| From | Ben Hutchings <> | Date | Wed, 24 Jul 2013 15:02:45 +0100 | Subject | [27/85] [media] media: dmxdev: remove dvb_ringbuffer_flush() on writer side |
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3.2.49-rc1 review patch. If anyone has any objections, please let me know.
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From: Soeren Moch <smoch@web.de>
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 <smoch@web.de> Reviewed-by: Sakari Ailus <sakari.ailus@iki.fi> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com> [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- 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;
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