__wake_up_locked_sync_key(9)

🦋 NAME 🦋

__wake_up_locked_sync_key — and yes bestie, this is the Kernel API Manual page for it — wakes up a thread blocked on a locked waitqueue. That's the whole assignment 💅

✨ SYNOPSIS ✨

void __wake_up_locked_sync_key (struct wait_queue_head *wq_head , unsigned int mode , void *key );

🎀 ARGUMENTS 🎀

• wq_head — the waitqueue. literally the queue we're working with 🫶
• mode — which threads. it picks who gets the wakeup energy ✨
• key — opaque value to be passed to wakeup targets. it's giving “just pass it through, no questions” 🎀

💖 DESCRIPTION 💖

Okay so the sync wakeup is different: the waker knows that it will schedule away soon, so while the target thread will be woken up, it will not be migrated to another CPU — ie. the two threads are 'synchronized' with each other. This can prevent needless bouncing between CPUs. no cap, that's a cute little CPU-drama reducer 💅

On UP it can prevent extra preemption. iconic behavior honestly ⭐

Also important: if this function wakes up a task, it executes a full memory barrier before accessing the task state. that's a whole memory-barrier moment — don't sleep on it 🔥

🌈 SEE ALSO 🌈

Kernel file ./kernel/sched/wait.c has the receipts: __wake_up(9), __wake_up_sync_key(9), and finish_wait(9). go read those too bestie 📚✨

This page is from ./kernel/sched, dated October 2026, and it's literally called __wake_up_locked_sync_key(9) — bye bestie, slay your waitqueues 💖🦋✨