[PATCH v4 4/8] dma-buf: Make .invalidate_mapping() truly optional

Leon Romanovsky
2026-01-21T12:59:43Z

From: Leon Romanovsky <leonro@nvidia.com>

The .invalidate_mapping() callback is documented as optional, yet it
effectively became mandatory whenever importer_ops were provided. This
led to cases where RDMA non-ODP code had to supply an empty stub.

Relax the checks in the dma-buf core so the callback can be omitted,
allowing RDMA code to drop the unnecessary function.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
drivers/dma-buf/dma-buf.c | 6 ++----
drivers/infiniband/core/umem_dmabuf.c | 13 -------------
2 files changed, 2 insertions(+), 17 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index cd68c1c0bfd7..1629312d364a 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -947,9 +947,6 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
if (WARN_ON(!dmabuf || !dev))
return ERR_PTR(-EINVAL);

- if (WARN_ON(importer_ops && !importer_ops->invalidate_mappings))
- return ERR_PTR(-EINVAL);
-
attach = kzalloc(sizeof(*attach), GFP_KERNEL);
if (!attach)
return ERR_PTR(-ENOMEM);
@@ -1260,7 +1257,8 @@ void dma_buf_invalidate_mappings(struct dma_buf *dmabuf)
dma_resv_assert_held(dmabuf->resv);

list_for_each_entry(attach, &dmabuf->attachments, node)
- if (attach->importer_ops)
+ if (attach->importer_ops &&
+ attach->importer_ops->invalidate_mappings)
attach->importer_ops->invalidate_mappings(attach);
}
EXPORT_SYMBOL_NS_GPL(dma_buf_invalidate_mappings, "DMA_BUF");
diff --git a/drivers/infiniband/core/umem_dmabuf.c b/drivers/infiniband/core/umem_dmabuf.c
index d77a739cfe7a..256e34c15e6b 100644
--- a/drivers/infiniband/core/umem_dmabuf.c
+++ b/drivers/infiniband/core/umem_dmabuf.c
@@ -129,9 +129,6 @@ ib_umem_dmabuf_get_with_dma_device(struct ib_device *device,
if (check_add_overflow(offset, (unsigned long)size, &end))
return ret;

- if (unlikely(!ops || !ops->invalidate_mappings))
- return ret;
-
dmabuf = dma_buf_get(fd);
if (IS_ERR(dmabuf))
return ERR_CAST(dmabuf);
@@ -184,18 +181,8 @@ struct ib_umem_dmabuf *ib_umem_dmabuf_get(struct ib_device *device,
}
EXPORT_SYMBOL(ib_umem_dmabuf_get);

-static void
-ib_umem_dmabuf_unsupported_move_notify(struct dma_buf_attachment *attach)
-{
- struct ib_umem_dmabuf *umem_dmabuf = attach->importer_priv;
-
- ibdev_warn_ratelimited(umem_dmabuf->umem.ibdev,
- "Invalidate callback should not be called when memory is pinned\n");
-}
-
static struct dma_buf_attach_ops ib_umem_dmabuf_attach_pinned_ops = {
.allow_peer2peer = true,
- .invalidate_mappings = ib_umem_dmabuf_unsupported_move_notify,
};

struct ib_umem_dmabuf *

--
2.52.0