skb_shift(9)

💫 skb_shift(9) — Kernel API Manual 💫

okay bestie, strap in, because this is the function page for skb_shift(9) from the Kernel API Manual and it's genuinely so much cooler than it sounds. it's giving "quietly moving your stuff around behind the scenes" energy 🎀

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🌸 NAME 🌸

skb_shift — shifts paged data partially from skb to another

like, partially, bestie. not the whole thing. we're doing a little relocation, not a full move-out 🚚

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✨ SYNOPSIS ✨

int skb_shift (struct sk_buff *tgt , struct sk_buff *skb , int shiftlen
);

three args, one int back. clean, iconic, no notes 💅

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🫶 ARGUMENTS 🫶

• tgt — the buffer where the tail data gets added. she's the destination, the host, the one receiving 💖
• skb — the buffer the paged data comes from. she's the source, the giver, the one being raided 🧚
• shiftlen — shift up to this many bytes. it's a ceiling, not a promise, okay? 🙈

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🔥 DESCRIPTION 🔥

So the whole vibe: it attempts to shift up to shiftlen worth of bytes from skb to tgt, and returns the number of bytes shifted. and lowkey important — that byte count may be less than the length of the skb. so don't assume you moved everything!!

⚠️ heads up bestie: it's up to the caller to free skb if everything was shifted. the function will not do your cleanup for you. main character energy means taking responsibility for your own skbs 💀

And if tgt runs out of frags, the whole operation is aborted. no partial credit, no half-shift, we're just done. ✋

Also, the vibes must match: skb cannot include anything else but paged data, while tgt is allowed to have non-paged data as well. so skb is strictly paged, tgt is flexible. slay for her honestly 💅

TODO: full sized shift could be optimized but that would need a specialized skb free'er to handle frags without up-to-date nr_frags. so like, it's on the list, it's just not happening today 🫠

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👑 SEE ALSO 👑

Kernel file ./net/core/skbuff.c — and honestly the whole extended friend group:

• 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_zerocopy(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_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)

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okay that's the whole page, and yes every single one of those is a real function, i checked, no cap 💜

<div align="center">🌸 🌈 ✨ 🎀 ✨ 🌈 🌸</div>

so this masterpiece lives over in ./net/core, dated October 2026, and it's literally titled skb_shift(9) in the Kernel API Manual. that's the whole sign-off bestie, go shift some paged data responsibly 🦋💖