On Mon, Jul 20, 2020 at 10:28:55AM -0700, Andy Lutomirski wrote: > > Sure, I'd consider that implementation detail for the actual patch(es) > > for this issue. > > There’s a corner case, though: doesn’t io_uring submission frequently do the > work synchronously in the context of the calling thread?
Yes. > If so, can a thread do a 64-bit submit with 32-bit work or vice versa? In theory you could share an fd created in a 32-bit thread to a 64-bit thread or vice versa, but I think at that point you absolutely are in "you get to keep the pieces" land. > Sometimes I think that in_compat_syscall() should have a mode in which > calling it warns (e.g. not actually in a syscall when doing things in > io_uring). And the relevant operations should be properly wired up to avoid > global state like this. What do you mean with "properly wired up". Do you really want to spread ->compat_foo methods everywhere, including read and write? I found in_compat_syscall() a lot small and easier to maintain than all the separate compat cruft.
