[PATCH 06/25] IB/uverbs: Helper function to initialize ufile member of uverbs_attr_bundle

[Shamir Rabinovitch <srabinov7@gmail.com>]

From: Shamir Rabinovitch <shamir.rabinovitch@oracle.com>

Helper function to initialize ufile member of structure uverbs_attr_bundle.

This helper produce structure uverbs_attr_bundle that is safe for the below
operations on the given ufile:

- uobj_get_[read|write]
- uobj_alloc_commit
- uobj_alloc_abort

The last 2 ops are more complicated. Abort for example triggers the
below which pass the uverbs_attr_bundle driver_udata down to the
drivers level:

uobj_alloc_abort
 rdma_alloc_abort_uobject
  uverbs_destroy_uobject
   uobj->uapi_object->type_class->destroy_hw
    destroy_hw_idr_uobject
     idr_type->destroy_object
      uverbs_free_pd
       ib_dealloc_pd_user
        pd->device->ops.dealloc_pd
	 mlx4_ib_dealloc_pd

For more information about the potential issues, please see
commit f89adedaf3fe ("RDMA/uverbs: Initialize udata struct
on destroy flows")

Cc: Gal Pressman <galpress@amazon.com>
Signed-off-by: Shamir Rabinovitch <shamir.rabinovitch@oracle.com>
Signed-off-by: Shamir Rabinovitch <srabinov7@gmail.com>
---
 drivers/infiniband/core/uverbs_cmd.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index d1f0c04f0ae8..4f42f9732dca 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -3773,6 +3773,24 @@ static int ib_uverbs_ex_modify_cq(struct uverbs_attr_bundle *attrs)
 	return ret;
 }
 
+/**
+ * uverbs_init_attrs_ufile - Helper function to create minimal
+ * uverbs_attr_bundle out of ib_uverbs_file that is suitable
+ * for the below operations:
+ *
+ * - uobj_get_[read|write]
+ * - uobj_alloc_commit
+ * - uobj_alloc_abort
+ */
+static void uverbs_init_attrs_ufile(struct uverbs_attr_bundle *attrs_bundle,
+				    struct ib_uverbs_file *ufile)
+{
+	*attrs_bundle = (struct uverbs_attr_bundle) {
+		.ufile = ufile,
+		.context = ufile->ucontext,
+	};
+}
+
 /*
  * Describe the input structs for write(). Some write methods have an input
  * only struct, most have an input and output. If the struct has an output then
-- 
2.20.1