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 1.103.4.5 2009/04/04 23:36:27 snj Exp $   */
    2 
    3 /*-
    4  * Copyright (c) 2003, 2007, 2008, 2009 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, and by Andrew Doran.
    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  *
   19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   29  * POSSIBILITY OF SUCH DAMAGE.
   30  */
   31 
   32 /*
   33  * Copyright (c) 1996 John S. Dyson
   34  * All rights reserved.
   35  *
   36  * Redistribution and use in source and binary forms, with or without
   37  * modification, are permitted provided that the following conditions
   38  * are met:
   39  * 1. Redistributions of source code must retain the above copyright
   40  *    notice immediately at the beginning of the file, without modification,
   41  *    this list of conditions, and the following disclaimer.
   42  * 2. Redistributions in binary form must reproduce the above copyright
   43  *    notice, this list of conditions and the following disclaimer in the
   44  *    documentation and/or other materials provided with the distribution.
   45  * 3. Absolutely no warranty of function or purpose is made by the author
   46  *    John S. Dyson.
   47  * 4. Modifications may be freely made to this file if the above conditions
   48  *    are met.
   49  */
   50 
   51 /*
   52  * This file contains a high-performance replacement for the socket-based
   53  * pipes scheme originally used.  It does not support all features of
   54  * sockets, but does do everything that pipes normally do.
   55  *
   56  * This code has two modes of operation, a small write mode and a large
   57  * write mode.  The small write mode acts like conventional pipes with
   58  * a kernel buffer.  If the buffer is less than PIPE_MINDIRECT, then the
   59  * "normal" pipe buffering is done.  If the buffer is between PIPE_MINDIRECT
   60  * and PIPE_SIZE in size it is mapped read-only into the kernel address space
   61  * using the UVM page loan facility from where the receiving process can copy
   62  * the data directly from the pages in the sending process.
   63  *
   64  * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
   65  * happen for small transfers so that the system will not spend all of
   66  * its time context switching.  PIPE_SIZE is constrained by the
   67  * amount of kernel virtual memory.
   68  */
   69 
   70 #include <sys/cdefs.h>
   71 __KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.103.4.5 2009/04/04 23:36:27 snj Exp $");
   72 
   73 #include <sys/param.h>
   74 #include <sys/systm.h>
   75 #include <sys/proc.h>
   76 #include <sys/fcntl.h>
   77 #include <sys/file.h>
   78 #include <sys/filedesc.h>
   79 #include <sys/filio.h>
   80 #include <sys/kernel.h>
   81 #include <sys/ttycom.h>
   82 #include <sys/stat.h>
   83 #include <sys/poll.h>
   84 #include <sys/signalvar.h>
   85 #include <sys/vnode.h>
   86 #include <sys/uio.h>
   87 #include <sys/select.h>
   88 #include <sys/mount.h>
   89 #include <sys/syscallargs.h>
   90 #include <sys/sysctl.h>
   91 #include <sys/kauth.h>
   92 #include <sys/atomic.h>
   93 #include <sys/pipe.h>
   94 
   95 #include <uvm/uvm.h>
   96 
   97 /* Use this define if you want to disable *fancy* VM things. */
   98 /* XXX Disabled for now; rare hangs switching between direct/buffered */
   99 #define PIPE_NODIRECT
  100 
  101 /*
  102  * interfaces to the outside world
  103  */
  104 static int pipe_read(struct file *fp, off_t *offset, struct uio *uio,
  105                 kauth_cred_t cred, int flags);
  106 static int pipe_write(struct file *fp, off_t *offset, struct uio *uio,
  107                 kauth_cred_t cred, int flags);
  108 static int pipe_close(struct file *fp);
  109 static int pipe_poll(struct file *fp, int events);
  110 static int pipe_kqfilter(struct file *fp, struct knote *kn);
  111 static int pipe_stat(struct file *fp, struct stat *sb);
  112 static int pipe_ioctl(struct file *fp, u_long cmd, void *data);
  113 
  114 static const struct fileops pipeops = {
  115         .fo_read = pipe_read,
  116         .fo_write = pipe_write,
  117         .fo_ioctl = pipe_ioctl,
  118         .fo_fcntl = fnullop_fcntl,
  119         .fo_poll = pipe_poll,
  120         .fo_stat = pipe_stat,
  121         .fo_close = pipe_close,
  122         .fo_kqfilter = pipe_kqfilter,
  123         .fo_drain = fnullop_drain,
  124 };
  125 
  126 /*
  127  * Default pipe buffer size(s), this can be kind-of large now because pipe
  128  * space is pageable.  The pipe code will try to maintain locality of
  129  * reference for performance reasons, so small amounts of outstanding I/O
  130  * will not wipe the cache.
  131  */
  132 #define MINPIPESIZE (PIPE_SIZE/3)
  133 #define MAXPIPESIZE (2*PIPE_SIZE/3)
  134 
  135 /*
  136  * Maximum amount of kva for pipes -- this is kind-of a soft limit, but
  137  * is there so that on large systems, we don't exhaust it.
  138  */
  139 #define MAXPIPEKVA (8*1024*1024)
  140 static u_int maxpipekva = MAXPIPEKVA;
  141 
  142 /*
  143  * Limit for direct transfers, we cannot, of course limit
  144  * the amount of kva for pipes in general though.
  145  */
  146 #define LIMITPIPEKVA (16*1024*1024)
  147 static u_int limitpipekva = LIMITPIPEKVA;
  148 
  149 /*
  150  * Limit the number of "big" pipes
  151  */
  152 #define LIMITBIGPIPES  32
  153 static u_int maxbigpipes = LIMITBIGPIPES;
  154 static u_int nbigpipe = 0;
  155 
  156 /*
  157  * Amount of KVA consumed by pipe buffers.
  158  */
  159 static u_int amountpipekva = 0;
  160 
  161 static void pipeclose(struct file *fp, struct pipe *pipe);
  162 static void pipe_free_kmem(struct pipe *pipe);
  163 static int pipe_create(struct pipe **pipep, pool_cache_t, kmutex_t *);
  164 static int pipelock(struct pipe *pipe, int catch);
  165 static inline void pipeunlock(struct pipe *pipe);
  166 static void pipeselwakeup(struct pipe *pipe, struct pipe *sigp, int code);
  167 #ifndef PIPE_NODIRECT
  168 static int pipe_direct_write(struct file *fp, struct pipe *wpipe,
  169     struct uio *uio);
  170 #endif
  171 static int pipespace(struct pipe *pipe, int size);
  172 static int pipe_ctor(void *, void *, int);
  173 static void pipe_dtor(void *, void *);
  174 
  175 #ifndef PIPE_NODIRECT
  176 static int pipe_loan_alloc(struct pipe *, int);
  177 static void pipe_loan_free(struct pipe *);
  178 #endif /* PIPE_NODIRECT */
  179 
  180 static pool_cache_t pipe_wr_cache;
  181 static pool_cache_t pipe_rd_cache;
  182 
  183 void
  184 pipe_init(void)
  185 {
  186 
  187         /* Writer side is not automatically allocated KVA. */
  188         pipe_wr_cache = pool_cache_init(sizeof(struct pipe), 0, 0, 0, "pipewr",
  189             NULL, IPL_NONE, pipe_ctor, pipe_dtor, NULL);
  190         KASSERT(pipe_wr_cache != NULL);
  191 
  192         /* Reader side gets preallocated KVA. */
  193         pipe_rd_cache = pool_cache_init(sizeof(struct pipe), 0, 0, 0, "piperd",
  194             NULL, IPL_NONE, pipe_ctor, pipe_dtor, (void *)1);
  195         KASSERT(pipe_rd_cache != NULL);
  196 }
  197 
  198 static int
  199 pipe_ctor(void *arg, void *obj, int flags)
  200 {
  201         struct pipe *pipe;
  202         vaddr_t va;
  203 
  204         pipe = obj;
  205 
  206         memset(pipe, 0, sizeof(struct pipe));
  207         if (arg != NULL) {
  208                 /* Preallocate space. */
  209                 va = uvm_km_alloc(kernel_map, PIPE_SIZE, 0,
  210                     UVM_KMF_PAGEABLE | UVM_KMF_WAITVA);
  211                 KASSERT(va != 0);
  212                 pipe->pipe_kmem = va;
  213                 atomic_add_int(&amountpipekva, PIPE_SIZE);
  214         }
  215         cv_init(&pipe->pipe_rcv, "piperd");
  216         cv_init(&pipe->pipe_wcv, "pipewr");
  217         cv_init(&pipe->pipe_draincv, "pipedrain");
  218         cv_init(&pipe->pipe_lkcv, "pipelk");
  219         selinit(&pipe->pipe_sel);
  220         pipe->pipe_state = PIPE_SIGNALR;
  221 
  222         return 0;
  223 }
  224 
  225 static void
  226 pipe_dtor(void *arg, void *obj)
  227 {
  228         struct pipe *pipe;
  229 
  230         pipe = obj;
  231 
  232         cv_destroy(&pipe->pipe_rcv);
  233         cv_destroy(&pipe->pipe_wcv);
  234         cv_destroy(&pipe->pipe_draincv);
  235         cv_destroy(&pipe->pipe_lkcv);
  236         seldestroy(&pipe->pipe_sel);
  237         if (pipe->pipe_kmem != 0) {
  238                 uvm_km_free(kernel_map, pipe->pipe_kmem, PIPE_SIZE,
  239                     UVM_KMF_PAGEABLE);
  240                 atomic_add_int(&amountpipekva, -PIPE_SIZE);
  241         }
  242 }
  243 
  244 /*
  245  * The pipe system call for the DTYPE_PIPE type of pipes
  246  */
  247 
  248 /* ARGSUSED */
  249 int
  250 sys_pipe(struct lwp *l, const void *v, register_t *retval)
  251 {
  252         struct file *rf, *wf;
  253         struct pipe *rpipe, *wpipe;
  254         kmutex_t *mutex;
  255         int fd, error;
  256         proc_t *p;
  257 
  258         p = curproc;
  259         rpipe = wpipe = NULL;
  260         mutex = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
  261         if (mutex == NULL)
  262                 return (ENOMEM);
  263         mutex_obj_hold(mutex);
  264         if (pipe_create(&rpipe, pipe_rd_cache, mutex) ||
  265             pipe_create(&wpipe, pipe_wr_cache, mutex)) {
  266                 pipeclose(NULL, rpipe);
  267                 pipeclose(NULL, wpipe);
  268                 return (ENFILE);
  269         }
  270 
  271         error = fd_allocfile(&rf, &fd);
  272         if (error)
  273                 goto free2;
  274         retval[0] = fd;
  275         rf->f_flag = FREAD;
  276         rf->f_type = DTYPE_PIPE;
  277         rf->f_data = (void *)rpipe;
  278         rf->f_ops = &pipeops;
  279 
  280         error = fd_allocfile(&wf, &fd);
  281         if (error)
  282                 goto free3;
  283         retval[1] = fd;
  284         wf->f_flag = FWRITE;
  285         wf->f_type = DTYPE_PIPE;
  286         wf->f_data = (void *)wpipe;
  287         wf->f_ops = &pipeops;
  288 
  289         rpipe->pipe_peer = wpipe;
  290         wpipe->pipe_peer = rpipe;
  291 
  292         fd_affix(p, rf, (int)retval[0]);
  293         fd_affix(p, wf, (int)retval[1]);
  294         return (0);
  295 free3:
  296         fd_abort(p, rf, (int)retval[0]);
  297 free2:
  298         pipeclose(NULL, wpipe);
  299         pipeclose(NULL, rpipe);
  300 
  301         return (error);
  302 }
  303 
  304 /*
  305  * Allocate kva for pipe circular buffer, the space is pageable
  306  * This routine will 'realloc' the size of a pipe safely, if it fails
  307  * it will retain the old buffer.
  308  * If it fails it will return ENOMEM.
  309  */
  310 static int
  311 pipespace(struct pipe *pipe, int size)
  312 {
  313         void *buffer;
  314 
  315         /*
  316          * Allocate pageable virtual address space.  Physical memory is
  317          * allocated on demand.
  318          */
  319         if (size == PIPE_SIZE && pipe->pipe_kmem != 0) {
  320                 buffer = (void *)pipe->pipe_kmem;
  321         } else {
  322                 buffer = (void *)uvm_km_alloc(kernel_map, round_page(size),
  323                     0, UVM_KMF_PAGEABLE);
  324                 if (buffer == NULL)
  325                         return (ENOMEM);
  326                 atomic_add_int(&amountpipekva, size);
  327         }
  328 
  329         /* free old resources if we're resizing */
  330         pipe_free_kmem(pipe);
  331         pipe->pipe_buffer.buffer = buffer;
  332         pipe->pipe_buffer.size = size;
  333         pipe->pipe_buffer.in = 0;
  334         pipe->pipe_buffer.out = 0;
  335         pipe->pipe_buffer.cnt = 0;
  336         return (0);
  337 }
  338 
  339 /*
  340  * Initialize and allocate VM and memory for pipe.
  341  */
  342 static int
  343 pipe_create(struct pipe **pipep, pool_cache_t cache, kmutex_t *mutex)
  344 {
  345         struct pipe *pipe;
  346         int error;
  347 
  348         pipe = pool_cache_get(cache, PR_WAITOK);
  349         KASSERT(pipe != NULL);
  350         *pipep = pipe;
  351         error = 0;
  352         getmicrotime(&pipe->pipe_ctime);
  353         pipe->pipe_atime = pipe->pipe_ctime;
  354         pipe->pipe_mtime = pipe->pipe_ctime;
  355         pipe->pipe_lock = mutex;
  356         if (cache == pipe_rd_cache) {
  357                 error = pipespace(pipe, PIPE_SIZE);
  358         } else {
  359                 pipe->pipe_buffer.buffer = NULL;
  360                 pipe->pipe_buffer.size = 0;
  361                 pipe->pipe_buffer.in = 0;
  362                 pipe->pipe_buffer.out = 0;
  363                 pipe->pipe_buffer.cnt = 0;
  364         }
  365         return error;
  366 }
  367 
  368 /*
  369  * Lock a pipe for I/O, blocking other access
  370  * Called with pipe spin lock held.
  371  * Return with pipe spin lock released on success.
  372  */
  373 static int
  374 pipelock(struct pipe *pipe, int catch)
  375 {
  376         int error;
  377 
  378         KASSERT(mutex_owned(pipe->pipe_lock));
  379 
  380         while (pipe->pipe_state & PIPE_LOCKFL) {
  381                 pipe->pipe_state |= PIPE_LWANT;
  382                 if (catch) {
  383                         error = cv_wait_sig(&pipe->pipe_lkcv, pipe->pipe_lock);
  384                         if (error != 0)
  385                                 return error;
  386                 } else
  387                         cv_wait(&pipe->pipe_lkcv, pipe->pipe_lock);
  388         }
  389 
  390         pipe->pipe_state |= PIPE_LOCKFL;
  391 
  392         return 0;
  393 }
  394 
  395 /*
  396  * unlock a pipe I/O lock
  397  */
  398 static inline void
  399 pipeunlock(struct pipe *pipe)
  400 {
  401 
  402         KASSERT(pipe->pipe_state & PIPE_LOCKFL);
  403 
  404         pipe->pipe_state &= ~PIPE_LOCKFL;
  405         if (pipe->pipe_state & PIPE_LWANT) {
  406                 pipe->pipe_state &= ~PIPE_LWANT;
  407                 cv_broadcast(&pipe->pipe_lkcv);
  408         }
  409 }
  410 
  411 /*
  412  * Select/poll wakup. This also sends SIGIO to peer connected to
  413  * 'sigpipe' side of pipe.
  414  */
  415 static void
  416 pipeselwakeup(struct pipe *selp, struct pipe *sigp, int code)
  417 {
  418         int band;
  419 
  420         switch (code) {
  421         case POLL_IN:
  422                 band = POLLIN|POLLRDNORM;
  423                 break;
  424         case POLL_OUT:
  425                 band = POLLOUT|POLLWRNORM;
  426                 break;
  427         case POLL_HUP:
  428                 band = POLLHUP;
  429                 break;
  430 #if POLL_HUP != POLL_ERR
  431         case POLL_ERR:
  432                 band = POLLERR;
  433                 break;
  434 #endif
  435         default:
  436                 band = 0;
  437 #ifdef DIAGNOSTIC
  438                 printf("bad siginfo code %d in pipe notification.\n", code);
  439 #endif
  440                 break;
  441         }
  442 
  443         selnotify(&selp->pipe_sel, band, NOTE_SUBMIT);
  444 
  445         if (sigp == NULL || (sigp->pipe_state & PIPE_ASYNC) == 0)
  446                 return;
  447 
  448         fownsignal(sigp->pipe_pgid, SIGIO, code, band, selp);
  449 }
  450 
  451 /* ARGSUSED */
  452 static int
  453 pipe_read(struct file *fp, off_t *offset, struct uio *uio, kauth_cred_t cred,
  454     int flags)
  455 {
  456         struct pipe *rpipe = (struct pipe *) fp->f_data;
  457         struct pipebuf *bp = &rpipe->pipe_buffer;
  458         kmutex_t *lock = rpipe->pipe_lock;
  459         int error;
  460         size_t nread = 0;
  461         size_t size;
  462         size_t ocnt;
  463 
  464         mutex_enter(lock);
  465         ++rpipe->pipe_busy;
  466         ocnt = bp->cnt;
  467 
  468 again:
  469         error = pipelock(rpipe, 1);
  470         if (error)
  471                 goto unlocked_error;
  472 
  473         while (uio->uio_resid) {
  474                 /*
  475                  * normal pipe buffer receive
  476                  */
  477                 if (bp->cnt > 0) {
  478                         size = bp->size - bp->out;
  479                         if (size > bp->cnt)
  480                                 size = bp->cnt;
  481                         if (size > uio->uio_resid)
  482                                 size = uio->uio_resid;
  483 
  484                         mutex_exit(lock);
  485                         error = uiomove((char *)bp->buffer + bp->out, size, uio);
  486                         mutex_enter(lock);
  487                         if (error)
  488                                 break;
  489 
  490                         bp->out += size;
  491                         if (bp->out >= bp->size)
  492                                 bp->out = 0;
  493 
  494                         bp->cnt -= size;
  495 
  496                         /*
  497                          * If there is no more to read in the pipe, reset
  498                          * its pointers to the beginning.  This improves
  499                          * cache hit stats.
  500                          */
  501                         if (bp->cnt == 0) {
  502                                 bp->in = 0;
  503                                 bp->out = 0;
  504                         }
  505                         nread += size;
  506                         continue;
  507                 }
  508 
  509 #ifndef PIPE_NODIRECT
  510                 if ((rpipe->pipe_state & PIPE_DIRECTR) != 0) {
  511                         /*
  512                          * Direct copy, bypassing a kernel buffer.
  513                          */
  514                         void *  va;
  515 
  516                         KASSERT(rpipe->pipe_state & PIPE_DIRECTW);
  517 
  518                         size = rpipe->pipe_map.cnt;
  519                         if (size > uio->uio_resid)
  520                                 size = uio->uio_resid;
  521 
  522                         va = (char *)rpipe->pipe_map.kva + rpipe->pipe_map.pos;
  523                         mutex_exit(lock);
  524                         error = uiomove(va, size, uio);
  525                         mutex_enter(lock);
  526                         if (error)
  527                                 break;
  528                         nread += size;
  529                         rpipe->pipe_map.pos += size;
  530                         rpipe->pipe_map.cnt -= size;
  531                         if (rpipe->pipe_map.cnt == 0) {
  532                                 rpipe->pipe_state &= ~PIPE_DIRECTR;
  533                                 cv_broadcast(&rpipe->pipe_wcv);
  534                         }
  535                         continue;
  536                 }
  537 #endif
  538                 /*
  539                  * Break if some data was read.
  540                  */
  541                 if (nread > 0)
  542                         break;
  543 
  544                 /*
  545                  * detect EOF condition
  546                  * read returns 0 on EOF, no need to set error
  547                  */
  548                 if (rpipe->pipe_state & PIPE_EOF)
  549                         break;
  550 
  551                 /*
  552                  * don't block on non-blocking I/O
  553                  */
  554                 if (fp->f_flag & FNONBLOCK) {
  555                         error = EAGAIN;
  556                         break;
  557                 }
  558 
  559                 /*
  560                  * Unlock the pipe buffer for our remaining processing.
  561                  * We will either break out with an error or we will
  562                  * sleep and relock to loop.
  563                  */
  564                 pipeunlock(rpipe);
  565 
  566                 /*
  567                  * Re-check to see if more direct writes are pending.
  568                  */
  569                 if ((rpipe->pipe_state & PIPE_DIRECTR) != 0)
  570                         goto again;
  571 
  572                 /*
  573                  * We want to read more, wake up select/poll.
  574                  */
  575                 pipeselwakeup(rpipe, rpipe->pipe_peer, POLL_OUT);
  576 
  577                 /*
  578                  * If the "write-side" is blocked, wake it up now.
  579                  */
  580                 cv_broadcast(&rpipe->pipe_wcv);
  581 
  582                 /* Now wait until the pipe is filled */
  583                 error = cv_wait_sig(&rpipe->pipe_rcv, lock);
  584                 if (error != 0)
  585                         goto unlocked_error;
  586                 goto again;
  587         }
  588 
  589         if (error == 0)
  590                 getmicrotime(&rpipe->pipe_atime);
  591         pipeunlock(rpipe);
  592 
  593 unlocked_error:
  594         --rpipe->pipe_busy;
  595         if (rpipe->pipe_busy == 0) {
  596                 cv_broadcast(&rpipe->pipe_draincv);
  597         }
  598         if (bp->cnt < MINPIPESIZE) {
  599                 cv_broadcast(&rpipe->pipe_wcv);
  600         }
  601 
  602         /*
  603          * If anything was read off the buffer, signal to the writer it's
  604          * possible to write more data. Also send signal if we are here for the
  605          * first time after last write.
  606          */
  607         if ((bp->size - bp->cnt) >= PIPE_BUF
  608             && (ocnt != bp->cnt || (rpipe->pipe_state & PIPE_SIGNALR))) {
  609                 pipeselwakeup(rpipe, rpipe->pipe_peer, POLL_OUT);
  610                 rpipe->pipe_state &= ~PIPE_SIGNALR;
  611         }
  612 
  613         mutex_exit(lock);
  614         return (error);
  615 }
  616 
  617 #ifndef PIPE_NODIRECT
  618 /*
  619  * Allocate structure for loan transfer.
  620  */
  621 static int
  622 pipe_loan_alloc(struct pipe *wpipe, int npages)
  623 {
  624         vsize_t len;
  625 
  626         len = (vsize_t)npages << PAGE_SHIFT;
  627         atomic_add_int(&amountpipekva, len);
  628         wpipe->pipe_map.kva = uvm_km_alloc(kernel_map, len, 0,
  629             UVM_KMF_VAONLY | UVM_KMF_WAITVA);
  630         if (wpipe->pipe_map.kva == 0) {
  631                 atomic_add_int(&amountpipekva, -len);
  632                 return (ENOMEM);
  633         }
  634 
  635         wpipe->pipe_map.npages = npages;
  636         wpipe->pipe_map.pgs = kmem_alloc(npages * sizeof(struct vm_page *),
  637             KM_SLEEP);
  638         return (0);
  639 }
  640 
  641 /*
  642  * Free resources allocated for loan transfer.
  643  */
  644 static void
  645 pipe_loan_free(struct pipe *wpipe)
  646 {
  647         vsize_t len;
  648 
  649         len = (vsize_t)wpipe->pipe_map.npages << PAGE_SHIFT;
  650         uvm_km_free(kernel_map, wpipe->pipe_map.kva, len, UVM_KMF_VAONLY);
  651         wpipe->pipe_map.kva = 0;
  652         atomic_add_int(&amountpipekva, -len);
  653         kmem_free(wpipe->pipe_map.pgs,
  654             wpipe->pipe_map.npages * sizeof(struct vm_page *));
  655         wpipe->pipe_map.pgs = NULL;
  656 }
  657 
  658 /*
  659  * NetBSD direct write, using uvm_loan() mechanism.
  660  * This implements the pipe buffer write mechanism.  Note that only
  661  * a direct write OR a normal pipe write can be pending at any given time.
  662  * If there are any characters in the pipe buffer, the direct write will
  663  * be deferred until the receiving process grabs all of the bytes from
  664  * the pipe buffer.  Then the direct mapping write is set-up.
  665  *
  666  * Called with the long-term pipe lock held.
  667  */
  668 static int
  669 pipe_direct_write(struct file *fp, struct pipe *wpipe, struct uio *uio)
  670 {
  671         int error, npages, j;
  672         struct vm_page **pgs;
  673         vaddr_t bbase, kva, base, bend;
  674         vsize_t blen, bcnt;
  675         voff_t bpos;
  676         kmutex_t *lock = wpipe->pipe_lock;
  677 
  678         KASSERT(mutex_owned(wpipe->pipe_lock));
  679         KASSERT(wpipe->pipe_map.cnt == 0);
  680 
  681         mutex_exit(lock);
  682 
  683         /*
  684          * Handle first PIPE_CHUNK_SIZE bytes of buffer. Deal with buffers
  685          * not aligned to PAGE_SIZE.
  686          */
  687         bbase = (vaddr_t)uio->uio_iov->iov_base;
  688         base = trunc_page(bbase);
  689         bend = round_page(bbase + uio->uio_iov->iov_len);
  690         blen = bend - base;
  691         bpos = bbase - base;
  692 
  693         if (blen > PIPE_DIRECT_CHUNK) {
  694                 blen = PIPE_DIRECT_CHUNK;
  695                 bend = base + blen;
  696                 bcnt = PIPE_DIRECT_CHUNK - bpos;
  697         } else {
  698                 bcnt = uio->uio_iov->iov_len;
  699         }
  700         npages = blen >> PAGE_SHIFT;
  701 
  702         /*
  703          * Free the old kva if we need more pages than we have
  704          * allocated.
  705          */
  706         if (wpipe->pipe_map.kva != 0 && npages > wpipe->pipe_map.npages)
  707                 pipe_loan_free(wpipe);
  708 
  709         /* Allocate new kva. */
  710         if (wpipe->pipe_map.kva == 0) {
  711                 error = pipe_loan_alloc(wpipe, npages);
  712                 if (error) {
  713                         mutex_enter(lock);
  714                         return (error);
  715                 }
  716         }
  717 
  718         /* Loan the write buffer memory from writer process */
  719         pgs = wpipe->pipe_map.pgs;
  720         error = uvm_loan(&uio->uio_vmspace->vm_map, base, blen,
  721                          pgs, UVM_LOAN_TOPAGE);
  722         if (error) {
  723                 pipe_loan_free(wpipe);
  724                 mutex_enter(lock);
  725                 return (ENOMEM); /* so that caller fallback to ordinary write */
  726         }
  727 
  728         /* Enter the loaned pages to kva */
  729         kva = wpipe->pipe_map.kva;
  730         for (j = 0; j < npages; j++, kva += PAGE_SIZE) {
  731                 pmap_kenter_pa(kva, VM_PAGE_TO_PHYS(pgs[j]), VM_PROT_READ);
  732         }
  733         pmap_update(pmap_kernel());
  734 
  735         /* Now we can put the pipe in direct write mode */
  736         wpipe->pipe_map.pos = bpos;
  737         wpipe->pipe_map.cnt = bcnt;
  738 
  739         /*
  740          * But before we can let someone do a direct read, we
  741          * have to wait until the pipe is drained.  Release the
  742          * pipe lock while we wait.
  743          */
  744         mutex_enter(lock);
  745         wpipe->pipe_state |= PIPE_DIRECTW;
  746         pipeunlock(wpipe);
  747 
  748         while (error == 0 && wpipe->pipe_buffer.cnt > 0) {
  749                 cv_broadcast(&wpipe->pipe_rcv);
  750                 error = cv_wait_sig(&wpipe->pipe_wcv, lock);
  751                 if (error == 0 && wpipe->pipe_state & PIPE_EOF)
  752                         error = EPIPE;
  753         }
  754 
  755         /* Pipe is drained; next read will off the direct buffer */
  756         wpipe->pipe_state |= PIPE_DIRECTR;
  757 
  758         /* Wait until the reader is done */
  759         while (error == 0 && (wpipe->pipe_state & PIPE_DIRECTR)) {
  760                 cv_broadcast(&wpipe->pipe_rcv);
  761                 pipeselwakeup(wpipe, wpipe, POLL_IN);
  762                 error = cv_wait_sig(&wpipe->pipe_wcv, lock);
  763                 if (error == 0 && wpipe->pipe_state & PIPE_EOF)
  764                         error = EPIPE;
  765         }
  766 
  767         /* Take pipe out of direct write mode */
  768         wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTR);
  769 
  770         /* Acquire the pipe lock and cleanup */
  771         (void)pipelock(wpipe, 0);
  772         mutex_exit(lock);
  773 
  774         if (pgs != NULL) {
  775                 pmap_kremove(wpipe->pipe_map.kva, blen);
  776                 pmap_update(pmap_kernel());
  777                 uvm_unloan(pgs, npages, UVM_LOAN_TOPAGE);
  778         }
  779         if (error || amountpipekva > maxpipekva)
  780                 pipe_loan_free(wpipe);
  781 
  782         mutex_enter(lock);
  783         if (error) {
  784                 pipeselwakeup(wpipe, wpipe, POLL_ERR);
  785 
  786                 /*
  787                  * If nothing was read from what we offered, return error
  788                  * straight on. Otherwise update uio resid first. Caller
  789                  * will deal with the error condition, returning short
  790                  * write, error, or restarting the write(2) as appropriate.
  791                  */
  792                 if (wpipe->pipe_map.cnt == bcnt) {
  793                         wpipe->pipe_map.cnt = 0;
  794                         cv_broadcast(&wpipe->pipe_wcv);
  795                         return (error);
  796                 }
  797 
  798                 bcnt -= wpipe->pipe_map.cnt;
  799         }
  800 
  801         uio->uio_resid -= bcnt;
  802         /* uio_offset not updated, not set/used for write(2) */
  803         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + bcnt;
  804         uio->uio_iov->iov_len -= bcnt;
  805         if (uio->uio_iov->iov_len == 0) {
  806                 uio->uio_iov++;
  807                 uio->uio_iovcnt--;
  808         }
  809 
  810         wpipe->pipe_map.cnt = 0;
  811         return (error);
  812 }
  813 #endif /* !PIPE_NODIRECT */
  814 
  815 static int
  816 pipe_write(struct file *fp, off_t *offset, struct uio *uio, kauth_cred_t cred,
  817     int flags)
  818 {
  819         struct pipe *wpipe, *rpipe;
  820         struct pipebuf *bp;
  821         kmutex_t *lock;
  822         int error;
  823 
  824         /* We want to write to our peer */
  825         rpipe = (struct pipe *) fp->f_data;
  826         lock = rpipe->pipe_lock;
  827         error = 0;
  828 
  829         mutex_enter(lock);
  830         wpipe = rpipe->pipe_peer;
  831 
  832         /*
  833          * Detect loss of pipe read side, issue SIGPIPE if lost.
  834          */
  835         if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) != 0) {
  836                 mutex_exit(lock);
  837                 return EPIPE;
  838         }
  839         ++wpipe->pipe_busy;
  840 
  841         /* Aquire the long-term pipe lock */
  842         if ((error = pipelock(wpipe, 1)) != 0) {
  843                 --wpipe->pipe_busy;
  844                 if (wpipe->pipe_busy == 0) {
  845                         cv_broadcast(&wpipe->pipe_draincv);
  846                 }
  847                 mutex_exit(lock);
  848                 return (error);
  849         }
  850 
  851         bp = &wpipe->pipe_buffer;
  852 
  853         /*
  854          * If it is advantageous to resize the pipe buffer, do so.
  855          */
  856         if ((uio->uio_resid > PIPE_SIZE) &&
  857             (nbigpipe < maxbigpipes) &&
  858 #ifndef PIPE_NODIRECT
  859             (wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
  860 #endif
  861             (bp->size <= PIPE_SIZE) && (bp->cnt == 0)) {
  862 
  863                 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
  864                         atomic_inc_uint(&nbigpipe);
  865         }
  866 
  867         while (uio->uio_resid) {
  868                 size_t space;
  869 
  870 #ifndef PIPE_NODIRECT
  871                 /*
  872                  * Pipe buffered writes cannot be coincidental with
  873                  * direct writes.  Also, only one direct write can be
  874                  * in progress at any one time.  We wait until the currently
  875                  * executing direct write is completed before continuing.
  876                  *
  877                  * We break out if a signal occurs or the reader goes away.
  878                  */
  879                 while (error == 0 && wpipe->pipe_state & PIPE_DIRECTW) {
  880                         cv_broadcast(&wpipe->pipe_rcv);
  881                         pipeunlock(wpipe);
  882                         error = cv_wait_sig(&wpipe->pipe_wcv, lock);
  883                         (void)pipelock(wpipe, 0);
  884                         if (wpipe->pipe_state & PIPE_EOF)
  885                                 error = EPIPE;
  886                 }
  887                 if (error)
  888                         break;
  889 
  890                 /*
  891                  * If the transfer is large, we can gain performance if
  892                  * we do process-to-process copies directly.
  893                  * If the write is non-blocking, we don't use the
  894                  * direct write mechanism.
  895                  *
  896                  * The direct write mechanism will detect the reader going
  897                  * away on us.
  898                  */
  899                 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) &&
  900                     (fp->f_flag & FNONBLOCK) == 0 &&
  901                     (wpipe->pipe_map.kva || (amountpipekva < limitpipekva))) {
  902                         error = pipe_direct_write(fp, wpipe, uio);
  903 
  904                         /*
  905                          * Break out if error occurred, unless it's ENOMEM.
  906                          * ENOMEM means we failed to allocate some resources
  907                          * for direct write, so we just fallback to ordinary
  908                          * write. If the direct write was successful,
  909                          * process rest of data via ordinary write.
  910                          */
  911                         if (error == 0)
  912                                 continue;
  913 
  914                         if (error != ENOMEM)
  915                                 break;
  916                 }
  917 #endif /* PIPE_NODIRECT */
  918 
  919                 space = bp->size - bp->cnt;
  920 
  921                 /* Writes of size <= PIPE_BUF must be atomic. */
  922                 if ((space < uio->uio_resid) && (uio->uio_resid <= PIPE_BUF))
  923                         space = 0;
  924 
  925                 if (space > 0) {
  926                         int size;       /* Transfer size */
  927                         int segsize;    /* first segment to transfer */
  928 
  929                         /*
  930                          * Transfer size is minimum of uio transfer
  931                          * and free space in pipe buffer.
  932                          */
  933                         if (space > uio->uio_resid)
  934                                 size = uio->uio_resid;
  935                         else
  936                                 size = space;
  937                         /*
  938                          * First segment to transfer is minimum of
  939                          * transfer size and contiguous space in
  940                          * pipe buffer.  If first segment to transfer
  941                          * is less than the transfer size, we've got
  942                          * a wraparound in the buffer.
  943                          */
  944                         segsize = bp->size - bp->in;
  945                         if (segsize > size)
  946                                 segsize = size;
  947 
  948                         /* Transfer first segment */
  949                         mutex_exit(lock);
  950                         error = uiomove((char *)bp->buffer + bp->in, segsize,
  951                             uio);
  952 
  953                         if (error == 0 && segsize < size) {
  954                                 /*
  955                                  * Transfer remaining part now, to
  956                                  * support atomic writes.  Wraparound
  957                                  * happened.
  958                                  */
  959 #ifdef DEBUG
  960                                 if (bp->in + segsize != bp->size)
  961                                         panic("Expected pipe buffer wraparound disappeared");
  962 #endif
  963 
  964                                 error = uiomove(bp->buffer,
  965                                     size - segsize, uio);
  966                         }
  967                         mutex_enter(lock);
  968                         if (error)
  969                                 break;
  970 
  971                         bp->in += size;
  972                         if (bp->in >= bp->size) {
  973 #ifdef DEBUG
  974                                 if (bp->in != size - segsize + bp->size)
  975                                         panic("Expected wraparound bad");
  976 #endif
  977                                 bp->in = size - segsize;
  978                         }
  979 
  980                         bp->cnt += size;
  981 #ifdef DEBUG
  982                         if (bp->cnt > bp->size)
  983                                 panic("Pipe buffer overflow");
  984 #endif
  985                 } else {
  986                         /*
  987                          * If the "read-side" has been blocked, wake it up now.
  988                          */
  989                         cv_broadcast(&wpipe->pipe_rcv);
  990 
  991                         /*
  992                          * don't block on non-blocking I/O
  993                          */
  994                         if (fp->f_flag & FNONBLOCK) {
  995                                 error = EAGAIN;
  996                                 break;
  997                         }
  998 
  999                         /*
 1000                          * We have no more space and have something to offer,
 1001                          * wake up select/poll.
 1002                          */
 1003                         if (bp->cnt)
 1004                                 pipeselwakeup(wpipe, wpipe, POLL_IN);
 1005 
 1006                         pipeunlock(wpipe);
 1007                         error = cv_wait_sig(&wpipe->pipe_wcv, lock);
 1008                         (void)pipelock(wpipe, 0);
 1009                         if (error != 0)
 1010                                 break;
 1011                         /*
 1012                          * If read side wants to go away, we just issue a signal
 1013                          * to ourselves.
 1014                          */
 1015                         if (wpipe->pipe_state & PIPE_EOF) {
 1016                                 error = EPIPE;
 1017                                 break;
 1018                         }
 1019                 }
 1020         }
 1021 
 1022         --wpipe->pipe_busy;
 1023         if (wpipe->pipe_busy == 0) {
 1024                 cv_broadcast(&wpipe->pipe_draincv);
 1025         }
 1026         if (bp->cnt > 0) {
 1027                 cv_broadcast(&wpipe->pipe_rcv);
 1028         }
 1029 
 1030         /*
 1031          * Don't return EPIPE if I/O was successful
 1032          */
 1033         if (error == EPIPE && bp->cnt == 0 && uio->uio_resid == 0)
 1034                 error = 0;
 1035 
 1036         if (error == 0)
 1037                 getmicrotime(&wpipe->pipe_mtime);
 1038 
 1039         /*
 1040          * We have something to offer, wake up select/poll.
 1041          * wpipe->pipe_map.cnt is always 0 in this point (direct write
 1042          * is only done synchronously), so check only wpipe->pipe_buffer.cnt
 1043          */
 1044         if (bp->cnt)
 1045                 pipeselwakeup(wpipe, wpipe, POLL_IN);
 1046 
 1047         /*
 1048          * Arrange for next read(2) to do a signal.
 1049          */
 1050         wpipe->pipe_state |= PIPE_SIGNALR;
 1051 
 1052         pipeunlock(wpipe);
 1053         mutex_exit(lock);
 1054         return (error);
 1055 }
 1056 
 1057 /*
 1058  * we implement a very minimal set of ioctls for compatibility with sockets.
 1059  */
 1060 int
 1061 pipe_ioctl(struct file *fp, u_long cmd, void *data)
 1062 {
 1063         struct pipe *pipe = fp->f_data;
 1064         kmutex_t *lock = pipe->pipe_lock;
 1065 
 1066         switch (cmd) {
 1067 
 1068         case FIONBIO:
 1069                 return (0);
 1070 
 1071         case FIOASYNC:
 1072                 mutex_enter(lock);
 1073                 if (*(int *)data) {
 1074                         pipe->pipe_state |= PIPE_ASYNC;
 1075                 } else {
 1076                         pipe->pipe_state &= ~PIPE_ASYNC;
 1077                 }
 1078                 mutex_exit(lock);
 1079                 return (0);
 1080 
 1081         case FIONREAD:
 1082                 mutex_enter(lock);
 1083 #ifndef PIPE_NODIRECT
 1084                 if (pipe->pipe_state & PIPE_DIRECTW)
 1085                         *(int *)data = pipe->pipe_map.cnt;
 1086                 else
 1087 #endif
 1088                         *(int *)data = pipe->pipe_buffer.cnt;
 1089                 mutex_exit(lock);
 1090                 return (0);
 1091 
 1092         case FIONWRITE:
 1093                 /* Look at other side */
 1094                 pipe = pipe->pipe_peer;
 1095                 mutex_enter(lock);
 1096 #ifndef PIPE_NODIRECT
 1097                 if (pipe->pipe_state & PIPE_DIRECTW)
 1098                         *(int *)data = pipe->pipe_map.cnt;
 1099                 else
 1100 #endif
 1101                         *(int *)data = pipe->pipe_buffer.cnt;
 1102                 mutex_exit(lock);
 1103                 return (0);
 1104 
 1105         case FIONSPACE:
 1106                 /* Look at other side */
 1107                 pipe = pipe->pipe_peer;
 1108                 mutex_enter(lock);
 1109 #ifndef PIPE_NODIRECT
 1110                 /*
 1111                  * If we're in direct-mode, we don't really have a
 1112                  * send queue, and any other write will block. Thus
 1113                  * zero seems like the best answer.
 1114                  */
 1115                 if (pipe->pipe_state & PIPE_DIRECTW)
 1116                         *(int *)data = 0;
 1117                 else
 1118 #endif
 1119                         *(int *)data = pipe->pipe_buffer.size -
 1120                             pipe->pipe_buffer.cnt;
 1121                 mutex_exit(lock);
 1122                 return (0);
 1123 
 1124         case TIOCSPGRP:
 1125         case FIOSETOWN:
 1126                 return fsetown(&pipe->pipe_pgid, cmd, data);
 1127 
 1128         case TIOCGPGRP:
 1129         case FIOGETOWN:
 1130                 return fgetown(pipe->pipe_pgid, cmd, data);
 1131 
 1132         }
 1133         return (EPASSTHROUGH);
 1134 }
 1135 
 1136 int
 1137 pipe_poll(struct file *fp, int events)
 1138 {
 1139         struct pipe *rpipe = fp->f_data;
 1140         struct pipe *wpipe;
 1141         int eof = 0;
 1142         int revents = 0;
 1143 
 1144         mutex_enter(rpipe->pipe_lock);
 1145         wpipe = rpipe->pipe_peer;
 1146 
 1147         if (events & (POLLIN | POLLRDNORM))
 1148                 if ((rpipe->pipe_buffer.cnt > 0) ||
 1149 #ifndef PIPE_NODIRECT
 1150                     (rpipe->pipe_state & PIPE_DIRECTR) ||
 1151 #endif
 1152                     (rpipe->pipe_state & PIPE_EOF))
 1153                         revents |= events & (POLLIN | POLLRDNORM);
 1154 
 1155         eof |= (rpipe->pipe_state & PIPE_EOF);
 1156 
 1157         if (wpipe == NULL)
 1158                 revents |= events & (POLLOUT | POLLWRNORM);
 1159         else {
 1160                 if (events & (POLLOUT | POLLWRNORM))
 1161                         if ((wpipe->pipe_state & PIPE_EOF) || (
 1162 #ifndef PIPE_NODIRECT
 1163                              (wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
 1164 #endif
 1165                              (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
 1166                                 revents |= events & (POLLOUT | POLLWRNORM);
 1167 
 1168                 eof |= (wpipe->pipe_state & PIPE_EOF);
 1169         }
 1170 
 1171         if (wpipe == NULL || eof)
 1172                 revents |= POLLHUP;
 1173 
 1174         if (revents == 0) {
 1175                 if (events & (POLLIN | POLLRDNORM))
 1176                         selrecord(curlwp, &rpipe->pipe_sel);
 1177 
 1178                 if (events & (POLLOUT | POLLWRNORM))
 1179                         selrecord(curlwp, &wpipe->pipe_sel);
 1180         }
 1181         mutex_exit(rpipe->pipe_lock);
 1182 
 1183         return (revents);
 1184 }
 1185 
 1186 static int
 1187 pipe_stat(struct file *fp, struct stat *ub)
 1188 {
 1189         struct pipe *pipe = fp->f_data;
 1190 
 1191         memset((void *)ub, 0, sizeof(*ub));
 1192         ub->st_mode = S_IFIFO | S_IRUSR | S_IWUSR;
 1193         ub->st_blksize = pipe->pipe_buffer.size;
 1194         if (ub->st_blksize == 0 && pipe->pipe_peer)
 1195                 ub->st_blksize = pipe->pipe_peer->pipe_buffer.size;
 1196         ub->st_size = pipe->pipe_buffer.cnt;
 1197         ub->st_blocks = (ub->st_size) ? 1 : 0;
 1198         TIMEVAL_TO_TIMESPEC(&pipe->pipe_atime, &ub->st_atimespec);
 1199         TIMEVAL_TO_TIMESPEC(&pipe->pipe_mtime, &ub->st_mtimespec);
 1200         TIMEVAL_TO_TIMESPEC(&pipe->pipe_ctime, &ub->st_ctimespec);
 1201         ub->st_uid = kauth_cred_geteuid(fp->f_cred);
 1202         ub->st_gid = kauth_cred_getegid(fp->f_cred);
 1203 
 1204         /*
 1205          * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen.
 1206          * XXX (st_dev, st_ino) should be unique.
 1207          */
 1208         return (0);
 1209 }
 1210 
 1211 /* ARGSUSED */
 1212 static int
 1213 pipe_close(struct file *fp)
 1214 {
 1215         struct pipe *pipe = fp->f_data;
 1216 
 1217         fp->f_data = NULL;
 1218         pipeclose(fp, pipe);
 1219         return (0);
 1220 }
 1221 
 1222 static void
 1223 pipe_free_kmem(struct pipe *pipe)
 1224 {
 1225 
 1226         if (pipe->pipe_buffer.buffer != NULL) {
 1227                 if (pipe->pipe_buffer.size > PIPE_SIZE) {
 1228                         atomic_dec_uint(&nbigpipe);
 1229                 }
 1230                 if (pipe->pipe_buffer.buffer != (void *)pipe->pipe_kmem) {
 1231                         uvm_km_free(kernel_map,
 1232                             (vaddr_t)pipe->pipe_buffer.buffer,
 1233                             pipe->pipe_buffer.size, UVM_KMF_PAGEABLE);
 1234                         atomic_add_int(&amountpipekva,
 1235                             -pipe->pipe_buffer.size);
 1236                 }
 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         kmutex_t *lock;
 1257         struct pipe *ppipe;
 1258 
 1259         if (pipe == NULL)
 1260                 return;
 1261 
 1262         KASSERT(cv_is_valid(&pipe->pipe_rcv));
 1263         KASSERT(cv_is_valid(&pipe->pipe_wcv));
 1264         KASSERT(cv_is_valid(&pipe->pipe_draincv));
 1265         KASSERT(cv_is_valid(&pipe->pipe_lkcv));
 1266 
 1267         lock = pipe->pipe_lock;
 1268         mutex_enter(lock);
 1269         pipeselwakeup(pipe, pipe, POLL_HUP);
 1270 
 1271         /*
 1272          * If the other side is blocked, wake it up saying that
 1273          * we want to close it down.
 1274          */
 1275         pipe->pipe_state |= PIPE_EOF;
 1276         if (pipe->pipe_busy) {
 1277                 while (pipe->pipe_busy) {
 1278                         cv_broadcast(&pipe->pipe_wcv);
 1279                         cv_wait_sig(&pipe->pipe_draincv, lock);
 1280                 }
 1281         }
 1282 
 1283         /*
 1284          * Disconnect from peer
 1285          */
 1286         if ((ppipe = pipe->pipe_peer) != NULL) {
 1287                 pipeselwakeup(ppipe, ppipe, POLL_HUP);
 1288                 ppipe->pipe_state |= PIPE_EOF;
 1289                 cv_broadcast(&ppipe->pipe_rcv);
 1290                 ppipe->pipe_peer = NULL;
 1291         }
 1292 
 1293         /*
 1294          * Any knote objects still left in the list are
 1295          * the one attached by peer.  Since no one will
 1296          * traverse this list, we just clear it.
 1297          */
 1298         SLIST_INIT(&pipe->pipe_sel.sel_klist);
 1299 
 1300         KASSERT((pipe->pipe_state & PIPE_LOCKFL) == 0);
 1301         mutex_exit(lock);
 1302 
 1303         /*
 1304          * free resources
 1305          */
 1306         pipe->pipe_pgid = 0;
 1307         pipe->pipe_state = PIPE_SIGNALR;
 1308         pipe_free_kmem(pipe);
 1309         if (pipe->pipe_kmem != 0) {
 1310                 pool_cache_put(pipe_rd_cache, pipe);
 1311         } else {
 1312                 pool_cache_put(pipe_wr_cache, pipe);
 1313         }
 1314         mutex_obj_free(lock);
 1315 }
 1316 
 1317 static void
 1318 filt_pipedetach(struct knote *kn)
 1319 {
 1320         struct pipe *pipe;
 1321         kmutex_t *lock;
 1322 
 1323         pipe = ((file_t *)kn->kn_obj)->f_data;
 1324         lock = pipe->pipe_lock;
 1325 
 1326         mutex_enter(lock);
 1327 
 1328         switch(kn->kn_filter) {
 1329         case EVFILT_WRITE:
 1330                 /* need the peer structure, not our own */
 1331                 pipe = pipe->pipe_peer;
 1332 
 1333                 /* if reader end already closed, just return */
 1334                 if (pipe == NULL) {
 1335                         mutex_exit(lock);
 1336                         return;
 1337                 }
 1338 
 1339                 break;
 1340         default:
 1341                 /* nothing to do */
 1342                 break;
 1343         }
 1344 
 1345 #ifdef DIAGNOSTIC
 1346         if (kn->kn_hook != pipe)
 1347                 panic("filt_pipedetach: inconsistent knote");
 1348 #endif
 1349 
 1350         SLIST_REMOVE(&pipe->pipe_sel.sel_klist, kn, knote, kn_selnext);
 1351         mutex_exit(lock);
 1352 }
 1353 
 1354 /*ARGSUSED*/
 1355 static int
 1356 filt_piperead(struct knote *kn, long hint)
 1357 {
 1358         struct pipe *rpipe = ((file_t *)kn->kn_obj)->f_data;
 1359         struct pipe *wpipe;
 1360 
 1361         if ((hint & NOTE_SUBMIT) == 0) {
 1362                 mutex_enter(rpipe->pipe_lock);
 1363         }
 1364         wpipe = rpipe->pipe_peer;
 1365         kn->kn_data = rpipe->pipe_buffer.cnt;
 1366 
 1367         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
 1368                 kn->kn_data = rpipe->pipe_map.cnt;
 1369 
 1370         if ((rpipe->pipe_state & PIPE_EOF) ||
 1371             (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
 1372                 kn->kn_flags |= EV_EOF;
 1373                 if ((hint & NOTE_SUBMIT) == 0) {
 1374                         mutex_exit(rpipe->pipe_lock);
 1375                 }
 1376                 return (1);
 1377         }
 1378 
 1379         if ((hint & NOTE_SUBMIT) == 0) {
 1380                 mutex_exit(rpipe->pipe_lock);
 1381         }
 1382         return (kn->kn_data > 0);
 1383 }
 1384 
 1385 /*ARGSUSED*/
 1386 static int
 1387 filt_pipewrite(struct knote *kn, long hint)
 1388 {
 1389         struct pipe *rpipe = ((file_t *)kn->kn_obj)->f_data;
 1390         struct pipe *wpipe;
 1391 
 1392         if ((hint & NOTE_SUBMIT) == 0) {
 1393                 mutex_enter(rpipe->pipe_lock);
 1394         }
 1395         wpipe = rpipe->pipe_peer;
 1396 
 1397         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
 1398                 kn->kn_data = 0;
 1399                 kn->kn_flags |= EV_EOF;
 1400                 if ((hint & NOTE_SUBMIT) == 0) {
 1401                         mutex_exit(rpipe->pipe_lock);
 1402                 }
 1403                 return (1);
 1404         }
 1405         kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
 1406         if (wpipe->pipe_state & PIPE_DIRECTW)
 1407                 kn->kn_data = 0;
 1408 
 1409         if ((hint & NOTE_SUBMIT) == 0) {
 1410                 mutex_exit(rpipe->pipe_lock);
 1411         }
 1412         return (kn->kn_data >= PIPE_BUF);
 1413 }
 1414 
 1415 static const struct filterops pipe_rfiltops =
 1416         { 1, NULL, filt_pipedetach, filt_piperead };
 1417 static const struct filterops pipe_wfiltops =
 1418         { 1, NULL, filt_pipedetach, filt_pipewrite };
 1419 
 1420 /*ARGSUSED*/
 1421 static int
 1422 pipe_kqfilter(struct file *fp, struct knote *kn)
 1423 {
 1424         struct pipe *pipe;
 1425         kmutex_t *lock;
 1426 
 1427         pipe = ((file_t *)kn->kn_obj)->f_data;
 1428         lock = pipe->pipe_lock;
 1429 
 1430         mutex_enter(lock);
 1431 
 1432         switch (kn->kn_filter) {
 1433         case EVFILT_READ:
 1434                 kn->kn_fop = &pipe_rfiltops;
 1435                 break;
 1436         case EVFILT_WRITE:
 1437                 kn->kn_fop = &pipe_wfiltops;
 1438                 pipe = pipe->pipe_peer;
 1439                 if (pipe == NULL) {
 1440                         /* other end of pipe has been closed */
 1441                         mutex_exit(lock);
 1442                         return (EBADF);
 1443                 }
 1444                 break;
 1445         default:
 1446                 mutex_exit(lock);
 1447                 return (EINVAL);
 1448         }
 1449 
 1450         kn->kn_hook = pipe;
 1451         SLIST_INSERT_HEAD(&pipe->pipe_sel.sel_klist, kn, kn_selnext);
 1452         mutex_exit(lock);
 1453 
 1454         return (0);
 1455 }
 1456 
 1457 /*
 1458  * Handle pipe sysctls.
 1459  */
 1460 SYSCTL_SETUP(sysctl_kern_pipe_setup, "sysctl kern.pipe subtree setup")
 1461 {
 1462 
 1463         sysctl_createv(clog, 0, NULL, NULL,
 1464                        CTLFLAG_PERMANENT,
 1465                        CTLTYPE_NODE, "kern", NULL,
 1466                        NULL, 0, NULL, 0,
 1467                        CTL_KERN, CTL_EOL);
 1468         sysctl_createv(clog, 0, NULL, NULL,
 1469                        CTLFLAG_PERMANENT,
 1470                        CTLTYPE_NODE, "pipe",
 1471                        SYSCTL_DESCR("Pipe settings"),
 1472                        NULL, 0, NULL, 0,
 1473                        CTL_KERN, KERN_PIPE, CTL_EOL);
 1474 
 1475         sysctl_createv(clog, 0, NULL, NULL,
 1476                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 1477                        CTLTYPE_INT, "maxkvasz",
 1478                        SYSCTL_DESCR("Maximum amount of kernel memory to be "
 1479                                     "used for pipes"),
 1480                        NULL, 0, &maxpipekva, 0,
 1481                        CTL_KERN, KERN_PIPE, KERN_PIPE_MAXKVASZ, CTL_EOL);
 1482         sysctl_createv(clog, 0, NULL, NULL,
 1483                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 1484                        CTLTYPE_INT, "maxloankvasz",
 1485                        SYSCTL_DESCR("Limit for direct transfers via page loan"),
 1486                        NULL, 0, &limitpipekva, 0,
 1487                        CTL_KERN, KERN_PIPE, KERN_PIPE_LIMITKVA, CTL_EOL);
 1488         sysctl_createv(clog, 0, NULL, NULL,
 1489                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 1490                        CTLTYPE_INT, "maxbigpipes",
 1491                        SYSCTL_DESCR("Maximum number of \"big\" pipes"),
 1492                        NULL, 0, &maxbigpipes, 0,
 1493                        CTL_KERN, KERN_PIPE, KERN_PIPE_MAXBIGPIPES, CTL_EOL);
 1494         sysctl_createv(clog, 0, NULL, NULL,
 1495                        CTLFLAG_PERMANENT,
 1496                        CTLTYPE_INT, "nbigpipes",
 1497                        SYSCTL_DESCR("Number of \"big\" pipes"),
 1498                        NULL, 0, &nbigpipe, 0,
 1499                        CTL_KERN, KERN_PIPE, KERN_PIPE_NBIGPIPES, CTL_EOL);
 1500         sysctl_createv(clog, 0, NULL, NULL,
 1501                        CTLFLAG_PERMANENT,
 1502                        CTLTYPE_INT, "kvasize",
 1503                        SYSCTL_DESCR("Amount of kernel memory consumed by pipe "
 1504                                     "buffers"),
 1505                        NULL, 0, &amountpipekva, 0,
 1506                        CTL_KERN, KERN_PIPE, KERN_PIPE_KVASIZE, CTL_EOL);
 1507 }

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