devcgroup_online(9)

💅 devcgroup_online — section 9, kernel API manual, bestie

okay so you found your way into devcgroup_online(9) and honestly? iconic of you. this is a section 9 kernel API page, so get comfy, it's giving "we're in the internals now" energy. ✨

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✨ NAME ✨

devcgroup_online — the little function that initializes devcgroup's behavior and exceptions based on parent's. like, it looks at what the parent cgroup is doing and sets the vibe accordingly. 🫶

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🌸 SYNOPSIS 🌸

int devcgroup_online (struct cgroup_subsys_state *css );

that's it, that's the whole signature. one argument, returns an int. short and slay. 💅

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🎀 ARGUMENTS 🎀

• css — the css that's getting online. and bestie, it returns 0 in case of success, error code otherwise — so 0 is the good ending, anything else means something went sideways. 😭

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🔥 SEE ALSO 🔥

the kernel file to go look at is ./security/device_cgroup.c — that's the main character. 👑

and then these icon friends all show up in the same universe:

• dev_exception_clean(9)
• match_exception(9)
• match_exception_partial(9)
• verify_new_ex(9)
• parent_allows_removal(9)
• may_allow_all(9)
• revalidate_active_exceptions(9)
• propagate_exception(9)
• devcgroup_legacy_check_permission(9)

no cap, that's the whole exception squad right there. go read them, iykyk. 📚

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ngl this page is short, but every single word in it is load-bearing. don't skip the return value. 0 = slay, error code = sound the alarms. 🚨

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okay that's the whole page, periodt. this gem lives over in ./security and the version/date stamp on it is October 2026 — so yeah, mark your calendar bestie, and go online those devcgroups responsibly. 🌈💖🧚