From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ilya Zykov Subject: Re: [PATCH 03/18] tty: Simplify tty buffer/ldisc interface with helper function Date: Wed, 20 Mar 2013 02:42:26 +0400 Message-ID: <5148E9D2.4030305@izyk.ru> References: <1363724513-15604-1-git-send-email-peter@hurleysoftware.com> <1363724513-15604-4-git-send-email-peter@hurleysoftware.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from 95-31-19-74.broadband.corbina.ru ([95.31.19.74]:53411 "EHLO mail.izyk.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933877Ab3CSWma (ORCPT ); Tue, 19 Mar 2013 18:42:30 -0400 In-Reply-To: <1363724513-15604-4-git-send-email-peter@hurleysoftware.com> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Peter Hurley Cc: Greg Kroah-Hartman , Jiri Slaby , Min Zhang , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org On 20.03.2013 0:21, Peter Hurley wrote: > Ldisc interface functions must be called with interrupts enabled. > Separating the ldisc calls into a helper function simplies the > spin lock management. > > Update the buffer's read index _after_ the data has been received > by the ldisc. > Hello Peter! It looks good for me. I think also we can remove two variables without waste: (char_buf), (flag_buf) and use without (&buf->lock) (head->char_buf_ptr + head->read), (head->char_buf_ptr + head->read), because (head->read) guarded by (TTYP_FLUSHING). I have little question about flush_to_ldisc(). Does can it be multithreaded? I think yes, because on SMP schedule_work() can work on different CPU paralleled. What do you think about this race condition? https://lkml.org/lkml/2011/11/7/98 Thank you. Ilya Zykov