batadv_mcas...date_headers(9)

💅 NAME

batadv_mcast_forw_shrink_update_headers — the glow-up artist that updates shrunk mc packet headers ✨

Ok so real talk: this is a page straight out of the Kernel API Manual, and it's all about one little function in the batman-adv multicast squad. Bestie, it keeps the headers cute and correct after somebody shrank the packet. Let's get into it 🫶

---

✨ SYNOPSIS ✨

unsigned int batadv_mcast_forw_shrink_update_headers (struct sk_buff
*skb , unsigned int num_dests_reduce );

That's the whole signature, copy it exactly bestie, no edits, no vibes-based rewrites 💅

---

🎀 ARGUMENTS 🎀

• skb — the batman-adv multicast packet whose headers we're updating. This is the packet, the main character 🦋
• num_dests_reduce — the number of destinations that were removed. Like, how many people left the group chat 😭

---

🔥 DESCRIPTION 🔥

So here's the tea ☕ — this function updates any fields of a batman-adv multicast packet that are affected by the reduced number of destinations in the multicast tracker TVLV. Basically the packet lost some friends and now its paperwork needs to match. No cap.

In particular, it updates these three iconic things:

• the num_dest field of the multicast tracker TVLV 🎯
• the TVLV length field of the according generic TVLV header 📏
• the batman-adv multicast packet's total TVLV length field 🧮

Lowkey it's just bookkeeping but somebody has to do it and she does it flawlessly.

---

💖 RETURN 💖

It returns the offset in skb's tail direction at which the new batman-adv multicast packet header needs to start. That's where the fresh header gets to make its entrance 👑

---

🌈 SEE ALSO 🌈

First up, the kernel file this lives in — go read the source bestie, it's giving lore:

• Kernel file ./net/batman-adv/multicast_forw.c

And now the whole friend group — every single one of these, present and accounted for 🫶:

• batadv_mcast_forw_skb_push(9)
• batadv_mcast_forw_push_padding(9)
• batadv_mcast_forw_push_est_padding(9)
• batadv_mcast_forw_orig_entry(9)
• batadv_mcast_forw_push_dest(9)
• batadv_mcast_forw_push_dests_list(9)
• batadv_mcast_forw_push_tt(9)
• batadv_mcast_forw_push_want_all(9)
• batadv_mcast_forw_push_want_rtr(9)
• batadv_mcast_forw_scrape(9)
• batadv_mcast_forw_push_scrape_padding(9)
• batadv_mcast_forw_push_insert_padding(9)
• batadv_mcast_forw_push_adjust_padding(9)
• batadv_mcast_forw_push_dests(9)
• batadv_mcast_forw_push_tracker(9)
• batadv_mcast_forw_push_tvlvs(9)
• batadv_mcast_forw_push_hdr(9)
• batadv_mcast_forw_scrub_dests(9)
• batadv_mcast_forw_shrink_fill(9)
• batadv_mcast_forw_shrink_pack_dests(9)
• batadv_mcast_forw_shrink_align_offset(9)
• batadv_mcast_forw_shrink_move_headers(9)
• batadv_mcast_forw_shrink_tracker(9)
• batadv_mcast_forw_packet(9)
• batadv_mcast_forw_tracker_tvlv_handler(9)
• batadv_mcast_forw_packet_hdrlen(9)
• batadv_mcast_forw_expand_head(9)
• batadv_mcast_forw_push(9)
• batadv_mcast_forw_mcsend(9)

---

Ngl, there are like zero scary warnings on this page — it's just a tidy little header updater. But stay in your lane and pass real values fr fr 💀

---

And that's a wrap, bestie 🎀 this page came from ./net/batman-adv, dated October 2026, and it's page batadv_mcas...date_headers(9) of the Kernel API Manual — iconic behavior only, periodt 💅✨