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

From: Alan Cox
Date: Tue Dec 04 2012 - 09:07:02 EST

On Tue, 04 Dec 2012 17:10:57 +0400
Ilya Zykov <ilya@xxxxxxx> 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@xxxxxxx>

Acked-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
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