__netif_txq_completed_wake(9)

💖 __netif_txq_completed_wake — from the Kernel API Manual, bestie 💖

okay so picture this: you're deep in the kernel networking trenches and you need to wake a Tx queue without locks — only if it actually needs it. That's literally this function. It's giving "low-level but make it chic." 🦋

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✨ SYNOPSIS ✨

__netif_txq_completed_wake (txq , pkts , bytes , get_desc , start_thrs ,
down_cond );

no cap, that's the whole call. six args, zero drama (well... mostly). 💅

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🎀 ARGUMENTS 🎀

• txq — the struct netdev_queue you're stopping or starting. main character of the whole operation, honestly.
• pkts — how many packets got completed. count 'em, report 'em.
• bytes — how many bytes got completed. the byte girlies deserve representation too. 🍓
• get_desc — gets you the current number of free descriptors. but bestie, read the requirements below, this one has RULES. 🙈
• start_thrs — the minimum number of descriptors needed to re-enable the queue. think of it as the vibe check threshold.
• down_cond — the "down condition": a predicate that says nope, don't wake the queue up even if descriptors are available. like do-not-disturb mode for your Tx queue. 💀

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🌸 DESCRIPTION 🌸

So here's the tea: all arguments may be evaluated multiple times. multiple times!! so don't go putting anything in there that gets weird when it runs more than once.

And get_desc is extra special — it must be a formula or a function call, and it must always return up-to-date information when evaluated. like, fresh-fresh. not stale. not cached. current. the function will be calling it and it needs the truth, the whole truth, and nothing but. ✨

As for what it actually does: it reports the completed pkts/bytes to BQL. that's the moment. slay. 👑

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⭐ RETURN ⭐

• 0 — the queue was woken up 🎉 (you did it, bestie)
• 1 — the queue was already enabled, or it's disabled but down_cond is true. either way, nothing to do here.
• -1 — the queue was left unchanged because start_thrs wasn't reached. not today, not with that descriptor count. 😭

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🦋 SEE ALSO 🦋

• Kernel file ./include/net/netdev_queues.h
• struct netdev_config(9)
• struct netdev_stat_ops(9)
• struct netdev_queue_mgmt_ops(9)
• Lockless queue stopping / waking helpers.(9)
• netif_txq_maybe_stop(9)

like, go read them. they're all in the same friend group, iykyk. 🫶

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fr fr — remember: get_desc has to be re-evaluable and always current, and every argument might get evaluated more than once. no side effects, no lying descriptors, periodt. 💜

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and that's the whole page, bestie! source lives at ./include/net, dated October 2026, and it's all part of the Kernel API Manual — catch you in the next manpage, mwah 💅💖🌈