/* $NetBSD: sys_pipe.c,v 1.140.12.2 2021/10/08 14:59:59 martin Exp $ */ /*- * Copyright (c) 2003, 2007, 2008, 2009 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Paul Kranenburg, and by Andrew Doran. * * 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. * * 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. */ /* * This file contains a high-performance replacement for the socket-based * pipes scheme originally used. It does not support all features of * sockets, but does do everything that pipes normally do. * * 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 1.140.12.2 2021/10/08 14:59:59 martin Exp $"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Use this to disable direct I/O and decrease the code size: * #define PIPE_NODIRECT */ /* XXX Disabled for now; rare hangs switching between direct/buffered */ #define PIPE_NODIRECT static int pipe_read(file_t *, off_t *, struct uio *, kauth_cred_t, int); static int pipe_write(file_t *, off_t *, struct uio *, kauth_cred_t, int); static int pipe_close(file_t *); static int pipe_poll(file_t *, int); static int pipe_kqfilter(file_t *, struct knote *); static int pipe_stat(file_t *, struct stat *); static int pipe_ioctl(file_t *, u_long, void *); static void pipe_restart(file_t *); static const struct fileops pipeops = { .fo_read = pipe_read, .fo_write = pipe_write, .fo_ioctl = pipe_ioctl, .fo_fcntl = fnullop_fcntl, .fo_poll = pipe_poll, .fo_stat = pipe_stat, .fo_close = pipe_close, .fo_kqfilter = pipe_kqfilter, .fo_restart = pipe_restart, }; /* * 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 u_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 u_int limitpipekva = LIMITPIPEKVA; /* * Limit the number of "big" pipes */ #define LIMITBIGPIPES 32 static u_int maxbigpipes = LIMITBIGPIPES; static u_int nbigpipe = 0; /* * Amount of KVA consumed by pipe buffers. */ static u_int amountpipekva = 0; static void pipeclose(struct pipe *); static void pipe_free_kmem(struct pipe *); static int pipe_create(struct pipe **, pool_cache_t); static int pipelock(struct pipe *, bool); static inline void pipeunlock(struct pipe *); static void pipeselwakeup(struct pipe *, struct pipe *, int); #ifndef PIPE_NODIRECT static int pipe_direct_write(file_t *, struct pipe *, struct uio *); #endif static int pipespace(struct pipe *, int); static int pipe_ctor(void *, void *, int); static void pipe_dtor(void *, void *); #ifndef PIPE_NODIRECT static int pipe_loan_alloc(struct pipe *, int); static void pipe_loan_free(struct pipe *); #endif /* PIPE_NODIRECT */ static pool_cache_t pipe_wr_cache; static pool_cache_t pipe_rd_cache; void pipe_init(void) { /* Writer side is not automatically allocated KVA. */ pipe_wr_cache = pool_cache_init(sizeof(struct pipe), 0, 0, 0, "pipewr", NULL, IPL_NONE, pipe_ctor, pipe_dtor, NULL); KASSERT(pipe_wr_cache != NULL); /* Reader side gets preallocated KVA. */ pipe_rd_cache = pool_cache_init(sizeof(struct pipe), 0, 0, 0, "piperd", NULL, IPL_NONE, pipe_ctor, pipe_dtor, (void *)1); KASSERT(pipe_rd_cache != NULL); } static int pipe_ctor(void *arg, void *obj, int flags) { struct pipe *pipe; vaddr_t va; pipe = obj; memset(pipe, 0, sizeof(struct pipe)); if (arg != NULL) { /* Preallocate space. */ va = uvm_km_alloc(kernel_map, PIPE_SIZE, 0, UVM_KMF_PAGEABLE | UVM_KMF_WAITVA); KASSERT(va != 0); pipe->pipe_kmem = va; atomic_add_int(&amountpipekva, PIPE_SIZE); } cv_init(&pipe->pipe_rcv, "pipe_rd"); cv_init(&pipe->pipe_wcv, "pipe_wr"); cv_init(&pipe->pipe_draincv, "pipe_drn"); cv_init(&pipe->pipe_lkcv, "pipe_lk"); selinit(&pipe->pipe_sel); pipe->pipe_state = PIPE_SIGNALR; return 0; } static void pipe_dtor(void *arg, void *obj) { struct pipe *pipe; pipe = obj; cv_destroy(&pipe->pipe_rcv); cv_destroy(&pipe->pipe_wcv); cv_destroy(&pipe->pipe_draincv); cv_destroy(&pipe->pipe_lkcv); seldestroy(&pipe->pipe_sel); if (pipe->pipe_kmem != 0) { uvm_km_free(kernel_map, pipe->pipe_kmem, PIPE_SIZE, UVM_KMF_PAGEABLE); atomic_add_int(&amountpipekva, -PIPE_SIZE); } } /* * The pipe system call for the DTYPE_PIPE type of pipes */ int pipe1(struct lwp *l, register_t *retval, int flags) { struct pipe *rpipe, *wpipe; file_t *rf, *wf; int fd, error; proc_t *p; if (flags & ~(O_CLOEXEC|O_NONBLOCK|O_NOSIGPIPE)) return EINVAL; p = curproc; rpipe = wpipe = NULL; if ((error = pipe_create(&rpipe, pipe_rd_cache)) || (error = pipe_create(&wpipe, pipe_wr_cache))) { goto free2; } rpipe->pipe_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE); wpipe->pipe_lock = rpipe->pipe_lock; mutex_obj_hold(wpipe->pipe_lock); error = fd_allocfile(&rf, &fd); if (error) goto free2; retval[0] = fd; error = fd_allocfile(&wf, &fd); if (error) goto free3; retval[1] = fd; rf->f_flag = FREAD | flags; rf->f_type = DTYPE_PIPE; rf->f_pipe = rpipe; rf->f_ops = &pipeops; fd_set_exclose(l, (int)retval[0], (flags & O_CLOEXEC) != 0); wf->f_flag = FWRITE | flags; wf->f_type = DTYPE_PIPE; wf->f_pipe = wpipe; wf->f_ops = &pipeops; fd_set_exclose(l, (int)retval[1], (flags & O_CLOEXEC) != 0); rpipe->pipe_peer = wpipe; wpipe->pipe_peer = rpipe; fd_affix(p, rf, (int)retval[0]); fd_affix(p, wf, (int)retval[1]); return (0); free3: fd_abort(p, rf, (int)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(struct pipe *pipe, int size) { void *buffer; /* * Allocate pageable virtual address space. Physical memory is * allocated on demand. */ if (size == PIPE_SIZE && pipe->pipe_kmem != 0) { buffer = (void *)pipe->pipe_kmem; } else { buffer = (void *)uvm_km_alloc(kernel_map, round_page(size), 0, UVM_KMF_PAGEABLE); if (buffer == NULL) return (ENOMEM); atomic_add_int(&amountpipekva, size); } /* 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; return (0); } /* * Initialize and allocate VM and memory for pipe. */ static int pipe_create(struct pipe **pipep, pool_cache_t cache) { struct pipe *pipe; int error; pipe = pool_cache_get(cache, PR_WAITOK); KASSERT(pipe != NULL); *pipep = pipe; error = 0; getnanotime(&pipe->pipe_btime); pipe->pipe_atime = pipe->pipe_mtime = pipe->pipe_btime; pipe->pipe_lock = NULL; if (cache == pipe_rd_cache) { error = pipespace(pipe, PIPE_SIZE); } else { pipe->pipe_buffer.buffer = NULL; pipe->pipe_buffer.size = 0; pipe->pipe_buffer.in = 0; pipe->pipe_buffer.out = 0; pipe->pipe_buffer.cnt = 0; } return error; } /* * Lock a pipe for I/O, blocking other access * Called with pipe spin lock held. */ static int pipelock(struct pipe *pipe, bool catch_p) { int error; KASSERT(mutex_owned(pipe->pipe_lock)); while (pipe->pipe_state & PIPE_LOCKFL) { pipe->pipe_state |= PIPE_LWANT; if (catch_p) { error = cv_wait_sig(&pipe->pipe_lkcv, pipe->pipe_lock); if (error != 0) return error; } else cv_wait(&pipe->pipe_lkcv, pipe->pipe_lock); } pipe->pipe_state |= PIPE_LOCKFL; return 0; } /* * unlock a pipe I/O lock */ static inline void pipeunlock(struct pipe *pipe) { KASSERT(pipe->pipe_state & PIPE_LOCKFL); pipe->pipe_state &= ~PIPE_LOCKFL; if (pipe->pipe_state & PIPE_LWANT) { pipe->pipe_state &= ~PIPE_LWANT; cv_broadcast(&pipe->pipe_lkcv); } } /* * Select/poll wakup. This also sends SIGIO to peer connected to * 'sigpipe' side of pipe. */ static void pipeselwakeup(struct pipe *selp, struct pipe *sigp, int code) { int band; switch (code) { case POLL_IN: band = POLLIN|POLLRDNORM; break; case POLL_OUT: band = POLLOUT|POLLWRNORM; break; case POLL_HUP: band = POLLHUP; break; case POLL_ERR: band = POLLERR; break; default: band = 0; #ifdef DIAGNOSTIC printf("bad siginfo code %d in pipe notification.\n", code); #endif break; } selnotify(&selp->pipe_sel, band, NOTE_SUBMIT); if (sigp == NULL || (sigp->pipe_state & PIPE_ASYNC) == 0) return; fownsignal(sigp->pipe_pgid, SIGIO, code, band, selp); } static int pipe_read(file_t *fp, off_t *offset, struct uio *uio, kauth_cred_t cred, int flags) { struct pipe *rpipe = fp->f_pipe; struct pipebuf *bp = &rpipe->pipe_buffer; kmutex_t *lock = rpipe->pipe_lock; int error; size_t nread = 0; size_t size; size_t ocnt; unsigned int wakeup_state = 0; mutex_enter(lock); ++rpipe->pipe_busy; ocnt = bp->cnt; again: error = pipelock(rpipe, true); 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; mutex_exit(lock); error = uiomove((char *)bp->buffer + bp->out, size, uio); mutex_enter(lock); 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; continue; } #ifndef PIPE_NODIRECT if ((rpipe->pipe_state & PIPE_DIRECTR) != 0) { struct pipemapping * const rmap = &rpipe->pipe_map; /* * Direct copy, bypassing a kernel buffer. */ void *va; u_int gen; KASSERT(rpipe->pipe_state & PIPE_DIRECTW); size = rmap->cnt; if (size > uio->uio_resid) size = uio->uio_resid; va = (char *)rmap->kva + rmap->pos; gen = rmap->egen; mutex_exit(lock); /* * Consume emap and read the data from loaned pages. */ uvm_emap_consume(gen); error = uiomove(va, size, uio); mutex_enter(lock); if (error) break; nread += size; rmap->pos += size; rmap->cnt -= size; if (rmap->cnt == 0) { rpipe->pipe_state &= ~PIPE_DIRECTR; cv_broadcast(&rpipe->pipe_wcv); } continue; } #endif /* * Break if some data was read. */ if (nread > 0) break; /* * Detect EOF condition. * Read returns 0 on EOF, no need to set error. */ if (rpipe->pipe_state & PIPE_EOF) break; /* * Don't block on non-blocking I/O. */ if (fp->f_flag & FNONBLOCK) { 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); /* * Re-check to see if more direct writes are pending. */ if ((rpipe->pipe_state & PIPE_DIRECTR) != 0) goto again; #if 1 /* XXX (dsl) I'm sure these aren't needed here ... */ /* * We want to read more, wake up select/poll. */ pipeselwakeup(rpipe, rpipe->pipe_peer, POLL_OUT); /* * If the "write-side" is blocked, wake it up now. */ cv_broadcast(&rpipe->pipe_wcv); #endif if (wakeup_state & PIPE_RESTART) { error = ERESTART; goto unlocked_error; } /* Now wait until the pipe is filled */ error = cv_wait_sig(&rpipe->pipe_rcv, lock); if (error != 0) goto unlocked_error; wakeup_state = rpipe->pipe_state; goto again; } if (error == 0) getnanotime(&rpipe->pipe_atime); pipeunlock(rpipe); unlocked_error: --rpipe->pipe_busy; if (rpipe->pipe_busy == 0) { rpipe->pipe_state &= ~PIPE_RESTART; cv_broadcast(&rpipe->pipe_draincv); } if (bp->cnt < MINPIPESIZE) { cv_broadcast(&rpipe->pipe_wcv); } /* * 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, POLL_OUT); rpipe->pipe_state &= ~PIPE_SIGNALR; } mutex_exit(lock); return (error); } #ifndef PIPE_NODIRECT /* * Allocate structure for loan transfer. */ static int pipe_loan_alloc(struct pipe *wpipe, int npages) { struct pipemapping * const wmap = &wpipe->pipe_map; const vsize_t len = ptoa(npages); atomic_add_int(&amountpipekva, len); wmap->kva = uvm_km_alloc(kernel_map, len, 0, UVM_KMF_COLORMATCH | UVM_KMF_VAONLY | UVM_KMF_WAITVA); if (wmap->kva == 0) { atomic_add_int(&amountpipekva, -len); return (ENOMEM); } wmap->npages = npages; wmap->pgs = kmem_alloc(npages * sizeof(struct vm_page *), KM_SLEEP); return (0); } /* * Free resources allocated for loan transfer. */ static void pipe_loan_free(struct pipe *wpipe) { struct pipemapping * const wmap = &wpipe->pipe_map; const vsize_t len = ptoa(wmap->npages); uvm_emap_remove(wmap->kva, len); /* XXX */ uvm_km_free(kernel_map, wmap->kva, len, UVM_KMF_VAONLY); wmap->kva = 0; atomic_add_int(&amountpipekva, -len); kmem_free(wmap->pgs, wmap->npages * sizeof(struct vm_page *)); wmap->pgs = NULL; #if 0 wmap->npages = 0; wmap->pos = 0; wmap->cnt = 0; #endif } /* * 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(file_t *fp, struct pipe *wpipe, struct uio *uio) { struct pipemapping * const wmap = &wpipe->pipe_map; kmutex_t * const lock = wpipe->pipe_lock; struct vm_page **pgs; vaddr_t bbase, base, bend; vsize_t blen, bcnt; int error, npages; voff_t bpos; u_int starting_color; KASSERT(mutex_owned(wpipe->pipe_lock)); KASSERT(wmap->cnt == 0); mutex_exit(lock); /* * 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 = atop(blen); starting_color = atop(base) & uvmexp.colormask; /* * Free the old kva if we need more pages than we have * allocated. */ if (wmap->kva != 0 && starting_color + npages > wmap->npages) pipe_loan_free(wpipe); /* Allocate new kva. */ if (wmap->kva == 0) { error = pipe_loan_alloc(wpipe, starting_color + npages); if (error) { mutex_enter(lock); return (error); } } /* Loan the write buffer memory from writer process */ pgs = wmap->pgs + starting_color; error = uvm_loan(&uio->uio_vmspace->vm_map, base, blen, pgs, UVM_LOAN_TOPAGE); if (error) { pipe_loan_free(wpipe); mutex_enter(lock); return (ENOMEM); /* so that caller fallback to ordinary write */ } /* Enter the loaned pages to KVA, produce new emap generation number. */ uvm_emap_enter(wmap->kva + ptoa(starting_color), pgs, npages); wmap->egen = uvm_emap_produce(); /* Now we can put the pipe in direct write mode */ wmap->pos = bpos + ptoa(starting_color); wmap->cnt = bcnt; /* * But before we can let someone do a direct read, we * have to wait until the pipe is drained. Release the * pipe lock while we wait. */ mutex_enter(lock); wpipe->pipe_state |= PIPE_DIRECTW; pipeunlock(wpipe); while (error == 0 && wpipe->pipe_buffer.cnt > 0) { cv_broadcast(&wpipe->pipe_rcv); error = cv_wait_sig(&wpipe->pipe_wcv, lock); 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)) { cv_broadcast(&wpipe->pipe_rcv); pipeselwakeup(wpipe, wpipe, POLL_IN); error = cv_wait_sig(&wpipe->pipe_wcv, lock); 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, false); mutex_exit(lock); if (pgs != NULL) { /* XXX: uvm_emap_remove */ uvm_unloan(pgs, npages, UVM_LOAN_TOPAGE); } if (error || amountpipekva > maxpipekva) pipe_loan_free(wpipe); mutex_enter(lock); if (error) { pipeselwakeup(wpipe, wpipe, POLL_ERR); /* * 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 (wmap->cnt == bcnt) { wmap->cnt = 0; cv_broadcast(&wpipe->pipe_wcv); return (error); } bcnt -= wpipe->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--; } wmap->cnt = 0; return (error); } #endif /* !PIPE_NODIRECT */ static int pipe_write(file_t *fp, off_t *offset, struct uio *uio, kauth_cred_t cred, int flags) { struct pipe *wpipe, *rpipe; struct pipebuf *bp; kmutex_t *lock; int error; unsigned int wakeup_state = 0; /* We want to write to our peer */ rpipe = fp->f_pipe; lock = rpipe->pipe_lock; error = 0; mutex_enter(lock); wpipe = rpipe->pipe_peer; /* * Detect loss of pipe read side, issue SIGPIPE if lost. */ if (wpipe == NULL || (wpipe->pipe_state & PIPE_EOF) != 0) { mutex_exit(lock); return EPIPE; } ++wpipe->pipe_busy; /* Aquire the long-term pipe lock */ if ((error = pipelock(wpipe, true)) != 0) { --wpipe->pipe_busy; if (wpipe->pipe_busy == 0) { wpipe->pipe_state &= ~PIPE_RESTART; cv_broadcast(&wpipe->pipe_draincv); } mutex_exit(lock); 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) atomic_inc_uint(&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) { cv_broadcast(&wpipe->pipe_rcv); pipeunlock(wpipe); error = cv_wait_sig(&wpipe->pipe_wcv, lock); (void)pipelock(wpipe, false); 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 && (wmap->kva || (amountpipekva < limitpipekva))) { error = pipe_direct_write(fp, wpipe, uio); /* * Break out if error occurred, 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 */ mutex_exit(lock); error = uiomove((char *)bp->buffer + bp->in, segsize, uio); if (error == 0 && segsize < size) { /* * Transfer remaining part now, to * support atomic writes. Wraparound * happened. */ KASSERT(bp->in + segsize == bp->size); error = uiomove(bp->buffer, size - segsize, uio); } mutex_enter(lock); if (error) break; bp->in += size; if (bp->in >= bp->size) { KASSERT(bp->in == size - segsize + bp->size); bp->in = size - segsize; } bp->cnt += size; KASSERT(bp->cnt <= bp->size); wakeup_state = 0; } else { /* * If the "read-side" has been blocked, wake it up now. */ cv_broadcast(&wpipe->pipe_rcv); /* * 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, POLL_IN); if (wakeup_state & PIPE_RESTART) { error = ERESTART; break; } /* * If read side wants to go away, we just issue a signal * to ourselves. */ if (wpipe->pipe_state & PIPE_EOF) { error = EPIPE; break; } pipeunlock(wpipe); error = cv_wait_sig(&wpipe->pipe_wcv, lock); (void)pipelock(wpipe, false); if (error != 0) break; wakeup_state = wpipe->pipe_state; } } --wpipe->pipe_busy; if (wpipe->pipe_busy == 0) { wpipe->pipe_state &= ~PIPE_RESTART; cv_broadcast(&wpipe->pipe_draincv); } if (bp->cnt > 0) { cv_broadcast(&wpipe->pipe_rcv); } /* * Don't return EPIPE if I/O was successful */ if (error == EPIPE && bp->cnt == 0 && uio->uio_resid == 0) error = 0; if (error == 0) getnanotime(&wpipe->pipe_mtime); /* * We have something to offer, wake up select/poll. * wmap->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, POLL_IN); /* * Arrange for next read(2) to do a signal. */ wpipe->pipe_state |= PIPE_SIGNALR; pipeunlock(wpipe); mutex_exit(lock); return (error); } /* * We implement a very minimal set of ioctls for compatibility with sockets. */ int pipe_ioctl(file_t *fp, u_long cmd, void *data) { struct pipe *pipe = fp->f_pipe; kmutex_t *lock = pipe->pipe_lock; switch (cmd) { case FIONBIO: return (0); case FIOASYNC: mutex_enter(lock); if (*(int *)data) { pipe->pipe_state |= PIPE_ASYNC; } else { pipe->pipe_state &= ~PIPE_ASYNC; } mutex_exit(lock); return (0); case FIONREAD: mutex_enter(lock); #ifndef PIPE_NODIRECT if (pipe->pipe_state & PIPE_DIRECTW) *(int *)data = pipe->pipe_map.cnt; else #endif *(int *)data = pipe->pipe_buffer.cnt; mutex_exit(lock); return (0); case FIONWRITE: /* Look at other side */ mutex_enter(lock); pipe = pipe->pipe_peer; if (pipe == NULL) *(int *)data = 0; #ifndef PIPE_NODIRECT else if (pipe->pipe_state & PIPE_DIRECTW) *(int *)data = pipe->pipe_map.cnt; else #endif *(int *)data = pipe->pipe_buffer.cnt; mutex_exit(lock); return (0); case FIONSPACE: /* Look at other side */ mutex_enter(lock); pipe = pipe->pipe_peer; if (pipe == NULL) *(int *)data = 0; else #ifndef PIPE_NODIRECT /* * If we're in direct-mode, we don't really have a * send queue, and any other write will block. Thus * zero seems like the best answer. */ if (pipe->pipe_state & PIPE_DIRECTW) *(int *)data = 0; else #endif *(int *)data = pipe->pipe_buffer.size - pipe->pipe_buffer.cnt; mutex_exit(lock); return (0); case TIOCSPGRP: case FIOSETOWN: return fsetown(&pipe->pipe_pgid, cmd, data); case TIOCGPGRP: case FIOGETOWN: return fgetown(pipe->pipe_pgid, cmd, data); } return (EPASSTHROUGH); } int pipe_poll(file_t *fp, int events) { struct pipe *rpipe = fp->f_pipe; struct pipe *wpipe; int eof = 0; int revents = 0; mutex_enter(rpipe->pipe_lock); wpipe = rpipe->pipe_peer; 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); 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); } if (wpipe == NULL || eof) revents |= POLLHUP; if (revents == 0) { if (events & (POLLIN | POLLRDNORM)) selrecord(curlwp, &rpipe->pipe_sel); if (events & (POLLOUT | POLLWRNORM)) selrecord(curlwp, &wpipe->pipe_sel); } mutex_exit(rpipe->pipe_lock); return (revents); } static int pipe_stat(file_t *fp, struct stat *ub) { struct pipe *pipe = fp->f_pipe; mutex_enter(pipe->pipe_lock); memset(ub, 0, sizeof(*ub)); ub->st_mode = S_IFIFO | S_IRUSR | S_IWUSR; ub->st_blksize = pipe->pipe_buffer.size; if (ub->st_blksize == 0 && pipe->pipe_peer) ub->st_blksize = pipe->pipe_peer->pipe_buffer.size; ub->st_size = pipe->pipe_buffer.cnt; ub->st_blocks = (ub->st_size) ? 1 : 0; ub->st_atimespec = pipe->pipe_atime; ub->st_mtimespec = pipe->pipe_mtime; ub->st_ctimespec = ub->st_birthtimespec = pipe->pipe_btime; ub->st_uid = kauth_cred_geteuid(fp->f_cred); ub->st_gid = kauth_cred_getegid(fp->f_cred); /* * Left as 0: st_dev, st_ino, st_nlink, st_rdev, st_flags, st_gen. * XXX (st_dev, st_ino) should be unique. */ mutex_exit(pipe->pipe_lock); return 0; } static int pipe_close(file_t *fp) { struct pipe *pipe = fp->f_pipe; fp->f_pipe = NULL; pipeclose(pipe); return (0); } static void pipe_restart(file_t *fp) { struct pipe *pipe = fp->f_pipe; /* * Unblock blocked reads/writes in order to allow close() to complete. * System calls return ERESTART so that the fd is revalidated. * (Partial writes return the transfer length.) */ mutex_enter(pipe->pipe_lock); pipe->pipe_state |= PIPE_RESTART; /* Wakeup both cvs, maybe we only need one, but maybe there are some * other paths where wakeup is needed, and it saves deciding which! */ cv_broadcast(&pipe->pipe_rcv); cv_broadcast(&pipe->pipe_wcv); mutex_exit(pipe->pipe_lock); } static void pipe_free_kmem(struct pipe *pipe) { if (pipe->pipe_buffer.buffer != NULL) { if (pipe->pipe_buffer.size > PIPE_SIZE) { atomic_dec_uint(&nbigpipe); } if (pipe->pipe_buffer.buffer != (void *)pipe->pipe_kmem) { uvm_km_free(kernel_map, (vaddr_t)pipe->pipe_buffer.buffer, pipe->pipe_buffer.size, UVM_KMF_PAGEABLE); atomic_add_int(&amountpipekva, -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.pos = 0; pipe->pipe_map.npages = 0; } #endif /* !PIPE_NODIRECT */ } /* * Shutdown the pipe. */ static void pipeclose(struct pipe *pipe) { kmutex_t *lock; struct pipe *ppipe; if (pipe == NULL) return; KASSERT(cv_is_valid(&pipe->pipe_rcv)); KASSERT(cv_is_valid(&pipe->pipe_wcv)); KASSERT(cv_is_valid(&pipe->pipe_draincv)); KASSERT(cv_is_valid(&pipe->pipe_lkcv)); lock = pipe->pipe_lock; if (lock == NULL) /* Must have failed during create */ goto free_resources; mutex_enter(lock); pipeselwakeup(pipe, pipe, POLL_HUP); /* * If the other side is blocked, wake it up saying that * we want to close it down. */ pipe->pipe_state |= PIPE_EOF; if (pipe->pipe_busy) { while (pipe->pipe_busy) { cv_broadcast(&pipe->pipe_wcv); cv_wait_sig(&pipe->pipe_draincv, lock); } } /* * Disconnect from peer. */ if ((ppipe = pipe->pipe_peer) != NULL) { pipeselwakeup(ppipe, ppipe, POLL_HUP); ppipe->pipe_state |= PIPE_EOF; cv_broadcast(&ppipe->pipe_rcv); ppipe->pipe_peer = NULL; } /* * Any knote objects still left in the list are * the one attached by peer. Since no one will * traverse this list, we just clear it. */ SLIST_INIT(&pipe->pipe_sel.sel_klist); KASSERT((pipe->pipe_state & PIPE_LOCKFL) == 0); mutex_exit(lock); mutex_obj_free(lock); /* * Free resources. */ free_resources: pipe->pipe_pgid = 0; pipe->pipe_state = PIPE_SIGNALR; pipe->pipe_peer = NULL; pipe->pipe_lock = NULL; pipe_free_kmem(pipe); if (pipe->pipe_kmem != 0) { pool_cache_put(pipe_rd_cache, pipe); } else { pool_cache_put(pipe_wr_cache, pipe); } } static void filt_pipedetach(struct knote *kn) { struct pipe *pipe; kmutex_t *lock; pipe = ((file_t *)kn->kn_obj)->f_pipe; lock = pipe->pipe_lock; mutex_enter(lock); switch(kn->kn_filter) { case EVFILT_WRITE: /* Need the peer structure, not our own. */ pipe = pipe->pipe_peer; /* If reader end already closed, just return. */ if (pipe == NULL) { mutex_exit(lock); return; } break; default: /* Nothing to do. */ break; } KASSERT(kn->kn_hook == pipe); SLIST_REMOVE(&pipe->pipe_sel.sel_klist, kn, knote, kn_selnext); mutex_exit(lock); } static int filt_piperead(struct knote *kn, long hint) { struct pipe *rpipe = ((file_t *)kn->kn_obj)->f_pipe; struct pipe *wpipe; if ((hint & NOTE_SUBMIT) == 0) { mutex_enter(rpipe->pipe_lock); } wpipe = rpipe->pipe_peer; kn->kn_data = rpipe->pipe_buffer.cnt; if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW)) kn->kn_data = rpipe->pipe_map.cnt; if ((rpipe->pipe_state & PIPE_EOF) || (wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { kn->kn_flags |= EV_EOF; if ((hint & NOTE_SUBMIT) == 0) { mutex_exit(rpipe->pipe_lock); } return (1); } if ((hint & NOTE_SUBMIT) == 0) { mutex_exit(rpipe->pipe_lock); } return (kn->kn_data > 0); } static int filt_pipewrite(struct knote *kn, long hint) { struct pipe *rpipe = ((file_t *)kn->kn_obj)->f_pipe; struct pipe *wpipe; if ((hint & NOTE_SUBMIT) == 0) { mutex_enter(rpipe->pipe_lock); } wpipe = rpipe->pipe_peer; if ((wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) { kn->kn_data = 0; kn->kn_flags |= EV_EOF; if ((hint & NOTE_SUBMIT) == 0) { mutex_exit(rpipe->pipe_lock); } return (1); } kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt; if (wpipe->pipe_state & PIPE_DIRECTW) kn->kn_data = 0; if ((hint & NOTE_SUBMIT) == 0) { mutex_exit(rpipe->pipe_lock); } 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 }; static int pipe_kqfilter(file_t *fp, struct knote *kn) { struct pipe *pipe; kmutex_t *lock; pipe = ((file_t *)kn->kn_obj)->f_pipe; lock = pipe->pipe_lock; mutex_enter(lock); switch (kn->kn_filter) { case EVFILT_READ: kn->kn_fop = &pipe_rfiltops; break; case EVFILT_WRITE: kn->kn_fop = &pipe_wfiltops; pipe = pipe->pipe_peer; if (pipe == NULL) { /* Other end of pipe has been closed. */ mutex_exit(lock); return (EBADF); } break; default: mutex_exit(lock); return (EINVAL); } kn->kn_hook = pipe; SLIST_INSERT_HEAD(&pipe->pipe_sel.sel_klist, kn, kn_selnext); mutex_exit(lock); return (0); } /* * Handle pipe sysctls. */ SYSCTL_SETUP(sysctl_kern_pipe_setup, "sysctl kern.pipe subtree setup") { sysctl_createv(clog, 0, NULL, NULL, CTLFLAG_PERMANENT, CTLTYPE_NODE, "pipe", SYSCTL_DESCR("Pipe settings"), NULL, 0, NULL, 0, CTL_KERN, KERN_PIPE, CTL_EOL); sysctl_createv(clog, 0, NULL, NULL, CTLFLAG_PERMANENT|CTLFLAG_READWRITE, CTLTYPE_INT, "maxkvasz", SYSCTL_DESCR("Maximum amount of kernel memory to be " "used for pipes"), NULL, 0, &maxpipekva, 0, CTL_KERN, KERN_PIPE, KERN_PIPE_MAXKVASZ, CTL_EOL); sysctl_createv(clog, 0, NULL, NULL, CTLFLAG_PERMANENT|CTLFLAG_READWRITE, CTLTYPE_INT, "maxloankvasz", SYSCTL_DESCR("Limit for direct transfers via page loan"), NULL, 0, &limitpipekva, 0, CTL_KERN, KERN_PIPE, KERN_PIPE_LIMITKVA, CTL_EOL); sysctl_createv(clog, 0, NULL, NULL, CTLFLAG_PERMANENT|CTLFLAG_READWRITE, CTLTYPE_INT, "maxbigpipes", SYSCTL_DESCR("Maximum number of \"big\" pipes"), NULL, 0, &maxbigpipes, 0, CTL_KERN, KERN_PIPE, KERN_PIPE_MAXBIGPIPES, CTL_EOL); sysctl_createv(clog, 0, NULL, NULL, CTLFLAG_PERMANENT, CTLTYPE_INT, "nbigpipes", SYSCTL_DESCR("Number of \"big\" pipes"), NULL, 0, &nbigpipe, 0, CTL_KERN, KERN_PIPE, KERN_PIPE_NBIGPIPES, CTL_EOL); sysctl_createv(clog, 0, NULL, NULL, CTLFLAG_PERMANENT, CTLTYPE_INT, "kvasize", SYSCTL_DESCR("Amount of kernel memory consumed by pipe " "buffers"), NULL, 0, &amountpipekva, 0, CTL_KERN, KERN_PIPE, KERN_PIPE_KVASIZE, CTL_EOL); }