From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Soeren Moch , Sakari Ailus , Mauro Carvalho Chehab , Ben Hutchings , Jianguo Wu Subject: [PATCH 3.4 128/134] media: dmxdev: remove dvb_ringbuffer_flush() on writer side Date: Wed, 9 Apr 2014 20:24:04 -0700 Message-Id: <20140410032315.812850098@linuxfoundation.org> In-Reply-To: <20140410032259.587501440@linuxfoundation.org> References: <20140410032259.587501440@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.4-stable 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 Cc: Jianguo Wu Signed-off-by: Greg Kroah-Hartman --- 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 @@ -379,10 +379,8 @@ 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); @@ -418,10 +416,8 @@ 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;