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path: root/drivers/char/tty_io.c
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Diffstat (limited to 'drivers/char/tty_io.c')
-rw-r--r--drivers/char/tty_io.c104
1 files changed, 70 insertions, 34 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index eb8b5be4e249..e9bba94fc898 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -253,6 +253,7 @@ static void tty_buffer_free_all(struct tty_struct *tty)
static 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;
@@ -266,6 +267,9 @@ static struct tty_buffer *tty_buffer_alloc(size_t size)
p->used = 0;
p->size = size;
p->next = NULL;
+ p->active = 0;
+ p->commit = 0;
+ p->read = 0;
p->char_buf_ptr = (char *)(p->data);
p->flag_buf_ptr = (unsigned char *)p->char_buf_ptr + size;
/* printk("Flip create %p\n", p); */
@@ -296,6 +300,8 @@ static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size)
*tbh = t->next;
t->next = NULL;
t->used = 0;
+ t->commit = 0;
+ t->read = 0;
/* DEBUG ONLY */
memset(t->data, '*', size);
/* printk("Flip recycle %p\n", t); */
@@ -312,25 +318,37 @@ static struct tty_buffer *tty_buffer_find(struct tty_struct *tty, size_t size)
int tty_buffer_request_room(struct tty_struct *tty, size_t size)
{
- struct tty_buffer *b = tty->buf.tail, *n;
- int left = 0;
+ 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 != NULL)
+ if ((b = tty->buf.tail) != NULL) {
left = b->size - b->used;
- if(left >= size)
- return size;
- /* This is the slow path - looking for new buffers to use */
- n = tty_buffer_find(tty, size);
- if(n == NULL)
- return left;
- if(b != NULL)
- b->next = n;
- else
- tty->buf.head = n;
- tty->buf.tail = n;
+ b->active = 1;
+ } 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->active = 0;
+ b->commit = b->used;
+ } else
+ tty->buf.head = n;
+ tty->buf.tail = n;
+ n->active = 1;
+ } else
+ size = left;
+ }
+
+ spin_unlock_irqrestore(&tty->buf.lock, flags);
return size;
}
@@ -396,10 +414,12 @@ EXPORT_SYMBOL_GPL(tty_insert_flip_string_flags);
int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars, size_t size)
{
int space = tty_buffer_request_room(tty, size);
- 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;
+ 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;
}
@@ -416,10 +436,12 @@ EXPORT_SYMBOL_GPL(tty_prepare_flip_string);
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);
- struct tty_buffer *tb = tty->buf.tail;
- *chars = tb->char_buf_ptr + tb->used;
- *flags = tb->flag_buf_ptr + tb->used;
- tb->used += space;
+ 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;
}
@@ -1819,7 +1841,6 @@ static void release_dev(struct file * filp)
tty_closing = tty->count <= 1;
o_tty_closing = o_tty &&
(o_tty->count <= (pty_master ? 1 : 0));
- up(&tty_sem);
do_sleep = 0;
if (tty_closing) {
@@ -1847,6 +1868,7 @@ static void release_dev(struct file * filp)
printk(KERN_WARNING "release_dev: %s: read/write wait queue "
"active!\n", tty_name(tty, buf));
+ up(&tty_sem);
schedule();
}
@@ -1855,8 +1877,6 @@ static void release_dev(struct file * filp)
* both sides, and we've completed the last operation that could
* block, so it's safe to proceed with closing.
*/
-
- down(&tty_sem);
if (pty_master) {
if (--o_tty->count < 0) {
printk(KERN_WARNING "release_dev: bad pty slave count "
@@ -1870,7 +1890,6 @@ static void release_dev(struct file * filp)
tty->count, tty_name(tty, buf));
tty->count = 0;
}
- up(&tty_sem);
/*
* We've decremented tty->count, so we need to remove this file
@@ -1915,6 +1934,8 @@ static void release_dev(struct file * filp)
read_unlock(&tasklist_lock);
}
+ up(&tty_sem);
+
/* check whether both sides are closing ... */
if (!tty_closing || (o_tty && !o_tty_closing))
return;
@@ -2735,6 +2756,9 @@ static void flush_to_ldisc(void *private_)
unsigned long flags;
struct tty_ldisc *disc;
struct tty_buffer *tbuf;
+ int count;
+ char *char_buf;
+ unsigned char *flag_buf;
disc = tty_ldisc_ref(tty);
if (disc == NULL) /* !TTY_LDISC */
@@ -2747,20 +2771,24 @@ static void flush_to_ldisc(void *private_)
schedule_delayed_work(&tty->buf.work, 1);
goto out;
}
- spin_lock_irqsave(&tty->read_lock, flags);
+ spin_lock_irqsave(&tty->buf.lock, flags);
while((tbuf = tty->buf.head) != NULL) {
+ while ((count = tbuf->commit - tbuf->read) != 0) {
+ char_buf = tbuf->char_buf_ptr + tbuf->read;
+ flag_buf = tbuf->flag_buf_ptr + tbuf->read;
+ tbuf->read += count;
+ spin_unlock_irqrestore(&tty->buf.lock, flags);
+ disc->receive_buf(tty, char_buf, flag_buf, count);
+ spin_lock_irqsave(&tty->buf.lock, flags);
+ }
+ if (tbuf->active)
+ break;
tty->buf.head = tbuf->next;
if (tty->buf.head == NULL)
tty->buf.tail = NULL;
- spin_unlock_irqrestore(&tty->read_lock, flags);
- /* printk("Process buffer %p for %d\n", tbuf, tbuf->used); */
- disc->receive_buf(tty, tbuf->char_buf_ptr,
- tbuf->flag_buf_ptr,
- tbuf->used);
- spin_lock_irqsave(&tty->read_lock, flags);
tty_buffer_free(tty, tbuf);
}
- spin_unlock_irqrestore(&tty->read_lock, flags);
+ spin_unlock_irqrestore(&tty->buf.lock, flags);
out:
tty_ldisc_deref(disc);
}
@@ -2852,6 +2880,14 @@ EXPORT_SYMBOL(tty_get_baud_rate);
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->active = 0;
+ tty->buf.tail->commit = tty->buf.tail->used;
+ }
+ spin_unlock_irqrestore(&tty->buf.lock, flags);
+
if (tty->low_latency)
flush_to_ldisc((void *) tty);
else
generated by cgit v1.2.3 (git 2.0.4) at 2024-11-08 09:32:38 +0000