wrapping_sub(9)

📦 version 7.3.1, in nixpkgs unstable

💅 wrapping_sub(9)

okay so this is a page from the Kernel API Manual and it's about wrapping_sub — yes bestie, subtraction that's allowed to wrap around, on purpose, no cap 🎀

✨ NAME ✨

wrapping_sub — intentionally perform a wrapping subtraction 🌀

like, the wrapping is the point, it's not a bug, it's a feature 💅

🌸 SYNOPSIS 🌸

wrapping_sub (type , a , b );

three things go in, one thing comes out, and the vibes are immaculate ✨

🦋 ARGUMENTS 🦋

  • type — the type for the result of the calculation 👑 this is what your answer is gonna be, so pick it with intention
  • a — the minuend; the value you're subtracting from 🫶 the main character of this operation, honestly
  • b — the subtrahend; the value you subtract from a 🌸 the supporting role, but she delivers
ngl the naming is lowkey giving math class but fr fr a - b and you're done 🍓

💖 DESCRIPTION 💖

Returns the potentially wrapped-around subtraction — and the whole reason this exists is so you don't trip any of the wrap-around sanitizers that might be enabled 😭✨

like bestie, the sanitizers will absolutely jump you if you do unsigned wrap math the "normal" way. this is the intentional, sanctioned, no-sneaky-surprises way to do it. the wrap is expected, the wrap is documented, the wrap is slaying 👑

it's giving "I know exactly what I'm doing" energy and I'm obsessed 💜

🌈 SEE ALSO 🌈

the kernel file ./include/linux/overflow.h is literally right there holding the whole overflow family together 🧚 and here's the entire squad, all (9) sections, no gatekeeping:

anyway that's the whole page, go forth and subtract with intent 💜🦋

signed, sealed, delivered from ./include/linux — October 2026 edition, mwah 😘🎀

📦 where this page comes from