skb_tailroom_reserve(9)

💅 skb_tailroom_reserve

okay bestie, welcome to the Kernel API Manual entry for skb_tailroom_reserve — yes that's the title, yes we're doing this, and yes it's actually kinda elegant once you get it ✨

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🌸 NAME 🌸

skb_tailroom_reserve — adjust reserved_tailroom 🎀

like, literally just tweaking the reserved tailroom. that's the whole gig. iykyk.

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🦋 SYNOPSIS 🦋

void skb_tailroom_reserve (struct sk_buff *skb , unsigned int mtu ,
       unsigned int needed_tailroom );

it returns nothing (void, so no gifts 🎁), and that's the whole signature, copied exactly, no cap.

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💖 ARGUMENTS 💖

• skb — the buffer you're altering 🫶 this is the main character, the sk_buff getting its moment
• mtu — the maximum amount of headlen permitted 🚦 like the ceiling, the limit, the "no ma'am" line
• needed_tailroom — the minimum amount of reserved_tailroom 💅 the floor, the bare minimum, the "at least this much" energy

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✨ DESCRIPTION ✨

so what it does: it sets reserved_tailroom such that headlen can be as large as possible — but not larger than mtu — and tailroom cannot be smaller than needed_tailroom. it's giving optimization with boundaries, honestly iconic 👑

⚠️ heads up bestie: the required headroom should already have been reserved before you use this function. like, do that part first. this function is not gonna do it for you, and it's not gonna be cute about it 🙈

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🔥 SEE ALSO 🔥

Kernel file ./include/linux/skbuff.h

and now, the moment you've all been waiting for, the entire friend group, in order, no skipping, no summarizing, we ride at dawn ⭐:

skb checksums(9), skb_frag_size(9), skb_frag_size_set(9), skb_frag_size_add(9), skb_frag_size_sub(9), skb_frag_must_loop(9), skb_frag_foreach_page(9), struct skb_shared_hwtstamps(9), dataref and headerless skbs(9), Basic sk_buff geometry(9), struct sk_buff(9), skb_pfmemalloc(9), skb_dst(9), skb_dstref_steal(9), skb_dstref_restore(9), skb_dst_set(9), skb_dst_set_noref(9), skb_dst_is_noref(9), skb_napi_id(9), skb_unref(9), kfree_skb(9), alloc_skb(9), skb_fclone_busy(9), alloc_skb_fclone(9), skb_pad(9), skb_queue_empty(9), skb_queue_empty_lockless(9), skb_queue_is_last(9), skb_queue_is_first(9), skb_queue_next(9), skb_queue_prev(9), skb_get(9), skb_cloned(9), skb_header_cloned(9), __skb_header_release(9), skb_shared(9), skb_share_check(9), skb_unshare(9), skb_peek(9), __skb_peek(9), skb_peek_next(9), skb_peek_tail(9), skb_queue_len(9), skb_queue_len_lockless(9), __skb_queue_head_init(9), skb_queue_splice(9), skb_queue_splice_init(9), skb_queue_splice_tail(9), skb_queue_splice_tail_init(9), __skb_queue_after(9), __skb_queue_head(9), __skb_queue_tail(9), __skb_dequeue(9), __skb_dequeue_tail(9), skb_len_add(9), __skb_fill_netmem_desc(9), skb_fill_page_desc(9), skb_fill_page_desc_noacc(9), skb_headroom(9), skb_tailroom(9), skb_availroom(9), skb_reserve(9), skb_reset_transport_header_careful(9), skb_set_transport_header_careful(9), pskb_trim_unique(9), skb_orphan(9), skb_orphan_frags(9), __skb_queue_purge_reason(9), netdev_alloc_frag(9), netdev_alloc_skb(9), __dev_alloc_pages(9), __dev_alloc_page(9), dev_page_is_reusable(9), skb_propagate_pfmemalloc(9), skb_frag_off(9), skb_frag_off_add(9), skb_frag_off_set(9), skb_frag_off_copy(9), skb_frag_net_iov(9), skb_frag_page(9), skb_frag_netmem(9), skb_frag_address(9), skb_frag_address_safe(9), skb_frag_phys(9), skb_frag_page_copy(9), __skb_frag_dma_map(9), skb_clone_writable(9), skb_cow(9), skb_cow_head(9), skb_padto(9), __skb_put_padto(9), skb_put_padto(9), skb_linearize(9), skb_has_shared_frag(9), skb_linearize_cow(9), skb_postpull_rcsum(9), skb_postpush_rcsum(9), skb_push_rcsum(9), pskb_trim_rcsum(9), skb_needs_linearize(9), skb_get_timestamp(9), skb_data_move(9), skb_postpull_data_move(9), skb_postpush_data_move(9), skb_complete_tx_timestamp(9), skb_tstamp_tx(9), skb_tx_timestamp(9), skb_complete_wifi_ack(9), skb_checksum_complete(9), struct skb_ext(9), skb_checksum_none_assert(9), skb_head_is_locked(9)

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and that's the page!! from ./include/linux, dated October 2026, in the Kernel API Manual. mwah 💋 go reserve some tailroom responsibly, bestie 🧚💜