On Thu, Jan 26, 2017 at 11:36:05AM +0100, Daniel Vetter wrote: > On Thu, Jan 26, 2017 at 09:22:46AM +0200, Oleksandr Andrushchenko wrote: > > From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx> > > > > From the description of the "DMA-BUF/GEM Object references > > and lifetime overview" it is not clear when exactly > > dma_buf gets destroyed and memory freed: only driver > > .release function mentioned which makes confusion on the > > real buffer's lifetime. > > > > Add more description so all the paths are covered. > > > > Cc: Rob Clark <robdclark@xxxxxxxxx> > > Cc: Dave Airlie <airlied@xxxxxxxx> > > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> > > Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx> > > --- > > drivers/gpu/drm/drm_prime.c | 9 ++++++++- > > 1 file changed, 8 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > > index 8d77b2462594..c061a0b29819 100644 > > --- a/drivers/gpu/drm/drm_prime.c > > +++ b/drivers/gpu/drm/drm_prime.c > > @@ -41,7 +41,7 @@ > > * object. It takes this reference in handle_to_fd_ioctl, when it > > * first calls .prime_export and stores the exporting GEM object in > > * the dma_buf priv. This reference is released when the dma_buf > > - * object goes away in the driver .release function. > > + * object goes away. > > This was meant to talke about the release function of the dma-buf file, > not the drm_driver. Note that not all drivers use the same _release > function, e.g. vmwgfx is ttm-based, not gem and hence can't use > drm_gem_dmabuf_release(). > > Maybe let's rewrite the entire sentence: > > "This refernce needs to be released when the final reference to the > &dma_buf itself is dropped and its &dma_buf_ops.release function is > called. For GEM-based drivers this is done by using > drm_gem_dmabuf_release()." For GEM-based drivers, the dmabuf should be exported using drm_gem_dmabuf_export() and then released by drm_gem_dmabuf_release(). Just the emphasize the symmetry (because of the internal magics)? -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
