atomic64_fetch_xor(9)

📦 version 7.3.1, in nixpkgs unstable

💅 atomic64_fetch_xor — like, the Kernel API Manual, but make it make sense

okay bestie, welcome to the <pink>Kernel API Manual</pink> ✨ page for atomic64_fetch_xor(9) — the tiny function that does a bitwise XOR and hands you back the old value, all atomically. she's giving main character energy and full ordering, no cap 💖

🦋 NAME

atomic64_fetch_xor — atomic bitwise XOR with full ordering. yes that's the whole pitch, and honestly? iconic.

✨ SYNOPSIS

s64 atomic64_fetch_xor (s64 i , atomic64_t *v );

like, that's it. two arguments. she's low maintenance 🎀

🧚 ARGUMENTS

  • i — an s64 value. that's the number you're XOR-ing in, bestie.
  • v — pointer to an atomic64_t. this is the poor little guy getting updated.

🔥 DESCRIPTION

so the way this works: it atomically updates v to (v ^ i) with full ordering. atomically means nobody can sneak in halfway through and see a cursed in-between state — she's one clean operation, periodt 💅

⚠️ no cap: it's unsafe to use in noinstr code. if you're in there, use raw_atomic64_fetch_xor instead. do not come for me if you ignore this 🙈

🎀 RETURN

the original value of v — meaning the value before the XOR happened. so you get the past, and v gets the future. both of you ate 💖

🌈 SEE ALSO

all her sisters and cousins, fr fr — the whole family lives in the kernel file ./include/linux/atomic/atomic-instrumented.h 🫶

the atomic_* girlies:

the atomic64_* squad (her actual sisters):

the atomic_long_* cousins (still family, still slay):

and that's the whole page, bestie!! 🌸 she lives in ./include/linux/atomic, the version vibes are from <blue>October 2026</blue>, and this lil group chat was brought to you by the Kernel API Manual. mwah, study her before your interview 💖💅✨

📦 where this page comes from