Re: [PATCH] tty: Correct tty buffer flush.

Alan Cox
2012-12-04T14:12:23Z

On Tue, 04 Dec 2012 17:10:57 +0400
Ilya Zykov <ilya@ilyx.ru> wrote:

> The root of problem is carelessly zeroing pointer(in function __tty_buffer_flush()),
> when another thread can use it. It can be cause of "NULL pointer dereference".
> Main idea of the patch, this is never free last (struct tty_buffer) in the active buffer.
> Only flush the data for ldisc(tty->buf.head->read = tty->buf.head->commit).
> At that moment driver can collect(write) data in buffer without conflict.
> It is repeat behavior of flush_to_ldisc(), only without feeding data to ldisc.
>
> Also revert:
> commit c56a00a165712fd73081f40044b1e64407bb1875
> tty: hold lock across tty buffer finding and buffer filling
> In order to delete the unneeded locks any more.
>
> Signed-off-by: Ilya Zykov <ilya@ilyx.ru>

Acked-by: Alan Cox <alan@linux.intel.com>