Hi Soeren,
Thanks for the patch!
On Sun, Apr 14, 2013 at 11:03:42AM +0200, Soeren Moch wrote:
> 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@xxxxxx>
> CC: <stable@xxxxxxxxxxxxxxx>
While the change the patch does itself appears sound to me, I need to ask
you to resend the patch using git send-email (it won't apply as-is). I can
do that this time, too; let me know what works for you.
Reviewed-by: Sakari Ailus <sakari.ailus@xxxxxx>
> --- a/drivers/media/dvb-core/dmxdev.c 2013-04-05 21:21:15.000000000 +0200
> +++ b/drivers/media/dvb-core/dmxdev.c 2013-04-14 09:01:58.000000000 +0200
> @@ -377,10 +377,8 @@ 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);
> @@ -416,10 +414,8 @@ 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;
>
--
Kind regards,
Sakari Ailus
e-mail: sakari.ailus@xxxxxx XMPP: sailus@xxxxxxxxxxxxxx
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