[PATCH 01/13] drm/gem-shmem: Acquire reservation lock in GEM pin/unpin callbacks

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Export drm_gem_shmem_pin_locked() and acquire the reservation lock
directly in GEM pin callback. Same for unpin. Prepares for further
changes.

Dma-buf locking semantics require callers to hold the buffer's
reservation lock when invoking the pin and unpin callbacks. Prepare
gem-shmem accordingly by pushing locking out of the implementation.
A follow-up patch will fix locking for all GEM code at once.

Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
---
 drivers/gpu/drm/drm_gem_shmem_helper.c |  6 ++++--
 include/drm/drm_gem_shmem_helper.h     | 16 ++++++++++++++--
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index e435f986cd135..0ac3dddb917f3 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -228,7 +228,7 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
 }
 EXPORT_SYMBOL(drm_gem_shmem_put_pages);
 
-static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
+int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
 {
 	int ret;
 
@@ -238,13 +238,15 @@ static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
 
 	return ret;
 }
+EXPORT_SYMBOL(drm_gem_shmem_pin_locked);
 
-static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
+void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
 {
 	dma_resv_assert_held(shmem->base.resv);
 
 	drm_gem_shmem_put_pages(shmem);
 }
+EXPORT_SYMBOL(drm_gem_shmem_unpin_locked);
 
 /**
  * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index bf0c31aa8fbe4..eb12aa9a8c556 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -108,6 +108,9 @@ void drm_gem_shmem_vunmap(struct drm_gem_shmem_object *shmem,
 			  struct iosys_map *map);
 int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct *vma);
 
+int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem);
+void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem);
+
 int drm_gem_shmem_madvise(struct drm_gem_shmem_object *shmem, int madv);
 
 static inline bool drm_gem_shmem_is_purgeable(struct drm_gem_shmem_object *shmem)
@@ -172,8 +175,15 @@ static inline void drm_gem_shmem_object_print_info(struct drm_printer *p, unsign
 static inline int drm_gem_shmem_object_pin(struct drm_gem_object *obj)
 {
 	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+	int ret;
+
+	ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
+	if (ret)
+		return ret;
+	ret = drm_gem_shmem_pin_locked(shmem);
+	dma_resv_unlock(shmem->base.resv);
 
-	return drm_gem_shmem_pin(shmem);
+	return ret;
 }
 
 /**
@@ -187,7 +197,9 @@ static inline void drm_gem_shmem_object_unpin(struct drm_gem_object *obj)
 {
 	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
 
-	drm_gem_shmem_unpin(shmem);
+	dma_resv_lock(shmem->base.resv, NULL);
+	drm_gem_shmem_unpin_locked(shmem);
+	dma_resv_unlock(shmem->base.resv);
 }
 
 /**
-- 
2.43.2