The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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 1.55.2.2 2004/07/23 15:49:46 tron 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 1.55.2.2 2004/07/23 15:49:46 tron 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/lock.h>
   97 #include <sys/ttycom.h>
   98 #include <sys/stat.h>
   99 #include <sys/malloc.h>
  100 #include <sys/poll.h>
  101 #include <sys/signalvar.h>
  102 #include <sys/vnode.h>
  103 #include <sys/uio.h>
  104 #include <sys/lock.h>
  105 #include <sys/select.h>
  106 #include <sys/mount.h>
  107 #include <sys/sa.h>
  108 #include <sys/syscallargs.h>
  109 #include <uvm/uvm.h>
  110 #include <sys/sysctl.h>
  111 #include <sys/kernel.h>
  112 
  113 #include <sys/pipe.h>
  114 
  115 /*
  116  * Avoid microtime(9), it's slow. We don't guard the read from time(9)
  117  * with splclock(9) since we don't actually need to be THAT sure the access
  118  * is atomic.
  119  */
  120 #define PIPE_TIMESTAMP(tvp)     (*(tvp) = time)
  121 
  122 
  123 /*
  124  * Use this define if you want to disable *fancy* VM things.  Expect an
  125  * approx 30% decrease in transfer rate.
  126  */
  127 /* #define PIPE_NODIRECT */
  128 
  129 /*
  130  * interfaces to the outside world
  131  */
  132 static int pipe_read(struct file *fp, off_t *offset, struct uio *uio, 
  133                 struct ucred *cred, int flags);
  134 static int pipe_write(struct file *fp, off_t *offset, struct uio *uio, 
  135                 struct ucred *cred, int flags);
  136 static int pipe_close(struct file *fp, struct proc *p);
  137 static int pipe_poll(struct file *fp, int events, struct proc *p);
  138 static int pipe_fcntl(struct file *fp, u_int com, void *data,
  139                 struct proc *p);
  140 static int pipe_kqfilter(struct file *fp, struct knote *kn);
  141 static int pipe_stat(struct file *fp, struct stat *sb, struct proc *p);
  142 static int pipe_ioctl(struct file *fp, u_long cmd, void *data,
  143                 struct proc *p);
  144 
  145 static struct fileops pipeops = {
  146         pipe_read, pipe_write, pipe_ioctl, pipe_fcntl, pipe_poll,
  147         pipe_stat, pipe_close, pipe_kqfilter
  148 };
  149 
  150 /*
  151  * Default pipe buffer size(s), this can be kind-of large now because pipe
  152  * space is pageable.  The pipe code will try to maintain locality of
  153  * reference for performance reasons, so small amounts of outstanding I/O
  154  * will not wipe the cache.
  155  */
  156 #define MINPIPESIZE (PIPE_SIZE/3)
  157 #define MAXPIPESIZE (2*PIPE_SIZE/3)
  158 
  159 /*
  160  * Maximum amount of kva for pipes -- this is kind-of a soft limit, but
  161  * is there so that on large systems, we don't exhaust it.
  162  */
  163 #define MAXPIPEKVA (8*1024*1024)
  164 static int maxpipekva = MAXPIPEKVA;
  165 
  166 /*
  167  * Limit for direct transfers, we cannot, of course limit
  168  * the amount of kva for pipes in general though.
  169  */
  170 #define LIMITPIPEKVA (16*1024*1024)
  171 static int limitpipekva = LIMITPIPEKVA;
  172 
  173 /*
  174  * Limit the number of "big" pipes
  175  */
  176 #define LIMITBIGPIPES  32
  177 static int maxbigpipes = LIMITBIGPIPES;
  178 static int nbigpipe = 0;
  179 
  180 /*
  181  * Amount of KVA consumed by pipe buffers.
  182  */
  183 static int amountpipekva = 0;
  184 
  185 MALLOC_DEFINE(M_PIPE, "pipe", "Pipe structures");
  186 
  187 static void pipeclose(struct file *fp, struct pipe *pipe);
  188 static void pipe_free_kmem(struct pipe *pipe);
  189 static int pipe_create(struct pipe **pipep, int allockva);
  190 static int pipelock(struct pipe *pipe, int catch);
  191 static __inline void pipeunlock(struct pipe *pipe);
  192 static void pipeselwakeup(struct pipe *pipe, struct pipe *sigp, void *data,
  193     int code);
  194 #ifndef PIPE_NODIRECT
  195 static int pipe_direct_write(struct file *fp, struct pipe *wpipe,
  196     struct uio *uio);
  197 #endif
  198 static int pipespace(struct pipe *pipe, int size);
  199 
  200 #ifndef PIPE_NODIRECT
  201 static int pipe_loan_alloc(struct pipe *, int);
  202 static void pipe_loan_free(struct pipe *);
  203 #endif /* PIPE_NODIRECT */
  204 
  205 static struct pool pipe_pool;
  206 
  207 /*
  208  * The pipe system call for the DTYPE_PIPE type of pipes
  209  */
  210 
  211 /* ARGSUSED */
  212 int
  213 sys_pipe(l, v, retval)
  214         struct lwp *l;
  215         void *v;
  216         register_t *retval;
  217 {
  218         struct file *rf, *wf;
  219         struct pipe *rpipe, *wpipe;
  220         int fd, error;
  221         struct proc *p;
  222 
  223         p = l->l_proc;
  224         rpipe = wpipe = NULL;
  225         if (pipe_create(&rpipe, 1) || pipe_create(&wpipe, 0)) {
  226                 pipeclose(NULL, rpipe);
  227                 pipeclose(NULL, wpipe);
  228                 return (ENFILE);
  229         }
  230 
  231         /*
  232          * Note: the file structure returned from falloc() is marked
  233          * as 'larval' initially. Unless we mark it as 'mature' by
  234          * FILE_SET_MATURE(), any attempt to do anything with it would
  235          * return EBADF, including e.g. dup(2) or close(2). This avoids
  236          * file descriptor races if we block in the second falloc().
  237          */
  238 
  239         error = falloc(p, &rf, &fd);
  240         if (error)
  241                 goto free2;
  242         retval[0] = fd;
  243         rf->f_flag = FREAD;
  244         rf->f_type = DTYPE_PIPE;
  245         rf->f_data = (caddr_t)rpipe;
  246         rf->f_ops = &pipeops;
  247 
  248         error = falloc(p, &wf, &fd);
  249         if (error)
  250                 goto free3;
  251         retval[1] = fd;
  252         wf->f_flag = FWRITE;
  253         wf->f_type = DTYPE_PIPE;
  254         wf->f_data = (caddr_t)wpipe;
  255         wf->f_ops = &pipeops;
  256 
  257         rpipe->pipe_peer = wpipe;
  258         wpipe->pipe_peer = rpipe;
  259 
  260         FILE_SET_MATURE(rf);
  261         FILE_SET_MATURE(wf);
  262         FILE_UNUSE(rf, p);
  263         FILE_UNUSE(wf, p);
  264         return (0);
  265 free3:
  266         FILE_UNUSE(rf, p);
  267         ffree(rf);
  268         fdremove(p->p_fd, retval[0]);
  269 free2:
  270         pipeclose(NULL, wpipe);
  271         pipeclose(NULL, rpipe);
  272 
  273         return (error);
  274 }
  275 
  276 /*
  277  * Allocate kva for pipe circular buffer, the space is pageable
  278  * This routine will 'realloc' the size of a pipe safely, if it fails
  279  * it will retain the old buffer.
  280  * If it fails it will return ENOMEM.
  281  */
  282 static int
  283 pipespace(pipe, size)
  284         struct pipe *pipe;
  285         int size;
  286 {
  287         caddr_t buffer;
  288         /*
  289          * Allocate pageable virtual address space. Physical memory is
  290          * allocated on demand.
  291          */
  292         buffer = (caddr_t) uvm_km_valloc(kernel_map, round_page(size));
  293         if (buffer == NULL)
  294                 return (ENOMEM);
  295 
  296         /* free old resources if we're resizing */
  297         pipe_free_kmem(pipe);
  298         pipe->pipe_buffer.buffer = buffer;
  299         pipe->pipe_buffer.size = size;
  300         pipe->pipe_buffer.in = 0;
  301         pipe->pipe_buffer.out = 0;
  302         pipe->pipe_buffer.cnt = 0;
  303         amountpipekva += pipe->pipe_buffer.size;
  304         return (0);
  305 }
  306 
  307 /*
  308  * Initialize and allocate VM and memory for pipe.
  309  */
  310 static int
  311 pipe_create(pipep, allockva)
  312         struct pipe **pipep;
  313         int allockva;
  314 {
  315         struct pipe *pipe;
  316         int error;
  317 
  318         pipe = *pipep = pool_get(&pipe_pool, PR_WAITOK);
  319 
  320         /* Initialize */ 
  321         memset(pipe, 0, sizeof(struct pipe));
  322         pipe->pipe_state = PIPE_SIGNALR;
  323 
  324         PIPE_TIMESTAMP(&pipe->pipe_ctime);
  325         pipe->pipe_atime = pipe->pipe_ctime;
  326         pipe->pipe_mtime = pipe->pipe_ctime;
  327         simple_lock_init(&pipe->pipe_slock);
  328         lockinit(&pipe->pipe_lock, PSOCK | PCATCH, "pipelk", 0, 0);
  329 
  330         if (allockva && (error = pipespace(pipe, PIPE_SIZE)))
  331                 return (error);
  332 
  333         return (0);
  334 }
  335 
  336 
  337 /*
  338  * Lock a pipe for I/O, blocking other access
  339  * Called with pipe spin lock held.
  340  * Return with pipe spin lock released on success.
  341  */
  342 static int
  343 pipelock(pipe, catch)
  344         struct pipe *pipe;
  345         int catch;
  346 {
  347         int error;
  348 
  349         LOCK_ASSERT(simple_lock_held(&pipe->pipe_slock));
  350 
  351         while (1) {
  352                 error = lockmgr(&pipe->pipe_lock, LK_EXCLUSIVE | LK_INTERLOCK,
  353                                 &pipe->pipe_slock);
  354                 if (error == 0)
  355                         break;
  356 
  357                 simple_lock(&pipe->pipe_slock);
  358                 if (catch || (error != EINTR && error != ERESTART))
  359                         break;
  360                 /*
  361                  * XXX XXX XXX
  362                  * The pipe lock is initialised with PCATCH on and we cannot
  363                  * override this in a lockmgr() call. Thus a pending signal
  364                  * will cause lockmgr() to return with EINTR or ERESTART.
  365                  * We cannot simply re-enter lockmgr() at this point since
  366                  * the pending signals have not yet been posted and would
  367                  * cause an immediate EINTR/ERESTART return again.
  368                  * As a workaround we pause for a while here, giving the lock
  369                  * a chance to drain, before trying again.
  370                  * XXX XXX XXX
  371                  *
  372                  * NOTE: Consider dropping PCATCH from this lock; in practice
  373                  * it is never held for long enough periods for having it
  374                  * interruptable at the start of pipe_read/pipe_write to be
  375                  * beneficial.
  376                  */
  377                 (void) ltsleep(&lbolt, PSOCK, "rstrtpipelock", hz,
  378                     &pipe->pipe_slock);
  379         }
  380         return (error);
  381 }
  382 
  383 /*
  384  * unlock a pipe I/O lock
  385  */
  386 static __inline void
  387 pipeunlock(pipe)
  388         struct pipe *pipe;
  389 {
  390 
  391         lockmgr(&pipe->pipe_lock, LK_RELEASE, NULL);
  392 }
  393 
  394 /*
  395  * Select/poll wakup. This also sends SIGIO to peer connected to
  396  * 'sigpipe' side of pipe.
  397  */
  398 static void
  399 pipeselwakeup(selp, sigp, data, code)
  400         struct pipe *selp, *sigp;
  401         void *data;
  402         int code;
  403 {
  404         int band;
  405 
  406         selnotify(&selp->pipe_sel, NOTE_SUBMIT);
  407 
  408         if (sigp == NULL || (sigp->pipe_state & PIPE_ASYNC) == 0)
  409                 return;
  410 
  411         switch (code) {
  412         case POLL_IN:
  413                 band = POLLIN|POLLRDNORM;
  414                 break;
  415         case POLL_OUT:
  416                 band = POLLOUT|POLLWRNORM;
  417                 break;
  418         case POLL_HUP:
  419                 band = POLLHUP;
  420                 break;
  421 #if POLL_HUP != POLL_ERR
  422         case POLL_ERR:
  423                 band = POLLERR;
  424                 break;
  425 #endif
  426         default:
  427                 band = 0;
  428 #ifdef DIAGNOSTIC
  429                 printf("bad siginfo code %d in pipe notification.\n", code);
  430 #endif
  431                 break;
  432         }
  433 
  434         fownsignal(sigp->pipe_pgid, SIGIO, code, band, selp);
  435 }
  436 
  437 /* ARGSUSED */
  438 static int
  439 pipe_read(fp, offset, uio, cred, flags)
  440         struct file *fp;
  441         off_t *offset;
  442         struct uio *uio;
  443         struct ucred *cred;
  444         int flags;
  445 {
  446         struct pipe *rpipe = (struct pipe *) fp->f_data;
  447         struct pipebuf *bp = &rpipe->pipe_buffer;
  448         int error;
  449         size_t nread = 0;
  450         size_t size;
  451         size_t ocnt;
  452 
  453         PIPE_LOCK(rpipe);
  454         ++rpipe->pipe_busy;
  455         ocnt = bp->cnt;
  456 
  457 again:
  458         error = pipelock(rpipe, 1);
  459         if (error)
  460                 goto unlocked_error;
  461 
  462         while (uio->uio_resid) {
  463                 /*
  464                  * normal pipe buffer receive
  465                  */
  466                 if (bp->cnt > 0) {
  467                         size = bp->size - bp->out;
  468                         if (size > bp->cnt)
  469                                 size = bp->cnt;
  470                         if (size > uio->uio_resid)
  471                                 size = uio->uio_resid;
  472 
  473                         error = uiomove(&bp->buffer[bp->out], size, uio);
  474                         if (error)
  475                                 break;
  476 
  477                         bp->out += size;
  478                         if (bp->out >= bp->size)
  479                                 bp->out = 0;
  480 
  481                         bp->cnt -= size;
  482 
  483                         /*
  484                          * If there is no more to read in the pipe, reset
  485                          * its pointers to the beginning.  This improves
  486                          * cache hit stats.
  487                          */
  488                         if (bp->cnt == 0) {
  489                                 bp->in = 0;
  490                                 bp->out = 0;
  491                         }
  492                         nread += size;
  493 #ifndef PIPE_NODIRECT
  494                 } else if ((rpipe->pipe_state & PIPE_DIRECTR) != 0) {
  495                         /*
  496                          * Direct copy, bypassing a kernel buffer.
  497                          */
  498                         caddr_t va;
  499 
  500                         KASSERT(rpipe->pipe_state & PIPE_DIRECTW);
  501 
  502                         size = rpipe->pipe_map.cnt;
  503                         if (size > uio->uio_resid)
  504                                 size = uio->uio_resid;
  505 
  506                         va = (caddr_t) rpipe->pipe_map.kva +
  507                             rpipe->pipe_map.pos;
  508                         error = uiomove(va, size, uio);
  509                         if (error)
  510                                 break;
  511                         nread += size;
  512                         rpipe->pipe_map.pos += size;
  513                         rpipe->pipe_map.cnt -= size;
  514                         if (rpipe->pipe_map.cnt == 0) {
  515                                 PIPE_LOCK(rpipe);
  516                                 rpipe->pipe_state &= ~PIPE_DIRECTR;
  517                                 wakeup(rpipe);
  518                                 PIPE_UNLOCK(rpipe);
  519                         }
  520 #endif
  521                 } else {
  522                         /*
  523                          * Break if some data was read.
  524                          */
  525                         if (nread > 0)
  526                                 break;
  527 
  528                         PIPE_LOCK(rpipe);
  529 
  530                         /*
  531                          * detect EOF condition
  532                          * read returns 0 on EOF, no need to set error
  533                          */
  534                         if (rpipe->pipe_state & PIPE_EOF) {
  535                                 PIPE_UNLOCK(rpipe);
  536                                 break;
  537                         }
  538 
  539                         /*
  540                          * don't block on non-blocking I/O
  541                          */
  542                         if (fp->f_flag & FNONBLOCK) {
  543                                 PIPE_UNLOCK(rpipe);
  544                                 error = EAGAIN;
  545                                 break;
  546                         }
  547 
  548                         /*
  549                          * Unlock the pipe buffer for our remaining processing.
  550                          * We will either break out with an error or we will
  551                          * sleep and relock to loop.
  552                          */
  553                         pipeunlock(rpipe);
  554 
  555                         /*
  556                          * The PIPE_DIRECTR flag is not under the control
  557                          * of the long-term lock (see pipe_direct_write()),
  558                          * so re-check now while holding the spin lock.
  559                          */
  560                         if ((rpipe->pipe_state & PIPE_DIRECTR) != 0)
  561                                 goto again;
  562 
  563                         /*
  564                          * We want to read more, wake up select/poll.
  565                          */
  566                         pipeselwakeup(rpipe, rpipe->pipe_peer, fp->f_data,
  567                             POLL_IN);
  568 
  569                         /*
  570                          * If the "write-side" is blocked, wake it up now.
  571                          */
  572                         if (rpipe->pipe_state & PIPE_WANTW) {
  573                                 rpipe->pipe_state &= ~PIPE_WANTW;
  574                                 wakeup(rpipe);
  575                         }
  576 
  577                         /* Now wait until the pipe is filled */
  578                         rpipe->pipe_state |= PIPE_WANTR;
  579                         error = ltsleep(rpipe, PSOCK | PCATCH,
  580                                         "piperd", 0, &rpipe->pipe_slock);
  581                         if (error != 0)
  582                                 goto unlocked_error;
  583                         goto again;
  584                 }
  585         }
  586 
  587         if (error == 0)
  588                 PIPE_TIMESTAMP(&rpipe->pipe_atime);
  589 
  590         PIPE_LOCK(rpipe);
  591         pipeunlock(rpipe);
  592 
  593 unlocked_error:
  594         --rpipe->pipe_busy;
  595 
  596         /*
  597          * PIPE_WANTCLOSE processing only makes sense if pipe_busy is 0.
  598          */
  599         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANTCLOSE)) {
  600                 rpipe->pipe_state &= ~(PIPE_WANTCLOSE|PIPE_WANTW);
  601                 wakeup(rpipe);
  602         } else if (bp->cnt < MINPIPESIZE) {
  603                 /*
  604                  * Handle write blocking hysteresis.
  605                  */
  606                 if (rpipe->pipe_state & PIPE_WANTW) {
  607                         rpipe->pipe_state &= ~PIPE_WANTW;
  608                         wakeup(rpipe);
  609                 }
  610         }
  611 
  612         /*
  613          * If anything was read off the buffer, signal to the writer it's
  614          * possible to write more data. Also send signal if we are here for the
  615          * first time after last write.
  616          */
  617         if ((bp->size - bp->cnt) >= PIPE_BUF
  618             && (ocnt != bp->cnt || (rpipe->pipe_state & PIPE_SIGNALR))) {
  619                 pipeselwakeup(rpipe, rpipe->pipe_peer, fp->f_data, POLL_OUT);
  620                 rpipe->pipe_state &= ~PIPE_SIGNALR;
  621         }
  622 
  623         PIPE_UNLOCK(rpipe);
  624         return (error);
  625 }
  626 
  627 #ifndef PIPE_NODIRECT
  628 /*
  629  * Allocate structure for loan transfer.
  630  */
  631 static int
  632 pipe_loan_alloc(wpipe, npages)
  633         struct pipe *wpipe;
  634         int npages;
  635 {
  636         vsize_t len;
  637 
  638         len = (vsize_t)npages << PAGE_SHIFT;
  639         wpipe->pipe_map.kva = uvm_km_valloc_wait(kernel_map, len);
  640         if (wpipe->pipe_map.kva == 0)
  641                 return (ENOMEM);
  642 
  643         amountpipekva += len;
  644         wpipe->pipe_map.npages = npages;
  645         wpipe->pipe_map.pgs = malloc(npages * sizeof(struct vm_page *), M_PIPE,
  646             M_WAITOK);
  647         return (0);
  648 }
  649 
  650 /*
  651  * Free resources allocated for loan transfer.
  652  */
  653 static void
  654 pipe_loan_free(wpipe)
  655         struct pipe *wpipe;
  656 {
  657         vsize_t len;
  658 
  659         len = (vsize_t)wpipe->pipe_map.npages << PAGE_SHIFT;
  660         uvm_km_free(kernel_map, wpipe->pipe_map.kva, len);
  661         wpipe->pipe_map.kva = 0;
  662         amountpipekva -= len;
  663         free(wpipe->pipe_map.pgs, M_PIPE);
  664         wpipe->pipe_map.pgs = NULL;
  665 }
  666 
  667 /*
  668  * NetBSD direct write, using uvm_loan() mechanism.
  669  * This implements the pipe buffer write mechanism.  Note that only
  670  * a direct write OR a normal pipe write can be pending at any given time.
  671  * If there are any characters in the pipe buffer, the direct write will
  672  * be deferred until the receiving process grabs all of the bytes from
  673  * the pipe buffer.  Then the direct mapping write is set-up.
  674  *
  675  * Called with the long-term pipe lock held.
  676  */
  677 static int
  678 pipe_direct_write(fp, wpipe, uio)
  679         struct file *fp;
  680         struct pipe *wpipe;
  681         struct uio *uio;
  682 {
  683         int error, npages, j;
  684         struct vm_page **pgs;
  685         vaddr_t bbase, kva, base, bend;
  686         vsize_t blen, bcnt;
  687         voff_t bpos;
  688 
  689         KASSERT(wpipe->pipe_map.cnt == 0);
  690 
  691         /*
  692          * Handle first PIPE_CHUNK_SIZE bytes of buffer. Deal with buffers
  693          * not aligned to PAGE_SIZE.
  694          */
  695         bbase = (vaddr_t)uio->uio_iov->iov_base;
  696         base = trunc_page(bbase);
  697         bend = round_page(bbase + uio->uio_iov->iov_len);
  698         blen = bend - base;
  699         bpos = bbase - base;
  700 
  701         if (blen > PIPE_DIRECT_CHUNK) {
  702                 blen = PIPE_DIRECT_CHUNK;
  703                 bend = base + blen;
  704                 bcnt = PIPE_DIRECT_CHUNK - bpos;
  705         } else {
  706                 bcnt = uio->uio_iov->iov_len;
  707         }
  708         npages = blen >> PAGE_SHIFT;
  709 
  710         /*
  711          * Free the old kva if we need more pages than we have
  712          * allocated.
  713          */
  714         if (wpipe->pipe_map.kva != 0 && npages > wpipe->pipe_map.npages)
  715                 pipe_loan_free(wpipe);
  716 
  717         /* Allocate new kva. */
  718         if (wpipe->pipe_map.kva == 0) {
  719                 error = pipe_loan_alloc(wpipe, npages);
  720                 if (error)
  721                         return (error);
  722         }
  723 
  724         /* Loan the write buffer memory from writer process */
  725         pgs = wpipe->pipe_map.pgs;
  726         error = uvm_loan(&uio->uio_procp->p_vmspace->vm_map, base, blen,
  727                          pgs, UVM_LOAN_TOPAGE);
  728         if (error) {
  729                 pipe_loan_free(wpipe);
  730                 return (error);
  731         }
  732 
  733         /* Enter the loaned pages to kva */
  734         kva = wpipe->pipe_map.kva;
  735         for (j = 0; j < npages; j++, kva += PAGE_SIZE) {
  736                 pmap_kenter_pa(kva, VM_PAGE_TO_PHYS(pgs[j]), VM_PROT_READ);
  737         }
  738         pmap_update(pmap_kernel());
  739 
  740         /* Now we can put the pipe in direct write mode */
  741         wpipe->pipe_map.pos = bpos;
  742         wpipe->pipe_map.cnt = bcnt;
  743         wpipe->pipe_state |= PIPE_DIRECTW;
  744 
  745         /*
  746          * But before we can let someone do a direct read,
  747          * we have to wait until the pipe is drained.
  748          */
  749 
  750         /* Relase the pipe lock while we wait */
  751         PIPE_LOCK(wpipe);
  752         pipeunlock(wpipe);
  753 
  754         while (error == 0 && wpipe->pipe_buffer.cnt > 0) {
  755                 if (wpipe->pipe_state & PIPE_WANTR) {
  756                         wpipe->pipe_state &= ~PIPE_WANTR;
  757                         wakeup(wpipe);
  758                 }
  759 
  760                 wpipe->pipe_state |= PIPE_WANTW;
  761                 error = ltsleep(wpipe, PSOCK | PCATCH, "pipdwc", 0,
  762                                 &wpipe->pipe_slock);
  763                 if (error == 0 && wpipe->pipe_state & PIPE_EOF)
  764                         error = EPIPE;
  765         }
  766 
  767         /* Pipe is drained; next read will off the direct buffer */
  768         wpipe->pipe_state |= PIPE_DIRECTR;
  769 
  770         /* Wait until the reader is done */
  771         while (error == 0 && (wpipe->pipe_state & PIPE_DIRECTR)) {
  772                 if (wpipe->pipe_state & PIPE_WANTR) {
  773                         wpipe->pipe_state &= ~PIPE_WANTR;
  774                         wakeup(wpipe);
  775                 }
  776                 pipeselwakeup(wpipe, wpipe, fp->f_data, POLL_IN);
  777                 error = ltsleep(wpipe, PSOCK | PCATCH, "pipdwt", 0,
  778                                 &wpipe->pipe_slock);
  779                 if (error == 0 && wpipe->pipe_state & PIPE_EOF)
  780                         error = EPIPE;
  781         }
  782 
  783         /* Take pipe out of direct write mode */
  784         wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTR);
  785 
  786         /* Acquire the pipe lock and cleanup */
  787         (void)pipelock(wpipe, 0);
  788         if (pgs != NULL) {
  789                 pmap_kremove(wpipe->pipe_map.kva, blen);
  790                 uvm_unloan(pgs, npages, UVM_LOAN_TOPAGE);
  791         }
  792         if (error || amountpipekva > maxpipekva)
  793                 pipe_loan_free(wpipe);
  794 
  795         if (error) {
  796                 pipeselwakeup(wpipe, wpipe, fp->f_data, POLL_ERR);
  797 
  798                 /*
  799                  * If nothing was read from what we offered, return error
  800                  * straight on. Otherwise update uio resid first. Caller
  801                  * will deal with the error condition, returning short
  802                  * write, error, or restarting the write(2) as appropriate.
  803                  */
  804                 if (wpipe->pipe_map.cnt == bcnt) {
  805                         wpipe->pipe_map.cnt = 0;
  806                         wakeup(wpipe);
  807                         return (error);
  808                 }
  809 
  810                 bcnt -= wpipe->pipe_map.cnt;
  811         }
  812 
  813         uio->uio_resid -= bcnt;
  814         /* uio_offset not updated, not set/used for write(2) */
  815         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + bcnt;
  816         uio->uio_iov->iov_len -= bcnt;
  817         if (uio->uio_iov->iov_len == 0) {
  818                 uio->uio_iov++;
  819                 uio->uio_iovcnt--;
  820         }
  821 
  822         wpipe->pipe_map.cnt = 0;
  823         return (error);
  824 }
  825 #endif /* !PIPE_NODIRECT */
  826 
  827 static int
  828 pipe_write(fp, offset, uio, cred, flags)
  829         struct file *fp;
  830         off_t *offset;
  831         struct uio *uio;
  832         struct ucred *cred;
  833         int flags;
  834 {
  835         struct pipe *wpipe, *rpipe;
  836         struct pipebuf *bp;
  837         int error;
  838 
  839         /* We want to write to our peer */
  840         rpipe = (struct pipe *) fp->f_data;
  841 
  842 retry:
  843         error = 0;
  844         PIPE_LOCK(rpipe);
  845         wpipe = rpipe->pipe_peer;
  846 
  847         /*
  848          * Detect loss of pipe read side, issue SIGPIPE if lost.
  849          */
  850         if (wpipe == NULL)
  851                 error = EPIPE;
  852         else if (simple_lock_try(&wpipe->pipe_slock) == 0) {
  853                 /* Deal with race for peer */
  854                 PIPE_UNLOCK(rpipe);
  855                 goto retry;
  856         } else if ((wpipe->pipe_state & PIPE_EOF) != 0) {
  857                 PIPE_UNLOCK(wpipe);
  858                 error = EPIPE;
  859         }
  860 
  861         PIPE_UNLOCK(rpipe);
  862         if (error != 0)
  863                 return (error);
  864 
  865         ++wpipe->pipe_busy;
  866 
  867         /* Aquire the long-term pipe lock */
  868         if ((error = pipelock(wpipe,1)) != 0) {
  869                 --wpipe->pipe_busy;
  870                 if (wpipe->pipe_busy == 0
  871                     && (wpipe->pipe_state & PIPE_WANTCLOSE)) {
  872                         wpipe->pipe_state &= ~(PIPE_WANTCLOSE | PIPE_WANTR);
  873                         wakeup(wpipe);
  874                 }
  875                 PIPE_UNLOCK(wpipe);
  876                 return (error);
  877         }
  878 
  879         bp = &wpipe->pipe_buffer;
  880 
  881         /*
  882          * If it is advantageous to resize the pipe buffer, do so.
  883          */
  884         if ((uio->uio_resid > PIPE_SIZE) &&
  885             (nbigpipe < maxbigpipes) &&
  886 #ifndef PIPE_NODIRECT
  887             (wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
  888 #endif
  889             (bp->size <= PIPE_SIZE) && (bp->cnt == 0)) {
  890 
  891                 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
  892                         nbigpipe++;
  893         }
  894 
  895         while (uio->uio_resid) {
  896                 size_t space;
  897 
  898 #ifndef PIPE_NODIRECT
  899                 /*
  900                  * Pipe buffered writes cannot be coincidental with
  901                  * direct writes.  Also, only one direct write can be
  902                  * in progress at any one time.  We wait until the currently
  903                  * executing direct write is completed before continuing.
  904                  *
  905                  * We break out if a signal occurs or the reader goes away.
  906                  */
  907                 while (error == 0 && wpipe->pipe_state & PIPE_DIRECTW) {
  908                         PIPE_LOCK(wpipe);
  909                         if (wpipe->pipe_state & PIPE_WANTR) {
  910                                 wpipe->pipe_state &= ~PIPE_WANTR;
  911                                 wakeup(wpipe);
  912                         }
  913                         pipeunlock(wpipe);
  914                         error = ltsleep(wpipe, PSOCK | PCATCH,
  915                                         "pipbww", 0, &wpipe->pipe_slock);
  916 
  917                         (void)pipelock(wpipe, 0);
  918                         if (wpipe->pipe_state & PIPE_EOF)
  919                                 error = EPIPE;
  920                 }
  921                 if (error)
  922                         break;
  923 
  924                 /*
  925                  * If the transfer is large, we can gain performance if
  926                  * we do process-to-process copies directly.
  927                  * If the write is non-blocking, we don't use the
  928                  * direct write mechanism.
  929                  *
  930                  * The direct write mechanism will detect the reader going
  931                  * away on us.
  932                  */
  933                 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) &&
  934                     (fp->f_flag & FNONBLOCK) == 0 &&
  935                     (wpipe->pipe_map.kva || (amountpipekva < limitpipekva))) {
  936                         error = pipe_direct_write(fp, wpipe, uio);
  937 
  938                         /*
  939                          * Break out if error occurred, unless it's ENOMEM.
  940                          * ENOMEM means we failed to allocate some resources
  941                          * for direct write, so we just fallback to ordinary
  942                          * write. If the direct write was successful,
  943                          * process rest of data via ordinary write.
  944                          */
  945                         if (error == 0)
  946                                 continue;
  947 
  948                         if (error != ENOMEM)
  949                                 break;
  950                 }
  951 #endif /* PIPE_NODIRECT */
  952 
  953                 space = bp->size - bp->cnt;
  954 
  955                 /* Writes of size <= PIPE_BUF must be atomic. */
  956                 if ((space < uio->uio_resid) && (uio->uio_resid <= PIPE_BUF))
  957                         space = 0;
  958 
  959                 if (space > 0) {
  960                         int size;       /* Transfer size */
  961                         int segsize;    /* first segment to transfer */
  962 
  963                         /*
  964                          * Transfer size is minimum of uio transfer
  965                          * and free space in pipe buffer.
  966                          */
  967                         if (space > uio->uio_resid)
  968                                 size = uio->uio_resid;
  969                         else
  970                                 size = space;
  971                         /*
  972                          * First segment to transfer is minimum of 
  973                          * transfer size and contiguous space in
  974                          * pipe buffer.  If first segment to transfer
  975                          * is less than the transfer size, we've got
  976                          * a wraparound in the buffer.
  977                          */
  978                         segsize = bp->size - bp->in;
  979                         if (segsize > size)
  980                                 segsize = size;
  981 
  982                         /* Transfer first segment */
  983                         error = uiomove(&bp->buffer[bp->in], segsize, uio);
  984 
  985                         if (error == 0 && segsize < size) {
  986                                 /* 
  987                                  * Transfer remaining part now, to
  988                                  * support atomic writes.  Wraparound
  989                                  * happened.
  990                                  */
  991 #ifdef DEBUG
  992                                 if (bp->in + segsize != bp->size)
  993                                         panic("Expected pipe buffer wraparound disappeared");
  994 #endif
  995 
  996                                 error = uiomove(&bp->buffer[0],
  997                                                 size - segsize, uio);
  998                         }
  999                         if (error)
 1000                                 break;
 1001 
 1002                         bp->in += size;
 1003                         if (bp->in >= bp->size) {
 1004 #ifdef DEBUG
 1005                                 if (bp->in != size - segsize + bp->size)
 1006                                         panic("Expected wraparound bad");
 1007 #endif
 1008                                 bp->in = size - segsize;
 1009                         }
 1010 
 1011                         bp->cnt += size;
 1012 #ifdef DEBUG
 1013                         if (bp->cnt > bp->size)
 1014                                 panic("Pipe buffer overflow");
 1015 #endif
 1016                 } else {
 1017                         /*
 1018                          * If the "read-side" has been blocked, wake it up now.
 1019                          */
 1020                         PIPE_LOCK(wpipe);
 1021                         if (wpipe->pipe_state & PIPE_WANTR) {
 1022                                 wpipe->pipe_state &= ~PIPE_WANTR;
 1023                                 wakeup(wpipe);
 1024                         }
 1025                         PIPE_UNLOCK(wpipe);
 1026 
 1027                         /*
 1028                          * don't block on non-blocking I/O
 1029                          */
 1030                         if (fp->f_flag & FNONBLOCK) {
 1031                                 error = EAGAIN;
 1032                                 break;
 1033                         }
 1034 
 1035                         /*
 1036                          * We have no more space and have something to offer,
 1037                          * wake up select/poll.
 1038                          */
 1039                         if (bp->cnt)
 1040                                 pipeselwakeup(wpipe, wpipe, fp->f_data,
 1041                                     POLL_OUT);
 1042 
 1043                         PIPE_LOCK(wpipe);
 1044                         pipeunlock(wpipe);
 1045                         wpipe->pipe_state |= PIPE_WANTW;
 1046                         error = ltsleep(wpipe, PSOCK | PCATCH, "pipewr", 0,
 1047                                         &wpipe->pipe_slock);
 1048                         (void)pipelock(wpipe, 0);
 1049                         if (error != 0)
 1050                                 break;
 1051                         /*
 1052                          * If read side wants to go away, we just issue a signal
 1053                          * to ourselves.
 1054                          */
 1055                         if (wpipe->pipe_state & PIPE_EOF) {
 1056                                 error = EPIPE;
 1057                                 break;
 1058                         }
 1059                 }
 1060         }
 1061 
 1062         PIPE_LOCK(wpipe);
 1063         --wpipe->pipe_busy;
 1064         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANTCLOSE)) {
 1065                 wpipe->pipe_state &= ~(PIPE_WANTCLOSE | PIPE_WANTR);
 1066                 wakeup(wpipe);
 1067         } else if (bp->cnt > 0) {
 1068                 /*
 1069                  * If we have put any characters in the buffer, we wake up
 1070                  * the reader.
 1071                  */
 1072                 if (wpipe->pipe_state & PIPE_WANTR) {
 1073                         wpipe->pipe_state &= ~PIPE_WANTR;
 1074                         wakeup(wpipe);
 1075                 }
 1076         }
 1077 
 1078         /*
 1079          * Don't return EPIPE if I/O was successful
 1080          */
 1081         if (error == EPIPE && bp->cnt == 0 && uio->uio_resid == 0)
 1082                 error = 0;
 1083 
 1084         if (error == 0)
 1085                 PIPE_TIMESTAMP(&wpipe->pipe_mtime);
 1086 
 1087         /*
 1088          * We have something to offer, wake up select/poll.
 1089          * wpipe->pipe_map.cnt is always 0 in this point (direct write
 1090          * is only done synchronously), so check only wpipe->pipe_buffer.cnt
 1091          */
 1092         if (bp->cnt)
 1093                 pipeselwakeup(wpipe, wpipe, fp->f_data, POLL_OUT);
 1094 
 1095         /*
 1096          * Arrange for next read(2) to do a signal.
 1097          */
 1098         wpipe->pipe_state |= PIPE_SIGNALR;
 1099 
 1100         pipeunlock(wpipe);
 1101         PIPE_UNLOCK(wpipe);
 1102         return (error);
 1103 }
 1104 
 1105 /*
 1106  * we implement a very minimal set of ioctls for compatibility with sockets.
 1107  */
 1108 int
 1109 pipe_ioctl(fp, cmd, data, p)
 1110         struct file *fp;
 1111         u_long cmd;
 1112         void *data;
 1113         struct proc *p;
 1114 {
 1115         struct pipe *pipe = (struct pipe *)fp->f_data;
 1116 
 1117         switch (cmd) {
 1118 
 1119         case FIONBIO:
 1120                 return (0);
 1121 
 1122         case FIOASYNC:
 1123                 PIPE_LOCK(pipe);
 1124                 if (*(int *)data) {
 1125                         pipe->pipe_state |= PIPE_ASYNC;
 1126                 } else {
 1127                         pipe->pipe_state &= ~PIPE_ASYNC;
 1128                 }
 1129                 PIPE_UNLOCK(pipe);
 1130                 return (0);
 1131 
 1132         case FIONREAD:
 1133                 PIPE_LOCK(pipe);
 1134 #ifndef PIPE_NODIRECT
 1135                 if (pipe->pipe_state & PIPE_DIRECTW)
 1136                         *(int *)data = pipe->pipe_map.cnt;
 1137                 else
 1138 #endif
 1139                         *(int *)data = pipe->pipe_buffer.cnt;
 1140                 PIPE_UNLOCK(pipe);
 1141                 return (0);
 1142 
 1143         case TIOCSPGRP:
 1144         case FIOSETOWN:
 1145                 return fsetown(p, &pipe->pipe_pgid, cmd, data);
 1146 
 1147         case TIOCGPGRP:
 1148         case FIOGETOWN:
 1149                 return fgetown(p, pipe->pipe_pgid, cmd, data);
 1150 
 1151         }
 1152         return (EPASSTHROUGH);
 1153 }
 1154 
 1155 int
 1156 pipe_poll(fp, events, td)
 1157         struct file *fp;
 1158         int events;
 1159         struct proc *td;
 1160 {
 1161         struct pipe *rpipe = (struct pipe *)fp->f_data;
 1162         struct pipe *wpipe;
 1163         int eof = 0;
 1164         int revents = 0;
 1165 
 1166 retry:
 1167         PIPE_LOCK(rpipe);
 1168         wpipe = rpipe->pipe_peer;
 1169         if (wpipe != NULL && simple_lock_try(&wpipe->pipe_slock) == 0) {
 1170                 /* Deal with race for peer */
 1171                 PIPE_UNLOCK(rpipe);
 1172                 goto retry;
 1173         }
 1174 
 1175         if (events & (POLLIN | POLLRDNORM))
 1176                 if ((rpipe->pipe_buffer.cnt > 0) ||
 1177 #ifndef PIPE_NODIRECT
 1178                     (rpipe->pipe_state & PIPE_DIRECTR) ||
 1179 #endif
 1180                     (rpipe->pipe_state & PIPE_EOF))
 1181                         revents |= events & (POLLIN | POLLRDNORM);
 1182 
 1183         eof |= (rpipe->pipe_state & PIPE_EOF);
 1184         PIPE_UNLOCK(rpipe);
 1185 
 1186         if (wpipe == NULL)
 1187                 revents |= events & (POLLOUT | POLLWRNORM);
 1188         else {
 1189                 if (events & (POLLOUT | POLLWRNORM))
 1190                         if ((wpipe->pipe_state & PIPE_EOF) || (
 1191 #ifndef PIPE_NODIRECT
 1192                              (wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
 1193 #endif
 1194                              (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
 1195                                 revents |= events & (POLLOUT | POLLWRNORM);
 1196 
 1197                 eof |= (wpipe->pipe_state & PIPE_EOF);
 1198                 PIPE_UNLOCK(wpipe);
 1199         }
 1200 
 1201         if (wpipe == NULL || eof)
 1202                 revents |= POLLHUP;
 1203 
 1204         if (revents == 0) {
 1205                 if (events & (POLLIN | POLLRDNORM))
 1206                         selrecord(td, &rpipe->pipe_sel);
 1207 
 1208                 if (events & (POLLOUT | POLLWRNORM))
 1209                         selrecord(td, &wpipe->pipe_sel);
 1210         }
 1211 
 1212         return (revents);
 1213 }
 1214 
 1215 static int
 1216 pipe_stat(fp, ub, td)
 1217         struct file *fp;
 1218         struct stat *ub;
 1219         struct proc *td;
 1220 {
 1221         struct pipe *pipe = (struct pipe *)fp->f_data;
 1222 
 1223         memset((caddr_t)ub, 0, sizeof(*ub));
 1224         ub->st_mode = S_IFIFO | S_IRUSR | S_IWUSR;
 1225         ub->st_blksize = pipe->pipe_buffer.size;
 1226         ub->st_size = pipe->pipe_buffer.cnt;
 1227         ub->st_blocks = (ub->st_size) ? 1 : 0;
 1228         TIMEVAL_TO_TIMESPEC(&pipe->pipe_atime, &ub->st_atimespec)
 1229         TIMEVAL_TO_TIMESPEC(&pipe->pipe_mtime, &ub->st_mtimespec);
 1230         TIMEVAL_TO_TIMESPEC(&pipe->pipe_ctime, &ub->st_ctimespec);
 1231         ub->st_uid = fp->f_cred->cr_uid;
 1232         ub->st_gid = fp->f_cred->cr_gid;
 1233         /*
 1234          * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen.
 1235          * XXX (st_dev, st_ino) should be unique.
 1236          */
 1237         return (0);
 1238 }
 1239 
 1240 /* ARGSUSED */
 1241 static int
 1242 pipe_close(fp, td)
 1243         struct file *fp;
 1244         struct proc *td;
 1245 {
 1246         struct pipe *pipe = (struct pipe *)fp->f_data;
 1247 
 1248         fp->f_data = NULL;
 1249         pipeclose(fp, pipe);
 1250         return (0);
 1251 }
 1252 
 1253 static void
 1254 pipe_free_kmem(pipe)
 1255         struct pipe *pipe;
 1256 {
 1257 
 1258         if (pipe->pipe_buffer.buffer != NULL) {
 1259                 if (pipe->pipe_buffer.size > PIPE_SIZE)
 1260                         --nbigpipe;
 1261                 amountpipekva -= pipe->pipe_buffer.size;
 1262                 uvm_km_free(kernel_map,
 1263                         (vaddr_t)pipe->pipe_buffer.buffer,
 1264                         pipe->pipe_buffer.size);
 1265                 pipe->pipe_buffer.buffer = NULL;
 1266         }
 1267 #ifndef PIPE_NODIRECT
 1268         if (pipe->pipe_map.kva != 0) {
 1269                 pipe_loan_free(pipe);
 1270                 pipe->pipe_map.cnt = 0;
 1271                 pipe->pipe_map.kva = 0;
 1272                 pipe->pipe_map.pos = 0;
 1273                 pipe->pipe_map.npages = 0;
 1274         }
 1275 #endif /* !PIPE_NODIRECT */
 1276 }
 1277 
 1278 /*
 1279  * shutdown the pipe
 1280  */
 1281 static void
 1282 pipeclose(fp, pipe)
 1283         struct file *fp;
 1284         struct pipe *pipe;
 1285 {
 1286         struct pipe *ppipe;
 1287 
 1288         if (pipe == NULL)
 1289                 return;
 1290 
 1291 retry:
 1292         PIPE_LOCK(pipe);
 1293 
 1294         if (fp)
 1295                 pipeselwakeup(pipe, pipe, fp->f_data, POLL_HUP);
 1296 
 1297         /*
 1298          * If the other side is blocked, wake it up saying that
 1299          * we want to close it down.
 1300          */
 1301         while (pipe->pipe_busy) {
 1302                 wakeup(pipe);
 1303                 pipe->pipe_state |= PIPE_WANTCLOSE | PIPE_EOF;
 1304                 ltsleep(pipe, PSOCK, "pipecl", 0, &pipe->pipe_slock);
 1305         }
 1306 
 1307         /*
 1308          * Disconnect from peer
 1309          */
 1310         if ((ppipe = pipe->pipe_peer) != NULL) {
 1311                 /* Deal with race for peer */
 1312                 if (simple_lock_try(&ppipe->pipe_slock) == 0) {
 1313                         PIPE_UNLOCK(pipe);
 1314                         goto retry;
 1315                 }
 1316                 if (fp)
 1317                         pipeselwakeup(ppipe, ppipe, fp->f_data, POLL_HUP);
 1318 
 1319                 ppipe->pipe_state |= PIPE_EOF;
 1320                 wakeup(ppipe);
 1321                 ppipe->pipe_peer = NULL;
 1322                 PIPE_UNLOCK(ppipe);
 1323         }
 1324 
 1325         (void)lockmgr(&pipe->pipe_lock, LK_DRAIN | LK_INTERLOCK,
 1326                         &pipe->pipe_slock);
 1327 
 1328         /*
 1329          * free resources
 1330          */
 1331         pipe_free_kmem(pipe);
 1332         pool_put(&pipe_pool, pipe);
 1333 }
 1334 
 1335 static void
 1336 filt_pipedetach(struct knote *kn)
 1337 {
 1338         struct pipe *pipe = (struct pipe *)kn->kn_fp->f_data;
 1339 
 1340         switch(kn->kn_filter) {
 1341         case EVFILT_WRITE:
 1342                 /* need the peer structure, not our own */
 1343                 pipe = pipe->pipe_peer;
 1344                 /* XXXSMP: race for peer */
 1345 
 1346                 /* if reader end already closed, just return */
 1347                 if (pipe == NULL)
 1348                         return;
 1349 
 1350                 break;
 1351         default:
 1352                 /* nothing to do */
 1353                 break;
 1354         }
 1355 
 1356 #ifdef DIAGNOSTIC
 1357         if (kn->kn_hook != pipe)
 1358                 panic("filt_pipedetach: inconsistent knote");
 1359 #endif
 1360 
 1361         PIPE_LOCK(pipe);
 1362         SLIST_REMOVE(&pipe->pipe_sel.sel_klist, kn, knote, kn_selnext);
 1363         PIPE_UNLOCK(pipe);
 1364 }
 1365 
 1366 /*ARGSUSED*/
 1367 static int
 1368 filt_piperead(struct knote *kn, long hint)
 1369 {
 1370         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
 1371         struct pipe *wpipe = rpipe->pipe_peer;
 1372 
 1373         if ((hint & NOTE_SUBMIT) == 0)
 1374                 PIPE_LOCK(rpipe);
 1375         kn->kn_data = rpipe->pipe_buffer.cnt;
 1376         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
 1377                 kn->kn_data = rpipe->pipe_map.cnt;
 1378 
 1379         /* XXXSMP: race for peer */
 1380         if ((rpipe->pipe_state & PIPE_EOF) ||
 1381             (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
 1382                 kn->kn_flags |= EV_EOF;
 1383                 if ((hint & NOTE_SUBMIT) == 0)
 1384                         PIPE_UNLOCK(rpipe);
 1385                 return (1);
 1386         }
 1387         if ((hint & NOTE_SUBMIT) == 0)
 1388                 PIPE_UNLOCK(rpipe);
 1389         return (kn->kn_data > 0);
 1390 }
 1391 
 1392 /*ARGSUSED*/
 1393 static int
 1394 filt_pipewrite(struct knote *kn, long hint)
 1395 {
 1396         struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
 1397         struct pipe *wpipe = rpipe->pipe_peer;
 1398 
 1399         if ((hint & NOTE_SUBMIT) == 0)
 1400                 PIPE_LOCK(rpipe);
 1401         /* XXXSMP: race for peer */
 1402         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
 1403                 kn->kn_data = 0;
 1404                 kn->kn_flags |= EV_EOF; 
 1405                 if ((hint & NOTE_SUBMIT) == 0)
 1406                         PIPE_UNLOCK(rpipe);
 1407                 return (1);
 1408         }
 1409         kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
 1410         if (wpipe->pipe_state & PIPE_DIRECTW)
 1411                 kn->kn_data = 0;
 1412 
 1413         if ((hint & NOTE_SUBMIT) == 0)
 1414                 PIPE_UNLOCK(rpipe);
 1415         return (kn->kn_data >= PIPE_BUF);
 1416 }
 1417 
 1418 static const struct filterops pipe_rfiltops =
 1419         { 1, NULL, filt_pipedetach, filt_piperead };
 1420 static const struct filterops pipe_wfiltops =
 1421         { 1, NULL, filt_pipedetach, filt_pipewrite };
 1422 
 1423 /*ARGSUSED*/
 1424 static int
 1425 pipe_kqfilter(struct file *fp, struct knote *kn)
 1426 {
 1427         struct pipe *pipe;
 1428 
 1429         pipe = (struct pipe *)kn->kn_fp->f_data;
 1430         switch (kn->kn_filter) {
 1431         case EVFILT_READ:
 1432                 kn->kn_fop = &pipe_rfiltops;
 1433                 break;
 1434         case EVFILT_WRITE:
 1435                 kn->kn_fop = &pipe_wfiltops;
 1436                 /* XXXSMP: race for peer */
 1437                 pipe = pipe->pipe_peer;
 1438                 if (pipe == NULL) {
 1439                         /* other end of pipe has been closed */
 1440                         return (EBADF);
 1441                 }
 1442                 break;
 1443         default:
 1444                 return (1);
 1445         }
 1446         kn->kn_hook = pipe;
 1447 
 1448         PIPE_LOCK(pipe);
 1449         SLIST_INSERT_HEAD(&pipe->pipe_sel.sel_klist, kn, kn_selnext);
 1450         PIPE_UNLOCK(pipe);
 1451         return (0);
 1452 }
 1453 
 1454 static int
 1455 pipe_fcntl(fp, cmd, data, p)
 1456         struct file *fp;
 1457         u_int cmd;
 1458         void *data;
 1459         struct proc *p;
 1460 {
 1461         if (cmd == F_SETFL)
 1462                 return (0);
 1463         else
 1464                 return (EOPNOTSUPP);
 1465 }
 1466 
 1467 /*
 1468  * Handle pipe sysctls.
 1469  */
 1470 SYSCTL_SETUP(sysctl_kern_pipe_setup, "sysctl kern.pipe subtree setup")
 1471 {
 1472 
 1473         sysctl_createv(clog, 0, NULL, NULL,
 1474                        CTLFLAG_PERMANENT,
 1475                        CTLTYPE_NODE, "kern", NULL,
 1476                        NULL, 0, NULL, 0,
 1477                        CTL_KERN, CTL_EOL);
 1478         sysctl_createv(clog, 0, NULL, NULL,
 1479                        CTLFLAG_PERMANENT,
 1480                        CTLTYPE_NODE, "pipe",
 1481                        SYSCTL_DESCR("Pipe settings"),
 1482                        NULL, 0, NULL, 0,
 1483                        CTL_KERN, KERN_PIPE, CTL_EOL);
 1484 
 1485         sysctl_createv(clog, 0, NULL, NULL,
 1486                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 1487                        CTLTYPE_INT, "maxkvasz",
 1488                        SYSCTL_DESCR("Maximum amount of kernel memory to be "
 1489                                     "used for pipes"),
 1490                        NULL, 0, &maxpipekva, 0,
 1491                        CTL_KERN, KERN_PIPE, KERN_PIPE_MAXKVASZ, CTL_EOL);
 1492         sysctl_createv(clog, 0, NULL, NULL,
 1493                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 1494                        CTLTYPE_INT, "maxloankvasz",
 1495                        SYSCTL_DESCR("Limit for direct transfers via page loan"),
 1496                        NULL, 0, &limitpipekva, 0,
 1497                        CTL_KERN, KERN_PIPE, KERN_PIPE_LIMITKVA, CTL_EOL);
 1498         sysctl_createv(clog, 0, NULL, NULL,
 1499                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 1500                        CTLTYPE_INT, "maxbigpipes",
 1501                        SYSCTL_DESCR("Maximum number of \"big\" pipes"),
 1502                        NULL, 0, &maxbigpipes, 0,
 1503                        CTL_KERN, KERN_PIPE, KERN_PIPE_MAXBIGPIPES, CTL_EOL);
 1504         sysctl_createv(clog, 0, NULL, NULL,
 1505                        CTLFLAG_PERMANENT,
 1506                        CTLTYPE_INT, "nbigpipes",
 1507                        SYSCTL_DESCR("Number of \"big\" pipes"),
 1508                        NULL, 0, &nbigpipe, 0,
 1509                        CTL_KERN, KERN_PIPE, KERN_PIPE_NBIGPIPES, CTL_EOL);
 1510         sysctl_createv(clog, 0, NULL, NULL,
 1511                        CTLFLAG_PERMANENT,
 1512                        CTLTYPE_INT, "kvasize",
 1513                        SYSCTL_DESCR("Amount of kernel memory consumed by pipe "
 1514                                     "buffers"),
 1515                        NULL, 0, &amountpipekva, 0,
 1516                        CTL_KERN, KERN_PIPE, KERN_PIPE_KVASIZE, CTL_EOL);
 1517 }
 1518 
 1519 /*
 1520  * Initialize pipe structs.
 1521  */
 1522 void
 1523 pipe_init(void)
 1524 {
 1525 
 1526         pool_init(&pipe_pool, sizeof(struct pipe), 0, 0, 0, "pipepl",
 1527             &pool_allocator_nointr);
 1528 }

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