STRUCT CMB_AREA(9)

💅 struct cmb_area(9) — like, the kernel API manual bestie 🎀

okay so real talk, this is page struct cmb_area(9) from the Kernel API Manual, and it's short but it matters, so let's get into it ✨

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✨ NAME ✨

struct cmb_area — the lil container that holds all your global cmb data 🫶 no cap, that's literally its whole job.

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🌸 SYNOPSIS 🌸

struct cmb_area {
    struct cmb *mem;
    struct list_head list;
    int num_channels;
    spinlock_t lock;
 };

periodt. four members. that's the whole struct. she's compact and she's iconic 💅

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🦋 Members 🦋

• mem — pointer to CMBs, but only in basic measurement mode 💖 (so if you're not in basic measurement mode, don't come looking here bestie, it's giving crickets)
• list — holds a linked list of all subchannels 🌈 yes, all of them, she keeps the whole squad together
• num_channels — the number of channels that are to be measured 👑 the headcount, essentially
• lock — a spinlock, and its whole personality is protecting concurrent access to mem and list 🔥. like, do not touch those two without holding the lock, i'm literally begging 🙈

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⭐ SEE ALSO ⭐

go read the rest of the family, iykyk 💜

Kernel file ./drivers/s390/cio/cmf.c, plus:

enum cmb_format(9), struct cmb_operations(9), struct cmb(9), struct cmbe(9), enable_cmf(9), __disable_cmf(9), disable_cmf(9), cmf_read(9), cmf_readall(9), cmf_reactivate(9)

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💀 friendly reminder that lock protects both mem and list — so like, respect the lock or things get real undefined-behaviour-y real fast 😭

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k bye bestie!! this page came from ./drivers/s390/cio and it's dated October 2026, so it's fresh 💖 mwah 💋 — go forth and lock your mem and list properly 🧚‍♀️✨