From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: Re: Possible software flow problem in serial_core Date: Thu, 20 Mar 2014 21:07:14 -0400 Message-ID: <532B90C2.8080405@hurleysoftware.com> References: <532B743F.2030705@hurleysoftware.com> <532B891E.80705@hurleysoftware.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: "Bollinger, Seth" Cc: "linux-kernel@vger.kernel.org" , linux-serial List-Id: linux-serial@vger.kernel.org On 03/20/2014 08:48 PM, Bollinger, Seth wrote: > >> Yeah, you're right; thanks for catching this. >> (I was busy looking at the ll driver and completely missed the bug in >> the serial core). >> >> uart_start() should not be conditioning the call to start_tx() on >> the ring buffer being empty; ll drivers should already be able to handle >> that because CTS flow control change will start_tx regardless of the ring >> buffer count. >> >> Will you send a patch? > > Sure thing. Just to be clear, you want to remove the ring buffer tests > and leave the tty tests, right? Yes. I would remove the NULL ptr test for xmit.buf as well. That way we can uncover any bugs in the ll drivers that mistakenly depend on it. The !stopped and !hw_stopped tests must remain. > This will have to wait for the morning though. :) Take your time. TTY/serial trees are closed until 3.15-rc1 anyway. Please be sure to address the patch to the serial maintainers. You can cc me in the patch. Thanks again, Peter Hurley