The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

FreeBSD/Linux Kernel Cross Reference
sys/kern/sys_pipe.c

Version: -  FREEBSD  -  FREEBSD-13-STABLE  -  FREEBSD-13-0  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  l41  -  OPENBSD  -  linux-2.6  -  MK84  -  PLAN9  -  xnu-8792 
SearchContext: -  none  -  3  -  10 

    1 /*
    2  * Copyright (c) 1996 John S. Dyson
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice immediately at the beginning of the file, without modification,
   10  *    this list of conditions, and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  * 3. Absolutely no warranty of function or purpose is made by the author
   15  *    John S. Dyson.
   16  * 4. Modifications may be freely made to this file if the above conditions
   17  *    are met.
   18  *
   19  * $FreeBSD: releng/5.1/sys/kern/sys_pipe.c 112981 2003-04-02 15:24:50Z hsu $
   20  */
   21 
   22 /*
   23  * This file contains a high-performance replacement for the socket-based
   24  * pipes scheme originally used in FreeBSD/4.4Lite.  It does not support
   25  * all features of sockets, but does do everything that pipes normally
   26  * do.
   27  */
   28 
   29 /*
   30  * This code has two modes of operation, a small write mode and a large
   31  * write mode.  The small write mode acts like conventional pipes with
   32  * a kernel buffer.  If the buffer is less than PIPE_MINDIRECT, then the
   33  * "normal" pipe buffering is done.  If the buffer is between PIPE_MINDIRECT
   34  * and PIPE_SIZE in size, it is fully mapped and wired into the kernel, and
   35  * the receiving process can copy it directly from the pages in the sending
   36  * process.
   37  *
   38  * If the sending process receives a signal, it is possible that it will
   39  * go away, and certainly its address space can change, because control
   40  * is returned back to the user-mode side.  In that case, the pipe code
   41  * arranges to copy the buffer supplied by the user process, to a pageable
   42  * kernel buffer, and the receiving process will grab the data from the
   43  * pageable kernel buffer.  Since signals don't happen all that often,
   44  * the copy operation is normally eliminated.
   45  *
   46  * The constant PIPE_MINDIRECT is chosen to make sure that buffering will
   47  * happen for small transfers so that the system will not spend all of
   48  * its time context switching.  PIPE_SIZE is constrained by the
   49  * amount of kernel virtual memory.
   50  */
   51 
   52 #include "opt_mac.h"
   53 
   54 #include <sys/param.h>
   55 #include <sys/systm.h>
   56 #include <sys/fcntl.h>
   57 #include <sys/file.h>
   58 #include <sys/filedesc.h>
   59 #include <sys/filio.h>
   60 #include <sys/kernel.h>
   61 #include <sys/lock.h>
   62 #include <sys/mac.h>
   63 #include <sys/mutex.h>
   64 #include <sys/ttycom.h>
   65 #include <sys/stat.h>
   66 #include <sys/malloc.h>
   67 #include <sys/poll.h>
   68 #include <sys/selinfo.h>
   69 #include <sys/signalvar.h>
   70 #include <sys/sysproto.h>
   71 #include <sys/pipe.h>
   72 #include <sys/proc.h>
   73 #include <sys/vnode.h>
   74 #include <sys/uio.h>
   75 #include <sys/event.h>
   76 
   77 #include <vm/vm.h>
   78 #include <vm/vm_param.h>
   79 #include <vm/vm_object.h>
   80 #include <vm/vm_kern.h>
   81 #include <vm/vm_extern.h>
   82 #include <vm/pmap.h>
   83 #include <vm/vm_map.h>
   84 #include <vm/vm_page.h>
   85 #include <vm/uma.h>
   86 
   87 /*
   88  * Use this define if you want to disable *fancy* VM things.  Expect an
   89  * approx 30% decrease in transfer rate.  This could be useful for
   90  * NetBSD or OpenBSD.
   91  */
   92 /* #define PIPE_NODIRECT */
   93 
   94 /*
   95  * interfaces to the outside world
   96  */
   97 static fo_rdwr_t        pipe_read;
   98 static fo_rdwr_t        pipe_write;
   99 static fo_ioctl_t       pipe_ioctl;
  100 static fo_poll_t        pipe_poll;
  101 static fo_kqfilter_t    pipe_kqfilter;
  102 static fo_stat_t        pipe_stat;
  103 static fo_close_t       pipe_close;
  104 
  105 static struct fileops pipeops = {
  106         pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter,
  107         pipe_stat, pipe_close, DFLAG_PASSABLE
  108 };
  109 
  110 static void     filt_pipedetach(struct knote *kn);
  111 static int      filt_piperead(struct knote *kn, long hint);
  112 static int      filt_pipewrite(struct knote *kn, long hint);
  113 
  114 static struct filterops pipe_rfiltops =
  115         { 1, NULL, filt_pipedetach, filt_piperead };
  116 static struct filterops pipe_wfiltops =
  117         { 1, NULL, filt_pipedetach, filt_pipewrite };
  118 
  119 #define PIPE_GET_GIANT(pipe)                                            \
  120         do {                                                            \
  121                 KASSERT(((pipe)->pipe_state & PIPE_LOCKFL) != 0,        \
  122                     ("%s:%d PIPE_GET_GIANT: line pipe not locked",      \
  123                      __FILE__, __LINE__));                              \
  124                 PIPE_UNLOCK(pipe);                                      \
  125                 mtx_lock(&Giant);                                       \
  126         } while (0)
  127 
  128 #define PIPE_DROP_GIANT(pipe)                                           \
  129         do {                                                            \
  130                 mtx_unlock(&Giant);                                     \
  131                 PIPE_LOCK(pipe);                                        \
  132         } while (0)
  133 
  134 /*
  135  * Default pipe buffer size(s), this can be kind-of large now because pipe
  136  * space is pageable.  The pipe code will try to maintain locality of
  137  * reference for performance reasons, so small amounts of outstanding I/O
  138  * will not wipe the cache.
  139  */
  140 #define MINPIPESIZE (PIPE_SIZE/3)
  141 #define MAXPIPESIZE (2*PIPE_SIZE/3)
  142 
  143 /*
  144  * Maximum amount of kva for pipes -- this is kind-of a soft limit, but
  145  * is there so that on large systems, we don't exhaust it.
  146  */
  147 #define MAXPIPEKVA (8*1024*1024)
  148 
  149 /*
  150  * Limit for direct transfers, we cannot, of course limit
  151  * the amount of kva for pipes in general though.
  152  */
  153 #define LIMITPIPEKVA (16*1024*1024)
  154 
  155 /*
  156  * Limit the number of "big" pipes
  157  */
  158 #define LIMITBIGPIPES   32
  159 static int nbigpipe;
  160 
  161 static int amountpipekva;
  162 
  163 static void pipeinit(void *dummy __unused);
  164 static void pipeclose(struct pipe *cpipe);
  165 static void pipe_free_kmem(struct pipe *cpipe);
  166 static int pipe_create(struct pipe **cpipep);
  167 static __inline int pipelock(struct pipe *cpipe, int catch);
  168 static __inline void pipeunlock(struct pipe *cpipe);
  169 static __inline void pipeselwakeup(struct pipe *cpipe);
  170 #ifndef PIPE_NODIRECT
  171 static int pipe_build_write_buffer(struct pipe *wpipe, struct uio *uio);
  172 static void pipe_destroy_write_buffer(struct pipe *wpipe);
  173 static int pipe_direct_write(struct pipe *wpipe, struct uio *uio);
  174 static void pipe_clone_write_buffer(struct pipe *wpipe);
  175 #endif
  176 static int pipespace(struct pipe *cpipe, int size);
  177 
  178 static uma_zone_t pipe_zone;
  179 
  180 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, pipeinit, NULL);
  181 
  182 static void
  183 pipeinit(void *dummy __unused)
  184 {
  185         pipe_zone = uma_zcreate("PIPE", sizeof(struct pipe), NULL,
  186             NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
  187 }
  188 
  189 /*
  190  * The pipe system call for the DTYPE_PIPE type of pipes
  191  */
  192 
  193 /* ARGSUSED */
  194 int
  195 pipe(td, uap)
  196         struct thread *td;
  197         struct pipe_args /* {
  198                 int     dummy;
  199         } */ *uap;
  200 {
  201         struct filedesc *fdp = td->td_proc->p_fd;
  202         struct file *rf, *wf;
  203         struct pipe *rpipe, *wpipe;
  204         struct mtx *pmtx;
  205         int fd, error;
  206         
  207         KASSERT(pipe_zone != NULL, ("pipe_zone not initialized"));
  208 
  209         pmtx = malloc(sizeof(*pmtx), M_TEMP, M_WAITOK | M_ZERO);
  210         
  211         rpipe = wpipe = NULL;
  212         if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
  213                 pipeclose(rpipe); 
  214                 pipeclose(wpipe); 
  215                 free(pmtx, M_TEMP);
  216                 return (ENFILE);
  217         }
  218         
  219         rpipe->pipe_state |= PIPE_DIRECTOK;
  220         wpipe->pipe_state |= PIPE_DIRECTOK;
  221 
  222         error = falloc(td, &rf, &fd);
  223         if (error) {
  224                 pipeclose(rpipe);
  225                 pipeclose(wpipe);
  226                 free(pmtx, M_TEMP);
  227                 return (error);
  228         }
  229         fhold(rf);
  230         td->td_retval[0] = fd;
  231 
  232         /*
  233          * Warning: once we've gotten past allocation of the fd for the
  234          * read-side, we can only drop the read side via fdrop() in order
  235          * to avoid races against processes which manage to dup() the read
  236          * side while we are blocked trying to allocate the write side.
  237          */
  238         FILE_LOCK(rf);
  239         rf->f_flag = FREAD | FWRITE;
  240         rf->f_type = DTYPE_PIPE;
  241         rf->f_data = rpipe;
  242         rf->f_ops = &pipeops;
  243         FILE_UNLOCK(rf);
  244         error = falloc(td, &wf, &fd);
  245         if (error) {
  246                 FILEDESC_LOCK(fdp);
  247                 if (fdp->fd_ofiles[td->td_retval[0]] == rf) {
  248                         fdp->fd_ofiles[td->td_retval[0]] = NULL;
  249                         FILEDESC_UNLOCK(fdp);
  250                         fdrop(rf, td);
  251                 } else
  252                         FILEDESC_UNLOCK(fdp);
  253                 fdrop(rf, td);
  254                 /* rpipe has been closed by fdrop(). */
  255                 pipeclose(wpipe);
  256                 free(pmtx, M_TEMP);
  257                 return (error);
  258         }
  259         FILE_LOCK(wf);
  260         wf->f_flag = FREAD | FWRITE;
  261         wf->f_type = DTYPE_PIPE;
  262         wf->f_data = wpipe;
  263         wf->f_ops = &pipeops;
  264         FILE_UNLOCK(wf);
  265         td->td_retval[1] = fd;
  266         rpipe->pipe_peer = wpipe;
  267         wpipe->pipe_peer = rpipe;
  268 #ifdef MAC
  269         /*
  270          * struct pipe represents a pipe endpoint.  The MAC label is shared
  271          * between the connected endpoints.  As a result mac_init_pipe() and
  272          * mac_create_pipe() should only be called on one of the endpoints
  273          * after they have been connected.
  274          */
  275         mac_init_pipe(rpipe);
  276         mac_create_pipe(td->td_ucred, rpipe);
  277 #endif
  278         mtx_init(pmtx, "pipe mutex", NULL, MTX_DEF | MTX_RECURSE);
  279         rpipe->pipe_mtxp = wpipe->pipe_mtxp = pmtx;
  280         fdrop(rf, td);
  281 
  282         return (0);
  283 }
  284 
  285 /*
  286  * Allocate kva for pipe circular buffer, the space is pageable
  287  * This routine will 'realloc' the size of a pipe safely, if it fails
  288  * it will retain the old buffer.
  289  * If it fails it will return ENOMEM.
  290  */
  291 static int
  292 pipespace(cpipe, size)
  293         struct pipe *cpipe;
  294         int size;
  295 {
  296         struct vm_object *object;
  297         caddr_t buffer;
  298         int npages, error;
  299 
  300         GIANT_REQUIRED;
  301         KASSERT(cpipe->pipe_mtxp == NULL || !mtx_owned(PIPE_MTX(cpipe)),
  302                ("pipespace: pipe mutex locked"));
  303 
  304         npages = round_page(size)/PAGE_SIZE;
  305         /*
  306          * Create an object, I don't like the idea of paging to/from
  307          * kernel_object.
  308          * XXX -- minor change needed here for NetBSD/OpenBSD VM systems.
  309          */
  310         object = vm_object_allocate(OBJT_DEFAULT, npages);
  311         buffer = (caddr_t) vm_map_min(kernel_map);
  312 
  313         /*
  314          * Insert the object into the kernel map, and allocate kva for it.
  315          * The map entry is, by default, pageable.
  316          * XXX -- minor change needed here for NetBSD/OpenBSD VM systems.
  317          */
  318         error = vm_map_find(kernel_map, object, 0,
  319                 (vm_offset_t *) &buffer, size, 1,
  320                 VM_PROT_ALL, VM_PROT_ALL, 0);
  321 
  322         if (error != KERN_SUCCESS) {
  323                 vm_object_deallocate(object);
  324                 return (ENOMEM);
  325         }
  326 
  327         /* free old resources if we're resizing */
  328         pipe_free_kmem(cpipe);
  329         cpipe->pipe_buffer.object = object;
  330         cpipe->pipe_buffer.buffer = buffer;
  331         cpipe->pipe_buffer.size = size;
  332         cpipe->pipe_buffer.in = 0;
  333         cpipe->pipe_buffer.out = 0;
  334         cpipe->pipe_buffer.cnt = 0;
  335         atomic_add_int(&amountpipekva, cpipe->pipe_buffer.size);
  336         return (0);
  337 }
  338 
  339 /*
  340  * initialize and allocate VM and memory for pipe
  341  */
  342 static int
  343 pipe_create(cpipep)
  344         struct pipe **cpipep;
  345 {
  346         struct pipe *cpipe;
  347         int error;
  348 
  349         *cpipep = uma_zalloc(pipe_zone, M_WAITOK);
  350         if (*cpipep == NULL)
  351                 return (ENOMEM);
  352 
  353         cpipe = *cpipep;
  354         
  355         /* so pipespace()->pipe_free_kmem() doesn't follow junk pointer */
  356         cpipe->pipe_buffer.object = NULL;
  357 #ifndef PIPE_NODIRECT
  358         cpipe->pipe_map.kva = 0;
  359 #endif
  360         /*
  361          * protect so pipeclose() doesn't follow a junk pointer
  362          * if pipespace() fails.
  363          */
  364         bzero(&cpipe->pipe_sel, sizeof(cpipe->pipe_sel));
  365         cpipe->pipe_state = 0;
  366         cpipe->pipe_peer = NULL;
  367         cpipe->pipe_busy = 0;
  368 
  369 #ifndef PIPE_NODIRECT
  370         /*
  371          * pipe data structure initializations to support direct pipe I/O
  372          */
  373         cpipe->pipe_map.cnt = 0;
  374         cpipe->pipe_map.kva = 0;
  375         cpipe->pipe_map.pos = 0;
  376         cpipe->pipe_map.npages = 0;
  377         /* cpipe->pipe_map.ms[] = invalid */
  378 #endif
  379 
  380         cpipe->pipe_mtxp = NULL;        /* avoid pipespace assertion */
  381         error = pipespace(cpipe, PIPE_SIZE);
  382         if (error)
  383                 return (error);
  384 
  385         vfs_timestamp(&cpipe->pipe_ctime);
  386         cpipe->pipe_atime = cpipe->pipe_ctime;
  387         cpipe->pipe_mtime = cpipe->pipe_ctime;
  388 
  389         return (0);
  390 }
  391 
  392 
  393 /*
  394  * lock a pipe for I/O, blocking other access
  395  */
  396 static __inline int
  397 pipelock(cpipe, catch)
  398         struct pipe *cpipe;
  399         int catch;
  400 {
  401         int error;
  402 
  403         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
  404         while (cpipe->pipe_state & PIPE_LOCKFL) {
  405                 cpipe->pipe_state |= PIPE_LWANT;
  406                 error = msleep(cpipe, PIPE_MTX(cpipe),
  407                     catch ? (PRIBIO | PCATCH) : PRIBIO,
  408                     "pipelk", 0);
  409                 if (error != 0) 
  410                         return (error);
  411         }
  412         cpipe->pipe_state |= PIPE_LOCKFL;
  413         return (0);
  414 }
  415 
  416 /*
  417  * unlock a pipe I/O lock
  418  */
  419 static __inline void
  420 pipeunlock(cpipe)
  421         struct pipe *cpipe;
  422 {
  423 
  424         PIPE_LOCK_ASSERT(cpipe, MA_OWNED);
  425         cpipe->pipe_state &= ~PIPE_LOCKFL;
  426         if (cpipe->pipe_state & PIPE_LWANT) {
  427                 cpipe->pipe_state &= ~PIPE_LWANT;
  428                 wakeup(cpipe);
  429         }
  430 }
  431 
  432 static __inline void
  433 pipeselwakeup(cpipe)
  434         struct pipe *cpipe;
  435 {
  436 
  437         if (cpipe->pipe_state & PIPE_SEL) {
  438                 cpipe->pipe_state &= ~PIPE_SEL;
  439                 selwakeup(&cpipe->pipe_sel);
  440         }
  441         if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio)
  442                 pgsigio(&cpipe->pipe_sigio, SIGIO, 0);
  443         KNOTE(&cpipe->pipe_sel.si_note, 0);
  444 }
  445 
  446 /* ARGSUSED */
  447 static int
  448 pipe_read(fp, uio, active_cred, flags, td)
  449         struct file *fp;
  450         struct uio *uio;
  451         struct ucred *active_cred;
  452         struct thread *td;
  453         int flags;
  454 {
  455         struct pipe *rpipe = fp->f_data;
  456         int error;
  457         int nread = 0;
  458         u_int size;
  459 
  460         PIPE_LOCK(rpipe);
  461         ++rpipe->pipe_busy;
  462         error = pipelock(rpipe, 1);
  463         if (error)
  464                 goto unlocked_error;
  465 
  466 #ifdef MAC
  467         error = mac_check_pipe_read(active_cred, rpipe);
  468         if (error)
  469                 goto locked_error;
  470 #endif
  471 
  472         while (uio->uio_resid) {
  473                 /*
  474                  * normal pipe buffer receive
  475                  */
  476                 if (rpipe->pipe_buffer.cnt > 0) {
  477                         size = rpipe->pipe_buffer.size - rpipe->pipe_buffer.out;
  478                         if (size > rpipe->pipe_buffer.cnt)
  479                                 size = rpipe->pipe_buffer.cnt;
  480                         if (size > (u_int) uio->uio_resid)
  481                                 size = (u_int) uio->uio_resid;
  482 
  483                         PIPE_UNLOCK(rpipe);
  484                         error = uiomove(&rpipe->pipe_buffer.buffer[rpipe->pipe_buffer.out],
  485                                         size, uio);
  486                         PIPE_LOCK(rpipe);
  487                         if (error)
  488                                 break;
  489 
  490                         rpipe->pipe_buffer.out += size;
  491                         if (rpipe->pipe_buffer.out >= rpipe->pipe_buffer.size)
  492                                 rpipe->pipe_buffer.out = 0;
  493 
  494                         rpipe->pipe_buffer.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 (rpipe->pipe_buffer.cnt == 0) {
  502                                 rpipe->pipe_buffer.in = 0;
  503                                 rpipe->pipe_buffer.out = 0;
  504                         }
  505                         nread += size;
  506 #ifndef PIPE_NODIRECT
  507                 /*
  508                  * Direct copy, bypassing a kernel buffer.
  509                  */
  510                 } else if ((size = rpipe->pipe_map.cnt) &&
  511                            (rpipe->pipe_state & PIPE_DIRECTW)) {
  512                         caddr_t va;
  513                         if (size > (u_int) uio->uio_resid)
  514                                 size = (u_int) uio->uio_resid;
  515 
  516                         va = (caddr_t) rpipe->pipe_map.kva +
  517                             rpipe->pipe_map.pos;
  518                         PIPE_UNLOCK(rpipe);
  519                         error = uiomove(va, size, uio);
  520                         PIPE_LOCK(rpipe);
  521                         if (error)
  522                                 break;
  523                         nread += size;
  524                         rpipe->pipe_map.pos += size;
  525                         rpipe->pipe_map.cnt -= size;
  526                         if (rpipe->pipe_map.cnt == 0) {
  527                                 rpipe->pipe_state &= ~PIPE_DIRECTW;
  528                                 wakeup(rpipe);
  529                         }
  530 #endif
  531                 } else {
  532                         /*
  533                          * detect EOF condition
  534                          * read returns 0 on EOF, no need to set error
  535                          */
  536                         if (rpipe->pipe_state & PIPE_EOF)
  537                                 break;
  538 
  539                         /*
  540                          * If the "write-side" has been blocked, wake it up now.
  541                          */
  542                         if (rpipe->pipe_state & PIPE_WANTW) {
  543                                 rpipe->pipe_state &= ~PIPE_WANTW;
  544                                 wakeup(rpipe);
  545                         }
  546 
  547                         /*
  548                          * Break if some data was read.
  549                          */
  550                         if (nread > 0)
  551                                 break;
  552 
  553                         /*
  554                          * Unlock the pipe buffer for our remaining processing.  We
  555                          * will either break out with an error or we will sleep and
  556                          * relock to loop.
  557                          */
  558                         pipeunlock(rpipe);
  559 
  560                         /*
  561                          * Handle non-blocking mode operation or
  562                          * wait for more data.
  563                          */
  564                         if (fp->f_flag & FNONBLOCK) {
  565                                 error = EAGAIN;
  566                         } else {
  567                                 rpipe->pipe_state |= PIPE_WANTR;
  568                                 if ((error = msleep(rpipe, PIPE_MTX(rpipe),
  569                                     PRIBIO | PCATCH,
  570                                     "piperd", 0)) == 0)
  571                                         error = pipelock(rpipe, 1);
  572                         }
  573                         if (error)
  574                                 goto unlocked_error;
  575                 }
  576         }
  577 #ifdef MAC
  578 locked_error:
  579 #endif
  580         pipeunlock(rpipe);
  581 
  582         /* XXX: should probably do this before getting any locks. */
  583         if (error == 0)
  584                 vfs_timestamp(&rpipe->pipe_atime);
  585 unlocked_error:
  586         --rpipe->pipe_busy;
  587 
  588         /*
  589          * PIPE_WANT processing only makes sense if pipe_busy is 0.
  590          */
  591         if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANT)) {
  592                 rpipe->pipe_state &= ~(PIPE_WANT|PIPE_WANTW);
  593                 wakeup(rpipe);
  594         } else if (rpipe->pipe_buffer.cnt < MINPIPESIZE) {
  595                 /*
  596                  * Handle write blocking hysteresis.
  597                  */
  598                 if (rpipe->pipe_state & PIPE_WANTW) {
  599                         rpipe->pipe_state &= ~PIPE_WANTW;
  600                         wakeup(rpipe);
  601                 }
  602         }
  603 
  604         if ((rpipe->pipe_buffer.size - rpipe->pipe_buffer.cnt) >= PIPE_BUF)
  605                 pipeselwakeup(rpipe);
  606 
  607         PIPE_UNLOCK(rpipe);
  608         return (error);
  609 }
  610 
  611 #ifndef PIPE_NODIRECT
  612 /*
  613  * Map the sending processes' buffer into kernel space and wire it.
  614  * This is similar to a physical write operation.
  615  */
  616 static int
  617 pipe_build_write_buffer(wpipe, uio)
  618         struct pipe *wpipe;
  619         struct uio *uio;
  620 {
  621         u_int size;
  622         int i;
  623         vm_offset_t addr, endaddr;
  624         vm_paddr_t paddr;
  625 
  626         GIANT_REQUIRED;
  627         PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
  628 
  629         size = (u_int) uio->uio_iov->iov_len;
  630         if (size > wpipe->pipe_buffer.size)
  631                 size = wpipe->pipe_buffer.size;
  632 
  633         endaddr = round_page((vm_offset_t)uio->uio_iov->iov_base + size);
  634         addr = trunc_page((vm_offset_t)uio->uio_iov->iov_base);
  635         for (i = 0; addr < endaddr; addr += PAGE_SIZE, i++) {
  636                 vm_page_t m;
  637 
  638                 /*
  639                  * vm_fault_quick() can sleep.  Consequently,
  640                  * vm_page_lock_queue() and vm_page_unlock_queue()
  641                  * should not be performed outside of this loop.
  642                  */
  643                 if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0 ||
  644                     (paddr = pmap_extract(vmspace_pmap(curproc->p_vmspace),
  645                      addr)) == 0) {
  646                         int j;
  647 
  648                         vm_page_lock_queues();
  649                         for (j = 0; j < i; j++)
  650                                 vm_page_unwire(wpipe->pipe_map.ms[j], 1);
  651                         vm_page_unlock_queues();
  652                         return (EFAULT);
  653                 }
  654 
  655                 m = PHYS_TO_VM_PAGE(paddr);
  656                 vm_page_lock_queues();
  657                 vm_page_wire(m);
  658                 vm_page_unlock_queues();
  659                 wpipe->pipe_map.ms[i] = m;
  660         }
  661 
  662 /*
  663  * set up the control block
  664  */
  665         wpipe->pipe_map.npages = i;
  666         wpipe->pipe_map.pos =
  667             ((vm_offset_t) uio->uio_iov->iov_base) & PAGE_MASK;
  668         wpipe->pipe_map.cnt = size;
  669 
  670 /*
  671  * and map the buffer
  672  */
  673         if (wpipe->pipe_map.kva == 0) {
  674                 /*
  675                  * We need to allocate space for an extra page because the
  676                  * address range might (will) span pages at times.
  677                  */
  678                 wpipe->pipe_map.kva = kmem_alloc_pageable(kernel_map,
  679                         wpipe->pipe_buffer.size + PAGE_SIZE);
  680                 atomic_add_int(&amountpipekva,
  681                     wpipe->pipe_buffer.size + PAGE_SIZE);
  682         }
  683         pmap_qenter(wpipe->pipe_map.kva, wpipe->pipe_map.ms,
  684                 wpipe->pipe_map.npages);
  685 
  686 /*
  687  * and update the uio data
  688  */
  689 
  690         uio->uio_iov->iov_len -= size;
  691         uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + size;
  692         if (uio->uio_iov->iov_len == 0)
  693                 uio->uio_iov++;
  694         uio->uio_resid -= size;
  695         uio->uio_offset += size;
  696         return (0);
  697 }
  698 
  699 /*
  700  * unmap and unwire the process buffer
  701  */
  702 static void
  703 pipe_destroy_write_buffer(wpipe)
  704         struct pipe *wpipe;
  705 {
  706         int i;
  707 
  708         GIANT_REQUIRED;
  709         PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
  710 
  711         if (wpipe->pipe_map.kva) {
  712                 pmap_qremove(wpipe->pipe_map.kva, wpipe->pipe_map.npages);
  713 
  714                 if (amountpipekva > MAXPIPEKVA) {
  715                         vm_offset_t kva = wpipe->pipe_map.kva;
  716                         wpipe->pipe_map.kva = 0;
  717                         kmem_free(kernel_map, kva,
  718                                 wpipe->pipe_buffer.size + PAGE_SIZE);
  719                         atomic_subtract_int(&amountpipekva,
  720                             wpipe->pipe_buffer.size + PAGE_SIZE);
  721                 }
  722         }
  723         vm_page_lock_queues();
  724         for (i = 0; i < wpipe->pipe_map.npages; i++)
  725                 vm_page_unwire(wpipe->pipe_map.ms[i], 1);
  726         vm_page_unlock_queues();
  727         wpipe->pipe_map.npages = 0;
  728 }
  729 
  730 /*
  731  * In the case of a signal, the writing process might go away.  This
  732  * code copies the data into the circular buffer so that the source
  733  * pages can be freed without loss of data.
  734  */
  735 static void
  736 pipe_clone_write_buffer(wpipe)
  737         struct pipe *wpipe;
  738 {
  739         int size;
  740         int pos;
  741 
  742         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
  743         size = wpipe->pipe_map.cnt;
  744         pos = wpipe->pipe_map.pos;
  745 
  746         wpipe->pipe_buffer.in = size;
  747         wpipe->pipe_buffer.out = 0;
  748         wpipe->pipe_buffer.cnt = size;
  749         wpipe->pipe_state &= ~PIPE_DIRECTW;
  750 
  751         PIPE_GET_GIANT(wpipe);
  752         bcopy((caddr_t) wpipe->pipe_map.kva + pos,
  753             wpipe->pipe_buffer.buffer, size);
  754         pipe_destroy_write_buffer(wpipe);
  755         PIPE_DROP_GIANT(wpipe);
  756 }
  757 
  758 /*
  759  * This implements the pipe buffer write mechanism.  Note that only
  760  * a direct write OR a normal pipe write can be pending at any given time.
  761  * If there are any characters in the pipe buffer, the direct write will
  762  * be deferred until the receiving process grabs all of the bytes from
  763  * the pipe buffer.  Then the direct mapping write is set-up.
  764  */
  765 static int
  766 pipe_direct_write(wpipe, uio)
  767         struct pipe *wpipe;
  768         struct uio *uio;
  769 {
  770         int error;
  771 
  772 retry:
  773         PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
  774         while (wpipe->pipe_state & PIPE_DIRECTW) {
  775                 if (wpipe->pipe_state & PIPE_WANTR) {
  776                         wpipe->pipe_state &= ~PIPE_WANTR;
  777                         wakeup(wpipe);
  778                 }
  779                 wpipe->pipe_state |= PIPE_WANTW;
  780                 error = msleep(wpipe, PIPE_MTX(wpipe),
  781                     PRIBIO | PCATCH, "pipdww", 0);
  782                 if (error)
  783                         goto error1;
  784                 if (wpipe->pipe_state & PIPE_EOF) {
  785                         error = EPIPE;
  786                         goto error1;
  787                 }
  788         }
  789         wpipe->pipe_map.cnt = 0;        /* transfer not ready yet */
  790         if (wpipe->pipe_buffer.cnt > 0) {
  791                 if (wpipe->pipe_state & PIPE_WANTR) {
  792                         wpipe->pipe_state &= ~PIPE_WANTR;
  793                         wakeup(wpipe);
  794                 }
  795                         
  796                 wpipe->pipe_state |= PIPE_WANTW;
  797                 error = msleep(wpipe, PIPE_MTX(wpipe),
  798                     PRIBIO | PCATCH, "pipdwc", 0);
  799                 if (error)
  800                         goto error1;
  801                 if (wpipe->pipe_state & PIPE_EOF) {
  802                         error = EPIPE;
  803                         goto error1;
  804                 }
  805                 goto retry;
  806         }
  807 
  808         wpipe->pipe_state |= PIPE_DIRECTW;
  809 
  810         pipelock(wpipe, 0);
  811         PIPE_GET_GIANT(wpipe);
  812         error = pipe_build_write_buffer(wpipe, uio);
  813         PIPE_DROP_GIANT(wpipe);
  814         pipeunlock(wpipe);
  815         if (error) {
  816                 wpipe->pipe_state &= ~PIPE_DIRECTW;
  817                 goto error1;
  818         }
  819 
  820         error = 0;
  821         while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) {
  822                 if (wpipe->pipe_state & PIPE_EOF) {
  823                         pipelock(wpipe, 0);
  824                         PIPE_GET_GIANT(wpipe);
  825                         pipe_destroy_write_buffer(wpipe);
  826                         PIPE_DROP_GIANT(wpipe);
  827                         pipeselwakeup(wpipe);
  828                         pipeunlock(wpipe);
  829                         error = EPIPE;
  830                         goto error1;
  831                 }
  832                 if (wpipe->pipe_state & PIPE_WANTR) {
  833                         wpipe->pipe_state &= ~PIPE_WANTR;
  834                         wakeup(wpipe);
  835                 }
  836                 pipeselwakeup(wpipe);
  837                 error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH,
  838                     "pipdwt", 0);
  839         }
  840 
  841         pipelock(wpipe,0);
  842         if (wpipe->pipe_state & PIPE_DIRECTW) {
  843                 /*
  844                  * this bit of trickery substitutes a kernel buffer for
  845                  * the process that might be going away.
  846                  */
  847                 pipe_clone_write_buffer(wpipe);
  848         } else {
  849                 PIPE_GET_GIANT(wpipe);
  850                 pipe_destroy_write_buffer(wpipe);
  851                 PIPE_DROP_GIANT(wpipe);
  852         }
  853         pipeunlock(wpipe);
  854         return (error);
  855 
  856 error1:
  857         wakeup(wpipe);
  858         return (error);
  859 }
  860 #endif
  861         
  862 static int
  863 pipe_write(fp, uio, active_cred, flags, td)
  864         struct file *fp;
  865         struct uio *uio;
  866         struct ucred *active_cred;
  867         struct thread *td;
  868         int flags;
  869 {
  870         int error = 0;
  871         int orig_resid;
  872         struct pipe *wpipe, *rpipe;
  873 
  874         rpipe = fp->f_data;
  875         wpipe = rpipe->pipe_peer;
  876 
  877         PIPE_LOCK(rpipe);
  878         /*
  879          * detect loss of pipe read side, issue SIGPIPE if lost.
  880          */
  881         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
  882                 PIPE_UNLOCK(rpipe);
  883                 return (EPIPE);
  884         }
  885 #ifdef MAC
  886         error = mac_check_pipe_write(active_cred, wpipe);
  887         if (error) {
  888                 PIPE_UNLOCK(rpipe);
  889                 return (error);
  890         }
  891 #endif
  892         ++wpipe->pipe_busy;
  893 
  894         /*
  895          * If it is advantageous to resize the pipe buffer, do
  896          * so.
  897          */
  898         if ((uio->uio_resid > PIPE_SIZE) &&
  899                 (nbigpipe < LIMITBIGPIPES) &&
  900                 (wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
  901                 (wpipe->pipe_buffer.size <= PIPE_SIZE) &&
  902                 (wpipe->pipe_buffer.cnt == 0)) {
  903 
  904                 if ((error = pipelock(wpipe, 1)) == 0) {
  905                         PIPE_GET_GIANT(wpipe);
  906                         if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
  907                                 nbigpipe++;
  908                         PIPE_DROP_GIANT(wpipe);
  909                         pipeunlock(wpipe);
  910                 }
  911         }
  912 
  913         /*
  914          * If an early error occured unbusy and return, waking up any pending
  915          * readers.
  916          */
  917         if (error) {
  918                 --wpipe->pipe_busy;
  919                 if ((wpipe->pipe_busy == 0) && 
  920                     (wpipe->pipe_state & PIPE_WANT)) {
  921                         wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
  922                         wakeup(wpipe);
  923                 }
  924                 PIPE_UNLOCK(rpipe);
  925                 return(error);
  926         }
  927                 
  928         orig_resid = uio->uio_resid;
  929 
  930         while (uio->uio_resid) {
  931                 int space;
  932 
  933 #ifndef PIPE_NODIRECT
  934                 /*
  935                  * If the transfer is large, we can gain performance if
  936                  * we do process-to-process copies directly.
  937                  * If the write is non-blocking, we don't use the
  938                  * direct write mechanism.
  939                  *
  940                  * The direct write mechanism will detect the reader going
  941                  * away on us.
  942                  */
  943                 if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) &&
  944                     (fp->f_flag & FNONBLOCK) == 0 &&
  945                         (wpipe->pipe_map.kva || (amountpipekva < LIMITPIPEKVA)) &&
  946                         (uio->uio_iov->iov_len >= PIPE_MINDIRECT)) {
  947                         error = pipe_direct_write(wpipe, uio);
  948                         if (error)
  949                                 break;
  950                         continue;
  951                 }
  952 #endif
  953 
  954                 /*
  955                  * Pipe buffered writes cannot be coincidental with
  956                  * direct writes.  We wait until the currently executing
  957                  * direct write is completed before we start filling the
  958                  * pipe buffer.  We break out if a signal occurs or the
  959                  * reader goes away.
  960                  */
  961         retrywrite:
  962                 while (wpipe->pipe_state & PIPE_DIRECTW) {
  963                         if (wpipe->pipe_state & PIPE_WANTR) {
  964                                 wpipe->pipe_state &= ~PIPE_WANTR;
  965                                 wakeup(wpipe);
  966                         }
  967                         error = msleep(wpipe, PIPE_MTX(rpipe), PRIBIO | PCATCH,
  968                             "pipbww", 0);
  969                         if (wpipe->pipe_state & PIPE_EOF)
  970                                 break;
  971                         if (error)
  972                                 break;
  973                 }
  974                 if (wpipe->pipe_state & PIPE_EOF) {
  975                         error = EPIPE;
  976                         break;
  977                 }
  978 
  979                 space = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
  980 
  981                 /* Writes of size <= PIPE_BUF must be atomic. */
  982                 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
  983                         space = 0;
  984 
  985                 if (space > 0 && (wpipe->pipe_buffer.cnt < PIPE_SIZE)) {
  986                         if ((error = pipelock(wpipe,1)) == 0) {
  987                                 int size;       /* Transfer size */
  988                                 int segsize;    /* first segment to transfer */
  989 
  990                                 /*
  991                                  * It is possible for a direct write to
  992                                  * slip in on us... handle it here...
  993                                  */
  994                                 if (wpipe->pipe_state & PIPE_DIRECTW) {
  995                                         pipeunlock(wpipe);
  996                                         goto retrywrite;
  997                                 }
  998                                 /* 
  999                                  * If a process blocked in uiomove, our
 1000                                  * value for space might be bad.
 1001                                  *
 1002                                  * XXX will we be ok if the reader has gone
 1003                                  * away here?
 1004                                  */
 1005                                 if (space > wpipe->pipe_buffer.size - 
 1006                                     wpipe->pipe_buffer.cnt) {
 1007                                         pipeunlock(wpipe);
 1008                                         goto retrywrite;
 1009                                 }
 1010 
 1011                                 /*
 1012                                  * Transfer size is minimum of uio transfer
 1013                                  * and free space in pipe buffer.
 1014                                  */
 1015                                 if (space > uio->uio_resid)
 1016                                         size = uio->uio_resid;
 1017                                 else
 1018                                         size = space;
 1019                                 /*
 1020                                  * First segment to transfer is minimum of 
 1021                                  * transfer size and contiguous space in
 1022                                  * pipe buffer.  If first segment to transfer
 1023                                  * is less than the transfer size, we've got
 1024                                  * a wraparound in the buffer.
 1025                                  */
 1026                                 segsize = wpipe->pipe_buffer.size - 
 1027                                         wpipe->pipe_buffer.in;
 1028                                 if (segsize > size)
 1029                                         segsize = size;
 1030                                 
 1031                                 /* Transfer first segment */
 1032 
 1033                                 PIPE_UNLOCK(rpipe);
 1034                                 error = uiomove(&wpipe->pipe_buffer.buffer[wpipe->pipe_buffer.in], 
 1035                                                 segsize, uio);
 1036                                 PIPE_LOCK(rpipe);
 1037                                 
 1038                                 if (error == 0 && segsize < size) {
 1039                                         /* 
 1040                                          * Transfer remaining part now, to
 1041                                          * support atomic writes.  Wraparound
 1042                                          * happened.
 1043                                          */
 1044                                         if (wpipe->pipe_buffer.in + segsize != 
 1045                                             wpipe->pipe_buffer.size)
 1046                                                 panic("Expected pipe buffer wraparound disappeared");
 1047                                                 
 1048                                         PIPE_UNLOCK(rpipe);
 1049                                         error = uiomove(&wpipe->pipe_buffer.buffer[0],
 1050                                                         size - segsize, uio);
 1051                                         PIPE_LOCK(rpipe);
 1052                                 }
 1053                                 if (error == 0) {
 1054                                         wpipe->pipe_buffer.in += size;
 1055                                         if (wpipe->pipe_buffer.in >=
 1056                                             wpipe->pipe_buffer.size) {
 1057                                                 if (wpipe->pipe_buffer.in != size - segsize + wpipe->pipe_buffer.size)
 1058                                                         panic("Expected wraparound bad");
 1059                                                 wpipe->pipe_buffer.in = size - segsize;
 1060                                         }
 1061                                 
 1062                                         wpipe->pipe_buffer.cnt += size;
 1063                                         if (wpipe->pipe_buffer.cnt > wpipe->pipe_buffer.size)
 1064                                                 panic("Pipe buffer overflow");
 1065                                 
 1066                                 }
 1067                                 pipeunlock(wpipe);
 1068                         }
 1069                         if (error)
 1070                                 break;
 1071 
 1072                 } else {
 1073                         /*
 1074                          * If the "read-side" has been blocked, wake it up now.
 1075                          */
 1076                         if (wpipe->pipe_state & PIPE_WANTR) {
 1077                                 wpipe->pipe_state &= ~PIPE_WANTR;
 1078                                 wakeup(wpipe);
 1079                         }
 1080 
 1081                         /*
 1082                          * don't block on non-blocking I/O
 1083                          */
 1084                         if (fp->f_flag & FNONBLOCK) {
 1085                                 error = EAGAIN;
 1086                                 break;
 1087                         }
 1088 
 1089                         /*
 1090                          * We have no more space and have something to offer,
 1091                          * wake up select/poll.
 1092                          */
 1093                         pipeselwakeup(wpipe);
 1094 
 1095                         wpipe->pipe_state |= PIPE_WANTW;
 1096                         error = msleep(wpipe, PIPE_MTX(rpipe),
 1097                             PRIBIO | PCATCH, "pipewr", 0);
 1098                         if (error != 0)
 1099                                 break;
 1100                         /*
 1101                          * If read side wants to go away, we just issue a signal
 1102                          * to ourselves.
 1103                          */
 1104                         if (wpipe->pipe_state & PIPE_EOF) {
 1105                                 error = EPIPE;
 1106                                 break;
 1107                         }       
 1108                 }
 1109         }
 1110 
 1111         --wpipe->pipe_busy;
 1112 
 1113         if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANT)) {
 1114                 wpipe->pipe_state &= ~(PIPE_WANT | PIPE_WANTR);
 1115                 wakeup(wpipe);
 1116         } else if (wpipe->pipe_buffer.cnt > 0) {
 1117                 /*
 1118                  * If we have put any characters in the buffer, we wake up
 1119                  * the reader.
 1120                  */
 1121                 if (wpipe->pipe_state & PIPE_WANTR) {
 1122                         wpipe->pipe_state &= ~PIPE_WANTR;
 1123                         wakeup(wpipe);
 1124                 }
 1125         }
 1126 
 1127         /*
 1128          * Don't return EPIPE if I/O was successful
 1129          */
 1130         if ((wpipe->pipe_buffer.cnt == 0) &&
 1131             (uio->uio_resid == 0) &&
 1132             (error == EPIPE)) {
 1133                 error = 0;
 1134         }
 1135 
 1136         if (error == 0)
 1137                 vfs_timestamp(&wpipe->pipe_mtime);
 1138 
 1139         /*
 1140          * We have something to offer,
 1141          * wake up select/poll.
 1142          */
 1143         if (wpipe->pipe_buffer.cnt)
 1144                 pipeselwakeup(wpipe);
 1145 
 1146         PIPE_UNLOCK(rpipe);
 1147         return (error);
 1148 }
 1149 
 1150 /*
 1151  * we implement a very minimal set of ioctls for compatibility with sockets.
 1152  */
 1153 static int
 1154 pipe_ioctl(fp, cmd, data, active_cred, td)
 1155         struct file *fp;
 1156         u_long cmd;
 1157         void *data;
 1158         struct ucred *active_cred;
 1159         struct thread *td;
 1160 {
 1161         struct pipe *mpipe = fp->f_data;
 1162 #ifdef MAC
 1163         int error;
 1164 #endif
 1165 
 1166         PIPE_LOCK(mpipe);
 1167 
 1168 #ifdef MAC
 1169         error = mac_check_pipe_ioctl(active_cred, mpipe, cmd, data);
 1170         if (error)
 1171                 return (error);
 1172 #endif
 1173 
 1174         switch (cmd) {
 1175 
 1176         case FIONBIO:
 1177                 PIPE_UNLOCK(mpipe);
 1178                 return (0);
 1179 
 1180         case FIOASYNC:
 1181                 if (*(int *)data) {
 1182                         mpipe->pipe_state |= PIPE_ASYNC;
 1183                 } else {
 1184                         mpipe->pipe_state &= ~PIPE_ASYNC;
 1185                 }
 1186                 PIPE_UNLOCK(mpipe);
 1187                 return (0);
 1188 
 1189         case FIONREAD:
 1190                 if (mpipe->pipe_state & PIPE_DIRECTW)
 1191                         *(int *)data = mpipe->pipe_map.cnt;
 1192                 else
 1193                         *(int *)data = mpipe->pipe_buffer.cnt;
 1194                 PIPE_UNLOCK(mpipe);
 1195                 return (0);
 1196 
 1197         case FIOSETOWN:
 1198                 PIPE_UNLOCK(mpipe);
 1199                 return (fsetown(*(int *)data, &mpipe->pipe_sigio));
 1200 
 1201         case FIOGETOWN:
 1202                 PIPE_UNLOCK(mpipe);
 1203                 *(int *)data = fgetown(&mpipe->pipe_sigio);
 1204                 return (0);
 1205 
 1206         /* This is deprecated, FIOSETOWN should be used instead. */
 1207         case TIOCSPGRP:
 1208                 PIPE_UNLOCK(mpipe);
 1209                 return (fsetown(-(*(int *)data), &mpipe->pipe_sigio));
 1210 
 1211         /* This is deprecated, FIOGETOWN should be used instead. */
 1212         case TIOCGPGRP:
 1213                 PIPE_UNLOCK(mpipe);
 1214                 *(int *)data = -fgetown(&mpipe->pipe_sigio);
 1215                 return (0);
 1216 
 1217         }
 1218         PIPE_UNLOCK(mpipe);
 1219         return (ENOTTY);
 1220 }
 1221 
 1222 static int
 1223 pipe_poll(fp, events, active_cred, td)
 1224         struct file *fp;
 1225         int events;
 1226         struct ucred *active_cred;
 1227         struct thread *td;
 1228 {
 1229         struct pipe *rpipe = fp->f_data;
 1230         struct pipe *wpipe;
 1231         int revents = 0;
 1232 #ifdef MAC
 1233         int error;
 1234 #endif
 1235 
 1236         wpipe = rpipe->pipe_peer;
 1237         PIPE_LOCK(rpipe);
 1238 #ifdef MAC
 1239         error = mac_check_pipe_poll(active_cred, rpipe);
 1240         if (error)
 1241                 goto locked_error;
 1242 #endif
 1243         if (events & (POLLIN | POLLRDNORM))
 1244                 if ((rpipe->pipe_state & PIPE_DIRECTW) ||
 1245                     (rpipe->pipe_buffer.cnt > 0) ||
 1246                     (rpipe->pipe_state & PIPE_EOF))
 1247                         revents |= events & (POLLIN | POLLRDNORM);
 1248 
 1249         if (events & (POLLOUT | POLLWRNORM))
 1250                 if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) ||
 1251                     (((wpipe->pipe_state & PIPE_DIRECTW) == 0) &&
 1252                      (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
 1253                         revents |= events & (POLLOUT | POLLWRNORM);
 1254 
 1255         if ((rpipe->pipe_state & PIPE_EOF) ||
 1256             (wpipe == NULL) ||
 1257             (wpipe->pipe_state & PIPE_EOF))
 1258                 revents |= POLLHUP;
 1259 
 1260         if (revents == 0) {
 1261                 if (events & (POLLIN | POLLRDNORM)) {
 1262                         selrecord(td, &rpipe->pipe_sel);
 1263                         rpipe->pipe_state |= PIPE_SEL;
 1264                 }
 1265 
 1266                 if (events & (POLLOUT | POLLWRNORM)) {
 1267                         selrecord(td, &wpipe->pipe_sel);
 1268                         wpipe->pipe_state |= PIPE_SEL;
 1269                 }
 1270         }
 1271 #ifdef MAC
 1272 locked_error:
 1273 #endif
 1274         PIPE_UNLOCK(rpipe);
 1275 
 1276         return (revents);
 1277 }
 1278 
 1279 /*
 1280  * We shouldn't need locks here as we're doing a read and this should
 1281  * be a natural race.
 1282  */
 1283 static int
 1284 pipe_stat(fp, ub, active_cred, td)
 1285         struct file *fp;
 1286         struct stat *ub;
 1287         struct ucred *active_cred;
 1288         struct thread *td;
 1289 {
 1290         struct pipe *pipe = fp->f_data;
 1291 #ifdef MAC
 1292         int error;
 1293 
 1294         PIPE_LOCK(pipe);
 1295         error = mac_check_pipe_stat(active_cred, pipe);
 1296         PIPE_UNLOCK(pipe);
 1297         if (error)
 1298                 return (error);
 1299 #endif
 1300         bzero(ub, sizeof(*ub));
 1301         ub->st_mode = S_IFIFO;
 1302         ub->st_blksize = pipe->pipe_buffer.size;
 1303         ub->st_size = pipe->pipe_buffer.cnt;
 1304         ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
 1305         ub->st_atimespec = pipe->pipe_atime;
 1306         ub->st_mtimespec = pipe->pipe_mtime;
 1307         ub->st_ctimespec = pipe->pipe_ctime;
 1308         ub->st_uid = fp->f_cred->cr_uid;
 1309         ub->st_gid = fp->f_cred->cr_gid;
 1310         /*
 1311          * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen.
 1312          * XXX (st_dev, st_ino) should be unique.
 1313          */
 1314         return (0);
 1315 }
 1316 
 1317 /* ARGSUSED */
 1318 static int
 1319 pipe_close(fp, td)
 1320         struct file *fp;
 1321         struct thread *td;
 1322 {
 1323         struct pipe *cpipe = fp->f_data;
 1324 
 1325         fp->f_ops = &badfileops;
 1326         fp->f_data = NULL;
 1327         funsetown(&cpipe->pipe_sigio);
 1328         pipeclose(cpipe);
 1329         return (0);
 1330 }
 1331 
 1332 static void
 1333 pipe_free_kmem(cpipe)
 1334         struct pipe *cpipe;
 1335 {
 1336 
 1337         GIANT_REQUIRED;
 1338         KASSERT(cpipe->pipe_mtxp == NULL || !mtx_owned(PIPE_MTX(cpipe)),
 1339                ("pipespace: pipe mutex locked"));
 1340 
 1341         if (cpipe->pipe_buffer.buffer != NULL) {
 1342                 if (cpipe->pipe_buffer.size > PIPE_SIZE)
 1343                         --nbigpipe;
 1344                 atomic_subtract_int(&amountpipekva, cpipe->pipe_buffer.size);
 1345                 kmem_free(kernel_map,
 1346                         (vm_offset_t)cpipe->pipe_buffer.buffer,
 1347                         cpipe->pipe_buffer.size);
 1348                 cpipe->pipe_buffer.buffer = NULL;
 1349         }
 1350 #ifndef PIPE_NODIRECT
 1351         if (cpipe->pipe_map.kva != 0) {
 1352                 atomic_subtract_int(&amountpipekva,
 1353                     cpipe->pipe_buffer.size + PAGE_SIZE);
 1354                 kmem_free(kernel_map,
 1355                         cpipe->pipe_map.kva,
 1356                         cpipe->pipe_buffer.size + PAGE_SIZE);
 1357                 cpipe->pipe_map.cnt = 0;
 1358                 cpipe->pipe_map.kva = 0;
 1359                 cpipe->pipe_map.pos = 0;
 1360                 cpipe->pipe_map.npages = 0;
 1361         }
 1362 #endif
 1363 }
 1364 
 1365 /*
 1366  * shutdown the pipe
 1367  */
 1368 static void
 1369 pipeclose(cpipe)
 1370         struct pipe *cpipe;
 1371 {
 1372         struct pipe *ppipe;
 1373         int hadpeer;
 1374 
 1375         if (cpipe == NULL)
 1376                 return;
 1377 
 1378         hadpeer = 0;
 1379 
 1380         /* partially created pipes won't have a valid mutex. */
 1381         if (PIPE_MTX(cpipe) != NULL)
 1382                 PIPE_LOCK(cpipe);
 1383                 
 1384         pipeselwakeup(cpipe);
 1385 
 1386         /*
 1387          * If the other side is blocked, wake it up saying that
 1388          * we want to close it down.
 1389          */
 1390         while (cpipe->pipe_busy) {
 1391                 wakeup(cpipe);
 1392                 cpipe->pipe_state |= PIPE_WANT | PIPE_EOF;
 1393                 msleep(cpipe, PIPE_MTX(cpipe), PRIBIO, "pipecl", 0);
 1394         }
 1395 
 1396 #ifdef MAC
 1397         if (cpipe->pipe_label != NULL && cpipe->pipe_peer == NULL)
 1398                 mac_destroy_pipe(cpipe);
 1399 #endif
 1400 
 1401         /*
 1402          * Disconnect from peer
 1403          */
 1404         if ((ppipe = cpipe->pipe_peer) != NULL) {
 1405                 hadpeer++;
 1406                 pipeselwakeup(ppipe);
 1407 
 1408                 ppipe->pipe_state |= PIPE_EOF;
 1409                 wakeup(ppipe);
 1410                 KNOTE(&ppipe->pipe_sel.si_note, 0);
 1411                 ppipe->pipe_peer = NULL;
 1412         }
 1413         /*
 1414          * free resources
 1415          */
 1416         if (PIPE_MTX(cpipe) != NULL) {
 1417                 PIPE_UNLOCK(cpipe);
 1418                 if (!hadpeer) {
 1419                         mtx_destroy(PIPE_MTX(cpipe));
 1420                         free(PIPE_MTX(cpipe), M_TEMP);
 1421                 }
 1422         }
 1423         mtx_lock(&Giant);
 1424         pipe_free_kmem(cpipe);
 1425         uma_zfree(pipe_zone, cpipe);
 1426         mtx_unlock(&Giant);
 1427 }
 1428 
 1429 /*ARGSUSED*/
 1430 static int
 1431 pipe_kqfilter(struct file *fp, struct knote *kn)
 1432 {
 1433         struct pipe *cpipe;
 1434 
 1435         cpipe = kn->kn_fp->f_data;
 1436         switch (kn->kn_filter) {
 1437         case EVFILT_READ:
 1438                 kn->kn_fop = &pipe_rfiltops;
 1439                 break;
 1440         case EVFILT_WRITE:
 1441                 kn->kn_fop = &pipe_wfiltops;
 1442                 cpipe = cpipe->pipe_peer;
 1443                 if (cpipe == NULL)
 1444                         /* other end of pipe has been closed */
 1445                         return (EBADF);
 1446                 break;
 1447         default:
 1448                 return (1);
 1449         }
 1450         kn->kn_hook = cpipe;
 1451 
 1452         PIPE_LOCK(cpipe);
 1453         SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
 1454         PIPE_UNLOCK(cpipe);
 1455         return (0);
 1456 }
 1457 
 1458 static void
 1459 filt_pipedetach(struct knote *kn)
 1460 {
 1461         struct pipe *cpipe = (struct pipe *)kn->kn_hook;
 1462 
 1463         PIPE_LOCK(cpipe);
 1464         SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
 1465         PIPE_UNLOCK(cpipe);
 1466 }
 1467 
 1468 /*ARGSUSED*/
 1469 static int
 1470 filt_piperead(struct knote *kn, long hint)
 1471 {
 1472         struct pipe *rpipe = kn->kn_fp->f_data;
 1473         struct pipe *wpipe = rpipe->pipe_peer;
 1474 
 1475         PIPE_LOCK(rpipe);
 1476         kn->kn_data = rpipe->pipe_buffer.cnt;
 1477         if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
 1478                 kn->kn_data = rpipe->pipe_map.cnt;
 1479 
 1480         if ((rpipe->pipe_state & PIPE_EOF) ||
 1481             (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
 1482                 kn->kn_flags |= EV_EOF;
 1483                 PIPE_UNLOCK(rpipe);
 1484                 return (1);
 1485         }
 1486         PIPE_UNLOCK(rpipe);
 1487         return (kn->kn_data > 0);
 1488 }
 1489 
 1490 /*ARGSUSED*/
 1491 static int
 1492 filt_pipewrite(struct knote *kn, long hint)
 1493 {
 1494         struct pipe *rpipe = kn->kn_fp->f_data;
 1495         struct pipe *wpipe = rpipe->pipe_peer;
 1496 
 1497         PIPE_LOCK(rpipe);
 1498         if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
 1499                 kn->kn_data = 0;
 1500                 kn->kn_flags |= EV_EOF; 
 1501                 PIPE_UNLOCK(rpipe);
 1502                 return (1);
 1503         }
 1504         kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
 1505         if (wpipe->pipe_state & PIPE_DIRECTW)
 1506                 kn->kn_data = 0;
 1507 
 1508         PIPE_UNLOCK(rpipe);
 1509         return (kn->kn_data >= PIPE_BUF);
 1510 }

Cache object: 8a861610d3e9dd0425027e3e82b80f94


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.