skb_zerocopy(9)

💖 NAME 💖

okay bestie, this is skb_zerocopy(9) from the Kernel API Manual, and the name is literally skb_zerocopy — Zero copy skb to skb ✨

🌈 SYNOPSIS 🌈

int skb_zerocopy (struct sk_buff *to , struct sk_buff *from , int len ,
       int hlen );

🎀 ARGUMENTS 🎀

• to — destination buffer
• from — source buffer
• len — number of bytes to copy from source buffer
• hlen — size of linear headroom in destination buffer

🦋 DESCRIPTION 🦋

okay so the way this works is: it copies up to len bytes from from to to by creating references to the frags in the source buffer. lowkey iconic, zero-copy behavior 💅

The hlen, as calculated by skb_zerocopy_headlen, specifies the headroom in the to buffer. vibes = headroom, honestly 🎀

Return value, bestie:

• 0 — everything is OK
• -ENOMEM — couldn't orphan frags of from due to lack of memory
• -EFAULT — skb_copy_bits found some problem with skb geometry, or readable head payload would be mixed with unreadable frags

👑 SEE ALSO 👑

Kernel file ./net/core/skbuff.c is the spot, and the whole reference squad is:

• drop_reasons_register_subsys(9), drop_reasons_unregister_subsys(9), skb_panic(9), napi_skb_cache_get_bulk(9), __build_skb(9), build_skb_around(9), __napi_build_skb(9), napi_build_skb(9), __alloc_skb(9), __netdev_alloc_skb(9)
• napi_alloc_skb(9), skb_pp_cow_data(9), skb_pp_frag_ref(9), __kfree_skb(9), sk_skb_reason_drop(9), skb_tx_error(9), consume_skb(9), __consume_stateless_skb(9), napi_consume_skb(9), alloc_skb_for_msg(9)
• skb_morph(9), skb_copy_ubufs(9), skb_clone(9), skb_copy(9), __pskb_copy_fclone(9), pskb_expand_head(9), skb_expand_head(9), skb_copy_expand(9), __skb_pad(9), pskb_put(9)
• skb_put(9), skb_push(9), skb_pull(9), skb_pull_data(9), skb_trim(9), __pskb_pull_tail(9), skb_copy_bits(9), skb_store_bits(9), skb_dequeue(9), skb_dequeue_tail(9)
• skb_queue_purge_reason(9), skb_rbtree_purge(9), skb_queue_head(9), skb_queue_tail(9), skb_unlink(9), skb_append(9), skb_split(9), skb_shift(9), skb_prepare_seq_read(9), skb_seq_read(9)
• skb_abort_seq_read(9), skb_copy_seq_read(9), skb_find_text(9), skb_pull_rcsum(9), skb_segment(9), skb_to_sgvec(9), skb_cow_data(9), skb_clone_sk(9), skb_partial_csum_set(9), skb_checksum_setup(9)
• skb_checksum_maybe_trim(9), skb_checksum_trimmed(9), skb_try_coalesce(9), skb_scrub_packet(9), skb_eth_pop(9), skb_eth_push(9), skb_mpls_push(9), skb_mpls_pop(9), skb_mpls_update_lse(9), skb_mpls_dec_ttl(9)
• alloc_skb_with_frags(9), skb_condense(9), __skb_ext_alloc(9), __skb_ext_set(9), skb_ext_add(9), skb_attempt_defer_free(9), skb_splice_from_iter(9)

mwah 💋 this skb_zerocopy(9) page is from ./net/core and is dated October 2026 — catch u in the kernel, bestie 🫶