Add separate pages_pin_count for tracking of whether drm-shmem pages are
moveable or not. With the addition of memory shrinker support to drm-shmem,
the pages_use_count will no longer determine whether pages are hard-pinned
in memory, but whether pages exit and are soft-pinned (and could be swapped
out). The pages_pin_count > 1 will hard-pin pages in memory.
Suggested-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_gem_shmem_helper.c | 22 +++++++++++++++++-----
include/drm/drm_gem_shmem_helper.h | 10 ++++++++++
2 files changed, 27 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index d545d3d227d7..1a7e5c332fd8 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -234,14 +234,22 @@ static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
dma_resv_assert_held(shmem->base.resv);
+ if (kref_get_unless_zero(&shmem->pages_pin_count))
+ return 0;
+
ret = drm_gem_shmem_get_pages_locked(shmem);
+ if (!ret)
+ kref_init(&shmem->pages_pin_count);
return ret;
}
-static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
+static void drm_gem_shmem_kref_unpin_pages(struct kref *kref)
{
- dma_resv_assert_held(shmem->base.resv);
+ struct drm_gem_shmem_object *shmem;
+
+ shmem = container_of(kref, struct drm_gem_shmem_object,
+ pages_pin_count);
drm_gem_shmem_put_pages_locked(shmem);
}
@@ -263,6 +271,9 @@ int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem)
drm_WARN_ON(obj->dev, obj->import_attach);
+ if (kref_get_unless_zero(&shmem->pages_pin_count))
+ return 0;
+
ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
if (ret)
return ret;
@@ -286,9 +297,10 @@ void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem)
drm_WARN_ON(obj->dev, obj->import_attach);
- dma_resv_lock(shmem->base.resv, NULL);
- drm_gem_shmem_unpin_locked(shmem);
- dma_resv_unlock(shmem->base.resv);
+ if (kref_put_dma_resv(&shmem->pages_pin_count,
+ drm_gem_shmem_kref_unpin_pages,
+ obj->resv, NULL))
+ dma_resv_unlock(obj->resv);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_unpin);
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index ec2d8b24e3cf..afb7cd671e2a 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -39,6 +39,16 @@ struct drm_gem_shmem_object {
*/
unsigned int pages_use_count;
+ /**
+ * @pages_pin_count:
+ *
+ * Reference count on the pinned pages table.
+ * The pages allowed to be evicted and purged by memory
+ * shrinker only when the count is zero, otherwise pages
+ * are hard-pinned in memory.
+ */
+ struct kref pages_pin_count;
+
/**
* @madv: State for madvise
*
--
2.41.0
