From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Skeggs Subject: Re: [PATCH 10/10] drm/nouveau: fix off-by-one bugs related to command submission in IB mode Date: Mon, 20 Aug 2012 16:33:24 +1000 Message-ID: <20120820063323.GF2013@nisroch.redhat.com> References: <20120819210200.GA26902@joi.lan> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20120819210200.GA26902-OI9uyE9O0yo@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: nouveau-bounces+gcfxn-nouveau=m.gmane.org-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org Errors-To: nouveau-bounces+gcfxn-nouveau=m.gmane.org-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org To: Marcin Slusarz Cc: nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org List-Id: nouveau.vger.kernel.org On Sun, Aug 19, 2012 at 11:02:00PM +0200, Marcin Slusarz wrote: > Commit "drm/nouveau: port all engines to new engine module format" changed > IB size calculation to be less wasteful, but didn't take into account already > existing off-by-one bugs :). > > So: > - ib_max is the last entry, so we need to +1 when calculating number of > free entries > - nv50_dma_wait already does +1 (for FIRE_RING), so we don't need another +1 > on nouveau_gem_ioctl_pushbuf side > - there are 512 allocated IB entries (and it needs to be round number), so we > can accept at most 511 entries from userspace (we need one for FIRE_RING) - > fortunately userspace already flushes at 511, so nr_push check change won't > have any impact Also skipped this patch for now as I have work in progress that will improve this and related code. I should have it in the tree soon. > > Signed-off-by: Marcin Slusarz > --- > drivers/gpu/drm/nouveau/nouveau_chan.c | 2 +- > drivers/gpu/drm/nouveau/nouveau_dma.c | 2 +- > drivers/gpu/drm/nouveau/nouveau_gem.c | 4 ++-- > 3 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/nouveau/nouveau_chan.c b/drivers/gpu/drm/nouveau/nouveau_chan.c > index fd15ebf..d0c0271 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_chan.c > +++ b/drivers/gpu/drm/nouveau/nouveau_chan.c > @@ -318,7 +318,7 @@ nouveau_channel_init(struct nouveau_channel *chan, u32 vram, u32 gart) > chan->dma.ib_base = 0x10000 / 4; > chan->dma.ib_max = (0x01000 / 8) - 1; > chan->dma.ib_put = 0; > - chan->dma.ib_free = chan->dma.ib_max - chan->dma.ib_put; > + chan->dma.ib_free = chan->dma.ib_max - chan->dma.ib_put + 1; > chan->dma.max = chan->dma.ib_base; > break; > } > diff --git a/drivers/gpu/drm/nouveau/nouveau_dma.c b/drivers/gpu/drm/nouveau/nouveau_dma.c > index 40f91e1..e814fab 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_dma.c > +++ b/drivers/gpu/drm/nouveau/nouveau_dma.c > @@ -128,7 +128,7 @@ nv50_dma_push_wait(struct nouveau_channel *chan, int count) > > chan->dma.ib_free = get - chan->dma.ib_put; > if (chan->dma.ib_free <= 0) > - chan->dma.ib_free += chan->dma.ib_max; > + chan->dma.ib_free += chan->dma.ib_max + 1; > } > > return 0; > diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c > index 6454370..d19c7aa 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_gem.c > +++ b/drivers/gpu/drm/nouveau/nouveau_gem.c > @@ -662,7 +662,7 @@ nouveau_gem_ioctl_pushbuf(struct drm_device *dev, void *data, > if (unlikely(req->nr_push == 0)) > goto out_next; > > - if (unlikely(req->nr_push > NOUVEAU_GEM_MAX_PUSH)) { > + if (unlikely(req->nr_push >= NOUVEAU_GEM_MAX_PUSH)) { > NV_ERROR(drm, "pushbuf push count exceeds limit: %d max %d\n", > req->nr_push, NOUVEAU_GEM_MAX_PUSH); > return nouveau_abi16_put(abi16, -EINVAL); > @@ -718,7 +718,7 @@ nouveau_gem_ioctl_pushbuf(struct drm_device *dev, void *data, > } > > if (chan->dma.ib_max) { > - ret = nouveau_dma_wait(chan, req->nr_push + 1, 16); > + ret = nouveau_dma_wait(chan, req->nr_push, 16); > if (ret) { > NV_ERROR(drm, "nv50cal_space: %d\n", ret); > goto out; > -- > 1.7.8.6 > > _______________________________________________ > Nouveau mailing list > Nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org > http://lists.freedesktop.org/mailman/listinfo/nouveau