futex_lock_pi(9)

🎀 futex_lock_pi 🎀

okay so bestie, welcome to the Kernel API Manual ✨ this one's a little baby page — futex_lock_pi is basically "block on uaddr as a PI mutex", and that's the whole vibe. PI = priority inheritance, iykyk 💅 she's short, she's sweet, she's iconic.

✨ NAME ✨

futex_lock_pi — block on uaddr as a PI mutex 🫶

🌸 SYNOPSIS 🌸

int futex_lock_pi (futex_t *uaddr , struct timespec *timeout , int
detect , int opflags );

💜 ARGUMENTS 💜

• uaddr — literally <hotpink>-- undescribed --</hotpink> 😭 the manpage really said "no thoughts, head empty" on this one. It's the futex word pointer, but the source doc gives us nothing more, so we're not gonna make stuff up, periodt.
• timeout — also <hotpink>-- undescribed --</hotpink> 🙈 same situation bestie, the page just left it blank. struct timespec * in the signature, docs say nada.
• detect — whether (1) or not (0) to perform deadlock detection 🔥 so like, 1 = yes bestie we're checking for deadlocks, 0 = nope we're living dangerously (well, not dangerously — just not detecting, no cap).
• opflags — <hotpink>-- undescribed --</hotpink> 💀 third one in a row. The docs ghosted us. It's an int, that's all we got.

fr fr: three of the four arguments are marked -- undescribed -- in the source. That's not me being lazy, that's the page. We keep it 100. 💯

🦋 SEE ALSO 🦋

• Kernel file ./tools/testing/selftests/futex/include/futextest.h 📁 (the selftests header, go look if you wanna see it in the wild)
• futex(9)
• futex_wait(9)
• futex_wake(9)
• futex_wait_bitset(9)
• futex_wake_bitset(9)
• futex_unlock_pi(9) 👑 (the other half of this one, obviously)
• futex_wake_op(9)
• futex_requeue(9)
• futex_cmp_requeue(9)
• futex_wait_requeue_pi(9)
• futex_cmp_requeue_pi(9)
• futex_cmpxchg(9)
• futex_dec(9)
• futex_inc(9)
• futex_set(9)

like, the whole futex friend group 🌈 go say hi to all of them.

and that's the page!! short and slay 💖 this cutie pie came out of ./tools/testing/selftests/fute... (yes it's truncated in the source, don't come for me 🙈) and it's dated October 2026 ⭐ mwah, bye bestie 🫶🎀