[PATCH 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.koe...@amd.com>
Cc: Matthew Brost <matthew.br...@intel.com>
Signed-off-by: Thomas Hellström <thomas.hellst...@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