usb_hcd_giveback_urb(9)

💖 usb_hcd_giveback_urb(9) — the Kernel API Manual, bestie edition 💖

okay so this one is from the Kernel API Manual, page usb_hcd_giveback_urb(9), and it's genuinely the "handing your friend back their hoodie" of kernel functions 🫶

✨ NAME ✨

usb_hcd_giveback_urb — return URB from HCD to device driver

✨ SYNOPSIS ✨

void usb_hcd_giveback_urb (struct usb_hcd *hcd , struct urb *urb , int
status );

💅 ARGUMENTS 💅

• hcd — the host controller that's returning the URB 🎀
• urb — the urb being returned to the USB device driver.
• status — the completion status code for the URB, iykyk.

🌀 CONTEXT 🌀

atomic. No cap, that's the whole vibe.

Here's the tea ☕: the completion callback gets invoked either in a work queue (BH) context or in the caller's context — which one depends on whether the HCD_BH flag is set in the hcd structure. One exception tho 🙈: URBs submitted to the root hub always complete in BH context. periodt.

🌸 DESCRIPTION 🌸

So what this does is hand the URB from the HCD over to its USB device driver, using its completion function. At this point the HCD has freed all per-urb resources (and is fully done using urb->hcpriv — like, it's moved on, it's not looking back 💅). It's also released all HCD locks, so the device driver literally won't cause problems if it frees, modifies, or resubmits this URB. go off, king 👑

If urb was unlinked, the value of status will be overridden by urb->unlinked. That's just how it is, bestie.

Also, erroneous short transfers are detected in case the HCD hasn't checked for them. considerate of it fr fr 🧚

👑 SEE ALSO 👑

Kernel file ./drivers/usb/core/hcd.c — plus the whole friend group:

ascii2desc(9), rh_string(9), usb_bus_init(9), usb_register_bus(9), usb_deregister_bus(9), register_root_hub(9), usb_calc_bus_time(9), usb_hcd_link_urb_to_ep(9), usb_hcd_check_unlink_urb(9), usb_hcd_unlink_urb_from_ep(9), usb_hcd_alloc_bandwidth(9), usb_hcd_reset_endpoint(9), usb_alloc_streams(9), usb_free_streams(9), usb_hcd_resume_root_hub(9), usb_bus_start_enum(9), usb_hcd_irq(9), usb_hc_died(9), usb_create_shared_hcd(9), usb_create_hcd(9), usb_stop_hcd(9), usb_add_hcd(9), usb_remove_hcd(9)

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that's the whole page, bestie!! 🦋 this one lives in ./drivers/usb/core and it's dated October 2026 — so like, future vibes only ⭐ mwah, go read some kernel source 💜