diff options
| author |   Paul Fulghum <paulkf@microgate.com> | 2006-02-10 01:51:14 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@g5.osdl.org> | 2006-02-10 08:13:12 -0800 |
| commit | 8977d929e49021d9a6e031310aab01fa72f849c2 (patch) | |
| tree | 13697e607b1153666139114242964f9982acc328 /drivers | |
| parent | [PATCH] slab: Avoid deadlock at kmem_cache_create/kmem_cache_destroy (diff) | |
| download | linux-dev-8977d929e49021d9a6e031310aab01fa72f849c2.tar.xz linux-dev-8977d929e49021d9a6e031310aab01fa72f849c2.zip | |
[PATCH] tty buffering stall fix
Prevent stalled processing of received data when a driver allocates tty
buffer space but does not immediately follow the allocation with more data
and a call to schedule receive tty processing. (example: hvc_console) This
bug was introduced by the first locking patch for the new tty buffering.
Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/char/tty_io.c | 30 |
1 files changed, 22 insertions, 8 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index 076e07c1da38..a23816d3e9a1 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -268,6 +268,8 @@ static struct tty_buffer *tty_buffer_alloc(size_t size) 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); */ @@ -298,6 +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); */ @@ -335,6 +339,7 @@ int tty_buffer_request_room(struct tty_struct *tty, size_t size) if (b != NULL) { b->next = n; b->active = 0; + b->commit = b->used; } else tty->buf.head = n; tty->buf.tail = n; @@ -2752,6 +2757,9 @@ 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 */ @@ -2765,16 +2773,20 @@ static void flush_to_ldisc(void *private_) goto out; } spin_lock_irqsave(&tty->buf.lock, flags); - while((tbuf = tty->buf.head) != NULL && !tbuf->active) { + 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->buf.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->buf.lock, flags); tty_buffer_free(tty, tbuf); } spin_unlock_irqrestore(&tty->buf.lock, flags); @@ -2871,8 +2883,10 @@ void tty_flip_buffer_push(struct tty_struct *tty) { unsigned long flags; spin_lock_irqsave(&tty->buf.lock, flags); - if (tty->buf.tail != NULL) + 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) |