From: Daniel Vetter <daniel@ffwll.ch>
To: Chris Wilson <chris@chris-wilson.co.uk>,
Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>,
intel-gfx@lists.freedesktop.org, daniel.vetter@ffwll.ch,
dri-devel@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 3/3] drm/dp/mst: Track available time slots in DP Multi-Stream Transport Packet
Date: Fri, 18 Nov 2016 09:44:42 +0100 [thread overview]
Message-ID: <20161118084442.zgwqqtqhlpshxx6m@phenom.ffwll.local> (raw)
In-Reply-To: <20161118065701.GA8159@nuc-i3427.alporthouse.com>
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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next prev parent reply other threads:[~2016-11-18 8:44 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-18 2:03 [PATCH 0/3] Track available link bandwidth for DP MST Dhinakaran Pandiyan
2016-11-18 2:03 ` [PATCH 1/3] drm/i915/dp: Fail DP MST config when there are not enough vcpi slots Dhinakaran Pandiyan
2016-11-18 8:43 ` Daniel Vetter
2016-11-18 9:17 ` Daniel Vetter
2016-11-19 0:04 ` Pandiyan, Dhinakaran
2016-11-21 9:09 ` [Intel-gfx] " Daniel Vetter
2016-11-18 2:03 ` [PATCH 2/3] drm/dp/mst: Calculate total link bandwidth instead of hardcoding it Dhinakaran Pandiyan
2016-11-19 2:01 ` Pandiyan, Dhinakaran
2016-11-29 20:58 ` Ville Syrjälä
2016-11-29 21:04 ` Pandiyan, Dhinakaran
2016-11-18 2:03 ` [PATCH 3/3] drm/dp/mst: Track available time slots in DP Multi-Stream Transport Packet Dhinakaran Pandiyan
2016-11-18 5:53 ` kbuild test robot
2016-11-18 6:19 ` Manasi Navare
2016-11-18 6:57 ` [Intel-gfx] " Chris Wilson
2016-11-18 8:44 ` Daniel Vetter [this message]
2016-11-19 0:07 ` Pandiyan, Dhinakaran
2016-11-18 8:16 ` ✓ Fi.CI.BAT: success for Track available link bandwidth for DP MST Patchwork
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