FUTEX_LOCK_PI2(2const)

💖 FUTEX_LOCK_PI2 💖

okay so bestie, welcome to FUTEX_LOCK_PI2 — it's a 2const manual page, and it's literally about locking a priority-inheritance futex. yes we're doing kernel things today, and yes you're gonna slay it 🫶

It lives in the Standard C library (libc, -lc). iconic behavior honestly.

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✨ SYNOPSIS ✨

#include <linux/futex.h>  /* Definition of FUTEX_* constants */
#include <sys/syscall.h>  /* Definition of SYS_* constants */
#include <unistd.h>

long syscall(SYS_futex, uint32_t *uaddr, FUTEX_LOCK_PI2, 0,
             const struct timespec *timeout);

like yes you're calling syscall(2) directly, main character energy, no wrapper, periodt 💅

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🌸 DESCRIPTION 🌸

So this operation is the same as FUTEX_LOCK_PI(2const) — like, same vibes, same lock, same priority inheritance — except for one little glow-up: the clock that timeout gets measured against is selectable. that's the whole flex. 🦋

By default, the (absolute) timeout you pass in timeout is measured against the CLOCK_MONOTONIC clock. no cap.

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🎀 RETURN VALUE 🎀

Go read FUTEX_LOCK_PI(2const), bestie. it's all there. 📖

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💀 ERRORS 💀

Also FUTEX_LOCK_PI(2const). same page, same energy. go look 👀

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⭐ STANDARDS ⭐

Linux. that's it. that's the standard. 🐧

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🕰️ HISTORY 🕰️

It showed up in Linux 5.14. a whole era. 👑

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🔥 SEE ALSO 🔥

• futex(2)

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ngl, if you were hoping for a long list of flags to memorize, this is not that page. this one is short, sweet, and points you straight at FUTEX_LOCK_PI(2const). iykyk 💜

okay bye bestie, go lock some futexes responsibly 💖✨

— written up in Linux man-pages 6.20, dated 2025-05-30. 🎀🌈