/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2008 Ed Schouten * All rights reserved. * * Portions of this software were developed under sponsorship from Snow * B.V., the Netherlands. * * 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 AUTHOR 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 AUTHOR 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. */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include /* * TTY output queue buffering. * * The previous design of the TTY layer offered the so-called clists. * These clists were used for both the input queues and the output * queue. We don't use certain features on the output side, like quoting * bits for parity marking and such. This mechanism is similar to the * old clists, but only contains the features we need to buffer the * output. */ struct ttyoutq_block { struct ttyoutq_block *tob_next; char tob_data[TTYOUTQ_DATASIZE]; }; static uma_zone_t ttyoutq_zone; #define TTYOUTQ_INSERT_TAIL(to, tob) do { \ if (to->to_end == 0) { \ tob->tob_next = to->to_firstblock; \ to->to_firstblock = tob; \ } else { \ tob->tob_next = to->to_lastblock->tob_next; \ to->to_lastblock->tob_next = tob; \ } \ to->to_nblocks++; \ } while (0) #define TTYOUTQ_REMOVE_HEAD(to) do { \ to->to_firstblock = to->to_firstblock->tob_next; \ to->to_nblocks--; \ } while (0) #define TTYOUTQ_RECYCLE(to, tob) do { \ if (to->to_quota <= to->to_nblocks) \ uma_zfree(ttyoutq_zone, tob); \ else \ TTYOUTQ_INSERT_TAIL(to, tob); \ } while(0) void ttyoutq_flush(struct ttyoutq *to) { to->to_begin = 0; to->to_end = 0; } int ttyoutq_setsize(struct ttyoutq *to, struct tty *tp, size_t size) { struct ttyoutq_block *tob; to->to_quota = howmany(size, TTYOUTQ_DATASIZE); while (to->to_quota > to->to_nblocks) { /* * List is getting bigger. * Add new blocks to the tail of the list. * * We must unlock the TTY temporarily, because we need * to allocate memory. This won't be a problem, because * in the worst case, another thread ends up here, which * may cause us to allocate too many blocks, but this * will be caught by the loop below. */ tty_unlock(tp); tob = uma_zalloc(ttyoutq_zone, M_WAITOK); tty_lock(tp); if (tty_gone(tp)) { uma_zfree(ttyoutq_zone, tob); return (ENXIO); } TTYOUTQ_INSERT_TAIL(to, tob); } return (0); } void ttyoutq_free(struct ttyoutq *to) { struct ttyoutq_block *tob; ttyoutq_flush(to); to->to_quota = 0; while ((tob = to->to_firstblock) != NULL) { TTYOUTQ_REMOVE_HEAD(to); uma_zfree(ttyoutq_zone, tob); } MPASS(to->to_nblocks == 0); } size_t ttyoutq_read(struct ttyoutq *to, void *buf, size_t len) { char *cbuf = buf; while (len > 0) { struct ttyoutq_block *tob; size_t cbegin, cend, clen; /* See if there still is data. */ if (to->to_begin == to->to_end) break; tob = to->to_firstblock; if (tob == NULL) break; /* * The end address should be the lowest of these three: * - The write pointer * - The blocksize - we can't read beyond the block * - The end address if we could perform the full read */ cbegin = to->to_begin; cend = MIN(MIN(to->to_end, to->to_begin + len), TTYOUTQ_DATASIZE); clen = cend - cbegin; /* Copy the data out of the buffers. */ memcpy(cbuf, tob->tob_data + cbegin, clen); cbuf += clen; len -= clen; if (cend == to->to_end) { /* Read the complete queue. */ to->to_begin = 0; to->to_end = 0; } else if (cend == TTYOUTQ_DATASIZE) { /* Read the block until the end. */ TTYOUTQ_REMOVE_HEAD(to); to->to_begin = 0; to->to_end -= TTYOUTQ_DATASIZE; TTYOUTQ_RECYCLE(to, tob); } else { /* Read the block partially. */ to->to_begin += clen; } } return (cbuf - (char *)buf); } /* * An optimized version of ttyoutq_read() which can be used in pseudo * TTY drivers to directly copy data from the outq to userspace, instead * of buffering it. * * We can only copy data directly if we need to read the entire block * back to the user, because we temporarily remove the block from the * queue. Otherwise we need to copy it to a temporary buffer first, to * make sure data remains in the correct order. */ int ttyoutq_read_uio(struct ttyoutq *to, struct tty *tp, struct uio *uio) { while (uio->uio_resid > 0) { int error; struct ttyoutq_block *tob; size_t cbegin, cend, clen; /* See if there still is data. */ if (to->to_begin == to->to_end) return (0); tob = to->to_firstblock; if (tob == NULL) return (0); /* * The end address should be the lowest of these three: * - The write pointer * - The blocksize - we can't read beyond the block * - The end address if we could perform the full read */ cbegin = to->to_begin; cend = MIN(MIN(to->to_end, to->to_begin + uio->uio_resid), TTYOUTQ_DATASIZE); clen = cend - cbegin; /* * We can prevent buffering in some cases: * - We need to read the block until the end. * - We don't need to read the block until the end, but * there is no data beyond it, which allows us to move * the write pointer to a new block. */ if (cend == TTYOUTQ_DATASIZE || cend == to->to_end) { /* * Fast path: zero copy. Remove the first block, * so we can unlock the TTY temporarily. */ TTYOUTQ_REMOVE_HEAD(to); to->to_begin = 0; if (to->to_end <= TTYOUTQ_DATASIZE) to->to_end = 0; else to->to_end -= TTYOUTQ_DATASIZE; /* Temporary unlock and copy the data to userspace. */ tty_unlock(tp); error = uiomove(tob->tob_data + cbegin, clen, uio); tty_lock(tp); /* Block can now be readded to the list. */ TTYOUTQ_RECYCLE(to, tob); } else { char ob[TTYOUTQ_DATASIZE - 1]; /* * Slow path: store data in a temporary buffer. */ memcpy(ob, tob->tob_data + cbegin, clen); to->to_begin += clen; MPASS(to->to_begin < TTYOUTQ_DATASIZE); /* Temporary unlock and copy the data to userspace. */ tty_unlock(tp); error = uiomove(ob, clen, uio); tty_lock(tp); } if (error != 0) return (error); } return (0); } size_t ttyoutq_write(struct ttyoutq *to, const void *buf, size_t nbytes) { const char *cbuf = buf; struct ttyoutq_block *tob; unsigned int boff; size_t l; while (nbytes > 0) { boff = to->to_end % TTYOUTQ_DATASIZE; if (to->to_end == 0) { /* First time we're being used or drained. */ MPASS(to->to_begin == 0); tob = to->to_firstblock; if (tob == NULL) { /* Queue has no blocks. */ break; } to->to_lastblock = tob; } else if (boff == 0) { /* We reached the end of this block on last write. */ tob = to->to_lastblock->tob_next; if (tob == NULL) { /* We've reached the watermark. */ break; } to->to_lastblock = tob; } else { tob = to->to_lastblock; } /* Don't copy more than was requested. */ l = MIN(nbytes, TTYOUTQ_DATASIZE - boff); MPASS(l > 0); memcpy(tob->tob_data + boff, cbuf, l); cbuf += l; nbytes -= l; to->to_end += l; } return (cbuf - (const char *)buf); } int ttyoutq_write_nofrag(struct ttyoutq *to, const void *buf, size_t nbytes) { size_t ret __unused; if (ttyoutq_bytesleft(to) < nbytes) return (-1); /* We should always be able to write it back. */ ret = ttyoutq_write(to, buf, nbytes); MPASS(ret == nbytes); return (0); } static void ttyoutq_startup(void *dummy) { ttyoutq_zone = uma_zcreate("ttyoutq", sizeof(struct ttyoutq_block), NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); } SYSINIT(ttyoutq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyoutq_startup, NULL);