2 * Copyright (c) 1996 John S. Dyson
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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
16 * 4. Modifications may be freely made to this file if the above conditions
19 * $FreeBSD: src/sys/kern/sys_pipe.c,v 1.60.2.13 2002/08/05 15:05:15 des Exp $
20 * $DragonFly: src/sys/kern/sys_pipe.c,v 1.50 2008/09/09 04:06:13 dillon Exp $
24 * This file contains a high-performance replacement for the socket-based
25 * pipes scheme originally used in FreeBSD/4.4Lite. It does not support
26 * all features of sockets, but does do everything that pipes normally
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/kernel.h>
33 #include <sys/fcntl.h>
35 #include <sys/filedesc.h>
36 #include <sys/filio.h>
37 #include <sys/ttycom.h>
40 #include <sys/select.h>
41 #include <sys/signalvar.h>
42 #include <sys/sysproto.h>
44 #include <sys/vnode.h>
46 #include <sys/event.h>
47 #include <sys/globaldata.h>
48 #include <sys/module.h>
49 #include <sys/malloc.h>
50 #include <sys/sysctl.h>
51 #include <sys/socket.h>
54 #include <vm/vm_param.h>
56 #include <vm/vm_object.h>
57 #include <vm/vm_kern.h>
58 #include <vm/vm_extern.h>
60 #include <vm/vm_map.h>
61 #include <vm/vm_page.h>
62 #include <vm/vm_zone.h>
64 #include <sys/file2.h>
65 #include <sys/signal2.h>
67 #include <machine/cpufunc.h>
70 * interfaces to the outside world
72 static int pipe_read (struct file *fp, struct uio *uio,
73 struct ucred *cred, int flags);
74 static int pipe_write (struct file *fp, struct uio *uio,
75 struct ucred *cred, int flags);
76 static int pipe_close (struct file *fp);
77 static int pipe_shutdown (struct file *fp, int how);
78 static int pipe_poll (struct file *fp, int events, struct ucred *cred);
79 static int pipe_kqfilter (struct file *fp, struct knote *kn);
80 static int pipe_stat (struct file *fp, struct stat *sb, struct ucred *cred);
81 static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data,
82 struct ucred *cred, struct sysmsg *msg);
84 static struct fileops pipeops = {
86 .fo_write = pipe_write,
87 .fo_ioctl = pipe_ioctl,
89 .fo_kqfilter = pipe_kqfilter,
91 .fo_close = pipe_close,
92 .fo_shutdown = pipe_shutdown
95 static void filt_pipedetach(struct knote *kn);
96 static int filt_piperead(struct knote *kn, long hint);
97 static int filt_pipewrite(struct knote *kn, long hint);
99 static struct filterops pipe_rfiltops =
100 { 1, NULL, filt_pipedetach, filt_piperead };
101 static struct filterops pipe_wfiltops =
102 { 1, NULL, filt_pipedetach, filt_pipewrite };
104 MALLOC_DEFINE(M_PIPE, "pipe", "pipe structures");
107 * Default pipe buffer size(s), this can be kind-of large now because pipe
108 * space is pageable. The pipe code will try to maintain locality of
109 * reference for performance reasons, so small amounts of outstanding I/O
110 * will not wipe the cache.
112 #define MINPIPESIZE (PIPE_SIZE/3)
113 #define MAXPIPESIZE (2*PIPE_SIZE/3)
116 * Limit the number of "big" pipes
118 #define LIMITBIGPIPES 64
119 #define PIPEQ_MAX_CACHE 16 /* per-cpu pipe structure cache */
121 static int pipe_maxbig = LIMITBIGPIPES;
122 static int pipe_maxcache = PIPEQ_MAX_CACHE;
123 static int pipe_bigcount;
124 static int pipe_nbig;
125 static int pipe_bcache_alloc;
126 static int pipe_bkmem_alloc;
127 static int pipe_rblocked_count;
128 static int pipe_wblocked_count;
130 SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation");
131 SYSCTL_INT(_kern_pipe, OID_AUTO, nbig,
132 CTLFLAG_RD, &pipe_nbig, 0, "numer of big pipes allocated");
133 SYSCTL_INT(_kern_pipe, OID_AUTO, bigcount,
134 CTLFLAG_RW, &pipe_bigcount, 0, "number of times pipe expanded");
135 SYSCTL_INT(_kern_pipe, OID_AUTO, rblocked,
136 CTLFLAG_RW, &pipe_rblocked_count, 0, "number of times pipe expanded");
137 SYSCTL_INT(_kern_pipe, OID_AUTO, wblocked,
138 CTLFLAG_RW, &pipe_wblocked_count, 0, "number of times pipe expanded");
139 SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache,
140 CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu");
141 SYSCTL_INT(_kern_pipe, OID_AUTO, maxbig,
142 CTLFLAG_RW, &pipe_maxbig, 0, "max number of big pipes");
144 static int pipe_delay = 5000; /* 5uS default */
145 SYSCTL_INT(_kern_pipe, OID_AUTO, delay,
146 CTLFLAG_RW, &pipe_delay, 0, "SMP delay optimization in ns");
147 static int pipe_mpsafe = 1;
148 SYSCTL_INT(_kern_pipe, OID_AUTO, mpsafe,
149 CTLFLAG_RW, &pipe_mpsafe, 0, "");
151 #if !defined(NO_PIPE_SYSCTL_STATS)
152 SYSCTL_INT(_kern_pipe, OID_AUTO, bcache_alloc,
153 CTLFLAG_RW, &pipe_bcache_alloc, 0, "pipe buffer from pcpu cache");
154 SYSCTL_INT(_kern_pipe, OID_AUTO, bkmem_alloc,
155 CTLFLAG_RW, &pipe_bkmem_alloc, 0, "pipe buffer from kmem");
158 static void pipeclose (struct pipe *cpipe);
159 static void pipe_free_kmem (struct pipe *cpipe);
160 static int pipe_create (struct pipe **cpipep);
161 static __inline void pipeselwakeup (struct pipe *cpipe);
162 static int pipespace (struct pipe *cpipe, int size);
165 pipeseltest(struct pipe *cpipe)
167 return ((cpipe->pipe_state & PIPE_SEL) ||
168 ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) ||
169 SLIST_FIRST(&cpipe->pipe_sel.si_note));
173 pipeselwakeup(struct pipe *cpipe)
175 if (cpipe->pipe_state & PIPE_SEL) {
177 cpipe->pipe_state &= ~PIPE_SEL;
178 selwakeup(&cpipe->pipe_sel);
181 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) {
183 pgsigio(cpipe->pipe_sigio, SIGIO, 0);
186 if (SLIST_FIRST(&cpipe->pipe_sel.si_note)) {
188 KNOTE(&cpipe->pipe_sel.si_note, 0);
194 * These routines are called before and after a UIO. The UIO
195 * may block, causing our held tokens to be lost temporarily.
197 * We use these routines to serialize reads against other reads
198 * and writes against other writes.
200 * The read token is held on entry so *ipp does not race.
203 pipe_start_uio(struct pipe *cpipe, int *ipp)
209 error = tsleep(ipp, PCATCH, "pipexx", 0);
218 pipe_end_uio(struct pipe *cpipe, int *ipp)
230 pipe_get_mplock(int *save)
233 if (pipe_mpsafe == 0) {
244 pipe_rel_mplock(int *save)
254 * The pipe system call for the DTYPE_PIPE type of pipes
256 * pipe_ARgs(int dummy)
261 sys_pipe(struct pipe_args *uap)
263 struct thread *td = curthread;
264 struct proc *p = td->td_proc;
265 struct file *rf, *wf;
266 struct pipe *rpipe, *wpipe;
271 rpipe = wpipe = NULL;
272 if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
278 error = falloc(p, &rf, &fd1);
284 uap->sysmsg_fds[0] = fd1;
287 * Warning: once we've gotten past allocation of the fd for the
288 * read-side, we can only drop the read side via fdrop() in order
289 * to avoid races against processes which manage to dup() the read
290 * side while we are blocked trying to allocate the write side.
292 rf->f_type = DTYPE_PIPE;
293 rf->f_flag = FREAD | FWRITE;
294 rf->f_ops = &pipeops;
296 error = falloc(p, &wf, &fd2);
298 fsetfd(p, NULL, fd1);
300 /* rpipe has been closed by fdrop(). */
304 wf->f_type = DTYPE_PIPE;
305 wf->f_flag = FREAD | FWRITE;
306 wf->f_ops = &pipeops;
308 uap->sysmsg_fds[1] = fd2;
310 rpipe->pipe_slock = kmalloc(sizeof(struct lock),
311 M_PIPE, M_WAITOK|M_ZERO);
312 wpipe->pipe_slock = rpipe->pipe_slock;
313 rpipe->pipe_peer = wpipe;
314 wpipe->pipe_peer = rpipe;
315 lockinit(rpipe->pipe_slock, "pipecl", 0, 0);
318 * Once activated the peer relationship remains valid until
319 * both sides are closed.
330 * Allocate kva for pipe circular buffer, the space is pageable
331 * This routine will 'realloc' the size of a pipe safely, if it fails
332 * it will retain the old buffer.
333 * If it fails it will return ENOMEM.
336 pipespace(struct pipe *cpipe, int size)
338 struct vm_object *object;
342 npages = round_page(size) / PAGE_SIZE;
343 object = cpipe->pipe_buffer.object;
346 * [re]create the object if necessary and reserve space for it
347 * in the kernel_map. The object and memory are pageable. On
348 * success, free the old resources before assigning the new
351 if (object == NULL || object->size != npages) {
353 object = vm_object_allocate(OBJT_DEFAULT, npages);
354 buffer = (caddr_t)vm_map_min(&kernel_map);
356 error = vm_map_find(&kernel_map, object, 0,
357 (vm_offset_t *)&buffer, size,
360 VM_PROT_ALL, VM_PROT_ALL,
363 if (error != KERN_SUCCESS) {
364 vm_object_deallocate(object);
368 pipe_free_kmem(cpipe);
370 cpipe->pipe_buffer.object = object;
371 cpipe->pipe_buffer.buffer = buffer;
372 cpipe->pipe_buffer.size = size;
377 cpipe->pipe_buffer.rindex = 0;
378 cpipe->pipe_buffer.windex = 0;
383 * Initialize and allocate VM and memory for pipe, pulling the pipe from
384 * our per-cpu cache if possible. For now make sure it is sized for the
385 * smaller PIPE_SIZE default.
388 pipe_create(struct pipe **cpipep)
390 globaldata_t gd = mycpu;
394 if ((cpipe = gd->gd_pipeq) != NULL) {
395 gd->gd_pipeq = cpipe->pipe_peer;
397 cpipe->pipe_peer = NULL;
398 cpipe->pipe_wantwcnt = 0;
400 cpipe = kmalloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO);
403 if ((error = pipespace(cpipe, PIPE_SIZE)) != 0)
405 vfs_timestamp(&cpipe->pipe_ctime);
406 cpipe->pipe_atime = cpipe->pipe_ctime;
407 cpipe->pipe_mtime = cpipe->pipe_ctime;
408 lwkt_token_init(&cpipe->pipe_rlock);
409 lwkt_token_init(&cpipe->pipe_wlock);
414 * MPALMOSTSAFE (acquires mplock)
417 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
423 u_int size; /* total bytes available */
424 u_int nsize; /* total bytes to read */
425 u_int rindex; /* contiguous bytes available */
433 if (uio->uio_resid == 0)
437 * Setup locks, calculate nbio
439 pipe_get_mplock(&mpsave);
440 rpipe = (struct pipe *)fp->f_data;
441 lwkt_gettoken(&rlock, &rpipe->pipe_rlock);
443 if (fflags & O_FBLOCKING)
445 else if (fflags & O_FNONBLOCKING)
447 else if (fp->f_flag & O_NONBLOCK)
453 * Reads are serialized. Note howeverthat pipe_buffer.buffer and
454 * pipe_buffer.size can change out from under us when the number
455 * of bytes in the buffer are zero due to the write-side doing a
458 error = pipe_start_uio(rpipe, &rpipe->pipe_rip);
460 pipe_rel_mplock(&mpsave);
461 lwkt_reltoken(&rlock);
466 bigread = (uio->uio_resid > 10 * 1024 * 1024);
469 while (uio->uio_resid) {
473 if (bigread && --bigcount == 0) {
476 if (CURSIG(curthread->td_lwp)) {
482 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
485 rindex = rpipe->pipe_buffer.rindex &
486 (rpipe->pipe_buffer.size - 1);
488 if (nsize > rpipe->pipe_buffer.size - rindex)
489 nsize = rpipe->pipe_buffer.size - rindex;
490 nsize = szmin(nsize, uio->uio_resid);
492 error = uiomove(&rpipe->pipe_buffer.buffer[rindex],
497 rpipe->pipe_buffer.rindex += nsize;
501 * If the FIFO is still over half full just continue
502 * and do not try to notify the writer yet.
504 if (size - nsize >= (rpipe->pipe_buffer.size >> 1)) {
510 * When the FIFO is less then half full notify any
511 * waiting writer. WANTW can be checked while
512 * holding just the rlock.
515 if ((rpipe->pipe_state & PIPE_WANTW) == 0)
520 * If the "write-side" was blocked we wake it up. This code
521 * is reached either when the buffer is completely emptied
522 * or if it becomes more then half-empty.
524 * Pipe_state can only be modified if both the rlock and
527 if (rpipe->pipe_state & PIPE_WANTW) {
528 lwkt_gettoken(&wlock, &rpipe->pipe_wlock);
529 if (rpipe->pipe_state & PIPE_WANTW) {
531 rpipe->pipe_state &= ~PIPE_WANTW;
532 lwkt_reltoken(&wlock);
535 lwkt_reltoken(&wlock);
540 * Pick up our copy loop again if the writer sent data to
541 * us while we were messing around.
543 * On a SMP box poll up to pipe_delay nanoseconds for new
544 * data. Typically a value of 2000 to 4000 is sufficient
545 * to eradicate most IPIs/tsleeps/wakeups when a pipe
546 * is used for synchronous communications with small packets,
547 * and 8000 or so (8uS) will pipeline large buffer xfers
548 * between cpus over a pipe.
550 * For synchronous communications a hit means doing a
551 * full Awrite-Bread-Bwrite-Aread cycle in less then 2uS,
552 * where as miss requiring a tsleep/wakeup sequence
553 * will take 7uS or more.
555 if (rpipe->pipe_buffer.windex != rpipe->pipe_buffer.rindex)
558 #if defined(SMP) && defined(_RDTSC_SUPPORTED_)
563 tsc_target = tsc_get_target(pipe_delay);
564 while (tsc_test_target(tsc_target) == 0) {
565 if (rpipe->pipe_buffer.windex !=
566 rpipe->pipe_buffer.rindex) {
577 * Detect EOF condition, do not set error.
579 if (rpipe->pipe_state & PIPE_REOF)
583 * Break if some data was read, or if this was a non-blocking
595 * Last chance, interlock with WANTR.
597 lwkt_gettoken(&wlock, &rpipe->pipe_wlock);
598 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
600 lwkt_reltoken(&wlock);
605 * Retest EOF - acquiring a new token can temporarily release
606 * tokens already held.
608 if (rpipe->pipe_state & PIPE_REOF) {
609 lwkt_reltoken(&wlock);
614 * If there is no more to read in the pipe, reset its
615 * pointers to the beginning. This improves cache hit
618 * We need both locks to modify both pointers, and there
619 * must also not be a write in progress or the uiomove()
620 * in the write might block and temporarily release
621 * its wlock, then reacquire and update windex. We are
622 * only serialized against reads, not writes.
624 * XXX should we even bother resetting the indices? It
625 * might actually be more cache efficient not to.
627 if (rpipe->pipe_buffer.rindex == rpipe->pipe_buffer.windex &&
628 rpipe->pipe_wip == 0) {
629 rpipe->pipe_buffer.rindex = 0;
630 rpipe->pipe_buffer.windex = 0;
634 * Wait for more data.
636 * Pipe_state can only be set if both the rlock and wlock
639 rpipe->pipe_state |= PIPE_WANTR;
640 tsleep_interlock(rpipe, PCATCH);
641 lwkt_reltoken(&wlock);
642 error = tsleep(rpipe, PCATCH | PINTERLOCKED, "piperd", 0);
643 ++pipe_rblocked_count;
647 pipe_end_uio(rpipe, &rpipe->pipe_rip);
650 * Uptime last access time
652 if (error == 0 && nread)
653 vfs_timestamp(&rpipe->pipe_atime);
656 * If we drained the FIFO more then half way then handle
657 * write blocking hysteresis.
659 * Note that PIPE_WANTW cannot be set by the writer without
660 * it holding both rlock and wlock, so we can test it
661 * while holding just rlock.
664 if (rpipe->pipe_state & PIPE_WANTW) {
665 lwkt_gettoken(&wlock, &rpipe->pipe_wlock);
666 if (rpipe->pipe_state & PIPE_WANTW) {
667 rpipe->pipe_state &= ~PIPE_WANTW;
668 lwkt_reltoken(&wlock);
671 lwkt_reltoken(&wlock);
674 if (pipeseltest(rpipe)) {
675 lwkt_gettoken(&wlock, &rpipe->pipe_wlock);
676 pipeselwakeup(rpipe);
677 lwkt_reltoken(&wlock);
680 /*size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;*/
681 lwkt_reltoken(&rlock);
683 pipe_rel_mplock(&mpsave);
688 * MPALMOSTSAFE - acquires mplock
691 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
696 struct pipe *wpipe, *rpipe;
706 pipe_get_mplock(&mpsave);
709 * Writes go to the peer. The peer will always exist.
711 rpipe = (struct pipe *) fp->f_data;
712 wpipe = rpipe->pipe_peer;
713 lwkt_gettoken(&wlock, &wpipe->pipe_wlock);
714 if (wpipe->pipe_state & PIPE_WEOF) {
715 pipe_rel_mplock(&mpsave);
716 lwkt_reltoken(&wlock);
721 * Degenerate case (EPIPE takes prec)
723 if (uio->uio_resid == 0) {
724 pipe_rel_mplock(&mpsave);
725 lwkt_reltoken(&wlock);
730 * Writes are serialized (start_uio must be called with wlock)
732 error = pipe_start_uio(wpipe, &wpipe->pipe_wip);
734 pipe_rel_mplock(&mpsave);
735 lwkt_reltoken(&wlock);
739 if (fflags & O_FBLOCKING)
741 else if (fflags & O_FNONBLOCKING)
743 else if (fp->f_flag & O_NONBLOCK)
749 * If it is advantageous to resize the pipe buffer, do
750 * so. We are write-serialized so we can block safely.
752 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) &&
753 (pipe_nbig < pipe_maxbig) &&
754 wpipe->pipe_wantwcnt > 4 &&
755 (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) {
757 * Recheck after lock.
759 lwkt_gettoken(&rlock, &wpipe->pipe_rlock);
760 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) &&
761 (pipe_nbig < pipe_maxbig) &&
762 (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) {
763 atomic_add_int(&pipe_nbig, 1);
764 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
767 atomic_subtract_int(&pipe_nbig, 1);
769 lwkt_reltoken(&rlock);
772 orig_resid = uio->uio_resid;
775 bigwrite = (uio->uio_resid > 10 * 1024 * 1024);
778 while (uio->uio_resid) {
779 if (wpipe->pipe_state & PIPE_WEOF) {
787 if (bigwrite && --bigcount == 0) {
790 if (CURSIG(curthread->td_lwp)) {
796 windex = wpipe->pipe_buffer.windex &
797 (wpipe->pipe_buffer.size - 1);
798 space = wpipe->pipe_buffer.size -
799 (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex);
802 /* Writes of size <= PIPE_BUF must be atomic. */
803 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
807 * Write to fill, read size handles write hysteresis. Also
808 * additional restrictions can cause select-based non-blocking
815 * Transfer size is minimum of uio transfer
816 * and free space in pipe buffer.
818 * Limit each uiocopy to no more then PIPE_SIZE
819 * so we can keep the gravy train going on a
820 * SMP box. This doubles the performance for
821 * write sizes > 16K. Otherwise large writes
822 * wind up doing an inefficient synchronous
825 space = szmin(space, uio->uio_resid);
826 if (space > PIPE_SIZE)
830 * First segment to transfer is minimum of
831 * transfer size and contiguous space in
832 * pipe buffer. If first segment to transfer
833 * is less than the transfer size, we've got
834 * a wraparound in the buffer.
836 segsize = wpipe->pipe_buffer.size - windex;
842 * If this is the first loop and the reader is
843 * blocked, do a preemptive wakeup of the reader.
845 * On SMP the IPI latency plus the wlock interlock
846 * on the reader side is the fastest way to get the
847 * reader going. (The scheduler will hard loop on
850 * NOTE: We can't clear WANTR here without acquiring
851 * the rlock, which we don't want to do here!
853 if ((wpipe->pipe_state & PIPE_WANTR) && pipe_mpsafe > 1)
858 * Transfer segment, which may include a wrap-around.
859 * Update windex to account for both all in one go
860 * so the reader can read() the data atomically.
862 error = uiomove(&wpipe->pipe_buffer.buffer[windex],
864 if (error == 0 && segsize < space) {
865 segsize = space - segsize;
866 error = uiomove(&wpipe->pipe_buffer.buffer[0],
872 wpipe->pipe_buffer.windex += space;
878 * We need both the rlock and the wlock to interlock against
879 * the EOF, WANTW, and size checks, and to modify pipe_state.
881 * These are token locks so we do not have to worry about
884 lwkt_gettoken(&rlock, &wpipe->pipe_rlock);
887 * If the "read-side" has been blocked, wake it up now
888 * and yield to let it drain synchronously rather
891 if (wpipe->pipe_state & PIPE_WANTR) {
892 wpipe->pipe_state &= ~PIPE_WANTR;
897 * don't block on non-blocking I/O
900 lwkt_reltoken(&rlock);
906 * re-test whether we have to block in the writer after
907 * acquiring both locks, in case the reader opened up
910 space = wpipe->pipe_buffer.size -
911 (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex);
913 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
917 * Retest EOF - acquiring a new token can temporarily release
918 * tokens already held.
920 if (wpipe->pipe_state & PIPE_WEOF) {
921 lwkt_reltoken(&rlock);
927 * We have no more space and have something to offer,
928 * wake up select/poll.
931 wpipe->pipe_state |= PIPE_WANTW;
932 ++wpipe->pipe_wantwcnt;
933 pipeselwakeup(wpipe);
934 if (wpipe->pipe_state & PIPE_WANTW)
935 error = tsleep(wpipe, PCATCH, "pipewr", 0);
936 ++pipe_wblocked_count;
938 lwkt_reltoken(&rlock);
941 * Break out if we errored or the read side wants us to go
946 if (wpipe->pipe_state & PIPE_WEOF) {
951 pipe_end_uio(wpipe, &wpipe->pipe_wip);
954 * If we have put any characters in the buffer, we wake up
957 * Both rlock and wlock are required to be able to modify pipe_state.
959 if (wpipe->pipe_buffer.windex != wpipe->pipe_buffer.rindex) {
960 if (wpipe->pipe_state & PIPE_WANTR) {
961 lwkt_gettoken(&rlock, &wpipe->pipe_rlock);
962 if (wpipe->pipe_state & PIPE_WANTR) {
963 wpipe->pipe_state &= ~PIPE_WANTR;
964 lwkt_reltoken(&rlock);
967 lwkt_reltoken(&rlock);
970 if (pipeseltest(wpipe)) {
971 lwkt_gettoken(&rlock, &wpipe->pipe_rlock);
972 pipeselwakeup(wpipe);
973 lwkt_reltoken(&rlock);
978 * Don't return EPIPE if I/O was successful
980 if ((wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex) &&
981 (uio->uio_resid == 0) &&
987 vfs_timestamp(&wpipe->pipe_mtime);
990 * We have something to offer,
991 * wake up select/poll.
993 /*space = wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex;*/
994 lwkt_reltoken(&wlock);
995 pipe_rel_mplock(&mpsave);
1000 * MPALMOSTSAFE - acquires mplock
1002 * we implement a very minimal set of ioctls for compatibility with sockets.
1005 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data,
1006 struct ucred *cred, struct sysmsg *msg)
1014 pipe_get_mplock(&mpsave);
1015 mpipe = (struct pipe *)fp->f_data;
1017 lwkt_gettoken(&rlock, &mpipe->pipe_rlock);
1018 lwkt_gettoken(&wlock, &mpipe->pipe_wlock);
1023 mpipe->pipe_state |= PIPE_ASYNC;
1025 mpipe->pipe_state &= ~PIPE_ASYNC;
1030 *(int *)data = mpipe->pipe_buffer.windex -
1031 mpipe->pipe_buffer.rindex;
1036 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
1040 *(int *)data = fgetown(mpipe->pipe_sigio);
1044 /* This is deprecated, FIOSETOWN should be used instead. */
1046 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
1051 /* This is deprecated, FIOGETOWN should be used instead. */
1052 *(int *)data = -fgetown(mpipe->pipe_sigio);
1059 lwkt_reltoken(&rlock);
1060 lwkt_reltoken(&wlock);
1061 pipe_rel_mplock(&mpsave);
1067 * MPALMOSTSAFE - acquires mplock
1069 * poll for events (helper)
1072 pipe_poll_events(struct pipe *rpipe, struct pipe *wpipe, int events)
1077 if (events & (POLLIN | POLLRDNORM)) {
1078 if ((rpipe->pipe_buffer.windex != rpipe->pipe_buffer.rindex) ||
1079 (rpipe->pipe_state & PIPE_REOF)) {
1080 revents |= events & (POLLIN | POLLRDNORM);
1084 if (events & (POLLOUT | POLLWRNORM)) {
1085 if (wpipe == NULL || (wpipe->pipe_state & PIPE_WEOF)) {
1086 revents |= events & (POLLOUT | POLLWRNORM);
1088 space = wpipe->pipe_buffer.windex -
1089 wpipe->pipe_buffer.rindex;
1090 space = wpipe->pipe_buffer.size - space;
1091 if (space >= PIPE_BUF)
1092 revents |= events & (POLLOUT | POLLWRNORM);
1096 if ((rpipe->pipe_state & PIPE_REOF) ||
1098 (wpipe->pipe_state & PIPE_WEOF)) {
1105 * Poll for events from file pointer.
1108 pipe_poll(struct file *fp, int events, struct ucred *cred)
1110 lwkt_tokref rpipe_rlock;
1111 lwkt_tokref rpipe_wlock;
1112 lwkt_tokref wpipe_rlock;
1113 lwkt_tokref wpipe_wlock;
1119 pipe_get_mplock(&mpsave);
1120 rpipe = (struct pipe *)fp->f_data;
1121 wpipe = rpipe->pipe_peer;
1123 revents = pipe_poll_events(rpipe, wpipe, events);
1125 if (events & (POLLIN | POLLRDNORM)) {
1126 lwkt_gettoken(&rpipe_rlock, &rpipe->pipe_rlock);
1127 lwkt_gettoken(&rpipe_wlock, &rpipe->pipe_wlock);
1129 if (events & (POLLOUT | POLLWRNORM)) {
1130 lwkt_gettoken(&wpipe_rlock, &wpipe->pipe_rlock);
1131 lwkt_gettoken(&wpipe_wlock, &wpipe->pipe_wlock);
1133 revents = pipe_poll_events(rpipe, wpipe, events);
1135 if (events & (POLLIN | POLLRDNORM)) {
1136 selrecord(curthread, &rpipe->pipe_sel);
1137 rpipe->pipe_state |= PIPE_SEL;
1140 if (events & (POLLOUT | POLLWRNORM)) {
1141 selrecord(curthread, &wpipe->pipe_sel);
1142 wpipe->pipe_state |= PIPE_SEL;
1145 if (events & (POLLIN | POLLRDNORM)) {
1146 lwkt_reltoken(&rpipe_rlock);
1147 lwkt_reltoken(&rpipe_wlock);
1149 if (events & (POLLOUT | POLLWRNORM)) {
1150 lwkt_reltoken(&wpipe_rlock);
1151 lwkt_reltoken(&wpipe_wlock);
1154 pipe_rel_mplock(&mpsave);
1162 pipe_stat(struct file *fp, struct stat *ub, struct ucred *cred)
1167 pipe_get_mplock(&mpsave);
1168 pipe = (struct pipe *)fp->f_data;
1170 bzero((caddr_t)ub, sizeof(*ub));
1171 ub->st_mode = S_IFIFO;
1172 ub->st_blksize = pipe->pipe_buffer.size;
1173 ub->st_size = pipe->pipe_buffer.windex - pipe->pipe_buffer.rindex;
1174 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1175 ub->st_atimespec = pipe->pipe_atime;
1176 ub->st_mtimespec = pipe->pipe_mtime;
1177 ub->st_ctimespec = pipe->pipe_ctime;
1179 * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev,
1181 * XXX (st_dev, st_ino) should be unique.
1183 pipe_rel_mplock(&mpsave);
1188 * MPALMOSTSAFE - acquires mplock
1191 pipe_close(struct file *fp)
1196 cpipe = (struct pipe *)fp->f_data;
1197 fp->f_ops = &badfileops;
1199 funsetown(cpipe->pipe_sigio);
1206 * Shutdown one or both directions of a full-duplex pipe.
1208 * MPALMOSTSAFE - acquires mplock
1211 pipe_shutdown(struct file *fp, int how)
1216 lwkt_tokref rpipe_rlock;
1217 lwkt_tokref rpipe_wlock;
1218 lwkt_tokref wpipe_rlock;
1219 lwkt_tokref wpipe_wlock;
1222 pipe_get_mplock(&mpsave);
1223 rpipe = (struct pipe *)fp->f_data;
1224 wpipe = rpipe->pipe_peer;
1227 * We modify pipe_state on both pipes, which means we need
1230 lwkt_gettoken(&rpipe_rlock, &rpipe->pipe_rlock);
1231 lwkt_gettoken(&rpipe_wlock, &rpipe->pipe_wlock);
1232 lwkt_gettoken(&wpipe_rlock, &wpipe->pipe_rlock);
1233 lwkt_gettoken(&wpipe_wlock, &wpipe->pipe_wlock);
1238 rpipe->pipe_state |= PIPE_REOF; /* my reads */
1239 rpipe->pipe_state |= PIPE_WEOF; /* peer writes */
1240 if (rpipe->pipe_state & PIPE_WANTR) {
1241 rpipe->pipe_state &= ~PIPE_WANTR;
1244 if (rpipe->pipe_state & PIPE_WANTW) {
1245 rpipe->pipe_state &= ~PIPE_WANTW;
1253 wpipe->pipe_state |= PIPE_REOF; /* peer reads */
1254 wpipe->pipe_state |= PIPE_WEOF; /* my writes */
1255 if (wpipe->pipe_state & PIPE_WANTR) {
1256 wpipe->pipe_state &= ~PIPE_WANTR;
1259 if (wpipe->pipe_state & PIPE_WANTW) {
1260 wpipe->pipe_state &= ~PIPE_WANTW;
1266 pipeselwakeup(rpipe);
1267 pipeselwakeup(wpipe);
1269 lwkt_reltoken(&rpipe_rlock);
1270 lwkt_reltoken(&rpipe_wlock);
1271 lwkt_reltoken(&wpipe_rlock);
1272 lwkt_reltoken(&wpipe_wlock);
1274 pipe_rel_mplock(&mpsave);
1279 pipe_free_kmem(struct pipe *cpipe)
1281 if (cpipe->pipe_buffer.buffer != NULL) {
1282 if (cpipe->pipe_buffer.size > PIPE_SIZE)
1283 atomic_subtract_int(&pipe_nbig, 1);
1284 kmem_free(&kernel_map,
1285 (vm_offset_t)cpipe->pipe_buffer.buffer,
1286 cpipe->pipe_buffer.size);
1287 cpipe->pipe_buffer.buffer = NULL;
1288 cpipe->pipe_buffer.object = NULL;
1293 * Close the pipe. The slock must be held to interlock against simultanious
1294 * closes. The rlock and wlock must be held to adjust the pipe_state.
1297 pipeclose(struct pipe *cpipe)
1301 lwkt_tokref cpipe_rlock;
1302 lwkt_tokref cpipe_wlock;
1303 lwkt_tokref ppipe_rlock;
1304 lwkt_tokref ppipe_wlock;
1310 * The slock may not have been allocated yet (close during
1313 * We need both the read and write tokens to modify pipe_state.
1315 if (cpipe->pipe_slock)
1316 lockmgr(cpipe->pipe_slock, LK_EXCLUSIVE);
1317 lwkt_gettoken(&cpipe_rlock, &cpipe->pipe_rlock);
1318 lwkt_gettoken(&cpipe_wlock, &cpipe->pipe_wlock);
1321 * Set our state, wakeup anyone waiting in select, and
1322 * wakeup anyone blocked on our pipe.
1324 cpipe->pipe_state |= PIPE_CLOSED | PIPE_REOF | PIPE_WEOF;
1325 pipeselwakeup(cpipe);
1326 if (cpipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) {
1327 cpipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW);
1332 * Disconnect from peer.
1334 if ((ppipe = cpipe->pipe_peer) != NULL) {
1335 lwkt_gettoken(&ppipe_rlock, &ppipe->pipe_rlock);
1336 lwkt_gettoken(&ppipe_wlock, &ppipe->pipe_wlock);
1337 ppipe->pipe_state |= PIPE_REOF | PIPE_WEOF;
1338 pipeselwakeup(ppipe);
1339 if (ppipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) {
1340 ppipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW);
1343 if (SLIST_FIRST(&ppipe->pipe_sel.si_note)) {
1345 KNOTE(&ppipe->pipe_sel.si_note, 0);
1348 lwkt_reltoken(&ppipe_rlock);
1349 lwkt_reltoken(&ppipe_wlock);
1353 * If the peer is also closed we can free resources for both
1354 * sides, otherwise we leave our side intact to deal with any
1355 * races (since we only have the slock).
1357 if (ppipe && (ppipe->pipe_state & PIPE_CLOSED)) {
1358 cpipe->pipe_peer = NULL;
1359 ppipe->pipe_peer = NULL;
1360 ppipe->pipe_slock = NULL; /* we will free the slock */
1365 lwkt_reltoken(&cpipe_rlock);
1366 lwkt_reltoken(&cpipe_wlock);
1367 if (cpipe->pipe_slock)
1368 lockmgr(cpipe->pipe_slock, LK_RELEASE);
1371 * If we disassociated from our peer we can free resources
1373 if (ppipe == NULL) {
1375 if (cpipe->pipe_slock) {
1376 kfree(cpipe->pipe_slock, M_PIPE);
1377 cpipe->pipe_slock = NULL;
1379 if (gd->gd_pipeqcount >= pipe_maxcache ||
1380 cpipe->pipe_buffer.size != PIPE_SIZE
1382 pipe_free_kmem(cpipe);
1383 kfree(cpipe, M_PIPE);
1385 cpipe->pipe_state = 0;
1386 cpipe->pipe_peer = gd->gd_pipeq;
1387 gd->gd_pipeq = cpipe;
1388 ++gd->gd_pipeqcount;
1394 * MPALMOSTSAFE - acquires mplock
1397 pipe_kqfilter(struct file *fp, struct knote *kn)
1402 cpipe = (struct pipe *)kn->kn_fp->f_data;
1404 switch (kn->kn_filter) {
1406 kn->kn_fop = &pipe_rfiltops;
1409 kn->kn_fop = &pipe_wfiltops;
1410 cpipe = cpipe->pipe_peer;
1411 if (cpipe == NULL) {
1412 /* other end of pipe has been closed */
1420 kn->kn_hook = (caddr_t)cpipe;
1422 SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
1428 filt_pipedetach(struct knote *kn)
1430 struct pipe *cpipe = (struct pipe *)kn->kn_hook;
1432 SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
1437 filt_piperead(struct knote *kn, long hint)
1439 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1441 kn->kn_data = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
1444 if (rpipe->pipe_state & PIPE_REOF) {
1445 kn->kn_flags |= EV_EOF;
1448 return (kn->kn_data > 0);
1453 filt_pipewrite(struct knote *kn, long hint)
1455 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1456 struct pipe *wpipe = rpipe->pipe_peer;
1460 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_WEOF)) {
1462 kn->kn_flags |= EV_EOF;
1465 space = wpipe->pipe_buffer.windex -
1466 wpipe->pipe_buffer.rindex;
1467 space = wpipe->pipe_buffer.size - space;
1468 kn->kn_data = space;
1469 return (kn->kn_data >= PIPE_BUF);