STRUCT RHASHTABLE(9)

💖 struct rhashtable(9) 💖

okay bestie, welcome to the Kernel API Manual — today's main character is struct rhashtable, aka the hash table handle, and honestly? she's iconic. let's get into it 🫶

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✨ NAME ✨

struct rhashtable — Hash table handle 💅

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🌸 SYNOPSIS 🌸

struct rhashtable {
    struct bucket_table *tbl;
    unsigned int                    key_len;
    unsigned int                    max_elems;
    struct rhashtable_params        p;
    bool rhlist;
    struct work_struct              run_work;
    struct irq_work                 run_irq_work;
    struct mutex                    mutex;
    spinlock_t lock;
    atomic_t nelems;
  #ifdef CONFIG_MEM_ALLOC_PROFILING;
    struct alloc_tag                *alloc_tag;
  #endif;
 };

no cap, that's the whole vibe right there ⬆️

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👑 Members 👑

every field gets her moment, periodt:

• tbl — Bucket table 🪣 (yes literally, that's the table of buckets, she's the whole point)
• key_len — Key length for hashfn 🔑 (how long your keys are, for the hash function's purposes)
• max_elems — Maximum number of elements in table 🍓 (the ceiling, the limit, the "we're full bestie" number)
• p — Configuration parameters ⚙️ (all the setup details live here)
• rhlist — True if this is an rhltable 💀 (like, bool true. it's an rhltable. that's the whole note)
• run_work — Deferred worker to expand/shrink asynchronously 🧚 (does the growing and shrinking later, in the background, no blocking)
• run_irq_work — Bounces the run_work kick through hard IRQ context. ⚡ (it relays the kick over to run_work by way of hard IRQ context, iykyk)
• mutex — Mutex to protect current/future table swapping 🔒 (guard duty for the table swapping, now and later)
• lock — Spin lock to protect walker list 🌀 (keeps the walker list safe)
• nelems — Number of elements in table 🔢 (how many are actually in there rn)

not me getting emotional over a struct with this many locks in it 😭 she's doing the most and we love her for it

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🦋 SEE ALSO 🦋

• Kernel file ./include/linux/rhashtable-types.h
• struct rhashtable_compare_arg(9)
• struct rhashtable_params(9)
• struct rhltable(9)
• struct rhashtable_walker(9)
• struct rhashtable_iter(9)

go read the whole friend group, they're all slay 🌈

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and that's the tea, bestie 🎀 this was brought to you from ./include/linux, October 2026 edition — mwah, ily, go touch some kernel code ✨💜