dev_uc_sync(9)

📦 version 7.3.1, in nixpkgs unstable

💖 dev_uc_sync — the kernel API manual, bestie edition 💖

Okay so real talk, this page lives in the Kernel API Manual (section 9, kernel girlies rise 🧚), and it's all about one little function that keeps a device's unicast list in sync with another device. Let's get into it ✨

✨ NAME ✨

dev_uc_sync — sync up a device's unicast list to another device. Literally copy-the-vibes-but-for-addresses 💅

🌸 SYNOPSIS 🌸

int dev_uc_sync (struct net_device *to , struct net_device *from );

Yes bestie, it takes two devices and returns an int. That's the whole mood 🎀

🦋 ARGUMENTS 🦋

  • to — the destination device, aka where the addresses are going 👑
  • from — the source device, aka where the addresses are coming from 🍓

💜 DESCRIPTION 💜

So here's the tea ☕: this function adds the newly added addresses over to the destination device, and it releases the addresses that have no users left. Cleanup era fr fr 🧹✨

⚠️ Okay important: the source device must be locked by netif_addr_lock_bh. Not optional, not "eh maybe", it's a must. Don't skip the lock bestie 😭🔒

This function is intended to be called from the dev->set_rx_mode function of layered software devices. That's its whole main character moment 🌈

And it also assumes that addresses will only ever be synced to the to devices and no other. No side-quests, no sneaky extra devices — just to. Periodt 💀

🔥 SEE ALSO 🔥

Kernel file ./net/core/dev_addr_lists.c — and the whole friend group 🫶:

And that's the whole page! Sourced from ./net/core, dated October 2026 — screenshot it, cite it, cite me, whatever 💅📸 mwah, go sync those unicast lists responsibly 🎀💖

📦 where this page comes from