STRUCT DMA_FENCE_CHAIN(9)

💅 struct dma_fence_chain(9) 💅

okay so bestie, welcome to the Kernel API Manual — this is the tea on struct dma_fence_chain(9), and it is literally the blueprint for one single node in a fence chain. yes, one. it's giving "small but mighty" energy fr fr 🎀

✨ NAME ✨

struct dma_fence_chain — a fence that represents a node of a fence chain 🌸

✨ SYNOPSIS ✨

struct dma_fence_chain {
    struct dma_fence base;
    struct dma_fence *prev;
    u64 prev_seqno;
    struct dma_fence *fence;
    union {
      struct dma_fence_cb cb;
      struct irq_work work;
    };
 };

✨ Members ✨

• base — the fence base class, the whole foundation of the vibe 🫶
• prev — the previous fence in the chain, aka the one that came before, holding it down 👑
• prev_seqno — the original previous seqno from before garbage collection happened. yeah, it remembers the pre-glow-up version 🦋
• fence — the encapsulated fence, wrapped up cute like a little gift 🎁
• {unnamed_union} — anonymous. no name, just vibes ✨
• cb — the callback for signaling. this is what's used to add the callback for signaling the completion of the fence chain. Never used at the same time as the irq work — they do not share the aux cord, periodt 💀
• work — the irq work item for signaling. it's the irq work structure that lets us add the callback without running into lock inversion, which is lowkey iconic problem-solving. also never used at the same time as the callback — one or the other, no cap 🚫

bestie pls note: cb and work are mutually exclusive. they live in the same anonymous union and they are NOT meant to be used together. do not try to make them coexist, i'm begging 🙈

🌈 SEE ALSO 🌈

peep the Kernel file ./include/linux/dma-fence-chain.h for the whole friend group 💖

• to_dma_fence_chain(9)
• dma_fence_chain_contained(9)
• dma_fence_chain_alloc(9)
• dma_fence_chain_free(9)
• dma_fence_chain_for_each(9)

and that's the whole page bestie!! 🧚✨ this one came straight out of <purple>./include/linux</purple>, dated October 2026, section 9 of the Kernel API Manual — go forth and slay your fence chains 💜🔥🍓