tracing_map_lookup(9)

📦 version 7.3.1, in nixpkgs unstable

🌸 tracing_map_lookup(9) 🌸

okay bestie, so this one lives in the Kernel API Manual — it's tracing_map_lookup(9) and it's literally the little function that goes "hey, do I know you?" to your tracing_map. let's get into it 💅

✨ NAME ✨

tracing_map_lookup — retrieve val from a tracing_map. that's it, that's the whole job 🎀

✨ SYNOPSIS ✨

struct tracing_map_elt * tracing_map_lookup (struct tracing_map *map ,
void *key );

like... it takes a map and a key and hands you back an element pointer. no cap, that's the whole signature 🦋

✨ ARGUMENTS ✨

  • map — the tracing_map you're doing the lookup on. the main character of this whole operation 👑
  • key — the key you're looking up. the thing you're hunting for 🔍

✨ DESCRIPTION ✨

so what it does is: it looks up key in tracing_map, and if it finds it, it returns the matching tracing_map_elt. simple, clean, iconic ✨

this is a lock-free lookup — yes bestie, LOCK-FREE, we love to see it. if you wanna know the details on tracing_map and how it actually works under the hood, go check out tracing_map_insert 🫶

every single time an element is retrieved, the hits value gets incremented. every. single. time. 💖

and then, ngl, the original page has a bit that's... a whole mood. we're keeping it exactly as it is, because the facts don't change even when the sentence decides to leave the group chat:

There is one user-visible tracing_map variable, is successfully retrieved, the hits value is incremented. The

yep. that's literally what it says. ship it 😭 (we're not fixing it, we're not merging it, we're not inventing anything — it stays fr fr)

✨ RETURN ✨

the tracing_map_elt pointer val associated with the key. 💫

and if the key wasn't found? you get NULL. that's it. no drama, no explanation, just NULL and vibes 💀

✨ SEE ALSO ✨

the kernel file ./kernel/trace/tracing_map.c, plus the whole friend group:

alright that's the whole page, bestie — it's giving kernel internals but make it cute. this one's sourced from ./kernel/trace, dated October 2026, and the page itself is tracing_map_lookup(9). go forth and look things up 💜🦋✨

📦 where this page comes from