From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753481Ab3GXOQr (ORCPT ); Wed, 24 Jul 2013 10:16:47 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:45744 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752319Ab3GXOGs (ORCPT ); Wed, 24 Jul 2013 10:06:48 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Soeren Moch" , "Sakari Ailus" , "Mauro Carvalho Chehab" Date: Wed, 24 Jul 2013 15:02:45 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [27/85] [media] media: dmxdev: remove dvb_ringbuffer_flush() on writer side In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.101 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.49-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Soeren Moch commit 414abbd2cd4c2618895f02ed3a76ec6647281436 upstream. In dvb_ringbuffer lock-less synchronizationof reader and writer threads is done with separateread and write pointers. Sincedvb_ringbuffer_flush() modifies the read pointer, this function must not be called from the writer thread. This patch removes the dvb_ringbuffer_flush() calls in the dmxdev ringbuffer write functions, this fixes Oopses "Unable to handle kernel paging request" I could observe for the call chaindvb_demux_read ->dvb_dmxdev_buffer_read -> dvb_ringbuffer_read_user -> __copy_to_user (the reader side of the ringbuffer). The flush calls at the write side are not necessary anyway since ringbuffer_flush is also called in dvb_dmxdev_buffer_read() when an error condition is set in the ringbuffer. This patch should also be applied to stable kernels. Signed-off-by: Soeren Moch Reviewed-by: Sakari Ailus Signed-off-by: Mauro Carvalho Chehab [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings --- drivers/media/dvb/dvb-core/dmxdev.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) --- a/drivers/media/dvb/dvb-core/dmxdev.c +++ b/drivers/media/dvb/dvb-core/dmxdev.c @@ -380,10 +380,8 @@ static int dvb_dmxdev_section_callback(c ret = dvb_dmxdev_buffer_write(&dmxdevfilter->buffer, buffer2, buffer2_len); } - if (ret < 0) { - dvb_ringbuffer_flush(&dmxdevfilter->buffer); + if (ret < 0) dmxdevfilter->buffer.error = ret; - } if (dmxdevfilter->params.sec.flags & DMX_ONESHOT) dmxdevfilter->state = DMXDEV_STATE_DONE; spin_unlock(&dmxdevfilter->dev->lock); @@ -419,10 +417,8 @@ static int dvb_dmxdev_ts_callback(const ret = dvb_dmxdev_buffer_write(buffer, buffer1, buffer1_len); if (ret == buffer1_len) ret = dvb_dmxdev_buffer_write(buffer, buffer2, buffer2_len); - if (ret < 0) { - dvb_ringbuffer_flush(buffer); + if (ret < 0) buffer->error = ret; - } spin_unlock(&dmxdevfilter->dev->lock); wake_up(&buffer->queue); return 0;