Re: [PATCH] usb: gadget: u_audio: don't exceed maxpacket when adding a residue frame

[sashiko-bot@kernel.org]

> u_audio_iso_complete() clamps the base packet size to ep->maxpacket
> and accumulates fractional-frame residue in p_residue_mil. Once a
> whole frame has accumulated, it is appended to the packet without
> checking whether it fits within ep->maxpacket.
> 
> Only append the extra frame if it fits. Consume the accumulated
> residue whether or not the frame is sent, preventing it from growing
> when the additional frame cannot fit. When the frame fits, behavior
> is unchanged. Otherwise, the stream cannot sustain the requested
> sample rate.
> 
> For example, with 27 channels of 32-bit samples at 19200 Hz on a
> high-speed link with p_hs_bint=3, the required packet size of 1080
> bytes is capped at 1024. The base packet is 972 bytes, but appending
> a residue frame increases it to 1080 bytes, exceeding the allocated
> request buffer by 56 bytes.
> 
> Fixes: 9bb87f168931 ("usb: gadget: f_uac2: send reasonably sized packets")
> Link: https://lore.kernel.org/linux-usb/sashiko-outbox-174688@kernel.org/
> Signed-off-by: Kyle Farrell <kaf@nwlink.com>

Sashiko has reviewed this patch and found no issues.

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