binder_alloc...pare_to_free(9)

📦 version 7.3.1, in nixpkgs unstable

✨ binder_alloc_prepare_to_free ✨

okay so we're diving into the Kernel API Manual today bestie, and this one is literally binder_alloc_prepare_to_free(9) — say that five times fast, i dare you 💀. it's giving "small function, big responsibilities" and honestly? iconic.

🌸 NAME 🌸

binder_alloc_prepare_to_free — get buffer given user ptr 🫶

like, you hand it a userspace pointer and it hands you back the buffer. matchmaker energy fr fr.

🎀 SYNOPSIS 🎀

struct binder_buffer * binder_alloc_prepare_to_free (struct binder_alloc
*alloc , unsigned long user_ptr );

yes the line break is real, yes we're keeping it, no we're not fixing it 💅

🦋 ARGUMENTS 🦋

  • alloc — the binder_alloc for this proc. it's the home base, the main character, the one who knows where everything lives 🔥
  • user_ptr — user pointer to buffer data. this is the little address you're trying to match up 👑

⭐ DESCRIPTION ⭐

so what does it actually do? it validates that userspace pointer to buffer data and returns the buffer that corresponds to that user pointer 💖. the way that it searches the rb tree for the buffer that matches the user data pointer?? that's the whole vibe. tree goes brrr, match gets found, slay 🌈.

no cap, that's it — validate the pointer, walk the rb tree, hand back what matches. periodt.

💜 RETURN 💜

pointer to buffer, or NULL 😭. that's the whole range. either you get your buffer or you get nothing, and NULL is the "sorry bestie, not today" of return values 🙈.

🔥 SEE ALSO 🔥

the kernel file lives at ./drivers/android/binder_alloc.c and it's surrounded by absolute legends, so let's give them their flowers 💐:

a whole friend group of functions, honestly 🧚

ngl, if you're here you're probably deep in binder internals — go drink some water and read the other pages too 🍓

okay bye bestie, this page came straight outta ./drivers/android and it's dated October 2026 — and yeah, the manual name up top is binder_alloc...pare_to_free(9) in case you were wondering why the title looks like it got cut off mid-sentence 😭💜

📦 where this page comes from