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Fix some edge cases in the TTY queues:

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- In the current design, when a TTY decreases its baud rate, it tries to
  shrink the queues. This may not always be possible, because it will
  not free any blocks that are still filled with data.

  Change the TTY queues to store a `quota' value as well, which means it
  will not free any blocks when changing the baud rate, but when placing
  blocks back into the queue. When the amount of blocks exceeds the
  quota, they get freed.

  It also fixes some edge cases, where TIOCSETA during read()/
  write()-calls could actually make the queue a tiny bit bigger than in
  normal cases.

- Don't leak blocks of memory when calling TIOCSETA when the device
  driver abandons the TTY while allocating memory.

- Create ttyoutq_init() and ttyinq_init() to initialize the queues,
  instead of initializing them by hand. The new TTY snoop driver also
  creates an outq, so it's good to have a proper interface to do this.

Obtained from:	//depot/projects/mpsafetty/...
This commit is contained in:
Ed Schouten 2008-08-30 09:18:27 +00:00
parent cec048ddf0
commit 74bb9e3ad5
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=182471
4 changed files with 81 additions and 107 deletions
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32
sys/kern/tty.c
View File

@ -112,23 +112,6 @@ tty_watermarks(struct tty *tp)
tp->t_outlow = (ttyoutq_getsize(&tp->t_outq) * 9) / 10;
}
static void
tty_freebuffers(struct tty *tp)
{
/* Destroy input buffers. */
ttyinq_flush(&tp->t_inq);
ttyinq_setsize(&tp->t_inq, NULL, 0);
MPASS(ttyinq_getsize(&tp->t_inq) == 0);
tp->t_inlow = 0;
/* Destroy output buffers. */
ttyoutq_flush(&tp->t_outq);
ttyoutq_setsize(&tp->t_outq, NULL, 0);
MPASS(ttyoutq_getsize(&tp->t_outq) == 0);
tp->t_outlow = 0;
}
static int
tty_drain(struct tty *tp)
{
@ -199,7 +182,10 @@ ttydev_leave(struct tty *tp)
ttydisc_close(tp);
/* Destroy associated buffers already. */
tty_freebuffers(tp);
ttyinq_free(&tp->t_inq);
tp->t_inlow = 0;
ttyoutq_free(&tp->t_outq);
tp->t_outlow = 0;
knlist_clear(&tp->t_inpoll.si_note, 1);
knlist_clear(&tp->t_outpoll.si_note, 1);
@ -875,8 +861,8 @@ tty_alloc(struct ttydevsw *tsw, void *sc, struct mtx *mutex)
cv_init(&tp->t_bgwait, "tty background");
cv_init(&tp->t_dcdwait, "tty dcd");
TAILQ_INIT(&tp->t_inq.ti_list);
STAILQ_INIT(&tp->t_outq.to_list);
ttyinq_init(&tp->t_inq);
ttyoutq_init(&tp->t_outq);
/* Allow drivers to use a custom mutex to lock the TTY. */
if (mutex != NULL) {
@ -907,6 +893,10 @@ tty_dealloc(void *arg)
tty_list_count--;
sx_xunlock(&tty_list_sx);
/* Make sure we haven't leaked buffers. */
MPASS(ttyinq_getsize(&tp->t_inq) == 0);
MPASS(ttyoutq_getsize(&tp->t_outq) == 0);
knlist_destroy(&tp->t_inpoll.si_note);
knlist_destroy(&tp->t_outpoll.si_note);
@ -935,8 +925,6 @@ tty_rel_free(struct tty *tp)
return;
}
tty_freebuffers(tp);
/* TTY can be deallocated. */
dev = tp->t_dev;
tp->t_dev = NULL;

67
sys/kern/tty_inq.c
View File

@ -89,12 +89,11 @@ static uma_zone_t ttyinq_zone;
void
ttyinq_setsize(struct ttyinq *ti, struct tty *tp, size_t size)
{
unsigned int nblocks;
struct ttyinq_block *tib;
nblocks = howmany(size, TTYINQ_DATASIZE);
ti->ti_quota = howmany(size, TTYINQ_DATASIZE);
while (nblocks > ti->ti_nblocks) {
while (ti->ti_quota > ti->ti_nblocks) {
/*
* List is getting bigger.
* Add new blocks to the tail of the list.
@ -109,36 +108,26 @@ ttyinq_setsize(struct ttyinq *ti, struct tty *tp, size_t size)
tib = uma_zalloc(ttyinq_zone, M_WAITOK);
tty_lock(tp);
if (tty_gone(tp))
return;
TAILQ_INSERT_TAIL(&ti->ti_list, tib, tib_list);
ti->ti_nblocks++;
}
}
while (nblocks < ti->ti_nblocks) {
/*
* List is getting smaller. Remove unused blocks at the
* end. This means we cannot guarantee this routine
* shrinks buffers properly, when we need to reclaim
* more space than there is available.
*
* XXX TODO: Two solutions here:
* - Throw data away
* - Temporarily hit the watermark until enough data has
* been flushed, so we can remove the blocks.
*/
void
ttyinq_free(struct ttyinq *ti)
{
struct ttyinq_block *tib;
ttyinq_flush(ti);
ti->ti_quota = 0;
if (ti->ti_end == 0)
tib = TAILQ_FIRST(&ti->ti_list);
else
tib = TAILQ_NEXT(ti->ti_lastblock, tib_list);
if (tib == NULL)
break;
while ((tib = TAILQ_FIRST(&ti->ti_list)) != NULL) {
TAILQ_REMOVE(&ti->ti_list, tib, tib_list);
uma_zfree(ttyinq_zone, tib);
ti->ti_nblocks--;
}
MPASS(ti->ti_nblocks == 0);
}
int
@ -217,21 +206,13 @@ ttyinq_read_uio(struct ttyinq *ti, struct tty *tp, struct uio *uio,
clen - flen, uio);
tty_lock(tp);
if (tty_gone(tp)) {
/* Something went bad - discard this block. */
uma_zfree(ttyinq_zone, tib);
return (ENXIO);
}
/* Block can now be readded to the list. */
/*
* XXX: we could remove the blocks here when the
* queue was shrunk, but still in use. See
* ttyinq_setsize().
*/
TAILQ_INSERT_TAIL(&ti->ti_list, tib, tib_list);
ti->ti_nblocks++;
if (error != 0)
return (error);
if (ti->ti_quota <= ti->ti_nblocks) {
uma_zfree(ttyinq_zone, tib);
} else {
TAILQ_INSERT_TAIL(&ti->ti_list, tib, tib_list);
ti->ti_nblocks++;
}
} else {
char ob[TTYINQ_DATASIZE - 1];
atomic_add_long(&ttyinq_nslow, 1);
@ -247,12 +228,12 @@ ttyinq_read_uio(struct ttyinq *ti, struct tty *tp, struct uio *uio,
tty_unlock(tp);
error = uiomove(ob, clen - flen, uio);
tty_lock(tp);
if (error != 0)
return (error);
if (tty_gone(tp))
return (ENXIO);
}
if (error != 0)
return (error);
if (tty_gone(tp))
return (ENXIO);
}
return (0);

71
sys/kern/tty_outq.c
View File

@ -78,12 +78,11 @@ ttyoutq_flush(struct ttyoutq *to)
void
ttyoutq_setsize(struct ttyoutq *to, struct tty *tp, size_t size)
{
unsigned int nblocks;
struct ttyoutq_block *tob;
nblocks = howmany(size, TTYOUTQ_DATASIZE);
to->to_quota = howmany(size, TTYOUTQ_DATASIZE);
while (nblocks > to->to_nblocks) {
while (to->to_quota > to->to_nblocks) {
/*
* List is getting bigger.
* Add new blocks to the tail of the list.
@ -98,40 +97,26 @@ ttyoutq_setsize(struct ttyoutq *to, struct tty *tp, size_t size)
tob = uma_zalloc(ttyoutq_zone, M_WAITOK);
tty_lock(tp);
if (tty_gone(tp))
return;
STAILQ_INSERT_TAIL(&to->to_list, tob, tob_list);
to->to_nblocks++;
}
}
while (nblocks < to->to_nblocks) {
/*
* List is getting smaller. Remove unused blocks at the
* end. This means we cannot guarantee this routine
* shrinks buffers properly, when we need to reclaim
* more space than there is available.
*
* XXX TODO: Two solutions here:
* - Throw data away
* - Temporarily hit the watermark until enough data has
* been flushed, so we can remove the blocks.
*/
void
ttyoutq_free(struct ttyoutq *to)
{
struct ttyoutq_block *tob;
ttyoutq_flush(to);
to->to_quota = 0;
if (to->to_end == 0) {
tob = STAILQ_FIRST(&to->to_list);
if (tob == NULL)
break;
STAILQ_REMOVE_HEAD(&to->to_list, tob_list);
} else {
tob = STAILQ_NEXT(to->to_lastblock, tob_list);
if (tob == NULL)
break;
STAILQ_REMOVE_NEXT(&to->to_list, to->to_lastblock, tob_list);
}
while ((tob = STAILQ_FIRST(&to->to_list)) != NULL) {
STAILQ_REMOVE_HEAD(&to->to_list, tob_list);
uma_zfree(ttyoutq_zone, tob);
to->to_nblocks--;
}
MPASS(to->to_nblocks == 0);
}
size_t
@ -164,7 +149,12 @@ ttyoutq_read(struct ttyoutq *to, void *buf, size_t len)
if (cend == TTYOUTQ_DATASIZE || cend == to->to_end) {
/* Read the block until the end. */
STAILQ_REMOVE_HEAD(&to->to_list, tob_list);
STAILQ_INSERT_TAIL(&to->to_list, tob, tob_list);
if (to->to_quota < to->to_nblocks) {
uma_zfree(ttyoutq_zone, tob);
to->to_nblocks--;
} else {
STAILQ_INSERT_TAIL(&to->to_list, tob, tob_list);
}
to->to_begin = 0;
if (to->to_end <= TTYOUTQ_DATASIZE) {
to->to_end = 0;
@ -251,15 +241,12 @@ ttyoutq_read_uio(struct ttyoutq *to, struct tty *tp, struct uio *uio)
tty_lock(tp);
/* Block can now be readded to the list. */
/*
* XXX: we could remove the blocks here when the
* queue was shrunk, but still in use. See
* ttyoutq_setsize().
*/
STAILQ_INSERT_TAIL(&to->to_list, tob, tob_list);
to->to_nblocks++;
if (error != 0)
return (error);
if (to->to_quota <= to->to_nblocks) {
uma_zfree(ttyoutq_zone, tob);
} else {
STAILQ_INSERT_TAIL(&to->to_list, tob, tob_list);
to->to_nblocks++;
}
} else {
char ob[TTYOUTQ_DATASIZE - 1];
atomic_add_long(&ttyoutq_nslow, 1);
@ -275,10 +262,10 @@ ttyoutq_read_uio(struct ttyoutq *to, struct tty *tp, struct uio *uio)
tty_unlock(tp);
error = uiomove(ob, clen, uio);
tty_lock(tp);
if (error != 0)
return (error);
}
if (error != 0)
return (error);
}
return (0);

18
sys/sys/ttyqueue.h
View File

@ -52,6 +52,7 @@ struct ttyinq {
unsigned int ti_reprint;
unsigned int ti_end;
unsigned int ti_nblocks;
unsigned int ti_quota;
};
#define TTYINQ_DATASIZE 128
@ -62,12 +63,14 @@ struct ttyoutq {
unsigned int to_begin;
unsigned int to_end;
unsigned int to_nblocks;
unsigned int to_quota;
};
#define TTYOUTQ_DATASIZE (256 - sizeof(STAILQ_ENTRY(ttyoutq_block)))
#ifdef _KERNEL
/* Input queue handling routines. */
void ttyinq_setsize(struct ttyinq *, struct tty *, size_t);
void ttyinq_free(struct ttyinq *);
int ttyinq_read_uio(struct ttyinq *, struct tty *, struct uio *,
size_t, size_t);
size_t ttyinq_write(struct ttyinq *, const void *, size_t, int);
@ -80,6 +83,13 @@ void ttyinq_unputchar(struct ttyinq *);
void ttyinq_reprintpos_set(struct ttyinq *);
void ttyinq_reprintpos_reset(struct ttyinq *);
static __inline void
ttyinq_init(struct ttyinq *ti)
{
TAILQ_INIT(&ti->ti_list);
}
static __inline size_t
ttyinq_getsize(struct ttyinq *ti)
{
@ -124,11 +134,19 @@ void ttyinq_line_iterate_from_reprintpos(struct ttyinq *,
/* Output queue handling routines. */
void ttyoutq_flush(struct ttyoutq *);
void ttyoutq_setsize(struct ttyoutq *, struct tty *, size_t);
void ttyoutq_free(struct ttyoutq *);
size_t ttyoutq_read(struct ttyoutq *, void *, size_t);
int ttyoutq_read_uio(struct ttyoutq *, struct tty *, struct uio *);
size_t ttyoutq_write(struct ttyoutq *, const void *, size_t);
int ttyoutq_write_nofrag(struct ttyoutq *, const void *, size_t);
static __inline void
ttyoutq_init(struct ttyoutq *to)
{
STAILQ_INIT(&to->to_list);
}
static __inline size_t
ttyoutq_getsize(struct ttyoutq *to)
{