STRUCT USB_SG_REQUEST(9)

✨ struct usb_sg_request(9) ✨

Okay bestie, welcome to the Kernel API Manual 💅 this one's about struct usb_sg_request and it's genuinely giving "scatter/gather I/O support" — like, that's the whole gig, no cap.

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🎀 NAME 🎀

struct usb_sg_request — literally support for scatter/gather I/O 🌸

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🦋 SYNOPSIS 🦋

struct usb_sg_request {
    int status;
    size_t bytes;
 };

That's the whole struct, bestie. Two members. Tiny. Iconic. 👑

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🌟 Members 🌟

• status — zero means slay (success 💖), anything else is a negative errno, so like… not slay 😭
• bytes — counts the bytes that actually got transferred, fr fr 🍓

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💜 Description 💜

So here's the vibe: these requests get initialized using usb_sg_init, and after that they're used as request handles passed to usb_sg_wait or usb_sg_cancel. That's their whole main character arc ✨

Most members of the request object aren't for driver access — like, they're not yours to touch, bestie, hands off 🙈

The status and bytecount values are valid only after usb_sg_wait returns. Read that again. Only after. Don't be out here reading them early, that's not the vibe 💀

If the status is zero, then the bytecount matches the total from the request 🎯

Heads up 🫶 after an error completion, drivers may need to clear a halt condition on the endpoint. Not optional energy, just so you know.

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🌈 SEE ALSO 🌈

Kernel file ./include/linux/usb.h — plus the whole friend group:

• struct usb_host_endpoint(9)
• struct usb_interface(9)
• usb_set_intfdata(9)
• struct usb_interface_cache(9)
• struct usb_host_config(9)
• struct usb_device(9)
• usb_hub_for_each_child(9)
• usb_interface_claimed(9)
• usb_make_path(9)
• USB_DEVICE(9)
• USB_DEVICE_VER(9)
• USB_DEVICE_INTERFACE_CLASS(9)
• USB_DEVICE_INTERFACE_PROTOCOL(9)
• USB_DEVICE_INTERFACE_NUMBER(9)
• USB_DEVICE_INFO(9)
• USB_INTERFACE_INFO(9)
• USB_DEVICE_AND_INTERFACE_INFO(9)
• USB_VENDOR_AND_INTERFACE_INFO(9)
• struct usb_driver(9)
• struct usb_device_driver(9)
• struct usb_class_driver(9)
• module_usb_driver(9)
• struct urb(9)
• usb_fill_control_urb(9)
• usb_fill_bulk_urb(9)
• usb_fill_int_urb(9)
• usb_urb_dir_in(9)
• usb_urb_dir_out(9)

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That's the whole page, bestie, you ate it up 💅🫶 this one lives in ./include/linux and it's dated October 2026 — mwah, go read your USB headers, ily, bye! 🌸💖✨