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 exist 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 | 24 ++++++++++++++++--------
include/drm/drm_gem_shmem_helper.h | 10 ++++++++++
2 files changed, 26 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 25e99468ced2..7e1e674e2c9f 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -236,18 +236,16 @@ static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
dma_resv_assert_held(shmem->base.resv);
+ if (refcount_inc_not_zero(&shmem->pages_pin_count))
+ return 0;
+
ret = drm_gem_shmem_get_pages_locked(shmem);
+ if (!ret)
+ refcount_set(&shmem->pages_pin_count, 1);
return ret;
}
-static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
-{
- dma_resv_assert_held(shmem->base.resv);
-
- drm_gem_shmem_put_pages_locked(shmem);
-}
-
/**
* drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
* @shmem: shmem GEM object
@@ -265,6 +263,9 @@ int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem)
drm_WARN_ON(obj->dev, obj->import_attach);
+ if (refcount_inc_not_zero(&shmem->pages_pin_count))
+ return 0;
+
ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
if (ret)
return ret;
@@ -288,8 +289,14 @@ void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem)
drm_WARN_ON(obj->dev, obj->import_attach);
+ if (refcount_dec_not_one(&shmem->pages_pin_count))
+ return;
+
dma_resv_lock(shmem->base.resv, NULL);
- drm_gem_shmem_unpin_locked(shmem);
+
+ if (refcount_dec_and_test(&shmem->pages_pin_count))
+ drm_gem_shmem_put_pages_locked(shmem);
+
dma_resv_unlock(shmem->base.resv);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_unpin);
@@ -634,6 +641,7 @@ void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
if (shmem->base.import_attach)
return;
+ drm_printf_indent(p, indent, "pages_pin_count=%u\n", refcount_read(&shmem->pages_pin_count));
drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);
drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 808083279fd5..1cd74ae5761a 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.
+ */
+ refcount_t pages_pin_count;
+
/**
* @madv: State for madvise
*
--
2.41.0
