tty_port_block_til_ready(9)

📦 version 7.3.1, in nixpkgs unstable

💖 tty_port_block_til_ready (9) — like, the Kernel API Manual, bestie 💖

okay so we're in the Kernel API Manual today and the main character is tty_port_block_til_ready(9). buckle up, this one's about waiting — and honestly? the waiting is the whole personality. 🎀

✨ NAME ✨

tty_port_block_til_ready — the waiting logic for tty open. literally just "we sit here until the tty is ready" energy. 💅

🌸 SYNOPSIS 🌸

int tty_port_block_til_ready (struct tty_port *port , struct tty_struct
*tty , struct file *filp );

🦋 ARGUMENTS 🦋

  • port — the tty port that's being opened rn. main character port, no cap.
  • tty — the tty device being bound. it's getting attached to the port, slay.
  • filp — the file pointer of whoever's opening it, or NULL. yeah, NULL is allowed, don't panic. 🙈

💜 DESCRIPTION 💜

so this function implements the core POSIX/SuS tty behaviour for when you're opening a tty device. it handles, and I mean it handles:

  • hangup — and that's both before and during. double duty. 😭
  • non blocking open
  • rts/dtr/dcd
  • signals
  • port flags and counts

the port you pass in must implement the port->ops->carrier_raised method if it can do carrier detect, and it must implement the port->ops->dtr_rts method if it supports software management of these lines. like, non-negotiable bestie, that's the vibe check. ⭐

and ngl the important little detail here: the dtr/rts raise gets done each iteration, because a hangup may have previously dropped them while we were waiting. so like, we keep re-raising them the whole time we wait. 🔥

caller holds the tty lock. that's the rule. no sneak. 👑

🌈 NOTE 🌈

this one's lowkey spicy: it may drop and reacquire the tty lock when blocking. which means tty and port may have changed state while you weren't looking — eg., they may have been hung up. 💀 so don't be out here assuming nothing moved, bestie, because things absolutely moved.

🫶 SEE ALSO 🫶

Kernel file ./drivers/tty/tty_port.c and honestly the whole friend group:

and that's the whole page, bestie 💖 this came at you from ./drivers/tty, dated October 2026, and it's signed tty_port_block_til_ready(9) — periodt. 🎀🦋✨

📦 where this page comes from