On Fri, Nov 18, 2016 at 06:57:01AM +0000, Chris Wilson wrote:
> On Thu, Nov 17, 2016 at 06:03:48PM -0800, Dhinakaran Pandiyan wrote:
> > static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
> > struct drm_dp_vcpi *vcpi, int pbn)
> > {
> > - int num_slots;
> > + int req_slots;
> > int ret;
> >
> > - num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
> > + req_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
> >
> > - if (num_slots > mgr->avail_slots)
> > - return -ENOSPC;
> > + mutex_lock(&mgr->lock);
> > + if (req_slots > mgr->avail_slots) {
> > + ret = -ENOSPC;
> > + goto out;
> > + }
>
> You are not atomically reducing the mgr->avail_slots, leading to
> possible overallocation of multiple streams?
Yup, see my lenghty reply to patch 1 for what needs to be done here to fix
this correctly.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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