libeth_rx_sync_for_cpu(9)

💅 libeth_rx_sync_for_cpu — the kernel API manual, but make it make sense

okay so bestie, welcome to the libeth_rx_sync_for_cpu(9) page, straight out of the Kernel API Manual ✨ this one's short and sweet and honestly kind of iconic — it's the little helper that decides whether a freshly-DMA'd buffer has actual data in it or is just gonna get yeeted right back. no cap, let's get into it 🫶

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🌸 NAME 🌸

libeth_rx_sync_for_cpu — synchronize or recycle a buffer post DMA. like, after the hardware's done writing to it, this is the vibe-check function 💅

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✨ SYNOPSIS ✨

bool libeth_rx_sync_for_cpu(const struct libeth_fqe *fqe, u32 len);

one function, two args, returns a bool. simple. elegant. we love her 👑

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🎀 ARGUMENTS 🎀

• fqe — the buffer to process, bestie. it's a const struct libeth_fqe *, so hands off the contents, we're just here to look 🦋
• len — the frame length, the u32 you pulled straight off the descriptor. this is how much the HW said it wrote ✨

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💖 DESCRIPTION 💖

so here's the tea 🍵 this function processes the buffer after the hardware has written to it — like, HW already did its thing, the DMA is done, we're in the post-game now.

the regular path? it synchronizes DMA for the CPU so we can actually read the bytes without everything going sideways 😭 that's the main character path, that's the one you know and love.

but — and this is the part where it gets cute — if there's no data, the buffer doesn't just sit there awkwardly. nope. it gets immediately recycled back to its PP. instant. no waiting, no small talk. it's giving "thank u, next" 🦋

fr fr there are two outcomes here and the function picks one for you: sync-for-CPU, or yeet-back-to-PP. that's the whole plot 💀

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⭐ RETURN ⭐

• returns true when there's data to process 🔥
• returns false otherwise 🎀

that's it. that's the return value. flow control via vibes 💅

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🌈 SEE ALSO 🌈

if you're the kind of person who reads the whole series (and honestly? obsessed), go look at:

• the kernel file ./include/net/libeth/rx.h
• struct libeth_fqe(9)
• enum libeth_fqe_type(9)
• struct libeth_fq(9)
• libeth_rx_alloc(9)
• struct libeth_rx_csum(9)
• struct libeth_rqe_info(9)
• libeth_rx_pt_get_ip_ver(9)
• libeth_rx_pt_set_hash(9)

all of these are literally in the same friend group, iykyk 🧚💜

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and that's the whole page, bestie!! this one lives in ./include/net/libeth, dated October 2026 — so mark your calendars and go sync some buffers 💖✨🎀