drm/i915: Make i915_gem_object_phys_attach() use obj->mm.lock more appropriately

Actually transferring from shmemfs to the physically contiguous set of
pages should be wholly guarded by its obj->mm.lock!

v2: Remember to free the old pages.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170726160038.29487-2-chris@chris-wilson.co.uk
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 6faabf3..12dddba 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -565,7 +565,8 @@ int
 i915_gem_object_attach_phys(struct drm_i915_gem_object *obj,
                            int align)
 {
-       int ret;
+       struct sg_table *pages;
+       int err;
 
        if (align > obj->base.size)
                return -EINVAL;
@@ -573,32 +574,51 @@ i915_gem_object_attach_phys(struct drm_i915_gem_object *obj,
        if (obj->ops == &i915_gem_phys_ops)
                return 0;
 
-       if (obj->mm.madv != I915_MADV_WILLNEED)
-               return -EFAULT;
-
-       if (obj->base.filp == NULL)
+       if (obj->ops != &i915_gem_object_ops)
                return -EINVAL;
 
-       ret = i915_gem_object_unbind(obj);
-       if (ret)
-               return ret;
+       err = i915_gem_object_unbind(obj);
+       if (err)
+               return err;
+
+       mutex_lock(&obj->mm.lock);
 
-       __i915_gem_object_put_pages(obj, I915_MM_NORMAL);
-       if (obj->mm.pages)
-               return -EBUSY;
+       if (obj->mm.madv != I915_MADV_WILLNEED) {
+               err = -EFAULT;
+               goto err_unlock;
+       }
 
-       GEM_BUG_ON(obj->ops != &i915_gem_object_ops);
+       if (obj->mm.quirked) {
+               err = -EFAULT;
+               goto err_unlock;
+       }
+
+       if (obj->mm.mapping) {
+               err = -EBUSY;
+               goto err_unlock;
+       }
+
+       pages = obj->mm.pages;
        obj->ops = &i915_gem_phys_ops;
 
-       ret = i915_gem_object_pin_pages(obj);
-       if (ret)
+       err = __i915_gem_object_get_pages(obj);
+       if (err)
                goto err_xfer;
 
+       /* Perma-pin (until release) the physical set of pages */
+       __i915_gem_object_pin_pages(obj);
+
+       if (!IS_ERR_OR_NULL(pages))
+               i915_gem_object_ops.put_pages(obj, pages);
+       mutex_unlock(&obj->mm.lock);
        return 0;
 
 err_xfer:
        obj->ops = &i915_gem_object_ops;
-       return ret;
+       obj->mm.pages = pages;
+err_unlock:
+       mutex_unlock(&obj->mm.lock);
+       return err;
 }
 
 static int