xa_cmpxchg_irq(9)

💅 xa_cmpxchg_irq — from the Kernel API Manual, bestie ✨

Okay so picture this: you're deep in the kernel, you've got an XArray, and you need to swap out an entry only if it still holds the value you expect — and you need interrupts to stay ✨quiet✨ while you do it. That's this function. Welcome to xa_cmpxchg_irq(9). 🎀

---

✨ NAME ✨

xa_cmpxchg_irq — conditionally replace an entry in the XArray. Like, only if the vibe check on the old value passes. 🫶

---

🌸 SYNOPSIS 🌸

void * xa_cmpxchg_irq (struct xarray *xa , unsigned long index , void
       *old , void *entry , gfp_t gfp );

---

🦋 ARGUMENTS 🦋

• xa — the XArray. Your array. Your main character. 👑
• index — the index into the array. Where the drama happens.
• old — the old value to test against. If it doesn't match, no swap for you, sorry. 🙈
• entry — the new value to place in the array. The glow-up. ✨
• gfp — memory allocation flags. Let the kernel know how it's allowed to behave when it needs memory.

---

💖 DESCRIPTION 💖

So this is basically xa_cmpxchg, except — and this is the whole moment — it disables interrupts while holding the array lock. That's it, that's the difference. Two functions, same energy, one of them is interrupt-safe. Slay. 💅

---

🔥 CONTEXT 🔥

Process context, bestie. It takes and releases the xa_lock while disabling interrupts. And yes — it may sleep if the gfp flags permit, so don't come crying to me when your atomic context gets wrecked. You were warned. 😭

---

⭐ RETURN ⭐

The old value at this index — or xa_err if an error happened. That's the whole return story, no cap.

---

🌈 SEE ALSO 🌈

Kernel file ./include/linux/xarray.h, plus the entire friend group:

xa_mk_value(9), xa_to_value(9), xa_is_value(9), xa_tag_pointer(9), xa_untag_pointer(9), xa_pointer_tag(9), xa_is_zero(9), xa_is_err(9), xa_err(9), struct xa_limit(9), struct xarray(9), DEFINE_XARRAY_FLAGS(9), DEFINE_XARRAY(9), DEFINE_XARRAY_ALLOC(9), DEFINE_XARRAY_ALLOC1(9), xa_init_flags(9), xa_init(9), xa_empty(9), xa_marked(9), xa_for_each_range(9), xa_for_each_start(9), xa_for_each(9), xa_for_each_marked(9), xa_store_bh(9), xa_store_irq(9), xa_erase_bh(9), xa_erase_irq(9), xa_cmpxchg(9), xa_cmpxchg_bh(9), xa_insert(9), xa_insert_bh(9), xa_insert_irq(9), xa_alloc(9), xa_alloc_bh(9), xa_alloc_irq(9), xa_alloc_cyclic(9), xa_alloc_cyclic_bh(9), xa_alloc_cyclic_irq(9), xa_reserve(9), xa_reserve_bh(9), xa_reserve_irq(9), xa_release(9), xa_is_sibling(9), xa_is_retry(9), xa_is_advanced(9), xa_update_node_t(9), XA_STATE(9), XA_STATE_ORDER(9), xas_error(9), xas_set_err(9), xas_invalid(9), xas_valid(9), xas_is_node(9), xas_reset(9), xas_retry(9), xas_reload(9), xas_set(9), xas_advance(9), xas_set_order(9), xas_set_update(9), xas_next_entry(9), xas_next_marked(9), xas_for_each(9), xas_for_each_marked(9), xas_for_each_conflict(9), xas_prev(9), xas_next(9) — literally all of them, I'm not skipping a single one, that would be so rude. 🧚

---

ngl that reference list is giving "group project where everyone actually showed up". iconic. 🌸

---

And that's the page!! It lives in ./include/linux, dated October 2026, from the Kernel API Manual — xa_cmpxchg_irq(9), out. 💜🍓✨