put_disk(9)

💅 put_disk(9) — the kernel API manual, bestie edition 🎀

Okay so we're in the put_disk(9) page of the Kernel API Manual, and honestly? This one is short but she matters. Let's get into it ✨

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🌸 NAME 🌸

put_disk — decrements the gendisk refcount

Like, that's it. That's the whole job. One lil decrement. But miss it and your kernel is not gonna be okay 😭

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🦋 SYNOPSIS 🦋

void put_disk (struct gendisk *disk );

Yep. Void return, one pointer in. No drama, no return value to check, just vibes and refcounting 🫶

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💖 ARGUMENTS 💖

• disk — the struct gendisk to decrement the refcount for. That's the one. Hand her over and let her go 💅

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✨ DESCRIPTION ✨

So here's the tea ☕: this decrements the refcount for the struct gendisk. When that refcount reaches 0, we'll have disk_release called. That's the whole lifecycle arc, main character energy from start to finish 👑

Think of it as the polite way of saying "okay bestie, you can go now" — and once the last one is said, disk_release shows up to do the actual cleanup 🧚

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🔥 NOTE 🔥

Listen up, this one's important, no cap 🚨

For blk-mq disk, put_disk must be called before freeing the tag_set when handling probe errors — that is, before add_disk is called.

Do it in the wrong order and it's giving chaos. Not the cute kind 💀

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🌈 CONTEXT 🌈

Any context, bestie — go wild 🦋

BUT — and this is a big but — the last reference must not be dropped from atomic context. That's the one line you cannot skip, fr fr 😤

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⭐ SEE ALSO ⭐

Kernel file ./block/genhd.c, plus the whole friend group:

• bdev_count_inflight(9)
• __register_blkdev(9)
• add_disk_fwnode(9)
• device_add_disk(9)
• blk_mark_disk_dead(9)
• del_gendisk(9)
• invalidate_disk(9)
• disk_release(9)
• set_disk_ro(9)

iykyk 👀

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Okay go forth and decrement responsibly, bestie 🍓💜 This page lives in ./block and it's stamped October 2026 — mwah, slay, periodt 💅✨