On Tue, 2006-03-14 at 01:03 +0100, Oliver Endriss wrote:
> Andreas Oberritter wrote:
> > From: Andreas Oberritter <obi@xxxxxxxxxxx>
> >
> > Added variable 'error' to struct dvb_ringbuffer, which is set to zero on
> > init() and flush(). Also reset read an write pointers to zero on flush()
> > to get less fragmented data.
> >
> > Signed-off-by: Andreas Oberritter <obi@xxxxxxxxxxx>
> > ---
> >
> > A patch to make dmxdev use dvb_ringbuffer will follow.
> >
> > diff -r 427667c87c7b linux/drivers/media/dvb/dvb-core/dvb_ringbuffer.c
> > --- a/linux/drivers/media/dvb/dvb-core/dvb_ringbuffer.c Sun Mar 12 00:03:47 2006 -0300
> > +++ b/linux/drivers/media/dvb/dvb-core/dvb_ringbuffer.c Mon Mar 13 16:02:46 2006 +0100
> > ...
> > @@ -86,7 +87,8 @@ ssize_t dvb_ringbuffer_avail(struct dvb_
> >
> > void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf)
> > {
> > - rbuf->pread = rbuf->pwrite;
> > + rbuf->pread = rbuf->pwrite = 0;
> +++
>
> Attention, this will convert dvb_ringbuffer_flush() into a writer!
>
> from dvb_ringbuffer.h:
> | ** (2) If there is exactly one reader and one writer, there is no need
> | ** to lock read or write operations.
> | ** Two or more readers must be locked against each other.
> | ** Flushing the buffer counts as a read operation.
> +++++++++++++++++++++++++++++++++++++++++++++++
> | ** Two or more writers must be locked against each other.
>
> With this patch flushing the ring buffer is a read _and_ a write
> operation. It might break existing code. Are you aware of that?
Oliver, can you please take a look at the existing code? It's a
performance gain if it doesn't break.
Generally I'd expect a flush to return a buffer into its initial state.
Regards,
Andreas
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