This reverts commit 67b7836d4458790f1261e31fe0ce3250989784f0.
The locking appears incomplete. A caller of SHMEM helper's pin
function never acquires the dma-buf reservation lock. So we get
WARNING: CPU: 3 PID: 967 at drivers/gpu/drm/drm_gem_shmem_helper.c:243
drm_gem_shmem_pin+0x42/0x90 [drm_shmem_helper]
Signed-off-by: Thomas Zimmermann
---
drivers/gpu/drm/drm_gem_shmem_helper.c| 185 +++---
drivers/gpu/drm/lima/lima_gem.c | 8 +-
drivers/gpu/drm/panfrost/panfrost_drv.c | 7 +-
.../gpu/drm/panfrost/panfrost_gem_shrinker.c | 6 +-
drivers/gpu/drm/panfrost/panfrost_mmu.c | 19 +-
include/drm/drm_gem_shmem_helper.h| 14 +-
6 files changed, 148 insertions(+), 91 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c
b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 3d43e5961573..f75e50273d7a 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -88,6 +88,8 @@ __drm_gem_shmem_create(struct drm_device *dev, size_t size,
bool private)
if (ret)
goto err_release;
+ mutex_init(>pages_lock);
+ mutex_init(>vmap_lock);
INIT_LIST_HEAD(>madv_list);
if (!private) {
@@ -139,13 +141,11 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object
*shmem)
{
struct drm_gem_object *obj = >base;
+ drm_WARN_ON(obj->dev, shmem->vmap_use_count);
+
if (obj->import_attach) {
drm_prime_gem_destroy(obj, shmem->sgt);
} else {
- dma_resv_lock(shmem->base.resv, NULL);
-
- drm_WARN_ON(obj->dev, shmem->vmap_use_count);
-
if (shmem->sgt) {
dma_unmap_sgtable(obj->dev->dev, shmem->sgt,
DMA_BIDIRECTIONAL, 0);
@@ -154,18 +154,18 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object
*shmem)
}
if (shmem->pages)
drm_gem_shmem_put_pages(shmem);
-
- drm_WARN_ON(obj->dev, shmem->pages_use_count);
-
- dma_resv_unlock(shmem->base.resv);
}
+ drm_WARN_ON(obj->dev, shmem->pages_use_count);
+
drm_gem_object_release(obj);
+ mutex_destroy(>pages_lock);
+ mutex_destroy(>vmap_lock);
kfree(shmem);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_free);
-static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
+static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
{
struct drm_gem_object *obj = >base;
struct page **pages;
@@ -197,16 +197,35 @@ static int drm_gem_shmem_get_pages(struct
drm_gem_shmem_object *shmem)
}
/*
- * drm_gem_shmem_put_pages - Decrease use count on the backing pages for a
shmem GEM object
+ * drm_gem_shmem_get_pages - Allocate backing pages for a shmem GEM object
* @shmem: shmem GEM object
*
- * This function decreases the use count and puts the backing pages when use
drops to zero.
+ * This function makes sure that backing pages exists for the shmem GEM object
+ * and increases the use count.
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
*/
-void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
+int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
{
struct drm_gem_object *obj = >base;
+ int ret;
- dma_resv_assert_held(shmem->base.resv);
+ drm_WARN_ON(obj->dev, obj->import_attach);
+
+ ret = mutex_lock_interruptible(>pages_lock);
+ if (ret)
+ return ret;
+ ret = drm_gem_shmem_get_pages_locked(shmem);
+ mutex_unlock(>pages_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL(drm_gem_shmem_get_pages);
+
+static void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
+{
+ struct drm_gem_object *obj = >base;
if (drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count))
return;
@@ -224,6 +243,19 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object
*shmem)
shmem->pages_mark_accessed_on_put);
shmem->pages = NULL;
}
+
+/*
+ * drm_gem_shmem_put_pages - Decrease use count on the backing pages for a
shmem GEM object
+ * @shmem: shmem GEM object
+ *
+ * This function decreases the use count and puts the backing pages when use
drops to zero.
+ */
+void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
+{
+ mutex_lock(>pages_lock);
+ drm_gem_shmem_put_pages_locked(shmem);
+ mutex_unlock(>pages_lock);
+}
EXPORT_SYMBOL(drm_gem_shmem_put_pages);
/**
@@ -240,8 +272,6 @@ int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem)
{
struct drm_gem_object *obj = >base;
- dma_resv_assert_held(shmem->base.resv);
-
drm_WARN_ON(obj->dev, obj->import_attach);
return drm_gem_shmem_get_pages(shmem);
@@ -259,31 +289,14 @@ void drm_gem_shmem_unpin(struct drm_gem_shmem_object
*shmem)
{
