STRUCT BINDER_BUFFER(9)

✨ struct binder_buffer(9) ✨

okay so this is from the Kernel API Manual, and bestie, it's literally the vibe-check page for struct binder_buffer 💅

🌸 NAME 🌸

struct binder_buffer — the buffer used for binder transactions, no cap 🫶

🎀 SYNOPSIS 🎀

struct binder_buffer {
    struct list_head entry;
    struct rb_node rb_node;
    unsigned free:1;
    unsigned clear_on_free:1;
    unsigned allow_user_free:1;
    unsigned async_transaction:1;
    unsigned oneway_spam_suspect:1;
    unsigned debug_id:27;
    struct binder_transaction *transaction;
    struct binder_node *target_node;
    size_t data_size;
    size_t offsets_size;
    size_t extra_buffers_size;
    unsigned long user_data;
    int pid;
 };

🦋 Members 🦋

so like, here's the whole cast of characters, and yes every single one of them matters:

• entry — entry alloc->buffers. iconic little list link ✨
• rb_node — node for allocated_buffers/free_buffers rb trees 🌈
• free — true if buffer is free. that's it, that's the flag 💖
• clear_on_free — true if buffer must be zeroed after use. so like, wipe it down after, periodt 🧚
• allow_user_free — true if user is allowed to free buffer. permission slip energy 🎀
• async_transaction — true if buffer is in use for an async txn ⭐
• oneway_spam_suspect — true if total async allocate size just exceed spamming detect threshold. lowkey a red flag detector 🚩😭
• debug_id — unique ID for debugging. iykyk 🔥
• transaction — pointer to associated struct binder_transaction 💫
• target_node — struct binder_node associated with this buffer 👑
• data_size — size of transaction data 📦
• offsets_size — size of array of offsets
• extra_buffers_size — size of space for other objects (like sg lists) 🍓
• user_data — user pointer to base of buffer space
• pid — pid to attribute the buffer to (caller) 🫶

💜 Description 💜

Bookkeeping structure for binder transaction buffers. it's giving "totally unglamorous but absolutely load-bearing" and honestly we stan 🎀

👑 SEE ALSO 👑

• Kernel file ./drivers/android/binder_alloc.h struct
• binder_shrinker_mdata(9)
• struct binder_alloc(9)
• binder_alloc_get_free_async_space(9)

bestie please go read those, they're literally right there 💅

and that's the whole page! brought to you by ./drivers/android dated October 2026 — mwah, stay slay, and remember: bookkeeping structures are the main character too 🦋💖✨