`take_async` should only accept `Send` or `Sync` types

[Max Obreiter]

I accidently passed &mut u8 instead of u8 and got weird errors. The data of the borrow can't be ensured to be valid and probably can't be accessed too. Not sure weather we have to restrict T to Send or Sync (or maybe even something else).

[Corey Lowman]

You mean you passed Vec<&mut u8>? Can you post minimal example/errors?

[Max Obreiter]

there is no error, it's just if you have CudaSlice<&mut u8> but your kernel code accepts unsigned char, then you will have weird values