/* $NetBSD: sys_pipe.c,v 1.38 2003/03/21 21:13:51 dsl Exp $ */ /*- * Copyright (c) 2003 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Paul Kranenburg. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 1996 John S. Dyson * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice immediately at the beginning of the file, without modification, * this list of conditions, and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Absolutely no warranty of function or purpose is made by the author * John S. Dyson. * 4. Modifications may be freely made to this file if the above conditions * are met. * * $FreeBSD: src/sys/kern/sys_pipe.c,v 1.95 2002/03/09 22:06:31 alfred Exp $ */ /* * This file contains a high-performance replacement for the socket-based * pipes scheme originally used in FreeBSD/4.4Lite. It does not support * all features of sockets, but does do everything that pipes normally * do. * * Adaption for NetBSD UVM, including uvm_loan() based direct write, was * written by Jaromir Dolecek. */ /* * This code has two modes of operation, a small write mode and a large * write mode. The small write mode acts like conventional pipes with * a kernel buffer. If the buffer is less than PIPE_MINDIRECT, then the * "normal" pipe buffering is done. If the buffer is between PIPE_MINDIRECT * and PIPE_SIZE in size it is mapped read-only into the kernel address space * using the UVM page loan facility from where the receiving process can copy * the data directly from the pages in the sending process. * * The constant PIPE_MINDIRECT is chosen to make sure that buffering will * happen for small transfers so that the system will not spend all of * its time context switching. PIPE_SIZE is constrained by the * amount of kernel virtual memory. */ #include __KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.38 2003/03/21 21:13:51 dsl Exp $"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Avoid microtime(9), it's slow. We don't guard the read from time(9) * with splclock(9) since we don't actually need to be THAT sure the access * is atomic. */ #define PIPE_TIMESTAMP(tvp) (*(tvp) = time) /* * Use this define if you want to disable *fancy* VM things. Expect an * approx 30% decrease in transfer rate. */ /* #define PIPE_NODIRECT */ /* * interfaces to the outside world */ static int pipe_read(struct file *fp, off_t *offset, struct uio *uio, struct ucred *cred, int flags); static int pipe_write(struct file *fp, off_t *offset, struct uio *uio, struct ucred *cred, int flags); static int pipe_close(struct file *fp, struct proc *p); static int pipe_poll(struct file *fp, int events, struct proc *p); static int pipe_fcntl(struct file *fp, u_int com, void *data, struct proc *p); static int pipe_kqfilter(struct file *fp, struct knote *kn); static int pipe_stat(struct file *fp, struct stat *sb, struct proc *p); static int pipe_ioctl(struct file *fp, u_long cmd, void *data, struct proc *p); static struct fileops pipeops = { pipe_read, pipe_write, pipe_ioctl, pipe_fcntl, pipe_poll, pipe_stat, pipe_close, pipe_kqfilter }; /* * Default pipe buffer size(s), this can be kind-of large now because pipe * space is pageable. The pipe code will try to maintain locality of * reference for performance reasons, so small amounts of outstanding I/O * will not wipe the cache. */ #define MINPIPESIZE (PIPE_SIZE/3) #define MAXPIPESIZE (2*PIPE_SIZE/3) /* * Maximum amount of kva for pipes -- this is kind-of a soft limit, but * is there so that on large systems, we don't exhaust it. */ #define MAXPIPEKVA (8*1024*1024) static int maxpipekva = MAXPIPEKVA; /* * Limit for direct transfers, we cannot, of course limit * the amount of kva for pipes in general though. */ #define LIMITPIPEKVA (16*1024*1024) static int limitpipekva = LIMITPIPEKVA; /* * Limit the number of "big" pipes */ #define LIMITBIGPIPES 32 static int maxbigpipes = LIMITBIGPIPES; static int nbigpipe = 0; /* * Amount of KVA consumed by pipe buffers. */ static int amountpipekva = 0; MALLOC_DEFINE(M_PIPE, "pipe", "Pipe structures"); static void pipeclose(struct pipe *pipe); static void pipe_free_kmem(struct pipe *pipe); static int pipe_create(struct pipe **pipep, int allockva); static int pipelock(struct pipe *pipe, int catch); static __inline void pipeunlock(struct pipe *pipe); static void pipeselwakeup(struct pipe *pipe, struct pipe *sigp); #ifndef PIPE_NODIRECT static int pipe_direct_write(struct pipe *wpipe, struct uio *uio); #endif static int pipespace(struct pipe *pipe, int size); #ifndef PIPE_NODIRECT static int pipe_loan_alloc(struct pipe *, int); static void pipe_loan_free(struct pipe *); #endif /* PIPE_NODIRECT */ static struct pool pipe_pool; /* * The pipe system call for the DTYPE_PIPE type of pipes */ /* ARGSUSED */ int sys_pipe(l, v, retval) struct lwp *l; void *v; register_t *retval; { struct file *rf, *wf; struct pipe *rpipe, *wpipe; int fd, error; struct proc *p; p = l->l_proc; rpipe = wpipe = NULL; if (pipe_create(&rpipe, 1) || pipe_create(&wpipe, 0)) { pipeclose(rpipe); pipeclose(wpipe); return (ENFILE); } /* * Note: the file structure returned from falloc() is marked * as 'larval' initially. Unless we mark it as 'mature' by * FILE_SET_MATURE(), any attempt to do anything with it would * return EBADF, including e.g. dup(2) or close(2). This avoids * file descriptor races if we block in the second falloc(). */ error = falloc(p, &rf, &fd); if (error) goto free2; retval[0] = fd; rf->f_flag = FREAD; rf->f_type = DTYPE_PIPE; rf->f_data = (caddr_t)rpipe; rf->f_ops = &pipeops; error = falloc(p, &wf, &fd); if (error) goto free3; retval[1] = fd; wf->f_flag = FWRITE; wf->f_type = DTYPE_PIPE; wf->f_data = (caddr_t)wpipe; wf->f_ops = &pipeops; rpipe->pipe_peer = wpipe; wpipe->pipe_peer = rpipe; FILE_SET_MATURE(rf); FILE_SET_MATURE(wf); FILE_UNUSE(rf, p); FILE_UNUSE(wf, p); return (0); free3: FILE_UNUSE(rf, p); ffree(rf); fdremove(p->p_fd, retval[0]); free2: pipeclose(wpipe); pipeclose(rpipe); return (error); } /* * Allocate kva for pipe circular buffer, the space is pageable * This routine will 'realloc' the size of a pipe safely, if it fails * it will retain the old buffer. * If it fails it will return ENOMEM. */ static int pipespace(pipe, size) struct pipe *pipe; int size; { caddr_t buffer; /* * Allocate pageable virtual address space. Physical memory is * allocated on demand. */ buffer = (caddr_t) uvm_km_valloc(kernel_map, round_page(size)); if (buffer == NULL) return (ENOMEM); /* free old resources if we're resizing */ pipe_free_kmem(pipe); pipe->pipe_buffer.buffer = buffer; pipe->pipe_buffer.size = size; pipe->pipe_buffer.in = 0; pipe->pipe_buffer.out = 0; pipe->pipe_buffer.cnt = 0; amountpipekva += pipe->pipe_buffer.size; return (0); } /* * Initialize and allocate VM and memory for pipe. */ static int pipe_create(pipep, allockva) struct pipe **pipep; int allockva; { struct pipe *pipe; int error; pipe = pool_get(&pipe_pool, M_WAITOK); if (pipe == NULL) return (ENOMEM); /* Initialize */ memset(pipe, 0, sizeof(struct pipe)); pipe->pipe_state = PIPE_SIGNALR; if (allockva && (error = pipespace(pipe, PIPE_SIZE))) return (error); PIPE_TIMESTAMP(&pipe->pipe_ctime); pipe->pipe_atime = pipe->pipe_ctime; pipe->pipe_mtime = pipe->pipe_ctime; simple_lock_init(&pipe->pipe_slock); lockinit(&pipe->pipe_lock, PRIBIO | PCATCH, "pipelk", 0, 0); *pipep = pipe; return (0); } /* * Lock a pipe for I/O, blocking other access * Called with pipe spin lock held. * Return with pipe spin lock released on success. */ static int pipelock(pipe, catch) struct pipe *pipe; int catch; { int error; LOCK_ASSERT(simple_lock_held(&pipe->pipe_slock)); while (1) { error = lockmgr(&pipe->pipe_lock, LK_EXCLUSIVE | LK_INTERLOCK, &pipe->pipe_slock); if (error == 0) break; simple_lock(&pipe->pipe_slock); if (catch || (error != EINTR && error != ERESTART)) break; } return (error); } /* * unlock a pipe I/O lock */ static __inline void pipeunlock(pipe) struct pipe *pipe; { lockmgr(&pipe->pipe_lock, LK_RELEASE, NULL); } /* * Select/poll wakup. This also sends SIGIO to peer connected to * 'sigpipe' side of pipe. */ static void pipeselwakeup(selp, sigp) struct pipe *selp, *sigp; { struct proc *p; pid_t pid; selnotify(&selp->pipe_sel, 0); if (sigp == NULL || (sigp->pipe_state & PIPE_ASYNC) == 0) return; pid = sigp->pipe_pgid; if (pid == 0) return; if (pid > 0) gsignal(pid, SIGIO); else if ((p = pfind(-pid)) != NULL) psignal(p, SIGIO); } /* ARGSUSED */ static int pipe_read(fp, offset, uio, cred, flags) struct file *fp; off_t *offset; struct uio *uio; struct ucred *cred; int flags; { struct pipe *rpipe = (struct pipe *) fp->f_data; struct pipebuf *bp = &rpipe->pipe_buffer; int error; size_t nread = 0; size_t size; size_t ocnt; PIPE_LOCK(rpipe); ++rpipe->pipe_busy; ocnt = bp->cnt; again: error = pipelock(rpipe, 1); if (error) goto unlocked_error; while (uio->uio_resid) { /* * normal pipe buffer receive */ if (bp->cnt > 0) { size = bp->size - bp->out; if (size > bp->cnt) size = bp->cnt; if (size > uio->uio_resid) size = uio->uio_resid; error = uiomove(&bp->buffer[bp->out], size, uio); if (error) break; bp->out += size; if (bp->out >= bp->size) bp->out = 0; bp->cnt -= size; /* * If there is no more to read in the pipe, reset * its pointers to the beginning. This improves * cache hit stats. */ if (bp->cnt == 0) { bp->in = 0; bp->out = 0; } nread += size; #ifndef PIPE_NODIRECT } else if ((rpipe->pipe_state & PIPE_DIRECTR) != 0) { /* * Direct copy, bypassing a kernel buffer. */ caddr_t va; KASSERT(rpipe->pipe_state & PIPE_DIRECTW); size = rpipe->pipe_map.cnt; if (size > uio->uio_resid) size = uio->uio_resid; va = (caddr_t) rpipe->pipe_map.kva + rpipe->pipe_map.pos; error = uiomove(va, size, uio); if (error) break; nread += size; rpipe->pipe_map.pos += size; rpipe->pipe_map.cnt -= size; if (rpipe->pipe_map.cnt == 0) { PIPE_LOCK(rpipe); rpipe->pipe_state &= ~PIPE_DIRECTR; wakeup(rpipe); PIPE_UNLOCK(rpipe); } #endif } else { /* * Break if some data was read. */ if (nread > 0) break; PIPE_LOCK(rpipe); /* * detect EOF condition * read returns 0 on EOF, no need to set error */ if (rpipe->pipe_state & PIPE_EOF) { PIPE_UNLOCK(rpipe); break; } /* * don't block on non-blocking I/O */ if (fp->f_flag & FNONBLOCK) { PIPE_UNLOCK(rpipe); error = EAGAIN; break; } /* * Unlock the pipe buffer for our remaining processing. * We will either break out with an error or we will * sleep and relock to loop. */ pipeunlock(rpipe); /* * The PIPE_DIRECTR flag is not under the control * of the long-term lock (see pipe_direct_write()), * so re-check now while holding the spin lock. */ if ((rpipe->pipe_state & PIPE_DIRECTR) != 0) goto again; /* * We want to read more, wake up select/poll. */ pipeselwakeup(rpipe, rpipe->pipe_peer); /* * If the "write-side" is blocked, wake it up now. */ if (rpipe->pipe_state & PIPE_WANTW) { rpipe->pipe_state &= ~PIPE_WANTW; wakeup(rpipe); } /* Now wait until the pipe is filled */ rpipe->pipe_state |= PIPE_WANTR; error = ltsleep(rpipe, PRIBIO | PCATCH, "piperd", 0, &rpipe->pipe_slock); if (error != 0) goto unlocked_error; goto again; } } if (error == 0) PIPE_TIMESTAMP(&rpipe->pipe_atime); PIPE_LOCK(rpipe); pipeunlock(rpipe); unlocked_error: --rpipe->pipe_busy; /* * PIPE_WANTCLOSE processing only makes sense if pipe_busy is 0. */ if ((rpipe->pipe_busy == 0) && (rpipe->pipe_state & PIPE_WANTCLOSE)) { rpipe->pipe_state &= ~(PIPE_WANTCLOSE|PIPE_WANTW); wakeup(rpipe); } else if (bp->cnt < MINPIPESIZE) { /* * Handle write blocking hysteresis. */ if (rpipe->pipe_state & PIPE_WANTW) { rpipe->pipe_state &= ~PIPE_WANTW; wakeup(rpipe); } } /* * If anything was read off the buffer, signal to the writer it's * possible to write more data. Also send signal if we are here for the * first time after last write. */ if ((bp->size - bp->cnt) >= PIPE_BUF && (ocnt != bp->cnt || (rpipe->pipe_state & PIPE_SIGNALR))) { pipeselwakeup(rpipe, rpipe->pipe_peer); rpipe->pipe_state &= ~PIPE_SIGNALR; } PIPE_UNLOCK(rpipe); return (error); } #ifndef PIPE_NODIRECT /* * Allocate structure for loan transfer. */ static int pipe_loan_alloc(wpipe, npages) struct pipe *wpipe; int npages; { vsize_t len; len = (vsize_t)npages << PAGE_SHIFT; wpipe->pipe_map.kva = uvm_km_valloc_wait(kernel_map, len); if (wpipe->pipe_map.kva == 0) return (ENOMEM); amountpipekva += len; wpipe->pipe_map.npages = npages; wpipe->pipe_map.pgs = malloc(npages * sizeof(struct vm_page *), M_PIPE, M_WAITOK); return (0); } /* * Free resources allocated for loan transfer. */ static void pipe_loan_free(wpipe) struct pipe *wpipe; { vsize_t len; len = (vsize_t)wpipe->pipe_map.npages << PAGE_SHIFT; uvm_km_free(kernel_map, wpipe->pipe_map.kva, len); wpipe->pipe_map.kva = 0; amountpipekva -= len; free(wpipe->pipe_map.pgs, M_PIPE); wpipe->pipe_map.pgs = NULL; } /* * NetBSD direct write, using uvm_loan() mechanism. * This implements the pipe buffer write mechanism. Note that only * a direct write OR a normal pipe write can be pending at any given time. * If there are any characters in the pipe buffer, the direct write will * be deferred until the receiving process grabs all of the bytes from * the pipe buffer. Then the direct mapping write is set-up. * * Called with the long-term pipe lock held. */ static int pipe_direct_write(wpipe, uio) struct pipe *wpipe; struct uio *uio; { int error, npages, j; struct vm_page **pgs; vaddr_t bbase, kva, base, bend; vsize_t blen, bcnt; voff_t bpos; KASSERT(wpipe->pipe_map.cnt == 0); /* * Handle first PIPE_CHUNK_SIZE bytes of buffer. Deal with buffers * not aligned to PAGE_SIZE. */ bbase = (vaddr_t)uio->uio_iov->iov_base; base = trunc_page(bbase); bend = round_page(bbase + uio->uio_iov->iov_len); blen = bend - base; bpos = bbase - base; if (blen > PIPE_DIRECT_CHUNK) { blen = PIPE_DIRECT_CHUNK; bend = base + blen; bcnt = PIPE_DIRECT_CHUNK - bpos; } else { bcnt = uio->uio_iov->iov_len; } npages = blen >> PAGE_SHIFT; /* * Free the old kva if we need more pages than we have * allocated. */ if (wpipe->pipe_map.kva != 0 && npages > wpipe->pipe_map.npages) pipe_loan_free(wpipe); /* Allocate new kva. */ if (wpipe->pipe_map.kva == 0) { error = pipe_loan_alloc(wpipe, npages); if (error) return (error); } /* Loan the write buffer memory from writer process */ pgs = wpipe->pipe_map.pgs; error = uvm_loan(&uio->uio_procp->p_vmspace->vm_map, base, blen, pgs, UVM_LOAN_TOPAGE); if (error) { pipe_loan_free(wpipe); return (error); } /* Enter the loaned pages to kva */ kva = wpipe->pipe_map.kva; for (j = 0; j < npages; j++, kva += PAGE_SIZE) { pmap_kenter_pa(kva, VM_PAGE_TO_PHYS(pgs[j]), VM_PROT_READ); } pmap_update(pmap_kernel()); /* Now we can put the pipe in direct write mode */ wpipe->pipe_map.pos = bpos; wpipe->pipe_map.cnt = bcnt; wpipe->pipe_state |= PIPE_DIRECTW; /* * But before we can let someone do a direct read, * we have to wait until the pipe is drained. */ /* Relase the pipe lock while we wait */ PIPE_LOCK(wpipe); pipeunlock(wpipe); while (error == 0 && wpipe->pipe_buffer.cnt > 0) { if (wpipe->pipe_state & PIPE_WANTR) { wpipe->pipe_state &= ~PIPE_WANTR; wakeup(wpipe); } wpipe->pipe_state |= PIPE_WANTW; error = ltsleep(wpipe, PRIBIO | PCATCH, "pipdwc", 0, &wpipe->pipe_slock); if (error == 0 && wpipe->pipe_state & PIPE_EOF) error = EPIPE; } /* Pipe is drained; next read will off the direct buffer */ wpipe->pipe_state |= PIPE_DIRECTR; /* Wait until the reader is done */ while (error == 0 && (wpipe->pipe_state & PIPE_DIRECTR)) { if (wpipe->pipe_state & PIPE_WANTR) { wpipe->pipe_state &= ~PIPE_WANTR; wakeup(wpipe); } pipeselwakeup(wpipe, wpipe); error = ltsleep(wpipe, PRIBIO | PCATCH, "pipdwt", 0, &wpipe->pipe_slock); if (error == 0 && wpipe->pipe_state & PIPE_EOF) error = EPIPE; } /* Take pipe out of direct write mode */ wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTR); /* Acquire the pipe lock and cleanup */ (void)pipelock(wpipe, 0); if (pgs != NULL) { pmap_kremove(wpipe->pipe_map.kva, blen); uvm_unloan(pgs, npages, UVM_LOAN_TOPAGE); } if (error || amountpipekva > maxpipekva) pipe_loan_free(wpipe); if (error) { pipeselwakeup(wpipe, wpipe); /* * If nothing was read from what we offered, return error * straight on. Otherwise update uio resid first. Caller * will deal with the error condition, returning short * write, error, or restarting the write(2) as appropriate. */ if (wpipe->pipe_map.cnt == bcnt) { wpipe->pipe_map.cnt = 0; wakeup(wpipe); return (error); } bcnt -= wpipe->pipe_map.cnt; } uio->uio_resid -= bcnt; /* uio_offset not updated, not set/used for write(2) */ uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + bcnt; uio->uio_iov->iov_len -= bcnt; if (uio->uio_iov->iov_len == 0) { uio->uio_iov++; uio->uio_iovcnt--; } wpipe->pipe_map.cnt = 0; return (error); } #endif /* !PIPE_NODIRECT */ static int pipe_write(fp, offset, uio, cred, flags) struct file *fp; off_t *offset; struct uio *uio; struct ucred *cred; int flags; { struct pipe *wpipe, *rpipe; struct pipebuf *bp; int error; /* We want to write to our peer */ rpipe = (struct pipe *) fp->f_data; retry: error = 0; PIPE_LOCK(rpipe); wpipe = rpipe->pipe_peer; /* * Detect loss of pipe read side, issue SIGPIPE if lost. */ if (wpipe == NULL) error = EPIPE; else if (simple_lock_try(&wpipe->pipe_slock) == 0) { /* Deal with race for peer */ PIPE_UNLOCK(rpipe); goto retry; } else if ((wpipe->pipe_state & PIPE_EOF) != 0) { PIPE_UNLOCK(wpipe); error = EPIPE; } PIPE_UNLOCK(rpipe); if (error != 0) return (error); ++wpipe->pipe_busy; /* Aquire the long-term pipe lock */ if ((error = pipelock(wpipe,1)) != 0) { --wpipe->pipe_busy; if (wpipe->pipe_busy == 0 && (wpipe->pipe_state & PIPE_WANTCLOSE)) { wpipe->pipe_state &= ~(PIPE_WANTCLOSE | PIPE_WANTR); wakeup(wpipe); } PIPE_UNLOCK(wpipe); return (error); } bp = &wpipe->pipe_buffer; /* * If it is advantageous to resize the pipe buffer, do so. */ if ((uio->uio_resid > PIPE_SIZE) && (nbigpipe < maxbigpipes) && #ifndef PIPE_NODIRECT (wpipe->pipe_state & PIPE_DIRECTW) == 0 && #endif (bp->size <= PIPE_SIZE) && (bp->cnt == 0)) { if (pipespace(wpipe, BIG_PIPE_SIZE) == 0) nbigpipe++; } while (uio->uio_resid) { size_t space; #ifndef PIPE_NODIRECT /* * Pipe buffered writes cannot be coincidental with * direct writes. Also, only one direct write can be * in progress at any one time. We wait until the currently * executing direct write is completed before continuing. * * We break out if a signal occurs or the reader goes away. */ while (error == 0 && wpipe->pipe_state & PIPE_DIRECTW) { PIPE_LOCK(wpipe); if (wpipe->pipe_state & PIPE_WANTR) { wpipe->pipe_state &= ~PIPE_WANTR; wakeup(wpipe); } pipeunlock(wpipe); error = ltsleep(wpipe, PRIBIO | PCATCH, "pipbww", 0, &wpipe->pipe_slock); (void)pipelock(wpipe, 0); if (wpipe->pipe_state & PIPE_EOF) error = EPIPE; } if (error) break; /* * If the transfer is large, we can gain performance if * we do process-to-process copies directly. * If the write is non-blocking, we don't use the * direct write mechanism. * * The direct write mechanism will detect the reader going * away on us. */ if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) && (fp->f_flag & FNONBLOCK) == 0 && (wpipe->pipe_map.kva || (amountpipekva < limitpipekva))) { error = pipe_direct_write(wpipe, uio); /* * Break out if error occured, unless it's ENOMEM. * ENOMEM means we failed to allocate some resources * for direct write, so we just fallback to ordinary * write. If the direct write was successful, * process rest of data via ordinary write. */ if (error == 0) continue; if (error != ENOMEM) break; } #endif /* PIPE_NODIRECT */ space = bp->size - bp->cnt; /* Writes of size <= PIPE_BUF must be atomic. */ if ((space < uio->uio_resid) && (uio->uio_resid <= PIPE_BUF)) space = 0; if (space > 0) { int size; /* Transfer size */ int segsize; /* first segment to transfer */ /* * Transfer size is minimum of uio transfer * and free space in pipe buffer. */ if (space > uio->uio_resid) size = uio->uio_resid; else size = space; /* * First segment to transfer is minimum of * transfer size and contiguous space in * pipe buffer. If first segment to transfer * is less than the transfer size, we've got * a wraparound in the buffer. */ segsize = bp->size - bp->in; if (segsize > size) segsize = size; /* Transfer first segment */ error = uiomove(&bp->buffer[bp->in], segsize, uio); if (error == 0 && segsize < size) { /* * Transfer remaining part now, to * support atomic writes. Wraparound * happened. */ #ifdef DEBUG if (bp->in + segsize != bp->size) panic("Expected pipe buffer wraparound disappeared"); #endif error = uiomove(&bp->buffer[0], size - segsize, uio); } if (error) break; bp->in += size; if (bp->in >= bp->size) { #ifdef DEBUG if (bp->in != size - segsize + bp->size) panic("Expected wraparound bad"); #endif bp->in = size - segsize; } bp->cnt += size; #ifdef DEBUG if (bp->cnt > bp->size) panic("Pipe buffer overflow"); #endif } else { /* * If the "read-side" has been blocked, wake it up now. */ PIPE_LOCK(wpipe); if (wpipe->pipe_state & PIPE_WANTR) { wpipe->pipe_state &= ~PIPE_WANTR; wakeup(wpipe); } PIPE_UNLOCK(wpipe); /* * don't block on non-blocking I/O */ if (fp->f_flag & FNONBLOCK) { error = EAGAIN; break; } /* * We have no more space and have something to offer, * wake up select/poll. */ if (bp->cnt) pipeselwakeup(wpipe, wpipe); PIPE_LOCK(wpipe); pipeunlock(wpipe); wpipe->pipe_state |= PIPE_WANTW; error = ltsleep(wpipe, PRIBIO | PCATCH, "pipewr", 0, &wpipe->pipe_slock); (void)pipelock(wpipe, 0); if (error != 0) break; /* * If read side wants to go away, we just issue a signal * to ourselves. */ if (wpipe->pipe_state & PIPE_EOF) { error = EPIPE; break; } } } PIPE_LOCK(wpipe); --wpipe->pipe_busy; if ((wpipe->pipe_busy == 0) && (wpipe->pipe_state & PIPE_WANTCLOSE)) { wpipe->pipe_state &= ~(PIPE_WANTCLOSE | PIPE_WANTR); wakeup(wpipe); } else if (bp->cnt > 0) { /* * If we have put any characters in the buffer, we wake up * the reader. */ if (wpipe->pipe_state & PIPE_WANTR) { wpipe->pipe_state &= ~PIPE_WANTR; wakeup(wpipe); } } /* * Don't return EPIPE if I/O was successful */ if (error == EPIPE && bp->cnt == 0 && uio->uio_resid == 0) error = 0; if (error == 0) PIPE_TIMESTAMP(&wpipe->pipe_mtime); /* * We have something to offer, wake up select/poll. * wpipe->pipe_map.cnt is always 0 in this point (direct write * is only done synchronously), so check only wpipe->pipe_buffer.cnt */ if (bp->cnt) pipeselwakeup(wpipe, wpipe); /* * Arrange for next read(2) to do a signal. */ wpipe->pipe_state |= PIPE_SIGNALR; pipeunlock(wpipe); PIPE_UNLOCK(wpipe); return (error); } /* * we implement a very minimal set of ioctls for compatibility with sockets. */ int pipe_ioctl(fp, cmd, data, p) struct file *fp; u_long cmd; void *data; struct proc *p; { struct pipe *pipe = (struct pipe *)fp->f_data; pid_t pgid; int error; switch (cmd) { case FIONBIO: return (0); case FIOASYNC: PIPE_LOCK(pipe); if (*(int *)data) { pipe->pipe_state |= PIPE_ASYNC; } else { pipe->pipe_state &= ~PIPE_ASYNC; } PIPE_UNLOCK(pipe); return (0); case FIONREAD: PIPE_LOCK(pipe); #ifndef PIPE_NODIRECT if (pipe->pipe_state & PIPE_DIRECTW) *(int *)data = pipe->pipe_map.cnt; else #endif *(int *)data = pipe->pipe_buffer.cnt; PIPE_UNLOCK(pipe); return (0); case TIOCSPGRP: pgid = *(int *)data; if (pgid != 0) { error = pgid_in_session(p, pgid); if (error) return error; } pipe->pipe_pgid = pgid; return (0); case TIOCGPGRP: *(int *)data = pipe->pipe_pgid; return (0); } return (EPASSTHROUGH); } int pipe_poll(fp, events, td) struct file *fp; int events; struct proc *td; { struct pipe *rpipe = (struct pipe *)fp->f_data; struct pipe *wpipe; int eof = 0; int revents = 0; retry: PIPE_LOCK(rpipe); wpipe = rpipe->pipe_peer; if (wpipe != NULL && simple_lock_try(&wpipe->pipe_slock) == 0) { /* Deal with race for peer */ PIPE_UNLOCK(rpipe); goto retry; } if (events & (POLLIN | POLLRDNORM)) if ((rpipe->pipe_buffer.cnt > 0) || #ifndef PIPE_NODIRECT (rpipe->pipe_state & PIPE_DIRECTR) || #endif (rpipe->pipe_state & PIPE_EOF)) revents |= events & (POLLIN | POLLRDNORM); eof |= (rpipe->pipe_state & PIPE_EOF); PIPE_UNLOCK(rpipe); if (wpipe == NULL) revents |= events & (POLLOUT | POLLWRNORM); else { if (events & (POLLOUT | POLLWRNORM)) if ((wpipe->pipe_state & PIPE_EOF) || ( #ifndef PIPE_NODIRECT (wpipe->pipe_state & PIPE_DIRECTW) == 0 && #endif (wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF)) revents |= events & (POLLOUT | POLLWRNORM); eof |= (wpipe->pipe_state & PIPE_EOF); PIPE_UNLOCK(wpipe); } if (wpipe == NULL || eof) revents |= POLLHUP; if (revents == 0) { if (events & (POLLIN | POLLRDNORM)) selrecord(td, &rpipe->pipe_sel); if (events & (POLLOUT | POLLWRNORM)) selrecord(td, &wpipe->pipe_sel); } return (revents); } static int pipe_stat(fp, ub, td) struct file *fp; struct stat *ub; struct proc *td; { struct pipe *pipe = (struct pipe *)fp->f_data; memset((caddr_t)ub, 0, sizeof(*ub)); ub->st_mode = S_IFIFO | S_IRUSR | S_IWUSR; ub->st_blksize = pipe->pipe_buffer.size; ub->st_size = pipe->pipe_buffer.cnt; ub->st_blocks = (ub->st_size) ? 1 : 0; TIMEVAL_TO_TIMESPEC(&pipe->pipe_atime, &ub->st_atimespec) TIMEVAL_TO_TIMESPEC(&pipe->pipe_mtime, &ub->st_mtimespec); TIMEVAL_TO_TIMESPEC(&pipe->pipe_ctime, &ub->st_ctimespec); ub->st_uid = fp->f_cred->cr_uid; ub->st_gid = fp->f_cred->cr_gid; /* * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen. * XXX (st_dev, st_ino) should be unique. */ return (0); } /* ARGSUSED */ static int pipe_close(fp, td) struct file *fp; struct proc *td; { struct pipe *pipe = (struct pipe *)fp->f_data; fp->f_data = NULL; pipeclose(pipe); return (0); } static void pipe_free_kmem(pipe) struct pipe *pipe; { if (pipe->pipe_buffer.buffer != NULL) { if (pipe->pipe_buffer.size > PIPE_SIZE) --nbigpipe; amountpipekva -= pipe->pipe_buffer.size; uvm_km_free(kernel_map, (vaddr_t)pipe->pipe_buffer.buffer, pipe->pipe_buffer.size); pipe->pipe_buffer.buffer = NULL; } #ifndef PIPE_NODIRECT if (pipe->pipe_map.kva != 0) { pipe_loan_free(pipe); pipe->pipe_map.cnt = 0; pipe->pipe_map.kva = 0; pipe->pipe_map.pos = 0; pipe->pipe_map.npages = 0; } #endif /* !PIPE_NODIRECT */ } /* * shutdown the pipe */ static void pipeclose(pipe) struct pipe *pipe; { struct pipe *ppipe; if (pipe == NULL) return; retry: PIPE_LOCK(pipe); pipeselwakeup(pipe, pipe); /* * If the other side is blocked, wake it up saying that * we want to close it down. */ while (pipe->pipe_busy) { wakeup(pipe); pipe->pipe_state |= PIPE_WANTCLOSE | PIPE_EOF; ltsleep(pipe, PRIBIO, "pipecl", 0, &pipe->pipe_slock); } /* * Disconnect from peer */ if ((ppipe = pipe->pipe_peer) != NULL) { /* Deal with race for peer */ if (simple_lock_try(&ppipe->pipe_slock) == 0) { PIPE_UNLOCK(pipe); goto retry; } pipeselwakeup(ppipe, ppipe); ppipe->pipe_state |= PIPE_EOF; wakeup(ppipe); ppipe->pipe_peer = NULL; PIPE_UNLOCK(ppipe); } (void)lockmgr(&pipe->pipe_lock, LK_DRAIN | LK_INTERLOCK, &pipe->pipe_slock); /* * free resources */ pipe_free_kmem(pipe); pool_put(&pipe_pool, pipe); } static void filt_pipedetach(struct knote *kn) { struct pipe *pipe = (struct pipe *)kn->kn_fp->f_data; switch(kn->kn_filter) { case EVFILT_WRITE: /* need the peer structure, not our own */ pipe = pipe->pipe_peer; /* XXXSMP: race for peer */ /* if reader end already closed, just return */ if (pipe == NULL) return; break; default: /* nothing to do */ break; } #ifdef DIAGNOSTIC if (kn->kn_hook != pipe) panic("filt_pipedetach: inconsistent knote"); #endif PIPE_LOCK(pipe); SLIST_REMOVE(&pipe->pipe_sel.sel_klist, kn, knote, kn_selnext); PIPE_UNLOCK(pipe); } /*ARGSUSED*/ static int filt_piperead(struct knote *kn, long hint) { struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; struct pipe *wpipe = rpipe->pipe_peer; PIPE_LOCK(rpipe); kn->kn_data = rpipe->pipe_buffer.cnt; if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) kn->kn_data = rpipe->pipe_map.cnt; /* XXXSMP: race for peer */ if ((rpipe->pipe_state & PIPE_EOF) || (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { kn->kn_flags |= EV_EOF; PIPE_UNLOCK(rpipe); return (1); } PIPE_UNLOCK(rpipe); return (kn->kn_data > 0); } /*ARGSUSED*/ static int filt_pipewrite(struct knote *kn, long hint) { struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data; struct pipe *wpipe = rpipe->pipe_peer; PIPE_LOCK(rpipe); /* XXXSMP: race for peer */ if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { kn->kn_data = 0; kn->kn_flags |= EV_EOF; PIPE_UNLOCK(rpipe); return (1); } kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; if (wpipe->pipe_state & PIPE_DIRECTW) kn->kn_data = 0; PIPE_UNLOCK(rpipe); return (kn->kn_data >= PIPE_BUF); } static const struct filterops pipe_rfiltops = { 1, NULL, filt_pipedetach, filt_piperead }; static const struct filterops pipe_wfiltops = { 1, NULL, filt_pipedetach, filt_pipewrite }; /*ARGSUSED*/ static int pipe_kqfilter(struct file *fp, struct knote *kn) { struct pipe *pipe; pipe = (struct pipe *)kn->kn_fp->f_data; switch (kn->kn_filter) { case EVFILT_READ: kn->kn_fop = &pipe_rfiltops; break; case EVFILT_WRITE: kn->kn_fop = &pipe_wfiltops; /* XXXSMP: race for peer */ pipe = pipe->pipe_peer; if (pipe == NULL) { /* other end of pipe has been closed */ return (EBADF); } break; default: return (1); } kn->kn_hook = pipe; PIPE_LOCK(pipe); SLIST_INSERT_HEAD(&pipe->pipe_sel.sel_klist, kn, kn_selnext); PIPE_UNLOCK(pipe); return (0); } static int pipe_fcntl(fp, cmd, data, p) struct file *fp; u_int cmd; void *data; struct proc *p; { if (cmd == F_SETFL) return (0); else return (EOPNOTSUPP); } /* * Handle pipe sysctls. */ int sysctl_dopipe(name, namelen, oldp, oldlenp, newp, newlen) int *name; u_int namelen; void *oldp; size_t *oldlenp; void *newp; size_t newlen; { /* All sysctl names at this level are terminal. */ if (namelen != 1) return (ENOTDIR); /* overloaded */ switch (name[0]) { case KERN_PIPE_MAXKVASZ: return (sysctl_int(oldp, oldlenp, newp, newlen, &maxpipekva)); case KERN_PIPE_LIMITKVA: return (sysctl_int(oldp, oldlenp, newp, newlen, &limitpipekva)); case KERN_PIPE_MAXBIGPIPES: return (sysctl_int(oldp, oldlenp, newp, newlen, &maxbigpipes)); case KERN_PIPE_NBIGPIPES: return (sysctl_rdint(oldp, oldlenp, newp, nbigpipe)); case KERN_PIPE_KVASIZE: return (sysctl_rdint(oldp, oldlenp, newp, amountpipekva)); default: return (EOPNOTSUPP); } /* NOTREACHED */ } /* * Initialize pipe structs. */ void pipe_init(void) { pool_init(&pipe_pool, sizeof(struct pipe), 0, 0, 0, "pipepl", NULL); }