On Thu, May 14, 2020 at 09:16:54AM +0200, Thomas Zimmermann wrote:
> Hi
>
> Am 11.05.20 um 11:35 schrieb Daniel Vetter:
> > There's no direct harm, because for the shmem helpers these are noops
> > on imported buffers. The trouble is in the locks these take - I want
> > to change dma_buf_vmap locking, and so need to make sure that we only
> > ever take certain locks on one side of the dma-buf interface: Either
> > for exporters, or for importers.
> >
> > Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> > Cc: Rob Herring <robh@xxxxxxxxxx>
> > Cc: Noralf Trønnes <noralf@xxxxxxxxxxx>
> > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/drm_gem_shmem_helper.c | 17 +++++++++--------
> > 1 file changed, 9 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> > index 2a70159d50ef..b9cba5cc61c3 100644
> > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> > @@ -252,32 +252,33 @@ static void *drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)
> > if (shmem->vmap_use_count++ > 0)
> > return shmem->vaddr;
> >
> > - ret = drm_gem_shmem_get_pages(shmem);
> > - if (ret)
> > - goto err_zero_use;
> > -
> > if (obj->import_attach) {
> > shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
> > } else {
> > pgprot_t prot = PAGE_KERNEL;
> >
> > + ret = drm_gem_shmem_get_pages(shmem);
> > + if (ret)
> > + goto err;
> > +
> > if (!shmem->map_cached)
> > prot = pgprot_writecombine(prot);
> > shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
> > VM_MAP, prot);
> > +
> > + if (!shmem->vaddr)
> > + drm_gem_shmem_put_pages(shmem);
> > }
> >
> > if (!shmem->vaddr) {
> > DRM_DEBUG_KMS("Failed to vmap pages\n");
> > ret = -ENOMEM;
> > - goto err_put_pages;
> > + goto err;
> > }
> >
> > return shmem->vaddr;
> >
> > -err_put_pages:
> > - drm_gem_shmem_put_pages(shmem);
>
> I found the new code to be less readable. Maybe keep the error rollback
> as-is and protect _put_pages() with if (!import_attach).
Hm yeah I guess I can leave this as-is mostly, makes at least the diff
smaller. Imo it all looks a bit awkward, but what I've done isn't clearly
better than just leaving stuff mostly where it was.
-Daniel
>
> In any case
>
> Acked-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
>
> > -err_zero_use:
> > +err:
> > shmem->vmap_use_count = 0;
> >
> > return ERR_PTR(ret);
> >
>
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/dri-devel
