dma_fence_timeline_name(9)

📦 version 7.3.1, in nixpkgs unstable

💅 dma_fence_timeline_name — the Kernel API Manual ✨

okay so bestie, this one's from the Linux kernel API manual (the dma_fence_timeline_name(9) page) and it's lowkey about grabbing the timeline name off a fence. short page, big vibes, and one genuinely important warning that you absolutely do not want to fumble. let's get into it 🫶

✨ NAME ✨

dma_fence_timeline_name — access the timeline name, that's literally it, that's the whole job 🎀

🌸 SYNOPSIS 🌸

const char __rcu * dma_fence_timeline_name (struct dma_fence *fence );

note the __rcu on the return type — that little tag is doing so much work, bestie, and i'll explain why in a sec 💅

🦋 ARGUMENTS 🦋

  • fence — the fence you want to query. that's the one. the fence in question 🧚

🔥 DESCRIPTION 🔥

Returns a timeline name that's provided by the dma-fence implementation. cute, simple, iconic ✨

IMPORTANT CONSIDERATION: okay this is the part where you actually pay attention, no cap. the dma-fence contract stipulates that access to driver-provided data — meaning data that is not directly embedded into the object itself — is forbidden after the fence has been signalled. what counts as driver-provided data? things like dma_fence.lock, and memory that may potentially be accessed by the dma_fence.ops functions. drivers are allowed to free that data, and some of them do. so yeah, this isn't theoretical 😭

To allow safe access, drivers are mandated to guarantee a RCU grace period between signalling the fence and freeing said data. so there's a whole grace-period situation happening in the background keeping you safe 🙏

As such, access to the driver name is only valid inside a RCU locked section. and now the loud part:

The pointer MUST be both queried and USED ONLY WITHIN a SINGLE block guarded by the rcu_read_lock and rcu_read_unlock pair.

like — queried and used. same block. one single block. do not query it, leave the lock, and then come back to use it, because that's not a vibe check that ends well 💀🔒

👑 SEE ALSO 👑

that's the whole reading list, bestie — go forth and be literate 📚💖

and that's the page! it's from the Kernel API Manual, lives under ./drivers/dma-buf, dated October 2026 — so mark your calendar, mwah 💋 stay in your RCU lock, don't touch freed driver data, and slay 🎀✨

📦 where this page comes from