Linus Torvalds criticized a RISC-V Linux kernel contribution from a Google engineer as “garbage code.” The discussion focuses on the helper function make_u32_from_two_u16() versus Linus's proposed explicit code. Let's discuss the importance of using proper type casting, bit manipulation, and creating a safer, reusable macro or function for clarity and bug reduction.

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A detailed analysis of Linus Torvalds' criticism of a RISC-V kernel contribution, examining the technical merits of helper functions versus explicit bit manipulation code. The author argues that proper helper functions with type casting and bit masking are safer and more maintainable than inline expressions, demonstrating correct implementations in both C macros and C++ constexpr functions.

Linus Torvalds and the Supposedly “Garbage Code”

I believe Linus’ outrage comes from sending a patch late into the merge window that should be RISC-V specific, but touches generic headers.
When I first read that snippet, my first reaction to a function (or a macro?) called <code>make_u32_from_two_u16</code> was “AI wrote this”.
Then there’s the conundrum of introducing that helper. If it’s in a generic header, does that mean we go back and use this newly introduced helper on all places in the kernel where we’re combining two u16 into a u32? If yes, then great, but that’s a lot of code to go through. If not, then that leaves other devs with “why is this here and why isn’t it used everywhere”? Granted, they could look at the commit dates and understand that it’s been introduced later on.
As for the C++ example in the post… I find it weird. The kernel is written in C, not in C++, so who exactly is this example for?

This is shit post. In mailing list Torvald expressed that he hated helper function, explained why he hated and also mentioned that is in wrong place (generic headers). All these points are valid.
I personally would hate encounter function like that in code. Torvald talk is bit harsh but It shows how passionate he is. And I fucking love it.