RDMA: Add ib_is_udata_in_empty()

If the driver doesn't yet support any request driver data it should check
that it is all zeroed. This is a common pattern, add a helper around
_ib_copy_validate_udata_in() to do this.

Link: https://patch.msgid.link/r/6-v3-bd56dd443069+49-bnxt_re_uapi_jgg@nvidia.com
Tested-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Acked-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/include/rdma/uverbs_ioctl.h b/include/rdma/uverbs_ioctl.h
index 38a11bfe137430336a071dd90885d8c7a984c086..e2af17da3e32ceb798521a5279787123e129e641 100644 (file)
--- a/include/rdma/uverbs_ioctl.h
+++ b/include/rdma/uverbs_ioctl.h
@@ -1075,6 +1075,21 @@ int _ib_copy_validate_udata_cm_fail(struct ib_udata *udata, u64 req_cm,
                ret;                                                          \
        })
 
+/**
+ * ib_is_udata_in_empty - Check if the udata input buffer is all zeros
+ * @udata: The system calls ib_udata struct
+ *
+ * This should be used if the driver does not currently define a driver data
+ * struct. Returns 0 if the buffer is empty or all zeros, -EOPNOTSUPP if
+ * non-zero data is present, or a negative error code on failure.
+ */
+static inline int ib_is_udata_in_empty(struct ib_udata *udata)
+{
+       if (!udata || udata->inlen == 0)
+               return 0;
+       return _ib_copy_validate_udata_in(udata, NULL, 0, 0);
+}
+
 /**
  * ib_respond_udata - Copy a driver data response to userspace
  * @_udata: The system calls ib_udata struct