STRUCT F_ECM_OPTS(9)

💖 struct f_ecm_opts(9) — the ECM function options glow-up 💖

okay so bestie, this is a page from the Kernel API Manual and it's all about struct f_ecm_opts, which is literally the options bundle for the ECM function. no cap, it's shorter than it looks, so let's get into it 😌✨

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✨ NAME ✨

struct f_ecm_opts — ECM function options 🎀

Like, that's it. That's the whole name. Iconic brevity, honestly.

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🌸 SYNOPSIS 🌸

struct f_ecm_opts {
    struct usb_function_instance    func_inst;
    struct net_device               *net;
    bool bound;
    int bind_count;
    struct mutex                    lock;
    int refcnt;
 };

okay so quick vibe check: there's a trailing space situation before that closing brace in the original and we are keeping it, because facts are facts and we do not touch the code 💅

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🦋 Members 🦋

• func_inst — USB function instance. that's the whole description bestie, short and sweet 🫶
• net — the net_device that's associated with the ECM function.
• bound — true if the net_device is shared and pre-registered during the legacy composite driver's bind phase (like, multi.c does that). if it's false, then the ECM function registers the net_device during its own bind phase instead. so like, who's doing the registering? depends on this flag. iykyk 😭
• bind_count — tracks how many configurations the ECM function is bound to, and the whole point is preventing double-registration of the net device. we love a counter with a purpose ✨
• lock — protects the data from concurrent access by configfs read/write and create symlink/remove symlink operations. so like, it's the bouncer at the club, nobody gets in at the same time 🚪💅
• refcnt — reference counter for the function instance. classic refcnt behaviour, no notes 💜

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🧚 SEE ALSO 🧚

• Kernel file ./drivers/usb/gadget/function/u_ecm.h — go read it, bestie, it's right there 👑

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⭐ friendly reminder that bound, bind_count, lock and refcnt all exist for real reasons: sharing, avoiding double-registration, concurrent access protection, and reference counting. don't sleep on them 🙈

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and that's the whole page, fr fr — shoutout to the source at ./drivers/usb/gadget/function, dated October 2026, and a big kiss to the struct f_ecm_opts(9) footer for keeping it all together 🌈💖 mwah, bye bestie! 🍓