relay_reserve(9)

🎀 relay_reserve(9) — the Kernel API Manual, bestie edition 🎀

okay so you're in the <pink>Kernel API Manual</pink>, section 9, and the star of the show is relay_reserve — yes that's the whole name, no cap ✨

💖 NAME 💖

relay_reserve — reserve a slot in the channel buffer 🫶 like grabbing your seat before the group chat descends, except it's bytes and it's kernel land

🌸 SYNOPSIS 🌸

void * relay_reserve (struct rchan *chan , size_t length );

literally that's it, that's the whole vibe check 💅

🦋 ARGUMENTS 🦋

• chan — the relay channel 💜 your main character struct, the one holding the buffer
• length — number of bytes to reserve 🎀 how much room you're claiming, in bytes, exactly

✨ DESCRIPTION ✨

Returns a pointer to the reserved slot, and NULL if it's full 😭 so pls check that return value, i'm begging

What it actually does: it reserves a slot in the <cyan>current cpu's</cyan> channel buffer 🔥 current CPU, not some other one, keep that in mind bestie

⚠️ and here's the important part 👑 it does not protect the buffer at all — the caller has to provide the appropriate synchronization. that's on you, not on it. no cap, it will not save you 💀

🌈 SEE ALSO 🌈

Kernel file ./include/linux/relay.h 🍓 plus these iconic siblings:

• relay_write(9)
• __relay_write(9)
• subbuf_start_reserve(9)

and that's the whole page, periodt 🧚 from ./include/linux, October 2026 — mwah, go reserve some slots responsibly, iykyk 💖✨🎀