From mboxrd@z Thu Jan 1 00:00:00 1970 From: Timur Tabi Subject: Re: [PATCH 6/7] tty/powerpc: introduce the ePAPR embedded hypervisor byte channel driver Date: Thu, 19 May 2011 11:05:49 -0500 Message-ID: <4DD53FDD.7070503@freescale.com> References: <1305813272-31826-1-git-send-email-timur@freescale.com> <1305813272-31826-7-git-send-email-timur@freescale.com> <20110519153358.5876f310@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110519153358.5876f310@lxorguk.ukuu.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Alan Cox Cc: kumar.gala@freescale.com, benh@kernel.crashing.org, greg@kroah.com, akpm@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-console@vger.kernel.org Alan Cox wrote: >> > + /* Pass the received data to the tty layer. Note that this >> > + * function calls tty_buffer_request_room(), so I'm not sure if >> > + * we should have also called tty_buffer_request_room(). >> > + */ >> > + ret = tty_insert_flip_string(ttys, buffer, len); > You only need to request_room in advance if you can't handle the case > where the insert_flip_string returns less than you stuffed down it. If tty_insert_flip_string() returns less than I stuffed down it, the characters it didn't accept will be dropped. That's because once I receive them, I have nowhere else to put them. I suppose I could implement a receive FIFO, but that seems overkill. If calling tty_buffer_request_room() ensures that tty_insert_flip_string() always accepts all the characters, I would rather do that. -- Timur Tabi Linux kernel developer at Freescale