drm/i915: Pin backing pages whilst exporting through a dmabuf vmap
We need to refcount our pages in order to prevent reaping them at
inopportune times, such as when they currently vmapped or exported to
another driver. However, we also wish to keep the lazy deallocation of
our pages so we need to take a pin/unpinned approach rather than a
simple refcount.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
index e4f1141..eca4726 100644
--- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
@@ -50,6 +50,8 @@
/* link the pages into an SG then map the sg */
sg = drm_prime_pages_to_sg(obj->pages, npages);
nents = dma_map_sg(attachment->dev, sg->sgl, sg->nents, dir);
+ i915_gem_object_pin_pages(obj);
+
out:
mutex_unlock(&dev->struct_mutex);
return sg;
@@ -102,6 +104,7 @@
}
obj->vmapping_count = 1;
+ i915_gem_object_pin_pages(obj);
out_unlock:
mutex_unlock(&dev->struct_mutex);
return obj->dma_buf_vmapping;
@@ -117,10 +120,11 @@
if (ret)
return;
- --obj->vmapping_count;
- if (obj->vmapping_count == 0) {
+ if (--obj->vmapping_count == 0) {
vunmap(obj->dma_buf_vmapping);
obj->dma_buf_vmapping = NULL;
+
+ i915_gem_object_unpin_pages(obj);
}
mutex_unlock(&dev->struct_mutex);
}