[PATCH v2 2/2] drm/ttm: Add a device flag to propagate -ENOSPC on OOM

[Thomas Hellström]

Some graphics APIs differentiate between out-of-graphics-memory and
out-of-host-memory (system memory). Add a device init flag to
have -ENOSPC propagated from the resource managers instead of being
converted to -ENOMEM, to aid driver stacks in determining what
error code to return or whether corrective action can be taken at
the driver level.

Cc: Christian König <christian.koenig at amd.com>
Cc: Matthew Brost <matthew.brost at intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c     |  2 +-
 drivers/gpu/drm/ttm/ttm_device.c |  1 +
 include/drm/ttm/ttm_device.h     | 13 +++++++++++++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 320592435252..c4bec2ad301b 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -835,7 +835,7 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
 
 	/* For backward compatibility with userspace */
 	if (ret == -ENOSPC)
-		return -ENOMEM;
+		return bo->bdev->propagate_enospc ? ret : -ENOMEM;
 
 	/*
 	 * We might need to add a TTM.
diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
index 0c85d10e5e0b..aee9d52d745b 100644
--- a/drivers/gpu/drm/ttm/ttm_device.c
+++ b/drivers/gpu/drm/ttm/ttm_device.c
@@ -203,6 +203,7 @@ int ttm_device_init(struct ttm_device *bdev, const struct ttm_device_funcs *func
 	}
 
 	bdev->funcs = funcs;
+	bdev->propagate_enospc = flags.propagate_enospc;
 
 	ttm_sys_man_init(bdev);
 
diff --git a/include/drm/ttm/ttm_device.h b/include/drm/ttm/ttm_device.h
index 1534bd946c78..f9da78bbd925 100644
--- a/include/drm/ttm/ttm_device.h
+++ b/include/drm/ttm/ttm_device.h
@@ -266,6 +266,13 @@ struct ttm_device {
 	 * @wq: Work queue structure for the delayed delete workqueue.
 	 */
 	struct workqueue_struct *wq;
+
+	/**
+	 * @propagate_enospc: Whether -ENOSPC should be propagated to the caller after
+	 * graphics memory allocation failure. If false, this will be converted to
+	 * -ENOMEM, which is the default behaviour.
+	 */
+	bool propagate_enospc;
 };
 
 int ttm_global_swapout(struct ttm_operation_ctx *ctx, gfp_t gfp_flags);
@@ -295,6 +302,12 @@ struct ttm_device_init_flags {
 	u32 use_dma_alloc : 1;
 	/** @use_dma32: If we should use GFP_DMA32 for device memory allocations. */
 	u32 use_dma32 : 1;
+	/**
+	 * @propagate_enospc: Whether -ENOSPC should be propagated to the caller after
+	 * graphics memory allocation failure. If false, this will be converted to
+	 * -ENOMEM, which is the default behaviour.
+	 */
+	u32 propagate_enospc : 1;
 };
 
 int ttm_device_init(struct ttm_device *bdev, const struct ttm_device_funcs *funcs,
-- 
2.46.0