From c5c34d4862e18ef07c1276d233507f540fb5a532 Mon Sep 17 00:00:00 2001 From: Paul Fulghum Date: Sat, 12 May 2007 10:36:55 -0700 Subject: [PATCH] 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 Cc: Antonino Ingargiola Signed-off-by: Paul Fulghum Cc: Theodore Ts'o Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/char/tty_io.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index bc849957508d..75d2a46e106f 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -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); -- 2.20.1