ccw_device_set_online(9)

✨ ccw_device_set_online(9) ✨

okay so bestie, we're in the Kernel API Manual today and this one is literally all about ccw_device_set_online — enabling a ccw device for I/O 🎀 no cap, that's the whole vibe.

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🌸 NAME 🌸

ccw_device_set_online — enable a ccw device for I/O 💅

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🦋 SYNOPSIS 🦋

int ccw_device_set_online (struct ccw_device *cdev );

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💖 ARGUMENTS 💖

• cdev — the target ccw device, iykyk 🎯

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✨ DESCRIPTION ✨

okay so here's the tea 🍓 — this function first enables cdev, and then, if the driver actually has one, it calls that driver's set_online function for cdev.

and like… if set_online returns an error? 😭 cdev gets disabled again. no half-online situations allowed, we don't do that here 💀

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🌈 RETURN 🌈

• 0 on success 🎉
• a negative error value on failure 🙈

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👑 CONTEXT 👑

enabled, and the ccw device lock is not held. periodt 💅

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⭐ SEE ALSO ⭐

the kernel file ./drivers/s390/cio/device.c, plus all these iconic siblings 🫶:

• ccw_device_set_offline(9)
• get_ccwdev_by_dev_id(9)
• ccw_purge_blacklisted(9)
• io_subchannel_sch_event(9)
• ccw_device_wait_idle(9)
• get_ccwdev_by_busid(9)
• ccw_driver_register(9)
• ccw_driver_unregister(9)
• ccw_device_sched_todo(9)
• ccw_device_siosl(9)

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and that's the whole page bestie 🧚💜 this lil gem lives in ./drivers/s390/cio, dated October 2026, and it's filed under ccw_device_set_online(9) — go forth and enable some devices, mwah 🎀🔥