Re: [PATCH rdma-next 1/2] RDMA/uverbs: Add DMABUF object type and operations

[Yishai Hadas]

On 20/01/2026 20:15, Jason Gunthorpe wrote:

On Thu, Jan 08, 2026 at 01:11:14PM +0200, Edward Srouji wrote:

  void rdma_user_mmap_entry_remove(struct rdma_user_mmap_entry *entry)
  {
+       struct ib_uverbs_dmabuf_file *uverbs_dmabuf, *tmp;
+
        if (!entry)
                return;

+ mutex_lock(&entry->dmabufs_lock);

        xa_lock(&entry->ucontext->mmap_xa);
        entry->driver_removed = true;
        xa_unlock(&entry->ucontext->mmap_xa);
+       list_for_each_entry_safe(uverbs_dmabuf, tmp, &entry->dmabufs, 
dmabufs_elm) {
+               dma_resv_lock(uverbs_dmabuf->dmabuf->resv, NULL);
+               list_del(&uverbs_dmabuf->dmabufs_elm);
+               uverbs_dmabuf->revoked = true;
+               dma_buf_move_notify(uverbs_dmabuf->dmabuf);
+               dma_resv_unlock(uverbs_dmabuf->dmabuf->resv);

This will need the same wait that Christian pointed out for VFIO..

Sure, I'll add.

diff --git a/drivers/infiniband/core/rdma_core.c 
b/drivers/infiniband/core/rdma_core.c
index 18918f463361..3e0a8b9cd288 100644
--- a/drivers/infiniband/core/rdma_core.c
+++ b/drivers/infiniband/core/rdma_core.c
@@ -465,7 +465,7 @@ alloc_begin_fd_uobject(const struct uverbs_api_object *obj,

fd_type =

                container_of(obj->type_attrs, struct uverbs_obj_fd_type, type);
-       if (WARN_ON(fd_type->fops->release != &uverbs_uobject_fd_release &&
+       if (WARN_ON(fd_type->fops && fd_type->fops->release != 
&uverbs_uobject_fd_release &&
                    fd_type->fops->release != &uverbs_async_event_release)) {
                ret = ERR_PTR(-EINVAL);
                goto err_fd;
@@ -477,14 +477,16 @@ alloc_begin_fd_uobject(const struct uverbs_api_object 
*obj,
                goto err_fd;
        }

- /* Note that uverbs_uobject_fd_release() is called during abort */

-       filp = anon_inode_getfile(fd_type->name, fd_type->fops, NULL,
-                                 fd_type->flags);
-       if (IS_ERR(filp)) {
-               ret = ERR_CAST(filp);
-               goto err_getfile;
+       if (fd_type->fops) {
+               /* Note that uverbs_uobject_fd_release() is called during abort 
*/
+               filp = anon_inode_getfile(fd_type->name, fd_type->fops, NULL,
+                                         fd_type->flags);
+               if (IS_ERR(filp)) {
+                       ret = ERR_CAST(filp);
+                       goto err_getfile;
+               }
+               uobj->object = filp;
        }
-       uobj->object = filp;

uobj->id = new_fd;

        return uobj;
@@ -561,7 +563,9 @@ static void alloc_abort_fd_uobject(struct ib_uobject *uobj)
  {
        struct file *filp = uobj->object;

- fput(filp);

+       if (filp)
+               fput(filp);
+
        put_unused_fd(uobj->id);

This stuff changing hw the uobjects work should probably be in its own
patch with its own explanation about creating a uobject that wrappers
an externally allocated file descriptor vs this automatic internal
allocation.

Sure, I’ll split the current patch into two patches.

index 797e2fcc8072..66287e8e7ad7 100644
--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -133,6 +133,16 @@ struct ib_uverbs_completion_event_file {
        struct ib_uverbs_event_queue            ev_queue;
  };

+struct ib_uverbs_dmabuf_file {

+       struct ib_uobject uobj;
+       struct dma_buf *dmabuf;
+       struct list_head dmabufs_elm;
+       struct rdma_user_mmap_entry *mmap_entry;
+       struct dma_buf_phys_vec phys_vec;

Oh, are we going to have weird merge conflicts with this Leon?

+static int uverbs_dmabuf_attach(struct dma_buf *dmabuf,
+                               struct dma_buf_attachment *attachment)
+{
+       struct ib_uverbs_dmabuf_file *priv = dmabuf->priv;
+
+       if (!attachment->peer2peer)
+               return -EOPNOTSUPP;
+
+       if (priv->revoked)
+               return -ENODEV;

This should only be checked in map

Please see Leon's answer on that.

Yishai