340 lines
8.6 KiB
C
340 lines
8.6 KiB
C
![]() |
/*-
|
||
|
* Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
|
||
|
* 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 <sys/cdefs.h>
|
||
|
__FBSDID("$FreeBSD$");
|
||
|
|
||
|
#include <sys/param.h>
|
||
|
#include <sys/kernel.h>
|
||
|
#include <sys/lock.h>
|
||
|
#include <sys/queue.h>
|
||
|
#include <sys/systm.h>
|
||
|
#include <sys/tty.h>
|
||
|
#include <sys/uio.h>
|
||
|
|
||
|
#include <vm/uma.h>
|
||
|
|
||
|
/*
|
||
|
* 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;
|
||
|
}
|
||
|
|
||
|
void
|
||
|
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);
|
||
|
|
||
|
TTYOUTQ_INSERT_TAIL(to, tob);
|
||
|
}
|
||
|
}
|
||
|
|
||
|
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;
|
||
|
|
||
|
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);
|