  * All rights reserved.
    6  *
    7  * This code is derived from software contributed to The NetBSD Foundation
    8  * by Paul Kranenburg.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. All advertising materials mentioning features or use of this software
   19  *    must display the following acknowledgement:
   20  *        This product includes software developed by the NetBSD
   21  *        Foundation, Inc. and its contributors.
   22  * 4. Neither the name of The NetBSD Foundation nor the names of its
   23  *    contributors may be used to endorse or promote products derived
   24  *    from this software without specific prior written permission.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   36  * POSSIBILITY OF SUCH DAMAGE.
   37  */
   38 
   39 /*
   40  * Copyright (c) 1996 John S. Dyson
   41  * All rights reserved.
   42  *
   43  * Redistribution and use in source and binary forms, with or without
   44  * modification, are permitted provided that the following conditions
   45  * are met:
   46  * 1. Redistributions of source code must retain the above copyright
   47  *    notice immediately at the beginning of the file, without modification,
   48  *    this list of conditions, and the following disclaimer.
   49  * 2. Redistributions in binary form must reproduce the above copyright
   50  *    notice, this list of conditions and the following disclaimer in the
   51  *    documentation and/or other materials provided with the distribution.
   52  * 3. Absolutely no warranty of function or purpose is made by the author
   53  *    John S. Dyson.
   54  * 4. Modifications may be freely made to this file if the above conditions
   55  *    are met.
   56  *
   57  * $FreeBSD: src/sys/kern/sys_pipe.c,v 1.95 2002/03/09 22:06:31 alfred Exp $
   58  */
   59 
   60 /*
   61  * This file contains a high-performance replacement for the socket-based
   62  * pipes scheme originally used in FreeBSD/4.4Lite.  It does not support
   63  * all features of sockets, but does do everything that pipes normally
   64  * do.
   65  *
   66  * Adaption for NetBSD UVM, including uvm_loan() based direct write, was
   67  * written by Jaromir Dolecek.
   68  */
   69 
   70 /*
   71  * This code has two modes of operation, a small write mode and a large
   72  * write mode.  The small write mode acts like conventional pipes with
   73  * a kernel buffer.  If the buffer is less than PIPE_MINDIRECT, then the
   74  * "normal" pipe buffering is done.  If the buffer is between PIPE_MINDIRECT
   75  * and PIPE_SIZE in size it is mapped read-only into the kernel address space
   76  * using the UVM page loan facility from where the receiving process can copy
   77  * the data directly from the pages in the sending process.
   78  *
   79  * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
   80  * happen for small transfers so that the system will not spend all of
   81  * its time context switching.  PIPE_SIZE is constrained by the
   82  * amount of kernel virtual memory.
   83  */
   84 
   85 #include <sys/cdefs.h>
   86 __KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.77 2006/11/01 10:17:59 yamt Exp $");
   87 
   88 #include <sys/param.h>
   89 #include <sys/systm.h>
   90 #include <sys/proc.h>
   91 #include <sys/fcntl.h>
   92 #include <sys/file.h>
   93 #include <sys/filedesc.h>
   94 #include <sys/filio.h>
   95 #include <sys/kernel.h>
   96 #include <sys/ttycom.h>
   97 #include <sys/stat.h>
   98 #include <sys/malloc.h>
   99 #include <sys/poll.h>
  100 #include <sys/signalvar.h>
  101 #include <sys/vnode.h>
  102 #include <sys/uio.h>
  103 #include <sys/lock.h>
  104 #include <sys/select.h>
  105 #include <sys/mount.h>
  106 #include <sys/sa.h>
  107 #include <sys/syscallargs.h>
  108 #include <uvm/uvm.h>
  109 #include <sys/sysctl.h>
  110 #include <sys/kernel.h>
  111 #include <sys/kauth.h>
  112 
  113 #include <sys/pipe.h>
  114 
  115 /*
  116  * Use this define if you want to disable *fancy* VM things.  Expect an
  117  * approx 30% decrease in transfer rate.
  118  */
  119 /* #define PIPE_NODIRECT */
  120 
  121 /*
  122  * interfaces to the outside world
  123  */
  124 static int pipe_read(struct file *fp, off_t *offset, struct uio *uio,
  125                 kauth_cred_t cred, int flags);
  126 static int pipe_write(struct file *fp, off_t *offset, struct uio *uio,
  127                 kauth_cred_t cred, int flags);
  128 static int pipe_close(struct file *fp, struct lwp *l);
  129 static int pipe_poll(struct file *fp, int events, struct lwp *l);
  130 static int pipe_kqfilter(struct file *fp, struct knote *kn);
  131 static int pipe_stat(struct file *fp, struct stat *sb, struct lwp *l);
  132 static int pipe_ioctl(struct file *fp, u_long cmd, void *data,
  133                 struct lwp *l);
  134 
  135 static const struct fileops pipeops = {
  136         pipe_read, pipe_write, pipe_ioctl, fnullop_fcntl, pipe_poll,
  137         pipe_stat, pipe_close, pipe_kqfilter
  138 };
  139 
  140 /*
  141  * Default pipe buffer size(s), this can be kind-of large now because pipe
  142  * space is pageable.  The pipe code will try to maintain locality of
  143  * reference for performance reasons, so small amounts of outstanding I/O
  144  * will not wipe the cache.
  145  */
  146 #define MINPIPESIZE (PIPE_SIZE/3)
  147 #define MAXPIPESIZE (2*PIPE_SIZE/3)
  148 
  149 /*
  150  * Maximum amount of kva for pipes -- this is kind-of a soft limit, but
  151  * is there so that on large systems, we don't exhaust it.
  152  */
  153 #define MAXPIPEKVA (8*1024*1024)
  154 static int maxpipekva = MAXPIPEKVA;
  155 
  156 /*
  157  * Limit for direct transfers, we cannot, of course limit
  158  * the amount of kva for pipes in general though.
  159  */
  160 #define LIMITPIPEKVA (16*1024*1024)
  161 static int limitpipekva = LIMITPIPEKVA;
  162 
  163 /*
  164  * Limit the number of "big" pipes
  165  */
  166 #define LIMITBIGPIPES  32
  167 static int maxbigpipes = LIMITBIGPIPES;
  168 static int nbigpipe = 0;
  169 
  170 /*
  171  * Amount of KVA consumed by pipe buffers.
  172  */
  173 static int amountpipekva = 0;
  174 
  175 MALLOC_DEFINE(M_PIPE, "pipe", "Pipe structures");
  176 
  177 static void pipeclose(struct file *fp, struct pipe *pipe);
  178 static void pipe_free_kmem(struct pipe *pipe);
  179 static int pipe_create(struct pipe **pipep, int allockva);
  180 static int pipelock(struct pipe *pipe, int catch);
  181 static inline void pipeunlock(struct pipe *pipe);
  182 static void pipeselwakeup(struct pipe *pipe, struct pipe *sigp, int code);
  183 #ifndef PIPE_NODIRECT
  184 static int pipe_direct_write(struct file *fp, struct pipe *wpipe,
  185     struct uio *uio);
  186 #endif
  187 static int pipespace(struct pipe *pipe, int size);
  188 
  189 #ifndef PIPE_NODIRECT
  190 static int pipe_loan_alloc(struct pipe *, int);
  191 static void pipe_loan_free(struct pipe *);
  192 #endif /* PIPE_NODIRECT */
  193 
  194 static POOL_INIT(pipe_pool, sizeof(struct pipe), 0, 0, 0, "pipepl",
  195     &pool_allocator_nointr);
  196 
  197 /*
  198  * The pipe system call for the DTYPE_PIPE type of pipes
  199  */
  200 
  201 /* ARGSUSED */
  202 int
  203 sys_pipe(struct lwp *l, void *v, register_t *retval)
  204 {
  205         struct file *rf, *wf;
  206         struct pipe *rpipe, *wpipe;
  207         int fd, error;
  208 
  209         rpipe = wpipe = NULL;
  210         if (pipe_create(&rpipe, 1) || pipe_create(&wpipe, 0)) {
  211                 pipeclose(NULL, rpipe);
  212                 pipeclose(NULL, wpipe);
  213                 return (ENFILE);
  214         }
  215 
  216         /*
  217          * Note: the file structure returned from falloc() is marked
  218          * as 'larval' initially. Unless we mark it as 'mature' by
  219          * FILE_SET_MATURE(), any attempt to do anything with it would
  220          * return EBADF, including e.g. dup(2) or close(2). This avoids
  221          * file descriptor races if we block in the second falloc().
  222          */
  223 
  224         error = falloc(l, &rf, &fd);
  225         if (error)
  226                 goto free2;
  227         retval[0] = fd;
  228         rf->f_flag = FREAD;
  229         rf->f_type = DTYPE_PIPE;
  230         rf->f_data = (caddr_t)rpipe;
  231         rf->f_ops = &pipeops;
  232 
  233         error = falloc(l, &wf, &fd);
  234         if (error)
  235                 goto free3;
  236         retval[1] = fd;
  237         wf->f_flag = FWRITE;
  238         wf->f_type = DTYPE_PIPE;
  239         wf->f_data = (caddr_t)wpipe;
  240         wf->f_ops = &pipeops;
  241 
  242         rpipe->pipe_peer = wpipe;
  243         wpipe->pipe_peer = rpipe;
  244 
  245         FILE_SET_MATURE(rf);
  246         FILE_SET_MATURE(wf);
  247         FILE_UNUSE(rf, l);
  248         FILE_UNUSE(wf, l);
  249         return (0);
  250 free3:
  251         FILE_UNUSE(rf, l);
  252         ffree(rf);
  253         fdremove(l->l_proc->p_fd, retval[0]);
  254 free2:
  255         pipeclose(NULL, wpipe);
  256         pipeclose(NULL, rpipe);
  257 
  258         return (error);
  259 }
  260 
  261 /*
  262  * Allocate kva for pipe circular buffer, the space is pageable
  263  * This routine will 'realloc' the size of a pipe safely, if it fails
  264  * it will retain the old buffer.
  265  * If it fails it will return ENOMEM.
  266  */
  267 static int
  268 pipespace(struct pipe *pipe, int size)
  269 {
  270         caddr_t buffer;
  271         /*
  272          * Allocate pageable virtual address space. Physical memory is
  273          * allocated on demand.
  274          */
  275         buffer = (caddr_t) uvm_km_alloc(kernel_map, round_page(size), 0,
  276             UVM_KMF_PAGEABLE);
  277         if (buffer == NULL)
  278                 return (ENOMEM);
  279 
  280         /* free old resources if we're resizing */
  281         pipe_free_kmem(pipe);
  282         pipe->pipe_buffer.buffer = buffer;
  283         pipe->pipe_buffer.size = size;
  284         pipe->pipe_buffer.in = 0;
  285         pipe->pipe_buffer.out = 0;
  286         pipe->pipe_buffer.cnt = 0;
  287         amountpipekva += pipe->pipe_buffer.size;
  288         return (0);
  289 }
  290 
  291 /*
  292  * Initialize and allocate VM and memory for pipe.
  293  */
  294 static int
  295 pipe_create(struct pipe **pipep, int allockva)
  296 {
  297         struct pipe *pipe;
  298         int error;
  299 
  300         pipe = *pipep = pool_get(&pipe_pool, PR_WAITOK);
  301 
  302         /* Initialize */
  303         memset(pipe, 0, sizeof(struct pipe));
  304         pipe->pipe_state = PIPE_SIGNALR;
  305 
  306         getmicrotime(&pipe->pipe_ctime);
  307         pipe->pipe_atime = pipe->pipe_ctime;
  308         pipe->pipe_mtime = pipe->pipe_ctime;
  309         simple_lock_init(&pipe->pipe_slock);
  310 
  311         if (allockva && (error = pipespace(pipe, PIPE_SIZE)))
  312                 return (error);
  313 
  314         return (0);
  315 }
  316 
  317 
  318 /*
  319  * Lock a pipe for I/O, blocking other access
  320  * Called with pipe spin lock held.
  321  * Return with pipe spin lock released on success.
  322  */
  323 static int
  324 pipelock(struct pipe *pipe, int catch)
  325 {
  326 
  327         LOCK_ASSERT(simple_lock_held(&pipe->pipe_slock));
  328 
  329         while (pipe->pipe_state & PIPE_LOCKFL) {
  330                 int error;
  331                 const int pcatch = catch ? PCATCH : 0;
  332 
  333                 pipe->pipe_state |= PIPE_LWANT;
  334                 error = ltsleep(pipe, PSOCK | pcatch, "pipelk", 0,
  335                     &pipe->pipe_slock);
  336                 if (error != 0)
  337                         return error;
  338         }
  339 
  340         pipe->pipe_state |= PIPE_LOCKFL;
  341         simple_unlock(&pipe->pipe_slock);
  342 
  343         return 0;
  344 }
  345 
  346 /*
  347  * unlock a pipe I/O lock
  348  */
  349 static inline void
  350 pipeunlock(struct pipe *pipe)
  351 {
  352 
  353         KASSERT(pipe->pipe_state & PIPE_LOCKFL);
  354 
  355         pipe->pipe_state &= ~PIPE_LOCKFL;
  356         if (pipe->pipe_state & PIPE_LWANT) {
  357                 pipe->pipe_state &= ~PIPE_LWANT;
  358                 wakeup(pipe);
  359         }
  360 }
  361 
  362 /*
  363  * Select/poll wakup. This also sends SIGIO to peer connected to
  364  * 'sigpipe' side of pipe.
  365  */
  366 static void
  367 pipeselwakeup(struct pipe *selp, struct pipe *sigp, int code)
  368 {
  369         int band;
  370 
  371         selnotify(&selp->pipe_sel, NOTE_SUBMIT);
  372 
  373         if (sigp == NULL || (sigp->pipe_state & PIPE_ASYNC) == 0)
  374                 return;
  375 
  376         switch (code) {
  377         case POLL_IN:
  378                 band = POLLIN|POLLRDNORM;
  379                 break;
  380         case POLL_OUT:
  381                 band = POLLOUT|POLLWRNORM;
  382                 break;
  383         case POLL_HUP:
  384                 band = POLLHUP;
  385                 break;
  386 #if POLL_HUP != POLL_ERR
  387         case POLL_ERR:
  388                 band = POLLERR;
  389                 break;
  390 #endif
  391         default:
  392                 band = 0;
  393 #ifdef DIAGNOSTIC
  394                 printf("bad siginfo code %d in pipe notification.\n", code);
  395 #endif
  396                 break;
  397         }
  398 
  399         fownsignal(sigp->pipe_pgid, SIGIO, code, band, selp);
  400 }
  401 
  402 /* ARGSUSED */
  403 static int
  404 pipe_read(struct file *fp, off_t *offset, struct uio *uio, kauth_cred_t cred,
  405     int flags)
  406 {
  407         struct pipe *rpipe = (struct pipe *) fp->f_data;
  408         struct pipebuf *bp = &rpipe->pipe_buffer;
  409         int error;
  410         size_t nread = 0;
  411         size_t size;
  412         size_t ocnt;
  413 
  414         PIPE_LOCK(rpipe);
  415         ++rpipe->pipe_busy;
  416         ocnt = bp->cnt;
  417 
  418 again:
  419         error = pipelock(rpipe, 1);
  420         if (error)
  421                 goto unlocked_error;
  422 
  423         while (uio->uio_resid) {
  424                 /*
  425                  * normal pipe buffer receive
  426                  */
  427                 if (bp->cnt > 0) {
  428                         size = bp->size - bp->out;
  429                         if (size > bp->cnt)
  430                                 size = bp->cnt;
  431                         if (size > uio->uio_resid)
  432                                 size = uio->uio_resid;
  433 
  434                         error = uiomove(&bp->buffer[bp->out], size, uio);
  435                         if (error)
  436                                 break;
  437 
  438                         bp->out += size;
  439                         if (bp->out >= bp->size)
  440                                 bp->out = 0;
  441 
  442                         bp->cnt -= size;
  443 
  444                         /*
  445                          * If there is no more to read in the pipe, reset
  446                          * its pointers to the beginning.  This improves
  447                          * cache hit stats.
  448                          */
  449                         if (bp->cnt == 0) {
  450                                 bp->in = 0;
  451                                 bp->out = 0;
  452                         }
  453                         nread += size;
  454 #ifndef PIPE_NODIRECT
  455                 } else if ((rpipe->pipe_state & PIPE_DIRECTR) != 0) {
  456                         /*
  457                          * Direct copy, bypassing a kernel buffer.
  458                          */
  459                         caddr_t va;
  460 
  461                         KASSERT(rpipe->pipe_state & PIPE_DIRECTW);
  462 
  463                         size = rpipe->pipe_map.cnt;
  464                         if (size > uio->uio_resid)
  465                                 size = uio->uio_resid;
  466 
  467                         va = (caddr_t) rpipe->pipe_map.kva +
  468                             rpipe->pipe_map.pos;
  469                         error = uiomove(va, size, uio);
  470                         if (error)
  471                                 break;
  472                         nread += size;
  473                         rpipe->pipe_map.pos += size;
  474                         rpipe->pipe_map.cnt -= size;
  475                         if (rpipe->pipe_map.cnt == 0) {
  476                                 PIPE_LOCK(rpipe);
  477                                 rpipe->pipe_state &= ~PIPE_DIRECTR;
  478                                 wakeup(rpipe);
  479                                 PIPE_UNLOCK(rpipe);
  480                         }
  481 #endif
  482                 } else {
  483                         /*
  484                          * Break if some data was read.
  485                          */
  486                         if (nread > 0)
  487                                 break;
  488 
  489                         PIPE_LOCK(rpipe);
  490 
  491                         /*
  492                          * detect EOF condition
  493                          * read returns 0 on EOF, no need to set error
  494                          */
  495                         if (rpipe->pipe_state & PIPE_EOF) {
  496                                 PIPE_UNLOCK(rpipe);
  497                                 break;
  498                         }
  499 
  500                         /*
  501                          * don't block on non-blocking I/O
  502                          */
  503                         if (fp->f_flag & FNONBLOCK) {
  504                                 PIPE_UNLOCK(rpipe);
  505                                 error = EAGAIN;
  506                                 break;
  507                         }
  508 
  509                         /*
  510                          * Unlock the pipe buffer for our remaining processing.
  511                          * We will either break out with an error or we will
  512                          * sleep and relock to loop.
  513                          */
  514                         pipeunlock(rpipe);
  515 
  516                         /*
  517                          * The PIPE_DIRECTR flag is not under the control
  518                          * of the long-term lock (see pipe_direct_write()),
  519                          * so re-check now while holding the spin lock.
  520                          */
  521                         if ((rpipe->pipe_state & PIPE_DIRECTR) != 0)
  522                                 goto again;
  523 
  524                         /*
  525                          * We want to read more, wake up select/poll.
  526                          */
  527                         pipeselwakeup(rpipe, rpipe->pipe_peer, POLL_IN);
  528 
  529                         /*
  530                          * If the "write-side" is blocked, wake it up now.
  531                          */
  532                         if (rpipe->pipe_state & PIPE_WANTW) {
  533                                 rpipe->pipe_state &= ~PIPE_WANTW;
  534                                 wakeup(rpipe);
  535                         }
  536 
  537                         /* Now wait until the pipe is filled */
  538                         rpipe->pipe_state |= PIPE_WANTR;
  539                         error = ltsleep(rpipe, PSOCK | PCATCH,
  540                                         "piperd", 0, &rpipe->pipe_slock);
  541                         if (error != 0)
  542                                 goto unlocked_error;
  543                         goto again;
  544                 }
  545         }
  546 
  547         if (error == 0)
  548                 getmicrotime(&rpipe->pipe_atime);
  549 
  550         PIPE_LOCK(rpipe);
  551         pipeunlock(rpipe);
  552 
  553 unlocked_error:
  554         --rpipe->pipe_busy;
  555 
  556         /*
  557          * PIPE_WANTCLOSE processing only makes sense if pipe_busy is 0.
  558          */
  559         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANTCLOSE)) {
  560                 rpipe->pipe_state &= ~(PIPE_WANTCLOSE|PIPE_WANTW);
  561                 wakeup(rpipe);
  562         } else if (bp->cnt < MINPIPESIZE) {
  563                 /*
  564                  * Handle write blocking hysteresis.
  565                  */
  566                 if (rpipe->pipe_state & PIPE_WANTW) {
  567                         rpipe->pipe_state &= ~PIPE_WANTW;
  568                         wakeup(rpipe);
  569                 }
  570         }
  571 
  572         /*
  573          * If anything was read off the buffer, signal to the writer it's
  574          * possible to write more data. Also send signal if we are here for the
  575          * first time after last write.
  576          */
  577         if ((bp->size - bp->cnt) >= PIPE_BUF
  578             && (ocnt != bp->cnt || (rpipe->pipe_state & PIPE_SIGNALR))) {
  579                 pipeselwakeup(rpipe, rpipe->pipe_peer, POLL_OUT);
  580                 rpipe->pipe_state &= ~PIPE_SIGNALR;
  581         }
  582 
  583         PIPE_UNLOCK(rpipe);
  584         return (error);
  585 }
  586 
  587 #ifndef PIPE_NODIRECT
  588 /*
  589  * Allocate structure for loan transfer.
  590  */
  591 static int
  592 pipe_loan_alloc(struct pipe *wpipe, int npages)
  593 {
  594         vsize_t len;
  595 
  596         len = (vsize_t)npages << PAGE_SHIFT;
  597         wpipe->pipe_map.kva = uvm_km_alloc(kernel_map, len, 0,
  598             UVM_KMF_VAONLY | UVM_KMF_WAITVA);
  599         if (wpipe->pipe_map.kva == 0)
  600                 return (ENOMEM);
  601 
  602         amountpipekva += len;
  603         wpipe->pipe_map.npages = npages;
  604         wpipe->pipe_map.pgs = malloc(npages * sizeof(struct vm_page *), M_PIPE,
  605             M_WAITOK);
  606         return (0);
  607 }
  608 
  609 /*
  610  * Free resources allocated for loan transfer.
  611  */
  612 static void
  613 pipe_loan_free(struct pipe *wpipe)
  614 {
  615         vsize_t len;
  616 
  617         len = (vsize_t)wpipe->pipe_map.npages << PAGE_SHIFT;
  618         uvm_km_free(kernel_map, wpipe->pipe_map.kva, len, UVM_KMF_VAONLY);
  619         wpipe->pipe_map.kva = 0;
  620         amountpipekva -= len;
  621         free(wpipe->pipe_map.pgs, M_PIPE);
  622         wpipe->pipe_map.pgs = NULL;
  623 }
  624 
  625 /*
  626  * NetBSD direct write, using uvm_loan() mechanism.
  627  * This implements the pipe buffer write mechanism.  Note that only
  628  * a direct write OR a normal pipe write can be pending at any given time.
  629  * If there are any characters in the pipe buffer, the direct write will
  630  * be deferred until the receiving process grabs all of the bytes from
  631  * the pipe buffer.  Then the direct mapping write is set-up.
  632  *
  633  * Called with the long-term pipe lock held.
  634  */
  635 static int
  636 pipe_direct_write(struct file *fp, struct pipe *wpipe, struct uio *uio)
  637 {
  638         int error, npages, j;
  639         struct vm_page **pgs;
  640         vaddr_t bbase, kva, base, bend;
  641         vsize_t blen, bcnt;
  642         voff_t bpos;
  643 
  644         KASSERT(wpipe->pipe_map.cnt == 0);
  645 
  646         /*
  647          * Handle first PIPE_CHUNK_SIZE bytes of buffer. Deal with buffers
  648          * not aligned to PAGE_SIZE.
  649          */
  650         bbase = (vaddr_t)uio->uio_iov->iov_base;
  651         base = trunc_page(bbase);
  652         bend = round_page(bbase + uio->uio_iov->iov_len);
  653         blen = bend - base;
  654         bpos = bbase - base;
  655 
  656         if (blen > PIPE_DIRECT_CHUNK) {
  657                 blen = PIPE_DIRECT_CHUNK;
  658                 bend = base + blen;
  659                 bcnt = PIPE_DIRECT_CHUNK - bpos;
  660         } else {
  661                 bcnt = uio->uio_iov->iov_len;
  662         }
  663         npages = blen >> PAGE_SHIFT;
  664 
  665         /*
  666          * Free the old kva if we need more pages than we have
  667          * allocated.
  668          */
  669         if (wpipe->pipe_map.kva != 0 && npages > wpipe->pipe_map.npages)
  670                 pipe_loan_free(wpipe);
  671 
  672         /* Allocate new kva. */
  673         if (wpipe->pipe_map.kva == 0) {
  674                 error = pipe_loan_alloc(wpipe, npages);
  675                 if (error)
  676                         return (error);
  677         }
  678 
  679         /* Loan the write buffer memory from writer process */
  680         pgs = wpipe->pipe_map.pgs;
  681         error = uvm_loan(&uio->uio_vmspace->vm_map, base, blen,
  682                          pgs, UVM_LOAN_TOPAGE);
  683         if (error) {
  684                 pipe_loan_free(wpipe);
  685                 return (ENOMEM); /* so that caller fallback to ordinary write */
  686         }
  687 
  688         /* Enter the loaned pages to kva */
  689         kva = wpipe->pipe_map.kva;
  690         for (j = 0; j < npages; j++, kva += PAGE_SIZE) {
  691                 pmap_kenter_pa(kva, VM_PAGE_TO_PHYS(pgs[j]), VM_PROT_READ);
  692         }
  693         pmap_update(pmap_kernel());
  694 
  695         /* Now we can put the pipe in direct write mode */
  696         wpipe->pipe_map.pos = bpos;
  697         wpipe->pipe_map.cnt = bcnt;
  698         wpipe->pipe_state |= PIPE_DIRECTW;
  699 
  700         /*
  701          * But before we can let someone do a direct read,
  702          * we have to wait until the pipe is drained.
  703          */
  704 
  705         /* Relase the pipe lock while we wait */
  706         PIPE_LOCK(wpipe);
  707         pipeunlock(wpipe);
  708 
  709         while (error == 0 && wpipe->pipe_buffer.cnt > 0) {
  710                 if (wpipe->pipe_state & PIPE_WANTR) {
  711                         wpipe->pipe_state &= ~PIPE_WANTR;
  712                         wakeup(wpipe);
  713                 }
  714 
  715                 wpipe->pipe_state |= PIPE_WANTW;
  716                 error = ltsleep(wpipe, PSOCK | PCATCH, "pipdwc", 0,
  717                                 &wpipe->pipe_slock);
  718                 if (error == 0 && wpipe->pipe_state & PIPE_EOF)
  719                         error = EPIPE;
  720         }
  721 
  722         /* Pipe is drained; next read will off the direct buffer */
  723         wpipe->pipe_state |= PIPE_DIRECTR;
  724 
  725         /* Wait until the reader is done */
  726         while (error == 0 && (wpipe->pipe_state & PIPE_DIRECTR)) {
  727                 if (wpipe->pipe_state & PIPE_WANTR) {
  728                         wpipe->pipe_state &= ~PIPE_WANTR;
  729                         wakeup(wpipe);
  730                 }
  731                 pipeselwakeup(wpipe, wpipe, POLL_IN);
  732                 error = ltsleep(wpipe, PSOCK | PCATCH, "pipdwt", 0,
  733                                 &wpipe->pipe_slock);
  734                 if (error == 0 && wpipe->pipe_state & PIPE_EOF)
  735                         error = EPIPE;
  736         }
  737 
  738         /* Take pipe out of direct write mode */
  739         wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTR);
  740 
  741         /* Acquire the pipe lock and cleanup */
  742         (void)pipelock(wpipe, 0);
  743         if (pgs != NULL) {
  744                 pmap_kremove(wpipe->pipe_map.kva, blen);
  745                 uvm_unloan(pgs, npages, UVM_LOAN_TOPAGE);
  746         }
  747         if (error || amountpipekva > maxpipekva)
  748                 pipe_loan_free(wpipe);
  749 
  750         if (error) {
  751                 pipeselwakeup(wpipe, wpipe, POLL_ERR);
  752 
  753                 /*
  754                  * If nothing was read from what we offered, return error
  755                  * straight on. Otherwise update uio resid first. Caller
  756                  * will deal with the error condition, returning short
  757                  * write, error, or restarting the write(2) as appropriate.
  758                  */
  759                 if (wpipe->pipe_map.cnt == bcnt) {
  760                         wpipe->pipe_map.cnt = 0;
  761                         wakeup(wpipe);
  762                         return (error);
  763                 }
  764 
  765                 bcnt -= wpipe->pipe_map.cnt;
  766         }
  767 
  768         uio->uio_resid -= bcnt;
  769         /* uio_offset not updated, not set/used for write(2) */
  770         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + bcnt;
  771         uio->uio_iov->iov_len -= bcnt;
  772         if (uio->uio_iov->iov_len == 0) {
  773                 uio->uio_iov++;
  774                 uio->uio_iovcnt--;
  775         }
  776 
  777         wpipe->pipe_map.cnt = 0;
  778         return (error);
  779 }
  780 #endif /* !PIPE_NODIRECT */
  781 
  782 static int
  783 pipe_write(struct file *fp, off_t *offset, struct uio *uio, kauth_cred_t cred,
  784     int flags)
  785 {
  786         struct pipe *wpipe, *rpipe;
  787         struct pipebuf *bp;
  788         int error;
  789 
  790         /* We want to write to our peer */
  791         rpipe = (struct pipe *) fp->f_data;
  792 
  793 retry:
  794         error = 0;
  795         PIPE_LOCK(rpipe);
  796         wpipe = rpipe->pipe_peer;
  797 
  798         /*
  799          * Detect loss of pipe read side, issue SIGPIPE if lost.
  800          */
  801         if (wpipe == NULL)
  802                 error = EPIPE;
  803         else if (simple_lock_try(&wpipe->pipe_slock) == 0) {
  804                 /* Deal with race for peer */
  805                 PIPE_UNLOCK(rpipe);
  806                 goto retry;
  807         } else if ((wpipe->pipe_state & PIPE_EOF) != 0) {
  808                 PIPE_UNLOCK(wpipe);
  809                 error = EPIPE;
  810         }
  811 
  812         PIPE_UNLOCK(rpipe);
  813         if (error != 0)
  814                 return (error);
  815 
  816         ++wpipe->pipe_busy;
  817 
  818         /* Aquire the long-term pipe lock */
  819         if ((error = pipelock(wpipe,1)) != 0) {
  820                 --wpipe->pipe_busy;
  821                 if (wpipe->pipe_busy == 0
  822                     && (wpipe->pipe_state & PIPE_WANTCLOSE)) {
  823                         wpipe->pipe_state &= ~(PIPE_WANTCLOSE | PIPE_WANTR);
  824                         wakeup(wpipe);
  825                 }
  826                 PIPE_UNLOCK(wpipe);
  827                 return (error);
  828         }
  829 
  830         bp = &wpipe->pipe_buffer;
  831 
  832         /*
  833          * If it is advantageous to resize the pipe buffer, do so.
  834          */
  835         if ((uio->uio_resid > PIPE_SIZE) &&
  836             (nbigpipe < maxbigpipes) &&
  837 #ifndef PIPE_NODIRECT
  838             (wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
  839 #endif
  840             (bp->size <= PIPE_SIZE) && (bp->cnt == 0)) {
  841 
  842                 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
  843                         nbigpipe++;
  844         }
  845 
  846         while (uio->uio_resid) {
  847                 size_t space;
  848 
  849 #ifndef PIPE_NODIRECT
  850                 /*
  851                  * Pipe buffered writes cannot be coincidental with
  852                  * direct writes.  Also, only one direct write can be
  853                  * in progress at any one time.  We wait until the currently
  854                  * executing direct write is completed before continuing.
  855                  *
  856                  * We break out if a signal occurs or the reader goes away.
  857                  */
  858                 while (error == 0 && wpipe->pipe_state & PIPE_DIRECTW) {
  859                         PIPE_LOCK(wpipe);
  860                         if (wpipe->pipe_state & PIPE_WANTR) {
  861                                 wpipe->pipe_state &= ~PIPE_WANTR;
  862                                 wakeup(wpipe);
  863                         }
  864                         pipeunlock(wpipe);
  865                         error = ltsleep(wpipe, PSOCK | PCATCH,
  866                                         "pipbww", 0, &wpipe->pipe_slock);
  867 
  868                         (void)pipelock(wpipe, 0);
  869                         if (wpipe->pipe_state & PIPE_EOF)
  870                                 error = EPIPE;
  871                 }
  872                 if (error)
  873                         break;
  874 
  875                 /*
  876                  * If the transfer is large, we can gain performance if
  877                  * we do process-to-process copies directly.
  878                  * If the write is non-blocking, we don't use the
  879                  * direct write mechanism.
  880                  *
  881                  * The direct write mechanism will detect the reader going
  882                  * away on us.
  883                  */
  884                 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) &&
  885                     (fp->f_flag & FNONBLOCK) == 0 &&
  886                     (wpipe->pipe_map.kva || (amountpipekva < limitpipekva))) {
  887                         error = pipe_direct_write(fp, wpipe, uio);
  888 
  889                         /*
  890                          * Break out if error occurred, unless it's ENOMEM.
  891                          * ENOMEM means we failed to allocate some resources
  892                          * for direct write, so we just fallback to ordinary
  893                          * write. If the direct write was successful,
  894                          * process rest of data via ordinary write.
  895                          */
  896                         if (error == 0)
  897                                 continue;
  898 
  899                         if (error != ENOMEM)
  900                                 break;
  901                 }
  902 #endif /* PIPE_NODIRECT */
  903 
  904                 space = bp->size - bp->cnt;
  905 
  906                 /* Writes of size <= PIPE_BUF must be atomic. */
  907                 if ((space < uio->uio_resid) && (uio->uio_resid <= PIPE_BUF))
  908                         space = 0;
  909 
  910                 if (space > 0) {
  911                         int size;       /* Transfer size */
  912                         int segsize;    /* first segment to transfer */
  913 
  914                         /*
  915                          * Transfer size is minimum of uio transfer
  916                          * and free space in pipe buffer.
  917                          */
  918                         if (space > uio->uio_resid)
  919                                 size = uio->uio_resid;
  920                         else
  921                                 size = space;
  922                         /*
  923                          * First segment to transfer is minimum of
  924                          * transfer size and contiguous space in
  925                          * pipe buffer.  If first segment to transfer
  926                          * is less than the transfer size, we've got
  927                          * a wraparound in the buffer.
  928                          */
  929                         segsize = bp->size - bp->in;
  930                         if (segsize > size)
  931                                 segsize = size;
  932 
  933                         /* Transfer first segment */
  934                         error = uiomove(&bp->buffer[bp->in], segsize, uio);
  935 
  936                         if (error == 0 && segsize < size) {
  937                                 /*
  938                                  * Transfer remaining part now, to
  939                                  * support atomic writes.  Wraparound
  940                                  * happened.
  941                                  */
  942 #ifdef DEBUG
  943                                 if (bp->in + segsize != bp->size)
  944                                         panic("Expected pipe buffer wraparound disappeared");
  945 #endif
  946 
  947                                 error = uiomove(&bp->buffer[0],
  948                                                 size - segsize, uio);
  949                         }
  950                         if (error)
  951                                 break;
  952 
  953                         bp->in += size;
  954                         if (bp->in >= bp->size) {
  955 #ifdef DEBUG
  956                                 if (bp->in != size - segsize + bp->size)
  957                                         panic("Expected wraparound bad");
  958 #endif
  959                                 bp->in = size - segsize;
  960                         }
  961 
  962                         bp->cnt += size;
  963 #ifdef DEBUG
  964                         if (bp->cnt > bp->size)
  965                                 panic("Pipe buffer overflow");
  966 #endif
  967                 } else {
  968                         /*
  969                          * If the "read-side" has been blocked, wake it up now.
  970                          */
  971                         PIPE_LOCK(wpipe);
  972                         if (wpipe->pipe_state & PIPE_WANTR) {
  973                                 wpipe->pipe_state &= ~PIPE_WANTR;
  974                                 wakeup(wpipe);
  975                         }
  976                         PIPE_UNLOCK(wpipe);
  977 
  978                         /*
  979                          * don't block on non-blocking I/O
  980                          */
  981                         if (fp->f_flag & FNONBLOCK) {
  982                                 error = EAGAIN;
  983                                 break;
  984                         }
  985 
  986                         /*
  987                          * We have no more space and have something to offer,
  988                          * wake up select/poll.
  989                          */
  990                         if (bp->cnt)
  991                                 pipeselwakeup(wpipe, wpipe, POLL_OUT);
  992 
  993                         PIPE_LOCK(wpipe);
  994                         pipeunlock(wpipe);
  995                         wpipe->pipe_state |= PIPE_WANTW;
  996                         error = ltsleep(wpipe, PSOCK | PCATCH, "pipewr", 0,
  997                                         &wpipe->pipe_slock);
  998                         (void)pipelock(wpipe, 0);
  999                         if (error != 0)
 1000                                 break;
 1001                         /*
 1002                          * If read side wants to go away, we just issue a signal
 1003                          * to ourselves.
 1004                          */
 1005                         if (wpipe->pipe_state & PIPE_EOF) {
 1006                                 error = EPIPE;
 1007                                 break;
 1008                         }
 1009                 }
 1010         }
 1011 
 1012         PIPE_LOCK(wpipe);
 1013         --wpipe->pipe_busy;
 1014         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANTCLOSE)) {
 1015                 wpipe->pipe_state &= ~(PIPE_WANTCLOSE | PIPE_WANTR);
 1016                 wakeup(wpipe);
 1017         } else if (bp->cnt > 0) {
 1018                 /*
 1019                  * If we have put any characters in the buffer, we wake up
 1020                  * the reader.
 1021                  */
 1022                 if (wpipe->pipe_state & PIPE_WANTR) {
 1023                         wpipe->pipe_state &= ~PIPE_WANTR;
 1024                         wakeup(wpipe);
 1025                 }
 1026         }
 1027 
 1028         /*
 1029          * Don't return EPIPE if I/O was successful
 1030          */
 1031         if (error == EPIPE && bp->cnt == 0 && uio->uio_resid == 0)
 1032                 error = 0;
 1033 
 1034         if (error == 0)
 1035                 getmicrotime(&wpipe->pipe_mtime);
 1036 
 1037         /*
 1038          * We have something to offer, wake up select/poll.
 1039          * wpipe->pipe_map.cnt is always 0 in this point (direct write
 1040          * is only done synchronously), so check only wpipe->pipe_buffer.cnt
 1041          */
 1042         if (bp->cnt)
 1043                 pipeselwakeup(wpipe, wpipe, POLL_OUT);
 1044 
 1045         /*
 1046          * Arrange for next read(2) to do a signal.
 1047          */
 1048         wpipe->pipe_state |= PIPE_SIGNALR;
 1049 
 1050         pipeunlock(wpipe);
 1051         PIPE_UNLOCK(wpipe);
 1052         return (error);
 1053 }
 1054 
 1055 /*
 1056  * we implement a very minimal set of ioctls for compatibility with sockets.
 1057  */
 1058 int
 1059 pipe_ioctl(struct file *fp, u_long cmd, void *data, struct lwp *l)
 1060 {
 1061         struct pipe *pipe = (struct pipe *)fp->f_data;
 1062         struct proc *p = l->l_proc;
 1063 
 1064         switch (cmd) {
 1065 
 1066         case FIONBIO:
 1067                 return (0);
 1068 
 1069         case FIOASYNC:
 1070                 PIPE_LOCK(pipe);
 1071                 if (*(int *)data) {
 1072                         pipe->pipe_state |= PIPE_ASYNC;
 1073                 } else {
 1074                         pipe->pipe_state &= ~PIPE_ASYNC;
 1075                 }
 1076                 PIPE_UNLOCK(pipe);
 1077                 return (0);
 1078 
 1079         case FIONREAD:
 1080                 PIPE_LOCK(pipe);
 1081 #ifndef PIPE_NODIRECT
 1082                 if (pipe->pipe_state & PIPE_DIRECTW)
 1083                         *(int *)data = pipe->pipe_map.cnt;
 1084                 else
 1085 #endif
 1086                         *(int *)data = pipe->pipe_buffer.cnt;
 1087                 PIPE_UNLOCK(pipe);
 1088                 return (0);
 1089 
 1090         case FIONWRITE:
 1091                 /* Look at other side */
 1092                 pipe = pipe->pipe_peer;
 1093                 PIPE_LOCK(pipe);
 1094 #ifndef PIPE_NODIRECT
 1095                 if (pipe->pipe_state & PIPE_DIRECTW)
 1096                         *(int *)data = pipe->pipe_map.cnt;
 1097                 else
 1098 #endif
 1099                         *(int *)data = pipe->pipe_buffer.cnt;
 1100                 PIPE_UNLOCK(pipe);
 1101                 return (0);
 1102 
 1103         case FIONSPACE:
 1104                 /* Look at other side */
 1105                 pipe = pipe->pipe_peer;
 1106                 PIPE_LOCK(pipe);
 1107 #ifndef PIPE_NODIRECT
 1108                 /*
 1109                  * If we're in direct-mode, we don't really have a
 1110                  * send queue, and any other write will block. Thus
 1111                  * zero seems like the best answer.
 1112                  */
 1113                 if (pipe->pipe_state & PIPE_DIRECTW)
 1114                         *(int *)data = 0;
 1115                 else
 1116 #endif
 1117                         *(int *)data = pipe->pipe_buffer.size -
 1118                                         pipe->pipe_buffer.cnt;
 1119                 PIPE_UNLOCK(pipe);
 1120                 return (0);
 1121 
 1122         case TIOCSPGRP:
 1123         case FIOSETOWN:
 1124                 return fsetown(p, &pipe->pipe_pgid, cmd, data);
 1125 
 1126         case TIOCGPGRP:
 1127         case FIOGETOWN:
 1128                 return fgetown(p, pipe->pipe_pgid, cmd, data);
 1129 
 1130         }
 1131         return (EPASSTHROUGH);
 1132 }
 1133 
 1134 int
 1135 pipe_poll(struct file *fp, int events, struct lwp *l)
 1136 {
 1137         struct pipe *rpipe = (struct pipe *)fp->f_data;
 1138         struct pipe *wpipe;
 1139         int eof = 0;
 1140         int revents = 0;
 1141 
 1142 retry:
 1143         PIPE_LOCK(rpipe);
 1144         wpipe = rpipe->pipe_peer;
 1145         if (wpipe != NULL && simple_lock_try(&wpipe->pipe_slock) == 0) {
 1146                 /* Deal with race for peer */
 1147                 PIPE_UNLOCK(rpipe);
 1148                 goto retry;
 1149         }
 1150 
 1151         if (events & (POLLIN | POLLRDNORM))
 1152                 if ((rpipe->pipe_buffer.cnt > 0) ||
 1153 #ifndef PIPE_NODIRECT
 1154                     (rpipe->pipe_state & PIPE_DIRECTR) ||
 1155 #endif
 1156                     (rpipe->pipe_state & PIPE_EOF))
 1157                         revents |= events & (POLLIN | POLLRDNORM);
 1158 
 1159         eof |= (rpipe->pipe_state & PIPE_EOF);
 1160         PIPE_UNLOCK(rpipe);
 1161 
 1162         if (wpipe == NULL)
 1163                 revents |= events & (POLLOUT | POLLWRNORM);
 1164         else {
 1165                 if (events & (POLLOUT | POLLWRNORM))
 1166                         if ((wpipe->pipe_state & PIPE_EOF) || (
 1167 #ifndef PIPE_NODIRECT
 1168                              (wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
 1169 #endif
 1170                              (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
 1171                                 revents |= events & (POLLOUT | POLLWRNORM);
 1172 
 1173                 eof |= (wpipe->pipe_state & PIPE_EOF);
 1174                 PIPE_UNLOCK(wpipe);
 1175         }
 1176 
 1177         if (wpipe == NULL || eof)
 1178                 revents |= POLLHUP;
 1179 
 1180         if (revents == 0) {
 1181                 if (events & (POLLIN | POLLRDNORM))
 1182                         selrecord(l, &rpipe->pipe_sel);
 1183 
 1184                 if (events & (POLLOUT | POLLWRNORM))
 1185                         selrecord(l, &wpipe->pipe_sel);
 1186         }
 1187 
 1188         return (revents);
 1189 }
 1190 
 1191 static int
 1192 pipe_stat(struct file *fp, struct stat *ub, struct lwp *l)
 1193 {
 1194         struct pipe *pipe = (struct pipe *)fp->f_data;
 1195 
 1196         memset((caddr_t)ub, 0, sizeof(*ub));
 1197         ub->st_mode = S_IFIFO | S_IRUSR | S_IWUSR;
 1198         ub->st_blksize = pipe->pipe_buffer.size;
 1199         if (ub->st_blksize == 0 && pipe->pipe_peer)
 1200                 ub->st_blksize = pipe->pipe_peer->pipe_buffer.size;
 1201         ub->st_size = pipe->pipe_buffer.cnt;
 1202         ub->st_blocks = (ub->st_size) ? 1 : 0;
 1203         TIMEVAL_TO_TIMESPEC(&pipe->pipe_atime, &ub->st_atimespec);
 1204         TIMEVAL_TO_TIMESPEC(&pipe->pipe_mtime, &ub->st_mtimespec);
 1205         TIMEVAL_TO_TIMESPEC(&pipe->pipe_ctime, &ub->st_ctimespec);
 1206         ub->st_uid = kauth_cred_geteuid(fp->f_cred);
 1207         ub->st_gid = kauth_cred_getegid(fp->f_cred);
 1208         /*
 1209          * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen.
 1210          * XXX (st_dev, st_ino) should be unique.
 1211          */
 1212         return (0);
 1213 }
 1214 
 1215 /* ARGSUSED */
 1216 static int
 1217 pipe_close(struct file *fp, struct lwp *l)
 1218 {
 1219         struct pipe *pipe = (struct pipe *)fp->f_data;
 1220 
 1221         fp->f_data = NULL;
 1222         pipeclose(fp, pipe);
 1223         return (0);
 1224 }
 1225 
 1226 static void
 1227 pipe_free_kmem(struct pipe *pipe)
 1228 {
 1229 
 1230         if (pipe->pipe_buffer.buffer != NULL) {
 1231                 if (pipe->pipe_buffer.size > PIPE_SIZE)
 1232                         --nbigpipe;
 1233                 amountpipekva -= pipe->pipe_buffer.size;
 1234                 uvm_km_free(kernel_map,
 1235                         (vaddr_t)pipe->pipe_buffer.buffer,
 1236                         pipe->pipe_buffer.size, UVM_KMF_PAGEABLE);
 1237                 pipe->pipe_buffer.buffer = NULL;
 1238         }
 1239 #ifndef PIPE_NODIRECT
 1240         if (pipe->pipe_map.kva != 0) {
 1241                 pipe_loan_free(pipe);
 1242                 pipe->pipe_map.cnt = 0;
 1243                 pipe->pipe_map.kva = 0;
 1244                 pipe->pipe_map.pos = 0;
 1245                 pipe->pipe_map.npages = 0;
 1246         }
 1247 #endif /* !PIPE_NODIRECT */
 1248 }
 1249 
 1250 /*
 1251  * shutdown the pipe
 1252  */
 1253 static void
 1254 pipeclose(struct file *fp, struct pipe *pipe)
 1255 {
 1256         struct pipe *ppipe;
 1257 
 1258         if (pipe == NULL)
 1259                 return;
 1260 
 1261 retry:
 1262         PIPE_LOCK(pipe);
 1263 
 1264         pipeselwakeup(pipe, pipe, POLL_HUP);
 1265 
 1266         /*
 1267          * If the other side is blocked, wake it up saying that
 1268          * we want to close it down.
 1269          */
 1270         pipe->pipe_state |= PIPE_EOF;
 1271         while (pipe->pipe_busy) {
 1272                 wakeup(pipe);
 1273                 pipe->pipe_state |= PIPE_WANTCLOSE;
 1274                 ltsleep(pipe, PSOCK, "pipecl", 0, &pipe->pipe_slock);
 1275         }
 1276 
 1277         /*
 1278          * Disconnect from peer
 1279          */
 1280         if ((ppipe = pipe->pipe_peer) != NULL) {
 1281                 /* Deal with race for peer */
 1282                 if (simple_lock_try(&ppipe->pipe_slock) == 0) {
 1283                         PIPE_UNLOCK(pipe);
 1284                         goto retry;
 1285                 }
 1286                 pipeselwakeup(ppipe, ppipe, POLL_HUP);
 1287 
 1288                 ppipe->pipe_state |= PIPE_EOF;
 1289                 wakeup(ppipe);
 1290                 ppipe->pipe_peer = NULL;
 1291                 PIPE_UNLOCK(ppipe);
 1292         }
 1293 
 1294         KASSERT((pipe->pipe_state & PIPE_LOCKFL) == 0);
 1295 
 1296         PIPE_UNLOCK(pipe);
 1297 
 1298         /*
 1299          * free resources
 1300          */
 1301         pipe_free_kmem(pipe);
 1302         pool_put(&pipe_pool, pipe);
 1303 }
 1304 
 1305 static void
 1306 filt_pipedetach(struct knote *kn)
 1307 {
 1308         struct pipe *pipe = (struct pipe *)kn->kn_fp->f_data;
 1309 
 1310         switch(kn->kn_filter) {
 1311         case EVFILT_WRITE:
 1312                 /* need the peer structure, not our own */
 1313                 pipe = pipe->pipe_peer;
 1314                 /* XXXSMP: race for peer */
 1315 
 1316                 /* if reader end already closed, just return */
 1317                 if (pipe == NULL)
 1318                         return;
 1319 
 1320                 break;
 1321         default:
 1322                 /* nothing to do */
 1323                 break;
 1324         }
 1325 
 1326 #ifdef DIAGNOSTIC
 1327         if (kn->kn_hook != pipe)
 1328                 panic("filt_pipedetach: inconsistent knote");
 1329 #endif
 1330 
 1331         PIPE_LOCK(pipe);
 1332         SLIST_REMOVE(&pipe->pipe_sel.sel_klist, kn, knote, kn_selnext);
 1333         PIPE_UNLOCK(pipe);
 1334 }
 1335 
 1336 /*ARGSUSED*/
 1337 static int
 1338 filt_piperead(struct knote *kn, long hint)
 1339 {
 1340         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
 1341         struct pipe *wpipe = rpipe->pipe_peer;
 1342 
 1343         if ((hint & NOTE_SUBMIT) == 0)
 1344                 PIPE_LOCK(rpipe);
 1345         kn->kn_data = rpipe->pipe_buffer.cnt;
 1346         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
 1347                 kn->kn_data = rpipe->pipe_map.cnt;
 1348 
 1349         /* XXXSMP: race for peer */
 1350         if ((rpipe->pipe_state & PIPE_EOF) ||
 1351             (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
 1352                 kn->kn_flags |= EV_EOF;
 1353                 if ((hint & NOTE_SUBMIT) == 0)
 1354                         PIPE_UNLOCK(rpipe);
 1355                 return (1);
 1356         }
 1357         if ((hint & NOTE_SUBMIT) == 0)
 1358                 PIPE_UNLOCK(rpipe);
 1359         return (kn->kn_data > 0);
 1360 }
 1361 
 1362 /*ARGSUSED*/
 1363 static int
 1364 filt_pipewrite(struct knote *kn, long hint)
 1365 {
 1366         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
 1367         struct pipe *wpipe = rpipe->pipe_peer;
 1368 
 1369         if ((hint & NOTE_SUBMIT) == 0)
 1370                 PIPE_LOCK(rpipe);
 1371         /* XXXSMP: race for peer */
 1372         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
 1373                 kn->kn_data = 0;
 1374                 kn->kn_flags |= EV_EOF;
 1375                 if ((hint & NOTE_SUBMIT) == 0)
 1376                         PIPE_UNLOCK(rpipe);
 1377                 return (1);
 1378         }
 1379         kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
 1380         if (wpipe->pipe_state & PIPE_DIRECTW)
 1381                 kn->kn_data = 0;
 1382 
 1383         if ((hint & NOTE_SUBMIT) == 0)
 1384                 PIPE_UNLOCK(rpipe);
 1385         return (kn->kn_data >= PIPE_BUF);
 1386 }
 1387 
 1388 static const struct filterops pipe_rfiltops =
 1389         { 1, NULL, filt_pipedetach, filt_piperead };
 1390 static const struct filterops pipe_wfiltops =
 1391         { 1, NULL, filt_pipedetach, filt_pipewrite };
 1392 
 1393 /*ARGSUSED*/
 1394 static int
 1395 pipe_kqfilter(struct file *fp, struct knote *kn)
 1396 {
 1397         struct pipe *pipe;
 1398 
 1399         pipe = (struct pipe *)kn->kn_fp->f_data;
 1400         switch (kn->kn_filter) {
 1401         case EVFILT_READ:
 1402                 kn->kn_fop = &pipe_rfiltops;
 1403                 break;
 1404         case EVFILT_WRITE:
 1405                 kn->kn_fop = &pipe_wfiltops;
 1406                 /* XXXSMP: race for peer */
 1407                 pipe = pipe->pipe_peer;
 1408                 if (pipe == NULL) {
 1409                         /* other end of pipe has been closed */
 1410                         return (EBADF);
 1411                 }
 1412                 break;
 1413         default:
 1414                 return (1);
 1415         }
 1416         kn->kn_hook = pipe;
 1417 
 1418         PIPE_LOCK(pipe);
 1419         SLIST_INSERT_HEAD(&pipe->pipe_sel.sel_klist, kn, kn_selnext);
 1420         PIPE_UNLOCK(pipe);
 1421         return (0);
 1422 }
 1423 
 1424 /*
 1425  * Handle pipe sysctls.
 1426  */
 1427 SYSCTL_SETUP(sysctl_kern_pipe_setup, "sysctl kern.pipe subtree setup")
 1428 {
 1429 
 1430         sysctl_createv(clog, 0, NULL, NULL,
 1431                        CTLFLAG_PERMANENT,
 1432                        CTLTYPE_NODE, "kern", NULL,
 1433                        NULL, 0, NULL, 0,
 1434                        CTL_KERN, CTL_EOL);
 1435         sysctl_createv(clog, 0, NULL, NULL,
 1436                        CTLFLAG_PERMANENT,
 1437                        CTLTYPE_NODE, "pipe",
 1438                        SYSCTL_DESCR("Pipe settings"),
 1439                        NULL, 0, NULL, 0,
 1440                        CTL_KERN, KERN_PIPE, CTL_EOL);
 1441 
 1442         sysctl_createv(clog, 0, NULL, NULL,
 1443                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 1444                        CTLTYPE_INT, "maxkvasz",
 1445                        SYSCTL_DESCR("Maximum amount of kernel memory to be "
 1446                                     "used for pipes"),
 1447                        NULL, 0, &maxpipekva, 0,
 1448                        CTL_KERN, KERN_PIPE, KERN_PIPE_MAXKVASZ, CTL_EOL);
 1449         sysctl_createv(clog, 0, NULL, NULL,
 1450                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 1451                        CTLTYPE_INT, "maxloankvasz",
 1452                        SYSCTL_DESCR("Limit for direct transfers via page loan"),
 1453                        NULL, 0, &limitpipekva, 0,
 1454                        CTL_KERN, KERN_PIPE, KERN_PIPE_LIMITKVA, CTL_EOL);
 1455         sysctl_createv(clog, 0, NULL, NULL,
 1456                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 1457                        CTLTYPE_INT, "maxbigpipes",
 1458                        SYSCTL_DESCR("Maximum number of \"big\" pipes"),
 1459                        NULL, 0, &maxbigpipes, 0,
 1460                        CTL_KERN, KERN_PIPE, KERN_PIPE_MAXBIGPIPES, CTL_EOL);
 1461         sysctl_createv(clog, 0, NULL, NULL,
 1462                        CTLFLAG_PERMANENT,
 1463                        CTLTYPE_INT, "nbigpipes",
 1464                        SYSCTL_DESCR("Number of \"big\" pipes"),
 1465                        NULL, 0, &nbigpipe, 0,
 1466                        CTL_KERN, KERN_PIPE, KERN_PIPE_NBIGPIPES, CTL_EOL);
 1467         sysctl_createv(clog, 0, NULL, NULL,
 1468                        CTLFLAG_PERMANENT,
 1469                        CTLTYPE_INT, "kvasize",
 1470                        SYSCTL_DESCR("Amount of kernel memory consumed by pipe "
 1471                                     "buffers"),
 1472                        NULL, 0, &amountpipekva, 0,
 1473                        CTL_KERN, KERN_PIPE, KERN_PIPE_KVASIZE, CTL_EOL);
 1474 }

Cache object: 479077884af7b08c2e4b0f0667a3ef3e


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