dma_fence_default_wait(9)

📦 version 7.3.1, in nixpkgs unstable

💤 dma_fence_default_wait(9) 💤

okay so this is a page from the Kernel API Manual — yes bestie, the kernel has a whole manual and this one's about waiting. the default sleep-until-the-fence-gets-signaled-or-until-the-timeout-elapses situation. and before you ask: it's giving "blocking call but make it ✨graceful✨". 🎀

🌸 NAME 🌸

dma_fence_default_wait — the default sleep until the fence gets signaled or until timeout elapses vibe. literally just napping on purpose, but for kernel fences, not for your 3pm lecture. 💅

✨ SYNOPSIS ✨

signed long dma_fence_default_wait (struct dma_fence *fence , bool intr
, signed long timeout );

that's the whole signature, copy it exactly if you're typing it out, no cap. 🫶

🧚 ARGUMENTS 🧚

  • fence — the fence you're waiting on. the main character of this whole operation, honestly. 👑
  • intr — if true, do an interruptible wait. as in, a signal can wake you up early. lowkey important. 😭
  • timeout — timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT. bestie, jiffies. yes that's the real unit name. 🕰️

🦋 DESCRIPTION 🦋

okay here's the tea on what it gives back: 💖

  • Returns -ERESTARTSYS if interrupted — like, someone poked the wait and said "wake up".
  • Returns 0 if the wait timed out — ngl, you waited and nothing happened. 💀
  • Returns the remaining timeout in jiffies on success — slay, it wrapped up early and handed you the leftover time.

and the iconic lil edge case: if timeout is zero, the value 1 is returned if the fence is already signaled — that's for consistency with other functions taking a jiffies timeout. fr fr, it's just so the rest of the family matches. 🌈

⚠️ don't skip that zero-timeout bit btw, it's the part everyone forgets and then goes "wait why is it returning 1??" — now you know. 🫡

💜 SEE ALSO 💜

the whole friend group, in the order they showed up:

okay that's the page!! 💖✨🎀🦋🌸💅🫶

cute sign-off time: this one lives in ./drivers/dma-buf, and it's dated October 2026 🌸 — so yeah, mark your calendar bestie, that's the version you're reading rn. stay sleepy, stay signaled, and remember: MAX_SCHEDULE_TIMEOUT exists so you can wait basically forever if you want to. iykyk 💜

📦 where this page comes from