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>
66 #include <machine/cpufunc.h>
69 * interfaces to the outside world
71 static int pipe_read (struct file *fp, struct uio *uio,
72 struct ucred *cred, int flags);
73 static int pipe_write (struct file *fp, struct uio *uio,
74 struct ucred *cred, int flags);
75 static int pipe_close (struct file *fp);
76 static int pipe_shutdown (struct file *fp, int how);
77 static int pipe_poll (struct file *fp, int events, struct ucred *cred);
78 static int pipe_kqfilter (struct file *fp, struct knote *kn);
79 static int pipe_stat (struct file *fp, struct stat *sb, struct ucred *cred);
80 static int pipe_ioctl (struct file *fp, u_long cmd, caddr_t data, struct ucred *cred);
82 static struct fileops pipeops = {
84 .fo_write = pipe_write,
85 .fo_ioctl = pipe_ioctl,
87 .fo_kqfilter = pipe_kqfilter,
89 .fo_close = pipe_close,
90 .fo_shutdown = pipe_shutdown
93 static void filt_pipedetach(struct knote *kn);
94 static int filt_piperead(struct knote *kn, long hint);
95 static int filt_pipewrite(struct knote *kn, long hint);
97 static struct filterops pipe_rfiltops =
98 { 1, NULL, filt_pipedetach, filt_piperead };
99 static struct filterops pipe_wfiltops =
100 { 1, NULL, filt_pipedetach, filt_pipewrite };
102 MALLOC_DEFINE(M_PIPE, "pipe", "pipe structures");
105 * Default pipe buffer size(s), this can be kind-of large now because pipe
106 * space is pageable. The pipe code will try to maintain locality of
107 * reference for performance reasons, so small amounts of outstanding I/O
108 * will not wipe the cache.
110 #define MINPIPESIZE (PIPE_SIZE/3)
111 #define MAXPIPESIZE (2*PIPE_SIZE/3)
114 * Limit the number of "big" pipes
116 #define LIMITBIGPIPES 64
117 #define PIPEQ_MAX_CACHE 16 /* per-cpu pipe structure cache */
119 static int pipe_maxbig = LIMITBIGPIPES;
120 static int pipe_maxcache = PIPEQ_MAX_CACHE;
121 static int pipe_bigcount;
122 static int pipe_nbig;
123 static int pipe_bcache_alloc;
124 static int pipe_bkmem_alloc;
125 static int pipe_rblocked_count;
126 static int pipe_wblocked_count;
128 SYSCTL_NODE(_kern, OID_AUTO, pipe, CTLFLAG_RW, 0, "Pipe operation");
129 SYSCTL_INT(_kern_pipe, OID_AUTO, nbig,
130 CTLFLAG_RD, &pipe_nbig, 0, "numer of big pipes allocated");
131 SYSCTL_INT(_kern_pipe, OID_AUTO, bigcount,
132 CTLFLAG_RW, &pipe_bigcount, 0, "number of times pipe expanded");
133 SYSCTL_INT(_kern_pipe, OID_AUTO, rblocked,
134 CTLFLAG_RW, &pipe_rblocked_count, 0, "number of times pipe expanded");
135 SYSCTL_INT(_kern_pipe, OID_AUTO, wblocked,
136 CTLFLAG_RW, &pipe_wblocked_count, 0, "number of times pipe expanded");
137 SYSCTL_INT(_kern_pipe, OID_AUTO, maxcache,
138 CTLFLAG_RW, &pipe_maxcache, 0, "max pipes cached per-cpu");
139 SYSCTL_INT(_kern_pipe, OID_AUTO, maxbig,
140 CTLFLAG_RW, &pipe_maxbig, 0, "max number of big pipes");
142 static int pipe_delay = 5000; /* 5uS default */
143 SYSCTL_INT(_kern_pipe, OID_AUTO, delay,
144 CTLFLAG_RW, &pipe_delay, 0, "SMP delay optimization in ns");
145 static int pipe_mpsafe = 1;
146 SYSCTL_INT(_kern_pipe, OID_AUTO, mpsafe,
147 CTLFLAG_RW, &pipe_mpsafe, 0, "");
149 #if !defined(NO_PIPE_SYSCTL_STATS)
150 SYSCTL_INT(_kern_pipe, OID_AUTO, bcache_alloc,
151 CTLFLAG_RW, &pipe_bcache_alloc, 0, "pipe buffer from pcpu cache");
152 SYSCTL_INT(_kern_pipe, OID_AUTO, bkmem_alloc,
153 CTLFLAG_RW, &pipe_bkmem_alloc, 0, "pipe buffer from kmem");
156 static void pipeclose (struct pipe *cpipe);
157 static void pipe_free_kmem (struct pipe *cpipe);
158 static int pipe_create (struct pipe **cpipep);
159 static __inline void pipeselwakeup (struct pipe *cpipe);
160 static int pipespace (struct pipe *cpipe, int size);
163 pipeselwakeup(struct pipe *cpipe)
165 if (cpipe->pipe_state & PIPE_SEL) {
167 cpipe->pipe_state &= ~PIPE_SEL;
168 selwakeup(&cpipe->pipe_sel);
171 if ((cpipe->pipe_state & PIPE_ASYNC) && cpipe->pipe_sigio) {
173 pgsigio(cpipe->pipe_sigio, SIGIO, 0);
176 if (SLIST_FIRST(&cpipe->pipe_sel.si_note)) {
178 KNOTE(&cpipe->pipe_sel.si_note, 0);
184 * These routines are called before and after a UIO. The UIO
185 * may block, causing our held tokens to be lost temporarily.
187 * We use these routines to serialize reads against other reads
188 * and writes against other writes.
190 * The read token is held on entry so *ipp does not race.
193 pipe_start_uio(struct pipe *cpipe, int *ipp)
199 error = tsleep(ipp, PCATCH, "pipexx", 0);
208 pipe_end_uio(struct pipe *cpipe, int *ipp)
220 pipe_get_mplock(int *save)
223 if (pipe_mpsafe == 0) {
234 pipe_rel_mplock(int *save)
244 * The pipe system call for the DTYPE_PIPE type of pipes
246 * pipe_ARgs(int dummy)
251 sys_pipe(struct pipe_args *uap)
253 struct thread *td = curthread;
254 struct proc *p = td->td_proc;
255 struct file *rf, *wf;
256 struct pipe *rpipe, *wpipe;
261 rpipe = wpipe = NULL;
262 if (pipe_create(&rpipe) || pipe_create(&wpipe)) {
268 error = falloc(p, &rf, &fd1);
274 uap->sysmsg_fds[0] = fd1;
277 * Warning: once we've gotten past allocation of the fd for the
278 * read-side, we can only drop the read side via fdrop() in order
279 * to avoid races against processes which manage to dup() the read
280 * side while we are blocked trying to allocate the write side.
282 rf->f_type = DTYPE_PIPE;
283 rf->f_flag = FREAD | FWRITE;
284 rf->f_ops = &pipeops;
286 error = falloc(p, &wf, &fd2);
288 fsetfd(p, NULL, fd1);
290 /* rpipe has been closed by fdrop(). */
294 wf->f_type = DTYPE_PIPE;
295 wf->f_flag = FREAD | FWRITE;
296 wf->f_ops = &pipeops;
298 uap->sysmsg_fds[1] = fd2;
300 rpipe->pipe_slock = kmalloc(sizeof(struct lock),
301 M_PIPE, M_WAITOK|M_ZERO);
302 wpipe->pipe_slock = rpipe->pipe_slock;
303 rpipe->pipe_peer = wpipe;
304 wpipe->pipe_peer = rpipe;
305 lockinit(rpipe->pipe_slock, "pipecl", 0, 0);
308 * Once activated the peer relationship remains valid until
309 * both sides are closed.
320 * Allocate kva for pipe circular buffer, the space is pageable
321 * This routine will 'realloc' the size of a pipe safely, if it fails
322 * it will retain the old buffer.
323 * If it fails it will return ENOMEM.
326 pipespace(struct pipe *cpipe, int size)
328 struct vm_object *object;
332 npages = round_page(size) / PAGE_SIZE;
333 object = cpipe->pipe_buffer.object;
336 * [re]create the object if necessary and reserve space for it
337 * in the kernel_map. The object and memory are pageable. On
338 * success, free the old resources before assigning the new
341 if (object == NULL || object->size != npages) {
343 object = vm_object_allocate(OBJT_DEFAULT, npages);
344 buffer = (caddr_t)vm_map_min(&kernel_map);
346 error = vm_map_find(&kernel_map, object, 0,
347 (vm_offset_t *)&buffer, size,
350 VM_PROT_ALL, VM_PROT_ALL,
353 if (error != KERN_SUCCESS) {
354 vm_object_deallocate(object);
358 pipe_free_kmem(cpipe);
360 cpipe->pipe_buffer.object = object;
361 cpipe->pipe_buffer.buffer = buffer;
362 cpipe->pipe_buffer.size = size;
367 cpipe->pipe_buffer.rindex = 0;
368 cpipe->pipe_buffer.windex = 0;
373 * Initialize and allocate VM and memory for pipe, pulling the pipe from
374 * our per-cpu cache if possible. For now make sure it is sized for the
375 * smaller PIPE_SIZE default.
378 pipe_create(struct pipe **cpipep)
380 globaldata_t gd = mycpu;
384 if ((cpipe = gd->gd_pipeq) != NULL) {
385 gd->gd_pipeq = cpipe->pipe_peer;
387 cpipe->pipe_peer = NULL;
388 cpipe->pipe_wantwcnt = 0;
390 cpipe = kmalloc(sizeof(struct pipe), M_PIPE, M_WAITOK|M_ZERO);
393 if ((error = pipespace(cpipe, PIPE_SIZE)) != 0)
395 vfs_timestamp(&cpipe->pipe_ctime);
396 cpipe->pipe_atime = cpipe->pipe_ctime;
397 cpipe->pipe_mtime = cpipe->pipe_ctime;
398 lwkt_token_init(&cpipe->pipe_rlock);
399 lwkt_token_init(&cpipe->pipe_wlock);
404 * MPALMOSTSAFE (acquires mplock)
407 pipe_read(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
414 u_int size; /* total bytes available */
415 u_int nsize; /* total bytes to read */
416 u_int rindex; /* contiguous bytes available */
425 orig_resid = uio->uio_resid;
430 * Setup locks, calculate nbio
432 pipe_get_mplock(&mpsave);
433 rpipe = (struct pipe *)fp->f_data;
434 lwkt_gettoken(&rlock, &rpipe->pipe_rlock);
436 if (fflags & O_FBLOCKING)
438 else if (fflags & O_FNONBLOCKING)
440 else if (fp->f_flag & O_NONBLOCK)
446 * Reads are serialized. Note howeverthat pipe_buffer.buffer and
447 * pipe_buffer.size can change out from under us when the number
448 * of bytes in the buffer are zero due to the write-side doing a
451 error = pipe_start_uio(rpipe, &rpipe->pipe_rip);
453 pipe_rel_mplock(&mpsave);
454 lwkt_reltoken(&rlock);
458 while (uio->uio_resid) {
459 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
462 rindex = rpipe->pipe_buffer.rindex &
463 (rpipe->pipe_buffer.size - 1);
465 if (nsize > rpipe->pipe_buffer.size - rindex)
466 nsize = rpipe->pipe_buffer.size - rindex;
467 if (nsize > (u_int)uio->uio_resid)
468 nsize = (u_int)uio->uio_resid;
470 error = uiomove(&rpipe->pipe_buffer.buffer[rindex],
475 rpipe->pipe_buffer.rindex += nsize;
479 * If the FIFO is still over half full just continue
480 * and do not try to notify the writer yet.
482 if (size - nsize >= (rpipe->pipe_buffer.size >> 1)) {
488 * When the FIFO is less then half full notify any
489 * waiting writer. WANTW can be checked while
490 * holding just the rlock.
493 if ((rpipe->pipe_state & PIPE_WANTW) == 0)
498 * If the "write-side" was blocked we wake it up. This code
499 * is reached either when the buffer is completely emptied
500 * or if it becomes more then half-empty.
502 * Pipe_state can only be modified if both the rlock and
505 if (rpipe->pipe_state & PIPE_WANTW) {
506 lwkt_gettoken(&wlock, &rpipe->pipe_wlock);
507 if (rpipe->pipe_state & PIPE_WANTW) {
509 rpipe->pipe_state &= ~PIPE_WANTW;
510 lwkt_reltoken(&wlock);
513 lwkt_reltoken(&wlock);
518 * Pick up our copy loop again if the writer sent data to
519 * us while we were messing around.
521 * On a SMP box poll up to pipe_delay nanoseconds for new
522 * data. Typically a value of 2000 to 4000 is sufficient
523 * to eradicate most IPIs/tsleeps/wakeups when a pipe
524 * is used for synchronous communications with small packets,
525 * and 8000 or so (8uS) will pipeline large buffer xfers
526 * between cpus over a pipe.
528 * For synchronous communications a hit means doing a
529 * full Awrite-Bread-Bwrite-Aread cycle in less then 2uS,
530 * where as miss requiring a tsleep/wakeup sequence
531 * will take 7uS or more.
533 if (rpipe->pipe_buffer.windex != rpipe->pipe_buffer.rindex)
536 #if defined(SMP) && defined(_RDTSC_SUPPORTED_)
541 tsc_target = tsc_get_target(pipe_delay);
542 while (tsc_test_target(tsc_target) == 0) {
543 if (rpipe->pipe_buffer.windex !=
544 rpipe->pipe_buffer.rindex) {
555 * Detect EOF condition, do not set error.
557 if (rpipe->pipe_state & PIPE_REOF)
561 * Break if some data was read, or if this was a non-blocking
573 * Last chance, interlock with WANTR.
575 lwkt_gettoken(&wlock, &rpipe->pipe_wlock);
576 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
578 lwkt_reltoken(&wlock);
583 * If there is no more to read in the pipe, reset its
584 * pointers to the beginning. This improves cache hit
587 * We need both locks to modify both pointers, and there
588 * must also not be a write in progress or the uiomove()
589 * in the write might block and temporarily release
590 * its wlock, then reacquire and update windex. We are
591 * only serialized against reads, not writes.
593 * XXX should we even bother resetting the indices? It
594 * might actually be more cache efficient not to.
596 if (rpipe->pipe_buffer.rindex == rpipe->pipe_buffer.windex &&
597 rpipe->pipe_wip == 0) {
598 rpipe->pipe_buffer.rindex = 0;
599 rpipe->pipe_buffer.windex = 0;
603 * Wait for more data.
605 * Pipe_state can only be set if both the rlock and wlock
608 rpipe->pipe_state |= PIPE_WANTR;
609 tsleep_interlock(rpipe, PCATCH);
610 lwkt_reltoken(&wlock);
611 error = tsleep(rpipe, PCATCH | PINTERLOCKED, "piperd", 0);
612 ++pipe_rblocked_count;
616 pipe_end_uio(rpipe, &rpipe->pipe_rip);
619 * Uptime last access time
621 if (error == 0 && nread)
622 vfs_timestamp(&rpipe->pipe_atime);
625 * If we drained the FIFO more then half way then handle
626 * write blocking hysteresis.
628 * Note that PIPE_WANTW cannot be set by the writer without
629 * it holding both rlock and wlock, so we can test it
630 * while holding just rlock.
633 if (rpipe->pipe_state & PIPE_WANTW) {
634 lwkt_gettoken(&wlock, &rpipe->pipe_wlock);
635 if (rpipe->pipe_state & PIPE_WANTW) {
636 rpipe->pipe_state &= ~PIPE_WANTW;
637 lwkt_reltoken(&wlock);
640 lwkt_reltoken(&wlock);
644 size = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
645 lwkt_reltoken(&rlock);
648 * If enough space is available in buffer then wakeup sel writers?
650 if ((rpipe->pipe_buffer.size - size) >= PIPE_BUF)
651 pipeselwakeup(rpipe);
652 pipe_rel_mplock(&mpsave);
657 * MPALMOSTSAFE - acquires mplock
660 pipe_write(struct file *fp, struct uio *uio, struct ucred *cred, int fflags)
665 struct pipe *wpipe, *rpipe;
673 pipe_get_mplock(&mpsave);
676 * Writes go to the peer. The peer will always exist.
678 rpipe = (struct pipe *) fp->f_data;
679 wpipe = rpipe->pipe_peer;
680 lwkt_gettoken(&wlock, &wpipe->pipe_wlock);
681 if (wpipe->pipe_state & PIPE_WEOF) {
682 pipe_rel_mplock(&mpsave);
683 lwkt_reltoken(&wlock);
688 * Degenerate case (EPIPE takes prec)
690 if (uio->uio_resid == 0) {
691 pipe_rel_mplock(&mpsave);
692 lwkt_reltoken(&wlock);
697 * Writes are serialized (start_uio must be called with wlock)
699 error = pipe_start_uio(wpipe, &wpipe->pipe_wip);
701 pipe_rel_mplock(&mpsave);
702 lwkt_reltoken(&wlock);
706 if (fflags & O_FBLOCKING)
708 else if (fflags & O_FNONBLOCKING)
710 else if (fp->f_flag & O_NONBLOCK)
716 * If it is advantageous to resize the pipe buffer, do
717 * so. We are write-serialized so we can block safely.
719 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) &&
720 (pipe_nbig < pipe_maxbig) &&
721 wpipe->pipe_wantwcnt > 4 &&
722 (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) {
724 * Recheck after lock.
726 lwkt_gettoken(&rlock, &wpipe->pipe_rlock);
727 if ((wpipe->pipe_buffer.size <= PIPE_SIZE) &&
728 (pipe_nbig < pipe_maxbig) &&
729 (wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex)) {
730 atomic_add_int(&pipe_nbig, 1);
731 if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
734 atomic_subtract_int(&pipe_nbig, 1);
736 lwkt_reltoken(&rlock);
739 orig_resid = uio->uio_resid;
742 while (uio->uio_resid) {
743 if (wpipe->pipe_state & PIPE_WEOF) {
748 windex = wpipe->pipe_buffer.windex &
749 (wpipe->pipe_buffer.size - 1);
750 space = wpipe->pipe_buffer.size -
751 (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex);
754 /* Writes of size <= PIPE_BUF must be atomic. */
755 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
759 * Write to fill, read size handles write hysteresis. Also
760 * additional restrictions can cause select-based non-blocking
767 * Transfer size is minimum of uio transfer
768 * and free space in pipe buffer.
770 * Limit each uiocopy to no more then PIPE_SIZE
771 * so we can keep the gravy train going on a
772 * SMP box. This doubles the performance for
773 * write sizes > 16K. Otherwise large writes
774 * wind up doing an inefficient synchronous
777 if (space > (u_int)uio->uio_resid)
778 space = (u_int)uio->uio_resid;
779 if (space > PIPE_SIZE)
783 * First segment to transfer is minimum of
784 * transfer size and contiguous space in
785 * pipe buffer. If first segment to transfer
786 * is less than the transfer size, we've got
787 * a wraparound in the buffer.
789 segsize = wpipe->pipe_buffer.size - windex;
795 * If this is the first loop and the reader is
796 * blocked, do a preemptive wakeup of the reader.
798 * On SMP the IPI latency plus the wlock interlock
799 * on the reader side is the fastest way to get the
800 * reader going. (The scheduler will hard loop on
803 * NOTE: We can't clear WANTR here without acquiring
804 * the rlock, which we don't want to do here!
806 if ((wpipe->pipe_state & PIPE_WANTR) && pipe_mpsafe > 1)
811 * Transfer segment, which may include a wrap-around.
812 * Update windex to account for both all in one go
813 * so the reader can read() the data atomically.
815 error = uiomove(&wpipe->pipe_buffer.buffer[windex],
817 if (error == 0 && segsize < space) {
818 segsize = space - segsize;
819 error = uiomove(&wpipe->pipe_buffer.buffer[0],
825 wpipe->pipe_buffer.windex += space;
831 * We need both the rlock and the wlock to interlock against
832 * the EOF, WANTW, and size checks, and to modify pipe_state.
834 * These are token locks so we do not have to worry about
837 lwkt_gettoken(&rlock, &wpipe->pipe_rlock);
840 * If the "read-side" has been blocked, wake it up now
841 * and yield to let it drain synchronously rather
844 if (wpipe->pipe_state & PIPE_WANTR) {
845 wpipe->pipe_state &= ~PIPE_WANTR;
850 * don't block on non-blocking I/O
853 lwkt_reltoken(&rlock);
859 * re-test whether we have to block in the writer after
860 * acquiring both locks, in case the reader opened up
863 space = wpipe->pipe_buffer.size -
864 (wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex);
866 if ((space < uio->uio_resid) && (orig_resid <= PIPE_BUF))
870 * We have no more space and have something to offer,
871 * wake up select/poll.
874 wpipe->pipe_state |= PIPE_WANTW;
875 ++wpipe->pipe_wantwcnt;
876 pipeselwakeup(wpipe);
877 if (wpipe->pipe_state & PIPE_WANTW)
878 error = tsleep(wpipe, PCATCH, "pipewr", 0);
879 ++pipe_wblocked_count;
881 lwkt_reltoken(&rlock);
884 * Break out if we errored or the read side wants us to go
889 if (wpipe->pipe_state & PIPE_WEOF) {
894 pipe_end_uio(wpipe, &wpipe->pipe_wip);
897 * If we have put any characters in the buffer, we wake up
900 * Both rlock and wlock are required to be able to modify pipe_state.
902 if (wpipe->pipe_buffer.windex != wpipe->pipe_buffer.rindex) {
903 if (wpipe->pipe_state & PIPE_WANTR) {
904 lwkt_gettoken(&rlock, &wpipe->pipe_rlock);
905 if (wpipe->pipe_state & PIPE_WANTR) {
906 wpipe->pipe_state &= ~PIPE_WANTR;
907 lwkt_reltoken(&rlock);
910 lwkt_reltoken(&rlock);
916 * Don't return EPIPE if I/O was successful
918 if ((wpipe->pipe_buffer.rindex == wpipe->pipe_buffer.windex) &&
919 (uio->uio_resid == 0) &&
925 vfs_timestamp(&wpipe->pipe_mtime);
928 * We have something to offer,
929 * wake up select/poll.
931 space = wpipe->pipe_buffer.windex - wpipe->pipe_buffer.rindex;
932 lwkt_reltoken(&wlock);
934 pipeselwakeup(wpipe);
935 pipe_rel_mplock(&mpsave);
940 * MPALMOSTSAFE - acquires mplock
942 * we implement a very minimal set of ioctls for compatibility with sockets.
945 pipe_ioctl(struct file *fp, u_long cmd, caddr_t data, struct ucred *cred)
953 pipe_get_mplock(&mpsave);
954 mpipe = (struct pipe *)fp->f_data;
956 lwkt_gettoken(&rlock, &mpipe->pipe_rlock);
957 lwkt_gettoken(&wlock, &mpipe->pipe_wlock);
962 mpipe->pipe_state |= PIPE_ASYNC;
964 mpipe->pipe_state &= ~PIPE_ASYNC;
969 *(int *)data = mpipe->pipe_buffer.windex -
970 mpipe->pipe_buffer.rindex;
975 error = fsetown(*(int *)data, &mpipe->pipe_sigio);
979 *(int *)data = fgetown(mpipe->pipe_sigio);
983 /* This is deprecated, FIOSETOWN should be used instead. */
985 error = fsetown(-(*(int *)data), &mpipe->pipe_sigio);
990 /* This is deprecated, FIOGETOWN should be used instead. */
991 *(int *)data = -fgetown(mpipe->pipe_sigio);
998 lwkt_reltoken(&rlock);
999 lwkt_reltoken(&wlock);
1000 pipe_rel_mplock(&mpsave);
1006 * MPALMOSTSAFE - acquires mplock
1009 pipe_poll(struct file *fp, int events, struct ucred *cred)
1017 pipe_get_mplock(&mpsave);
1018 rpipe = (struct pipe *)fp->f_data;
1019 wpipe = rpipe->pipe_peer;
1020 if (events & (POLLIN | POLLRDNORM)) {
1021 if ((rpipe->pipe_buffer.windex != rpipe->pipe_buffer.rindex) ||
1022 (rpipe->pipe_state & PIPE_REOF)) {
1023 revents |= events & (POLLIN | POLLRDNORM);
1027 if (events & (POLLOUT | POLLWRNORM)) {
1028 if (wpipe == NULL || (wpipe->pipe_state & PIPE_WEOF)) {
1029 revents |= events & (POLLOUT | POLLWRNORM);
1031 space = wpipe->pipe_buffer.windex -
1032 wpipe->pipe_buffer.rindex;
1033 space = wpipe->pipe_buffer.size - space;
1034 if (space >= PIPE_BUF)
1035 revents |= events & (POLLOUT | POLLWRNORM);
1039 if ((rpipe->pipe_state & PIPE_REOF) ||
1041 (wpipe->pipe_state & PIPE_WEOF))
1045 if (events & (POLLIN | POLLRDNORM)) {
1046 selrecord(curthread, &rpipe->pipe_sel);
1047 rpipe->pipe_state |= PIPE_SEL;
1050 if (events & (POLLOUT | POLLWRNORM)) {
1051 selrecord(curthread, &wpipe->pipe_sel);
1052 wpipe->pipe_state |= PIPE_SEL;
1055 pipe_rel_mplock(&mpsave);
1063 pipe_stat(struct file *fp, struct stat *ub, struct ucred *cred)
1068 pipe_get_mplock(&mpsave);
1069 pipe = (struct pipe *)fp->f_data;
1071 bzero((caddr_t)ub, sizeof(*ub));
1072 ub->st_mode = S_IFIFO;
1073 ub->st_blksize = pipe->pipe_buffer.size;
1074 ub->st_size = pipe->pipe_buffer.windex - pipe->pipe_buffer.rindex;
1075 ub->st_blocks = (ub->st_size + ub->st_blksize - 1) / ub->st_blksize;
1076 ub->st_atimespec = pipe->pipe_atime;
1077 ub->st_mtimespec = pipe->pipe_mtime;
1078 ub->st_ctimespec = pipe->pipe_ctime;
1080 * Left as 0: st_dev, st_ino, st_nlink, st_uid, st_gid, st_rdev,
1082 * XXX (st_dev, st_ino) should be unique.
1084 pipe_rel_mplock(&mpsave);
1089 * MPALMOSTSAFE - acquires mplock
1092 pipe_close(struct file *fp)
1097 cpipe = (struct pipe *)fp->f_data;
1098 fp->f_ops = &badfileops;
1100 funsetown(cpipe->pipe_sigio);
1107 * Shutdown one or both directions of a full-duplex pipe.
1109 * MPALMOSTSAFE - acquires mplock
1112 pipe_shutdown(struct file *fp, int how)
1117 lwkt_tokref rpipe_rlock;
1118 lwkt_tokref rpipe_wlock;
1119 lwkt_tokref wpipe_rlock;
1120 lwkt_tokref wpipe_wlock;
1123 pipe_get_mplock(&mpsave);
1124 rpipe = (struct pipe *)fp->f_data;
1125 wpipe = rpipe->pipe_peer;
1128 * We modify pipe_state on both pipes, which means we need
1131 lwkt_gettoken(&rpipe_rlock, &rpipe->pipe_rlock);
1132 lwkt_gettoken(&rpipe_wlock, &rpipe->pipe_wlock);
1133 lwkt_gettoken(&wpipe_rlock, &wpipe->pipe_rlock);
1134 lwkt_gettoken(&wpipe_wlock, &wpipe->pipe_wlock);
1139 rpipe->pipe_state |= PIPE_REOF; /* my reads */
1140 rpipe->pipe_state |= PIPE_WEOF; /* peer writes */
1141 if (rpipe->pipe_state & PIPE_WANTR) {
1142 rpipe->pipe_state &= ~PIPE_WANTR;
1145 if (rpipe->pipe_state & PIPE_WANTW) {
1146 rpipe->pipe_state &= ~PIPE_WANTW;
1154 wpipe->pipe_state |= PIPE_REOF; /* peer reads */
1155 wpipe->pipe_state |= PIPE_WEOF; /* my writes */
1156 if (wpipe->pipe_state & PIPE_WANTR) {
1157 wpipe->pipe_state &= ~PIPE_WANTR;
1160 if (wpipe->pipe_state & PIPE_WANTW) {
1161 wpipe->pipe_state &= ~PIPE_WANTW;
1167 pipeselwakeup(rpipe);
1168 pipeselwakeup(wpipe);
1170 lwkt_reltoken(&rpipe_rlock);
1171 lwkt_reltoken(&rpipe_wlock);
1172 lwkt_reltoken(&wpipe_rlock);
1173 lwkt_reltoken(&wpipe_wlock);
1175 pipe_rel_mplock(&mpsave);
1180 pipe_free_kmem(struct pipe *cpipe)
1182 if (cpipe->pipe_buffer.buffer != NULL) {
1183 if (cpipe->pipe_buffer.size > PIPE_SIZE)
1184 atomic_subtract_int(&pipe_nbig, 1);
1185 kmem_free(&kernel_map,
1186 (vm_offset_t)cpipe->pipe_buffer.buffer,
1187 cpipe->pipe_buffer.size);
1188 cpipe->pipe_buffer.buffer = NULL;
1189 cpipe->pipe_buffer.object = NULL;
1194 * Close the pipe. The slock must be held to interlock against simultanious
1195 * closes. The rlock and wlock must be held to adjust the pipe_state.
1198 pipeclose(struct pipe *cpipe)
1202 lwkt_tokref cpipe_rlock;
1203 lwkt_tokref cpipe_wlock;
1204 lwkt_tokref ppipe_rlock;
1205 lwkt_tokref ppipe_wlock;
1211 * The slock may not have been allocated yet (close during
1214 * We need both the read and write tokens to modify pipe_state.
1216 if (cpipe->pipe_slock)
1217 lockmgr(cpipe->pipe_slock, LK_EXCLUSIVE);
1218 lwkt_gettoken(&cpipe_rlock, &cpipe->pipe_rlock);
1219 lwkt_gettoken(&cpipe_wlock, &cpipe->pipe_wlock);
1222 * Set our state, wakeup anyone waiting in select, and
1223 * wakeup anyone blocked on our pipe.
1225 cpipe->pipe_state |= PIPE_CLOSED | PIPE_REOF | PIPE_WEOF;
1226 pipeselwakeup(cpipe);
1227 if (cpipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) {
1228 cpipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW);
1233 * Disconnect from peer.
1235 if ((ppipe = cpipe->pipe_peer) != NULL) {
1236 lwkt_gettoken(&ppipe_rlock, &ppipe->pipe_rlock);
1237 lwkt_gettoken(&ppipe_wlock, &ppipe->pipe_wlock);
1238 ppipe->pipe_state |= PIPE_REOF | PIPE_WEOF;
1239 pipeselwakeup(ppipe);
1240 if (ppipe->pipe_state & (PIPE_WANTR | PIPE_WANTW)) {
1241 ppipe->pipe_state &= ~(PIPE_WANTR | PIPE_WANTW);
1244 if (SLIST_FIRST(&ppipe->pipe_sel.si_note)) {
1246 KNOTE(&ppipe->pipe_sel.si_note, 0);
1249 lwkt_reltoken(&ppipe_rlock);
1250 lwkt_reltoken(&ppipe_wlock);
1254 * If the peer is also closed we can free resources for both
1255 * sides, otherwise we leave our side intact to deal with any
1256 * races (since we only have the slock).
1258 if (ppipe && (ppipe->pipe_state & PIPE_CLOSED)) {
1259 cpipe->pipe_peer = NULL;
1260 ppipe->pipe_peer = NULL;
1261 ppipe->pipe_slock = NULL; /* we will free the slock */
1266 lwkt_reltoken(&cpipe_rlock);
1267 lwkt_reltoken(&cpipe_wlock);
1268 if (cpipe->pipe_slock)
1269 lockmgr(cpipe->pipe_slock, LK_RELEASE);
1272 * If we disassociated from our peer we can free resources
1274 if (ppipe == NULL) {
1276 if (cpipe->pipe_slock) {
1277 kfree(cpipe->pipe_slock, M_PIPE);
1278 cpipe->pipe_slock = NULL;
1280 if (gd->gd_pipeqcount >= pipe_maxcache ||
1281 cpipe->pipe_buffer.size != PIPE_SIZE
1283 pipe_free_kmem(cpipe);
1284 kfree(cpipe, M_PIPE);
1286 cpipe->pipe_state = 0;
1287 cpipe->pipe_peer = gd->gd_pipeq;
1288 gd->gd_pipeq = cpipe;
1289 ++gd->gd_pipeqcount;
1295 * MPALMOSTSAFE - acquires mplock
1298 pipe_kqfilter(struct file *fp, struct knote *kn)
1303 cpipe = (struct pipe *)kn->kn_fp->f_data;
1305 switch (kn->kn_filter) {
1307 kn->kn_fop = &pipe_rfiltops;
1310 kn->kn_fop = &pipe_wfiltops;
1311 cpipe = cpipe->pipe_peer;
1312 if (cpipe == NULL) {
1313 /* other end of pipe has been closed */
1321 kn->kn_hook = (caddr_t)cpipe;
1323 SLIST_INSERT_HEAD(&cpipe->pipe_sel.si_note, kn, kn_selnext);
1329 filt_pipedetach(struct knote *kn)
1331 struct pipe *cpipe = (struct pipe *)kn->kn_hook;
1333 SLIST_REMOVE(&cpipe->pipe_sel.si_note, kn, knote, kn_selnext);
1338 filt_piperead(struct knote *kn, long hint)
1340 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1342 kn->kn_data = rpipe->pipe_buffer.windex - rpipe->pipe_buffer.rindex;
1345 if (rpipe->pipe_state & PIPE_REOF) {
1346 kn->kn_flags |= EV_EOF;
1349 return (kn->kn_data > 0);
1354 filt_pipewrite(struct knote *kn, long hint)
1356 struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
1357 struct pipe *wpipe = rpipe->pipe_peer;
1361 if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_WEOF)) {
1363 kn->kn_flags |= EV_EOF;
1366 space = wpipe->pipe_buffer.windex -
1367 wpipe->pipe_buffer.rindex;
1368 space = wpipe->pipe_buffer.size - space;
1369 kn->kn_data = space;
1370 return (kn->kn_data >= PIPE_BUF);