[PATCH v2 3/9] drm: Simplify drmm_alloc_ordered_workqueue return

[Matthew Brost]

Rather than returning ERR_PTR or NULL on failure, replace the NULL
return with ERR_PTR(-ENOMEM). This simplifies error handling at the
caller. While here, add kernel documentation for
drmm_alloc_ordered_workqueue.

Cc: Louis Chauvet <louis.chauvet at bootlin.com>
Signed-off-by: Matthew Brost <matthew.brost at intel.com>
---
 drivers/gpu/drm/vkms/vkms_crtc.c |  2 --
 include/drm/drm_managed.h        | 15 +++++++++++++--
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index 8c9898b9055d..e60573e0f3e9 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -302,8 +302,6 @@ struct vkms_output *vkms_crtc_init(struct drm_device *dev, struct drm_plane *pri
 	vkms_out->composer_workq = drmm_alloc_ordered_workqueue(dev, "vkms_composer", 0);
 	if (IS_ERR(vkms_out->composer_workq))
 		return ERR_CAST(vkms_out->composer_workq);
-	if (!vkms_out->composer_workq)
-		return ERR_PTR(-ENOMEM);
 
 	return vkms_out;
 }
diff --git a/include/drm/drm_managed.h b/include/drm/drm_managed.h
index 53017cc609ac..72bfac002c06 100644
--- a/include/drm/drm_managed.h
+++ b/include/drm/drm_managed.h
@@ -129,14 +129,25 @@ void __drmm_mutex_release(struct drm_device *dev, void *res);
 
 void __drmm_workqueue_release(struct drm_device *device, void *wq);
 
+/**
+ * drmm_alloc_ordered_workqueue - &drm_device managed alloc_ordered_workqueue()
+ * @dev: DRM device
+ * @fmt: printf format for the name of the workqueue
+ * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
+ * @args: args for @fmt
+ *
+ * This is a &drm_device-managed version of alloc_ordered_workqueue(). The
+ * allocated workqueue is automatically destroyed on the final drm_dev_put().
+ *
+ * Returns: workqueue on success, negative ERR_PTR otherwise.
+ */
 #define drmm_alloc_ordered_workqueue(dev, fmt, flags, args...)					\
 	({											\
 		struct workqueue_struct *wq = alloc_ordered_workqueue(fmt, flags, ##args);	\
 		wq ? ({										\
 			int ret = drmm_add_action_or_reset(dev, __drmm_workqueue_release, wq);	\
 			ret ? ERR_PTR(ret) : wq;						\
-		}) :										\
-			wq;									\
+		}) : ERR_PTR(-ENOMEM);								\
 	})
 
 #endif
-- 
2.34.1