STRUCT OBJPOOL_HEAD(9)

💖 struct objpool_head(9) 💖

okay so real talk, bestie — welcome to struct objpool_head(9), straight out of the Kernel API Manual (section 9, kernel-space gang 👑). this is the glow-up page for object pooling metadata, and honestly? it's giving backstage-pass energy. everything the pool needs to know about itself lives in this one little struct. let's get into it 🎀

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✨ NAME ✨

struct objpool_head — the object pooling metadata. that's it, that's the vibe. it's the struct that holds all the receipts for an object pool 🧾💅

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🦋 SYNOPSIS 🦋

periodt, here's the literal shape of it — no cap, copy it exactly:

struct objpool_head {
    int obj_size;
    int nr_objs;
    int nr_possible_cpus;
    int capacity;
    gfp_t gfp;
    refcount_t ref;
    unsigned long           flags;
    struct objpool_slot   **cpu_slots;
    objpool_fini_cb release;
    void *context;
 };

lowkey obsessed with how tidy that is. look at those members lined up like a friend group photo 📸

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🌸 Members 🌸

okay bestie, field-by-field tour, main-character energy only:

• obj_size — the size of one object, and it's aligned to sizeof(void *). yes, the alignment is not optional, the kernel does NOT do unaligned behaviour, we stan a struct that lines up 💫
• nr_objs — total objs, like, the whole headcount. these are the ones "to be pre-allocated with objpool" 🫶
• nr_possible_cpus — a cached value of num_possible_cpus. it's a little saved copy so nobody has to go ask again, iykyk 🙈
• capacity — max objs that one single objpool_slot can manage. per-slot limit, respect it 💅
• gfp — the gfp flags used for kmalloc & vmalloc. this is the "how do we allocate" mood ring ✨
• ref — the refcount of the objpool. classic refcount behaviour, keep it balanced or things get 😭
• flags — flags for objpool management. that's the official description, no extra clues, don't ask me for more 🎀
• cpu_slots — pointer to the array of objpool_slot. the tap-in point for the per-cpu squad 🌈
• release — the resource cleanup callback. it's the "we're wrapping up, clean your room" function 🧹
• context — caller-provided context. it's your stuff, you bring it, you own it 🍓

ngl these are the actual one-liners from the page — I'm not out here inventing kernel behaviour, that's not the move 💀

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👑 SEE ALSO 👑

go read these next, bestie, they're literally the rest of the lore 🔥

• Kernel file ./include/linux/objpool.h — the header itself, the mothership
• struct objpool_slot(9)
• objpool_init(9)
• objpool_pop(9)
• objpool_push(9)
• objpool_drop(9)
• objpool_free(9)
• objpool_fini(9)

it's a whole ecosystem, not just one page. ate and left no crumbs 💜

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and that's the whole thing, bestie 🫶 mwah 💋 — this page came from the ./include/linux source tree, dated October 2026, and it's filed as struct objpool_head(9). go forth and pool those objects responsibly ✨🌸💅