uprobe_register(9)

💅 uprobe_register(9) — like, the kernel API manual, but make it make sense

okay so bestie, buckle up — this one lives in the Kernel API Manual section 9 (the kernel-functions girlies), and it's literally called uprobe_register. Yes, it's a probe. Yes, you're registering it. We love a self-explanatory name. 🎀

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✨ NAME ✨

uprobe_register — register a probe 🦋

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🌸 SYNOPSIS 🌸

struct uprobe * uprobe_register (struct inode *inode , loff_t offset ,
       loff_t ref_ctr_offset , struct uprobe_consumer *uc );

like, that's the whole vibe check right there 💖

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🫶 ARGUMENTS 🫶

• inode — the file in which the probe has to be placed. that's the file, bestie, the actual one, the probee 📁
• offset — offset from the start of the file. so like, where in the file. count from zero, not from your feelings 💫
• ref_ctr_offset — offset of SDT marker / reference counter. yes, both of those things, that's what it says, I don't make the rules 🎯
• uc — information on howto handle the probe.. (the double period is canon, don't come for me 😭) like, your consumer, your instructions, your whole struct uprobe_consumer situation 👑

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💜 DESCRIPTION 💜

okay so here's the tea, and it's actually kind of elegant ngl ✨

Apart from the access refcount, uprobe_register takes a creation refcount (thro alloc_uprobe) if and only if this uprobe is getting inserted into the rbtree — that's the case where it's the first consumer for an inode:offset tuple 🌈. So like, first one in the door, you get the extra refcount. no cap.

and why do we care about this creation refcount? because it stops uprobe_unregister from freeing the uprobe even before the register operation is complete 😤🔥 — imagine being freed mid-registration, could not be me, embarrassing.

the creation refcount gets released when the last uc for the uprobe unregisters. last one out, lights off, refcount dropped 💅

⚠️ real talk though: the caller of uprobe_register is required to keep inode (and the containing mount) referenced. like, hold onto it. don't let it go. this is not optional, this is a requirement, periodt 👑

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⭐ RETURN ⭐

pointer to the new uprobe on success 🎉 or an ERR_PTR on failure 💀 (check it, bestie, always check it)

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🧚 SEE ALSO 🧚

Kernel file ./kernel/events/uprobes.c 💖 and also these iconic siblings:

• is_swbp_insn(9)
• is_trap_insn(9)
• set_swbp(9)
• set_orig_insn(9)
• uprobe_unregister_nosync(9)
• uprobe_apply(9)
• uprobe_get_swbp_addr(9)

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and that's the whole page, bestie 🫶 this one's from ./kernel/events, dated October 2026, and it's the uprobe_register(9) page — go forth and probe responsibly, mwah 💋🎀