hash_empty(9)

💖 NAME 💖

hash_empty — the lil vibe check that tells you whether your hashtable is literally empty or not ✨

okay so real talk, this is part of the Kernel API Manual and bestie, the page is called hash_empty(9) — that's the whole name, that's the whole job 🎀

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🌸 SYNOPSIS 🌸

hash_empty (hashtable );

that's it. that's the whole call. no cap, it's giving minimalism 👑

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🦋 ARGUMENTS 🦋

• hashtable — the hashtable you wanna check 🫶 like, the actual one. the one you're wondering about. hand it over and let the macro do its thing.

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🧚 DESCRIPTION 🧚

so here's the tea ☕ — this has to be a macro, and there's a genuinely iconic reason why: HASH_BITS will not work on pointers, because it calculates the size during preprocessing. 💅

like, it's not a choice, it's a whole structural requirement, iykyk. the preprocessor is doing math before the compiler even wakes up, so pointers simply cannot come to the function-call party. not me explaining macros at 2am but here we are 😭

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🔥 SEE ALSO 🔥

• the kernel file ./tools/include/linux/hashtable.h — like, the actual source, go read it bestie 📖
• hash_init(9)
• hash_add(9)
• hash_hashed(9)
• hash_del(9)
• hash_for_each(9)
• hash_for_each_safe(9)
• hash_for_each_possible(9)
• hash_for_each_possible_safe(9)

the whole hashtable friend group honestly, they all ate 🌈

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lowkey a whole family of macros and you're over here checking if one of them is empty. valid. iconic. no notes. 💜

and that's the page!! 🎀✨ this lil writeup lives in ./tools/include/linux, dated October 2026, and it goes by hash_empty(9) in case anyone asks — mwah, stay hydrated, go check your hashtables 💖🦋🌸