[$] Smart pointers for the kernel

Rust has a plethora of smart-pointer types, including reference-countedpointers, which have special support in the compiler to make themeasier to use. The Rust-for-Linux project would like to reap those same benefitsfor its smart pointers, which need to be written by hand to conform totheLinux kernelmemory model. Xiangfei Dingpresented at Kangrejos about the work to enable customsmart pointers to function the same as built-in smart pointers.