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tty: flush flip buffer on ldisc input queue flush 

Flush the tty flip buffer when the line discipline input queue is flushed,
including the user call tcflush(TCIFLUSH/TCIOFLUSH).  This prevents
unexpected stale data after a user application calls tcflush().

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Antonino Ingargiola <tritemio@gmail.com>
Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Paul Fulghum 2007-05-12 10:36:55 -07:00 committed by Linus Torvalds
parent e3bf460f3e
commit c5c34d4862
1 changed files with 33 additions and 0 deletions
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33
drivers/char/tty_io.c
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@ -368,6 +368,29 @@ static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b)
}
}
/**
* tty_buffer_flush - flush full tty buffers
* @tty: tty to flush
*
* flush all the buffers containing receive data
*
* Locking: none
*/
static void tty_buffer_flush(struct tty_struct *tty)
{
struct tty_buffer *thead;
unsigned long flags;
spin_lock_irqsave(&tty->buf.lock, flags);
while((thead = tty->buf.head) != NULL) {
tty->buf.head = thead->next;
tty_buffer_free(tty, thead);
}
tty->buf.tail = NULL;
spin_unlock_irqrestore(&tty->buf.lock, flags);
}
/**
* tty_buffer_find - find a free tty buffer
* @tty: tty owning the buffer
@ -1248,6 +1271,7 @@ void tty_ldisc_flush(struct tty_struct *tty)
ld->flush_buffer(tty);
tty_ldisc_deref(ld);
}
tty_buffer_flush(tty);
}
EXPORT_SYMBOL_GPL(tty_ldisc_flush);
@ -3350,6 +3374,15 @@ int tty_ioctl(struct inode * inode, struct file * file,
case TIOCMBIC:
case TIOCMBIS:
return tty_tiocmset(tty, file, cmd, p);
case TCFLSH:
switch (arg) {
case TCIFLUSH:
case TCIOFLUSH:
/* flush tty buffer and allow ldisc to process ioctl */
tty_buffer_flush(tty);
break;
}
break;
}
if (tty->driver->ioctl) {
retval = (tty->driver->ioctl)(tty, file, cmd, arg);