On Feb 22, 2023, at 4:57 PM, Axel Rasmussen axelrasmussen@google.com wrote:
Many userfaultfd ioctl functions take both a 'mode' and a 'wp_copy' argument. In future commits we plan to plumb the flags through to more places, so we'd be proliferating the very long argument list even further.
Let's take the time to simplify the argument list. Combine the two arguments into one - and generalize, so when we add more flags in the future, it doesn't imply more function arguments.
Since the modes (copy, zeropage, continue) are mutually exclusive, store them as an integer value (0, 1, 2) in the low bits. Place combine-able flag bits in the high bits.
Signed-off-by: Axel Rasmussen axelrasmussen@google.com
Hi Axel,
I sent a patch a long time ago called “userfaultfd: introduce uffd_flags”. For some reason it does not appear on lore, but you were a recipient.
It was pretty similar, but one thing that I preferred in my version is that it defined a different type to avoid confusion. Since “flags” is a very generic name, perhaps you’d like to adapt this approach.