xa_for_each(9)

💅 xa_for_each — the manual page, but make it make sense

okay so this is xa_for_each(9) from the Kernel API Manual, and honestly? she's iconic. let's get into it 🫶

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✨ NAME ✨

xa_for_each — the iterator that walks over all the present entries in an XArray. that's it, that's the vibe. 🦋

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🌸 SYNOPSIS 🌸

xa_for_each (xa , index , entry );

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🎀 ARGUMENTS 🎀

• xa — your XArray. the whole thing. the main character, lowkey 👑
• index — the index of an entry. yes bestie, you track where you're at with this 💅
• entry — the entry that got retrieved from the array. this is what you came for ✨

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💖 DESCRIPTION 💖

so during the iteration, entry is gonna hold the value of whatever entry is stored in xa at index. literally that simple, no cap.

and here's the cute part — you're allowed to modify index mid-iteration if you wanna skip some indices or reprocess them. honestly? flexible queen behaviour. 🧚 it's also safe to modify the array while you're iterating. go off.

at the end of the iteration, entry gets set to NULL and index will have a value less than or equal to max. so don't be weirded out when it ends like that, that's just how she wraps up 🎬

now for the part where you gotta pay attention, bestie, because this is the whole comparison saga:

• xa_for_each is O(n.log(n)) while xas_for_each is O(n). different tax brackets, fr fr 😭
• with xas_for_each you have to handle your own locking — yes, your own. and if you have to unlock after each iteration, it will also end up being O(n.log(n)). so like… the speed flex kind of evaporates 💀
• xa_for_each will spin if it hits a retry entry. so if you actually intend to see retry entries, you should use the xas_for_each iterator instead. periodt.
• xas_for_each will expand into more inline code than xa_for_each. so there's a tradeoff, iykyk 🌈

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🌟 CONTEXT 🌟

Any context. she takes and releases the RCU lock. that's it. she's low maintenance 🎀

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🔥 SEE ALSO 🔥

okay the cross-reference list is long long, but every single one of these deserves their moment. no skips, no cuts, we respect the whole squad 💜

• Kernel file ./include/linux/xarray.h
• 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_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_cmpxchg_irq(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)

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lowkey reminder bestie: xa_for_each will spin on a retry entry, and it's O(n.log(n)) — if that's a problem for your use case, xas_for_each is right there but you gotta do your own locking. know the difference, okay? 💅

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and that's the page!! mwah 💋 this one came to you from ./include/linux, dated October 2026, living in the Kernel API Manual — go forth and iterate, you absolute legend 🌈⭐👑