__sg_next(9)

✨ __sg_next — the kernel API manual, bestie edition ✨

okay so this page is from the Kernel API Manual, section 9 (kernel internals, iykyk). it's called __sg_next and honestly? she's a tiny little function with main character energy. let's get into it 💅

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🌸 NAME 🌸

__sg_next — return the next scatterlist entry in a list

like, literally what it says on the tin. you give her one scatterlist entry, she hands you the next one. no cap. 🦋

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🎀 SYNOPSIS 🎀

struct scatterlist * __sg_next (struct scatterlist *sg );

that's the whole signature, bestie — one arg in, one pointer out, and it returns a struct scatterlist *. periodt.

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💖 ARGUMENTS 💖

• sg — the current sg entry. like, the one you're standing on right now. she needs to know where you are before she can tell you where you're going 🫶

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🔥 DESCRIPTION 🔥

okay so here's the whole vibe check, and it's genuinely so simple:

• if the entry you passed in is the last one, she returns NULL. that's it. no next entry, no drama, just NULL 😭
• otherwise, she steps to the next element in the array — that's sg+1, literally just the next one, the way that pointer arithmetic ate 💀
• then: if that next thing is a chain pointer, she follows it. (chains are how sg lists get longer than the array, iykyk 🔗)
• otherwise (no chain pointer, just a regular entry), she just returns the pointer to the current element.

so to recap the flow: last? → NULL. chain pointer? → follow it 👑. anything else? → hand back the pointer and keep it moving ✨

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⭐ SEE ALSO ⭐

the kernel file that lives here is:

./drivers/gpu/drm/i915/i915_scatterlist.h

and the whole friend group she runs with:

• __for_each_sgt_daddr(9)
• __for_each_daddr_next(9)
• for_each_sgt_page(9)
• i915_sg_dma_sizes(9)
• struct i915_refct_sgt_ops(9)
• struct i915_refct_sgt(9)
• i915_refct_sgt_put(9)
• i915_refct_sgt_get(9)
• __i915_refct_sgt_init(9)

go say hi to them too, they're all in the same friend group 🧚💜

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and that's the page!! little sign-off moment 🌈 — this one's from ./drivers/gpu/drm/i915, dated October 2026, and it's the __sg_next(9) page. mwah 💋 go read a scatterlist or something, ily 🍓