Why the linux kernel uses double logical negations instead of casts to bools?

Question

Given that x is a variable of type int with the number 5 as its value, consider the following statement:

int y = !!x;

This is what I think it happens: x is implicitly casted to a bool and the first negation is executed, after that the last negation is made, so a cast and two negations.

My question is, isn't just casting to bool (executing int y = (bool)x; instead of int y = !!x) faster than using double negation, as you are saving two negations from executing.

I might be wrong because I see the double negation a lot in the Linux kernel, but I don't understand where my intuition goes wrong, maybe you can help me out.