STRUCT DMA_RESV_ITER(9)

💅 struct dma_resv_iter(9) — the Kernel API Manual, but make it cute

okay bestie, so we're deep in the Kernel API Manual today and the topic is struct dma_resv_iter, which is literally just current position into the dma_resv fences. that's it. that's the vibe. it's an iterator, it knows where you are in the fence list, and it's lowkey the main character of your dma_resv traversal. periodt. 🎀

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✨ SYNOPSIS ✨

here's the whole struct, char-for-char, no cap:

struct dma_resv_iter {
    struct dma_resv *obj;
    enum dma_resv_usage usage;
    struct dma_fence *fence;
    enum dma_resv_usage fence_usage;
    unsigned int index;
    struct dma_resv_list *fences;
    unsigned int num_fences;
    bool is_restarted;
};

🌸 Members (the cast of characters)

• obj — the dma_resv object we iterate over. our home base 🏠
• usage — return fences with this usage or lower. it's giving filter settings ✨
• fence — the currently handled fence. the one in the spotlight rn 💅
• fence_usage — the usage of the current fence. receipts for the current fence 🔥
• index — index into the shared fences. counting girlies stay winning 🔢
• fences — the shared fences; private, MUST not dereference 🚨 like fr fr do NOT touch, it's giving forbidden snack
• num_fences — number of fences. the math. the arithmetic. 🧮
• is_restarted — true if this is the first returned fence. plot twist detector 👀

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💖 DESCRIPTION 💖

okay so the actual instruction here is simple: don't touch this directly in the driver. use the accessor function instead. that's the whole rule. respect the boundary, bestie 🫶

⚠️ IMPORTANT ⚠️ when using the lockless iterators like dma_resv_iter_next_unlocked or dma_resv_for_each_fence_unlocked, beware that the iterator can be restarted. 😭 if your code accumulates statistics or similar, you need to check for this with dma_resv_iter_is_restarted. do not skip the vibe check, or your stats will be a whole lie. 💀

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🦋 SEE ALSO 🦋

everything else in the family, all of it, no skips:

• Kernel file ./include/linux/dma-resv.h — enum dma_resv_usage(9)
• dma_resv_usage_rw(9)
• struct dma_resv(9)
• dma_resv_iter_begin(9)
• dma_resv_iter_end(9)
• dma_resv_iter_usage(9)
• dma_resv_iter_is_restarted(9)
• dma_resv_for_each_fence_unlocked(9)
• dma_resv_for_each_fence(9)
• dma_resv_lock(9)
• dma_resv_lock_interruptible(9)
• dma_resv_lock_slow(9)
• dma_resv_lock_slow_interruptible(9)
• dma_resv_trylock(9)
• dma_resv_is_locked(9)
• dma_resv_locking_ctx(9)
• dma_resv_unlock(9)

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that's the whole page, bestie, you ate that 🍓

sign-off time: this icon was brought to you by the source at ./include/linux, dated October 2026, filed under struct dma_resv_iter(9) — go forth and iterate responsibly 💜✨