linux-kernel - [PATCH -next 0/2] tty: Correct tty buffer flush.

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Date:	Wed, 05 Dec 2012 12:47:54 +0400
From:	Ilya Zykov <ilya@...x.ru>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	Alan Cox <alan@...ux.intel.com>, Jiri Slaby <jslaby@...e.cz>,
	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org
Subject: [PATCH -next 0/2] tty: Correct tty buffer flush.

  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@...x.ru>
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