On Fri, 24 Jun 2016, Mat Martineau wrote:
The final version of the syscall that went in to kernel 4.7 added a
reserved arg to the KEYCTL_DH_COMPUTE syscall. In the future, this arg
will be used to optionally specify a key derivation function. For now,
it's needed so the system call doesn't return -1 (errno == EINVAL)
Let me tweak this commit message, v2 coming up.