On Tue, Apr 12, 2016 at 10:59:53AM +0100, Andrew Cooper wrote:
> On 12/04/16 10:57, Wei Liu wrote:
> > The variable out_cons was only used to temporarily hold the consumer
> > index. Use cons directly to simplify code a bit.
> >
> > No functional change introduced.
> >
> > Signed-off-by: Wei Liu <wei.l...@citrix.com>
> > ---
> > Cc: Stefano Stabellini <sstabell...@kernel.org>
> > Cc: Anthony Perard <anthony.per...@citrix.com>
> > ---
> > hw/display/xenfb.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
> > index 9866dfd..78a8dcd 100644
> > --- a/hw/display/xenfb.c
> > +++ b/hw/display/xenfb.c
> > @@ -770,16 +770,16 @@ static void xenfb_invalidate(void *opaque)
> >
> > static void xenfb_handle_events(struct XenFB *xenfb)
> > {
> > - uint32_t prod, cons, out_cons;
> > + uint32_t prod, cons;
> > struct xenfb_page *page = xenfb->c.page;
> >
> > prod = page->out_prod;
> > - out_cons = page->out_cons;
> > - if (prod - out_cons > XENFB_OUT_RING_LEN) {
> > + cons = page->out_cons;
>
> You need the xen_rmb() before the first use of prod or cons.
>
Good point. I overlooked that.
The change should belong to either previous patch or a new patch though.
Wei.
> ~Andrew
>
> > + if (prod - cons > XENFB_OUT_RING_LEN) {
> > return;
> > }
> > xen_rmb(); /* ensure we see ring contents up to prod */
> > - for (cons = out_cons; cons != prod; cons++) {
> > + for ( ; cons != prod; cons++) {
> > union xenfb_out_event *event = &XENFB_OUT_RING_REF(page, cons);
> > uint8_t type = event->type;
> > int x, y, w, h;
>
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