Hi, On Thu, 2019-04-25 at 10:42 -0700, Eric Anholt wrote: > Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx> writes: > > > The binner BO is not required until the V3D is in use, so avoid > > allocating it at probe and do it on the first non-dumb BO allocation. > > > > Keep track of which clients are using the V3D and liberate the buffer > > when there is none left, using a kref. Protect the logic with a > > mutex to avoid race conditions. > > > > The binner BO is created at the time of the first render ioctl and is > > destroyed when there is no client and no exec job using it left. > > > > The Out-Of-Memory (OOM) interrupt also gets some tweaking, to avoid > > enabling it before having allocated a binner bo. > > > > We also want to keep the BO alive during runtime suspend/resume to avoid > > failing to allocate it at resume. This happens when the CMA pool is > > full at that point and results in a hard crash. > > > > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx> > > --- > > drivers/gpu/drm/vc4/vc4_bo.c | 33 +++++++++++++++++++- > > drivers/gpu/drm/vc4/vc4_drv.c | 6 ++++ > > drivers/gpu/drm/vc4/vc4_drv.h | 14 +++++++++ > > drivers/gpu/drm/vc4/vc4_gem.c | 13 ++++++++ > > drivers/gpu/drm/vc4/vc4_irq.c | 21 +++++++++---- > > drivers/gpu/drm/vc4/vc4_v3d.c | 58 +++++++++++++++++++++++++++-------- > > 6 files changed, 125 insertions(+), 20 deletions(-) > > > > diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c > > index 88ebd681d7eb..2b3ec5926fe2 100644 > > --- a/drivers/gpu/drm/vc4/vc4_bo.c > > +++ b/drivers/gpu/drm/vc4/vc4_bo.c > > @@ -799,13 +799,38 @@ vc4_prime_import_sg_table(struct drm_device *dev, > > return obj; > > } > > > > +static int vc4_grab_bin_bo(struct vc4_dev *vc4, struct vc4_file *vc4file) > > +{ > > + int ret; > > + > > + if (!vc4->v3d) > > + return -ENODEV; > > + > > + if (vc4file->bin_bo_used) > > + return 0; > > + > > + ret = vc4_v3d_bin_bo_get(vc4); > > + if (ret) > > + return ret; > > + > > + vc4file->bin_bo_used = true; > > I think I found one last race. Multiple threads could be in an ioctl > trying to grab the bin BO at the same time (while this is only during > app startup, since the fd only needs to get the ref once, it's > particularly plausible given that allocating the bin BO is slow). I > think if you replace this line with: > > mutex_lock(&vc4->bin_bo_lock); > if (vc4file->bin_bo_used) { > mutex_unlock(&vc4->bin_bo_lock); > vc4_v3d_bin_bo_put(vc4); > } else { > vc4file->bin_bo_used = true; > mutex_unlock(&vc4->bin_bo_lock); > } Huh, very good catch once again, thanks! It took me some time to grasp this one, but as far as I understand, the risk is that we could ref our bin bo twice (although it would only be allocated once) since bin_bo_used is not protected. I'd like to suggest another solution, which would avoid re-locking and doing an extra put if we got an extra ref: adding a "bool *used" argument to vc4_v3d_bin_bo_get and, which only gets dereferenced with the bin_bo lock held. Then we can skip obtaining a new reference if (used && *used) in vc4_v3d_bin_bo_get. So we could pass a pointer to vc4file->bin_bo_used for vc4_grab_bin_bo and exec->bin_bo_used for the exec case (where there is no such issue since we'll only ever try to _get the bin bo once there anyway). What do you think? Cheers, Paul > that will be the last change we need. If you agree with this, feel free > to squash it in and apply the series with: > > Reviewed-by: Eric Anholt <eric@xxxxxxxxxx> > > > + > > + return 0; > > +} > > + > > int vc4_create_bo_ioctl(struct drm_device *dev, void *data, > > struct drm_file *file_priv) > > { > > struct drm_vc4_create_bo *args = data; > > + struct vc4_file *vc4file = file_priv->driver_priv; > > + struct vc4_dev *vc4 = to_vc4_dev(dev); > > struct vc4_bo *bo = NULL; > > int ret; > > > > + ret = vc4_grab_bin_bo(vc4, vc4file); > > + if (ret) > > + return ret; > > + > > /* > > * We can't allocate from the BO cache, because the BOs don't > > * get zeroed, and that might leak data between users. > > @@ -846,6 +871,8 @@ vc4_create_shader_bo_ioctl(struct drm_device *dev, void *data, > > struct drm_file *file_priv) > > { > > struct drm_vc4_create_shader_bo *args = data; > > + struct vc4_file *vc4file = file_priv->driver_priv; > > + struct vc4_dev *vc4 = to_vc4_dev(dev); > > struct vc4_bo *bo = NULL; > > int ret; > > > > @@ -865,6 +892,10 @@ vc4_create_shader_bo_ioctl(struct drm_device *dev, void *data, > > return -EINVAL; > > } > > > > + ret = vc4_grab_bin_bo(vc4, vc4file); > > + if (ret) > > + return ret; > > + > > bo = vc4_bo_create(dev, args->size, true, VC4_BO_TYPE_V3D_SHADER); > > if (IS_ERR(bo)) > > return PTR_ERR(bo); > > @@ -894,7 +925,7 @@ vc4_create_shader_bo_ioctl(struct drm_device *dev, void *data, > > */ > > ret = drm_gem_handle_create(file_priv, &bo->base.base, &args->handle); > > > > - fail: > > +fail: > > drm_gem_object_put_unlocked(&bo->base.base); > > > > return ret; > > Extraneous whitespace change? -- Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel