kernfs_dere..._node_locked(9)

💅 kernfs_dere..._node_locked(9) ✨

okay bestie, welcome to the Kernel API Manual 🎀 — no cap, this one's a short one but it's important, so like, pay attention fr fr.

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🌸 NAME 🌸

kernfs_deref_open_node_locked — grab the kernfs_open_node that matches @kn, that's literally the whole job 🫶

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✨ SYNOPSIS ✨

struct kernfs_open_node * kernfs_deref_open_node_locked (struct kernfs_node *kn );

like yes, that's the whole signature, she's lowkey minimal 💅

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🦋 ARGUMENTS 🦋

• kn — the target kernfs_node. this is the node you're asking about, bestie, hand her over and she'll hand you the goods ✨

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💖 DESCRIPTION 💖

okay so here's the vibe: this thing fetches and returns ->attr.open of kn — but only when the caller is already holding kernfs_open_file_mutex_ptr(kn). that's the whole deal, iykyk 🔥

and like, why does that matter? because updates to ->attr.open happen under kernfs_open_file_mutex_ptr(kn). so when the caller guarantees that this mutex is being held, other updaters literally can't touch ->attr.open, which means — and this is the iconic part — we can safely deref ->attr.open outside an RCU read-side critical section. no RCU era needed, we're free 🦋✨

⚠️ but listen: the caller needs to make sure that kernfs_open_file_mutex is held. that's not a suggestion, that's the whole contract, bestie. don't skip it 💀

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👑 RETURN 👑

kn->attr.open — returned when kernfs_open_file_mutex is held. that's it. that's the return value. periodt 💅

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🌈 SEE ALSO 🌈

• Kernel file ./fs/kernfs/file.c
• of_on(9)
• kernfs_get_open_node(9)
• kernfs_unlink_open_file(9)
• kernfs_notify(9)
• __kernfs_create_file(9)

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and that's the page, bestie!! 🎀🫶 mwah 💋 — this one came straight out of ./fs/kernfs, dated October 2026, under the same title kernfs_dere..._node_locked(9). slay, go hold that mutex 💜✨