525 lines
14 KiB
C
525 lines
14 KiB
C
/*
|
|
* Tty buffer allocation management
|
|
*/
|
|
|
|
#include <linux/types.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/tty.h>
|
|
#include <linux/tty_driver.h>
|
|
#include <linux/tty_flip.h>
|
|
#include <linux/timer.h>
|
|
#include <linux/string.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/init.h>
|
|
#include <linux/wait.h>
|
|
#include <linux/bitops.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/module.h>
|
|
|
|
/**
|
|
* tty_buffer_free_all - free buffers used by a tty
|
|
* @tty: tty to free from
|
|
*
|
|
* Remove all the buffers pending on a tty whether queued with data
|
|
* or in the free ring. Must be called when the tty is no longer in use
|
|
*
|
|
* Locking: none
|
|
*/
|
|
|
|
void tty_buffer_free_all(struct tty_struct *tty)
|
|
{
|
|
struct tty_buffer *thead;
|
|
while ((thead = tty->buf.head) != NULL) {
|
|
tty->buf.head = thead->next;
|
|
kfree(thead);
|
|
}
|
|
while ((thead = tty->buf.free) != NULL) {
|
|
tty->buf.free = thead->next;
|
|
kfree(thead);
|
|
}
|
|
tty->buf.tail = NULL;
|
|
tty->buf.memory_used = 0;
|
|
}
|
|
|
|
/**
|
|
* tty_buffer_alloc - allocate a tty buffer
|
|
* @tty: tty device
|
|
* @size: desired size (characters)
|
|
*
|
|
* Allocate a new tty buffer to hold the desired number of characters.
|
|
* Return NULL if out of memory or the allocation would exceed the
|
|
* per device queue
|
|
*
|
|
* Locking: Caller must hold tty->buf.lock
|
|
*/
|
|
|
|
static struct tty_buffer *tty_buffer_alloc(struct tty_struct *tty, size_t size)
|
|
{
|
|
struct tty_buffer *p;
|
|
|
|
if (tty->buf.memory_used + size > 65536)
|
|
return NULL;
|
|
p = kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
|
|
if (p == NULL)
|
|
return NULL;
|
|
p->used = 0;
|
|
p->size = size;
|
|
p->next = NULL;
|
|
p->commit = 0;
|
|
p->read = 0;
|
|
p->char_buf_ptr = (char *)(p->data);
|
|
p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size;
|
|
tty->buf.memory_used += size;
|
|
return p;
|
|
}
|
|
|
|
/**
|
|
* tty_buffer_free - free a tty buffer
|
|
* @tty: tty owning the buffer
|
|
* @b: the buffer to free
|
|
*
|
|
* Free a tty buffer, or add it to the free list according to our
|
|
* internal strategy
|
|
*
|
|
* Locking: Caller must hold tty->buf.lock
|
|
*/
|
|
|
|
static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b)
|
|
{
|
|
/* Dumb strategy for now - should keep some stats */
|
|
tty->buf.memory_used -= b->size;
|
|
WARN_ON(tty->buf.memory_used < 0);
|
|
|
|
if (b->size >= 512)
|
|
kfree(b);
|
|
else {
|
|
b->next = tty->buf.free;
|
|
tty->buf.free = b;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* __tty_buffer_flush - flush full tty buffers
|
|
* @tty: tty to flush
|
|
*
|
|
* flush all the buffers containing receive data. Caller must
|
|
* hold the buffer lock and must have ensured no parallel flush to
|
|
* ldisc is running.
|
|
*
|
|
* Locking: Caller must hold tty->buf.lock
|
|
*/
|
|
|
|
static void __tty_buffer_flush(struct tty_struct *tty)
|
|
{
|
|
struct tty_buffer *thead;
|
|
|
|
while ((thead = tty->buf.head) != NULL) {
|
|
tty->buf.head = thead->next;
|
|
tty_buffer_free(tty, thead);
|
|
}
|
|
tty->buf.tail = NULL;
|
|
}
|
|
|
|
/**
|
|
* tty_buffer_flush - flush full tty buffers
|
|
* @tty: tty to flush
|
|
*
|
|
* flush all the buffers containing receive data. If the buffer is
|
|
* being processed by flush_to_ldisc then we defer the processing
|
|
* to that function
|
|
*
|
|
* Locking: none
|
|
*/
|
|
|
|
void tty_buffer_flush(struct tty_struct *tty)
|
|
{
|
|
unsigned long flags;
|
|
spin_lock_irqsave(&tty->buf.lock, flags);
|
|
|
|
/* If the data is being pushed to the tty layer then we can't
|
|
process it here. Instead set a flag and the flush_to_ldisc
|
|
path will process the flush request before it exits */
|
|
if (test_bit(TTY_FLUSHING, &tty->flags)) {
|
|
set_bit(TTY_FLUSHPENDING, &tty->flags);
|
|
spin_unlock_irqrestore(&tty->buf.lock, flags);
|
|
wait_event(tty->read_wait,
|
|
test_bit(TTY_FLUSHPENDING, &tty->flags) == 0);
|
|
return;
|
|
} else
|
|
__tty_buffer_flush(tty);
|
|
spin_unlock_irqrestore(&tty->buf.lock, flags);
|
|
}
|
|
|
|
/**
|
|
* tty_buffer_find - find a free tty buffer
|
|
* @tty: tty owning the buffer
|
|
* @size: characters wanted
|
|
*
|
|
* Locate an existing suitable tty buffer or if we are lacking one then
|
|
* allocate a new one. We round our buffers off in 256 character chunks
|
|
* to get better allocation behaviour.
|
|
*
|
|
* Locking: Caller must hold tty->buf.lock
|
|
*/
|
|
|
|
static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size)
|
|
{
|
|
struct tty_buffer **tbh = &tty->buf.free;
|
|
while ((*tbh) != NULL) {
|
|
struct tty_buffer *t = *tbh;
|
|
if (t->size >= size) {
|
|
*tbh = t->next;
|
|
t->next = NULL;
|
|
t->used = 0;
|
|
t->commit = 0;
|
|
t->read = 0;
|
|
tty->buf.memory_used += t->size;
|
|
return t;
|
|
}
|
|
tbh = &((*tbh)->next);
|
|
}
|
|
/* Round the buffer size out */
|
|
size = (size + 0xFF) & ~0xFF;
|
|
return tty_buffer_alloc(tty, size);
|
|
/* Should possibly check if this fails for the largest buffer we
|
|
have queued and recycle that ? */
|
|
}
|
|
|
|
/**
|
|
* tty_buffer_request_room - grow tty buffer if needed
|
|
* @tty: tty structure
|
|
* @size: size desired
|
|
*
|
|
* Make at least size bytes of linear space available for the tty
|
|
* buffer. If we fail return the size we managed to find.
|
|
*
|
|
* Locking: Takes tty->buf.lock
|
|
*/
|
|
int tty_buffer_request_room(struct tty_struct *tty, size_t size)
|
|
{
|
|
struct tty_buffer *b, *n;
|
|
int left;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&tty->buf.lock, flags);
|
|
|
|
/* OPTIMISATION: We could keep a per tty "zero" sized buffer to
|
|
remove this conditional if its worth it. This would be invisible
|
|
to the callers */
|
|
if ((b = tty->buf.tail) != NULL)
|
|
left = b->size - b->used;
|
|
else
|
|
left = 0;
|
|
|
|
if (left < size) {
|
|
/* This is the slow path - looking for new buffers to use */
|
|
if ((n = tty_buffer_find(tty, size)) != NULL) {
|
|
if (b != NULL) {
|
|
b->next = n;
|
|
b->commit = b->used;
|
|
} else
|
|
tty->buf.head = n;
|
|
tty->buf.tail = n;
|
|
} else
|
|
size = left;
|
|
}
|
|
|
|
spin_unlock_irqrestore(&tty->buf.lock, flags);
|
|
return size;
|
|
}
|
|
EXPORT_SYMBOL_GPL(tty_buffer_request_room);
|
|
|
|
/**
|
|
* tty_insert_flip_string - Add characters to the tty buffer
|
|
* @tty: tty structure
|
|
* @chars: characters
|
|
* @size: size
|
|
*
|
|
* Queue a series of bytes to the tty buffering. All the characters
|
|
* passed are marked as without error. Returns the number added.
|
|
*
|
|
* Locking: Called functions may take tty->buf.lock
|
|
*/
|
|
|
|
int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars,
|
|
size_t size)
|
|
{
|
|
int copied = 0;
|
|
do {
|
|
int space = tty_buffer_request_room(tty, size - copied);
|
|
struct tty_buffer *tb = tty->buf.tail;
|
|
/* If there is no space then tb may be NULL */
|
|
if (unlikely(space == 0))
|
|
break;
|
|
memcpy(tb->char_buf_ptr + tb->used, chars, space);
|
|
memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
|
|
tb->used += space;
|
|
copied += space;
|
|
chars += space;
|
|
/* There is a small chance that we need to split the data over
|
|
several buffers. If this is the case we must loop */
|
|
} while (unlikely(size > copied));
|
|
return copied;
|
|
}
|
|
EXPORT_SYMBOL(tty_insert_flip_string);
|
|
|
|
/**
|
|
* tty_insert_flip_string_flags - Add characters to the tty buffer
|
|
* @tty: tty structure
|
|
* @chars: characters
|
|
* @flags: flag bytes
|
|
* @size: size
|
|
*
|
|
* Queue a series of bytes to the tty buffering. For each character
|
|
* the flags array indicates the status of the character. Returns the
|
|
* number added.
|
|
*
|
|
* Locking: Called functions may take tty->buf.lock
|
|
*/
|
|
|
|
int tty_insert_flip_string_flags(struct tty_struct *tty,
|
|
const unsigned char *chars, const char *flags, size_t size)
|
|
{
|
|
int copied = 0;
|
|
do {
|
|
int space = tty_buffer_request_room(tty, size - copied);
|
|
struct tty_buffer *tb = tty->buf.tail;
|
|
/* If there is no space then tb may be NULL */
|
|
if (unlikely(space == 0))
|
|
break;
|
|
memcpy(tb->char_buf_ptr + tb->used, chars, space);
|
|
memcpy(tb->flag_buf_ptr + tb->used, flags, space);
|
|
tb->used += space;
|
|
copied += space;
|
|
chars += space;
|
|
flags += space;
|
|
/* There is a small chance that we need to split the data over
|
|
several buffers. If this is the case we must loop */
|
|
} while (unlikely(size > copied));
|
|
return copied;
|
|
}
|
|
EXPORT_SYMBOL(tty_insert_flip_string_flags);
|
|
|
|
/**
|
|
* tty_schedule_flip - push characters to ldisc
|
|
* @tty: tty to push from
|
|
*
|
|
* Takes any pending buffers and transfers their ownership to the
|
|
* ldisc side of the queue. It then schedules those characters for
|
|
* processing by the line discipline.
|
|
*
|
|
* Locking: Takes tty->buf.lock
|
|
*/
|
|
|
|
void tty_schedule_flip(struct tty_struct *tty)
|
|
{
|
|
unsigned long flags;
|
|
spin_lock_irqsave(&tty->buf.lock, flags);
|
|
if (tty->buf.tail != NULL)
|
|
tty->buf.tail->commit = tty->buf.tail->used;
|
|
spin_unlock_irqrestore(&tty->buf.lock, flags);
|
|
schedule_delayed_work(&tty->buf.work, 1);
|
|
}
|
|
EXPORT_SYMBOL(tty_schedule_flip);
|
|
|
|
/**
|
|
* tty_prepare_flip_string - make room for characters
|
|
* @tty: tty
|
|
* @chars: return pointer for character write area
|
|
* @size: desired size
|
|
*
|
|
* Prepare a block of space in the buffer for data. Returns the length
|
|
* available and buffer pointer to the space which is now allocated and
|
|
* accounted for as ready for normal characters. This is used for drivers
|
|
* that need their own block copy routines into the buffer. There is no
|
|
* guarantee the buffer is a DMA target!
|
|
*
|
|
* Locking: May call functions taking tty->buf.lock
|
|
*/
|
|
|
|
int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars,
|
|
size_t size)
|
|
{
|
|
int space = tty_buffer_request_room(tty, size);
|
|
if (likely(space)) {
|
|
struct tty_buffer *tb = tty->buf.tail;
|
|
*chars = tb->char_buf_ptr + tb->used;
|
|
memset(tb->flag_buf_ptr + tb->used, TTY_NORMAL, space);
|
|
tb->used += space;
|
|
}
|
|
return space;
|
|
}
|
|
EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
|
|
|
|
/**
|
|
* tty_prepare_flip_string_flags - make room for characters
|
|
* @tty: tty
|
|
* @chars: return pointer for character write area
|
|
* @flags: return pointer for status flag write area
|
|
* @size: desired size
|
|
*
|
|
* Prepare a block of space in the buffer for data. Returns the length
|
|
* available and buffer pointer to the space which is now allocated and
|
|
* accounted for as ready for characters. This is used for drivers
|
|
* that need their own block copy routines into the buffer. There is no
|
|
* guarantee the buffer is a DMA target!
|
|
*
|
|
* Locking: May call functions taking tty->buf.lock
|
|
*/
|
|
|
|
int tty_prepare_flip_string_flags(struct tty_struct *tty,
|
|
unsigned char **chars, char **flags, size_t size)
|
|
{
|
|
int space = tty_buffer_request_room(tty, size);
|
|
if (likely(space)) {
|
|
struct tty_buffer *tb = tty->buf.tail;
|
|
*chars = tb->char_buf_ptr + tb->used;
|
|
*flags = tb->flag_buf_ptr + tb->used;
|
|
tb->used += space;
|
|
}
|
|
return space;
|
|
}
|
|
EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);
|
|
|
|
|
|
|
|
/**
|
|
* flush_to_ldisc
|
|
* @work: tty structure passed from work queue.
|
|
*
|
|
* This routine is called out of the software interrupt to flush data
|
|
* from the buffer chain to the line discipline.
|
|
*
|
|
* Locking: holds tty->buf.lock to guard buffer list. Drops the lock
|
|
* while invoking the line discipline receive_buf method. The
|
|
* receive_buf method is single threaded for each tty instance.
|
|
*/
|
|
|
|
static void flush_to_ldisc(struct work_struct *work)
|
|
{
|
|
struct tty_struct *tty =
|
|
container_of(work, struct tty_struct, buf.work.work);
|
|
unsigned long flags;
|
|
struct tty_ldisc *disc;
|
|
struct tty_buffer *tbuf, *head;
|
|
char *char_buf;
|
|
unsigned char *flag_buf;
|
|
|
|
disc = tty_ldisc_ref(tty);
|
|
if (disc == NULL) /* !TTY_LDISC */
|
|
return;
|
|
|
|
spin_lock_irqsave(&tty->buf.lock, flags);
|
|
/* So we know a flush is running */
|
|
set_bit(TTY_FLUSHING, &tty->flags);
|
|
head = tty->buf.head;
|
|
if (head != NULL) {
|
|
tty->buf.head = NULL;
|
|
for (;;) {
|
|
int count = head->commit - head->read;
|
|
if (!count) {
|
|
if (head->next == NULL)
|
|
break;
|
|
tbuf = head;
|
|
head = head->next;
|
|
tty_buffer_free(tty, tbuf);
|
|
continue;
|
|
}
|
|
/* Ldisc or user is trying to flush the buffers
|
|
we are feeding to the ldisc, stop feeding the
|
|
line discipline as we want to empty the queue */
|
|
if (test_bit(TTY_FLUSHPENDING, &tty->flags))
|
|
break;
|
|
if (!tty->receive_room) {
|
|
schedule_delayed_work(&tty->buf.work, 1);
|
|
break;
|
|
}
|
|
if (count > tty->receive_room)
|
|
count = tty->receive_room;
|
|
char_buf = head->char_buf_ptr + head->read;
|
|
flag_buf = head->flag_buf_ptr + head->read;
|
|
head->read += count;
|
|
spin_unlock_irqrestore(&tty->buf.lock, flags);
|
|
disc->ops->receive_buf(tty, char_buf,
|
|
flag_buf, count);
|
|
spin_lock_irqsave(&tty->buf.lock, flags);
|
|
}
|
|
/* Restore the queue head */
|
|
tty->buf.head = head;
|
|
}
|
|
/* We may have a deferred request to flush the input buffer,
|
|
if so pull the chain under the lock and empty the queue */
|
|
if (test_bit(TTY_FLUSHPENDING, &tty->flags)) {
|
|
__tty_buffer_flush(tty);
|
|
clear_bit(TTY_FLUSHPENDING, &tty->flags);
|
|
wake_up(&tty->read_wait);
|
|
}
|
|
clear_bit(TTY_FLUSHING, &tty->flags);
|
|
spin_unlock_irqrestore(&tty->buf.lock, flags);
|
|
|
|
tty_ldisc_deref(disc);
|
|
}
|
|
|
|
/**
|
|
* tty_flush_to_ldisc
|
|
* @tty: tty to push
|
|
*
|
|
* Push the terminal flip buffers to the line discipline.
|
|
*
|
|
* Must not be called from IRQ context.
|
|
*/
|
|
void tty_flush_to_ldisc(struct tty_struct *tty)
|
|
{
|
|
flush_to_ldisc(&tty->buf.work.work);
|
|
}
|
|
|
|
/**
|
|
* tty_flip_buffer_push - terminal
|
|
* @tty: tty to push
|
|
*
|
|
* Queue a push of the terminal flip buffers to the line discipline. This
|
|
* function must not be called from IRQ context if tty->low_latency is set.
|
|
*
|
|
* In the event of the queue being busy for flipping the work will be
|
|
* held off and retried later.
|
|
*
|
|
* Locking: tty buffer lock. Driver locks in low latency mode.
|
|
*/
|
|
|
|
void tty_flip_buffer_push(struct tty_struct *tty)
|
|
{
|
|
unsigned long flags;
|
|
spin_lock_irqsave(&tty->buf.lock, flags);
|
|
if (tty->buf.tail != NULL)
|
|
tty->buf.tail->commit = tty->buf.tail->used;
|
|
spin_unlock_irqrestore(&tty->buf.lock, flags);
|
|
|
|
if (tty->low_latency)
|
|
flush_to_ldisc(&tty->buf.work.work);
|
|
else
|
|
schedule_delayed_work(&tty->buf.work, 1);
|
|
}
|
|
EXPORT_SYMBOL(tty_flip_buffer_push);
|
|
|
|
/**
|
|
* tty_buffer_init - prepare a tty buffer structure
|
|
* @tty: tty to initialise
|
|
*
|
|
* Set up the initial state of the buffer management for a tty device.
|
|
* Must be called before the other tty buffer functions are used.
|
|
*
|
|
* Locking: none
|
|
*/
|
|
|
|
void tty_buffer_init(struct tty_struct *tty)
|
|
{
|
|
spin_lock_init(&tty->buf.lock);
|
|
tty->buf.head = NULL;
|
|
tty->buf.tail = NULL;
|
|
tty->buf.free = NULL;
|
|
tty->buf.memory_used = 0;
|
|
INIT_DELAYED_WORK(&tty->buf.work, flush_to_ldisc);
|
|
}
|
|
|