Re: [PATCH] USB: usblp: fix DMA to stack

Johan/Greg,

Since CUPS uses libusb to communicate with printers these days (well, for over a decade now) so that printing and scanning can coexist, the usblp driver really doesn't get any usage anymore.

On Jan 4, 2021, at 10:11 AM, Johan Hovold [off-list ref] wrote:

On Mon, Jan 04, 2021 at 03:59:02PM +0100, Greg Kroah-Hartman wrote:

quoted

On Mon, Jan 04, 2021 at 03:53:02PM +0100, Johan Hovold wrote:

quoted

Stack-allocated buffers cannot be used for DMA (on all architectures).

Replace the HP-channel macro with a helper function that allocates a
dedicated transfer buffer so that it can continue to be used with
arguments from the stack.

quoted

Wow, no one uses this driver anymore it seems, this should have
triggered a runtime warning on newer kernels :(

This helper is only used by the IOCNR_HP_SET_CHANNEL ioctl so perhaps
it's just that one which isn't used much.

Johan

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Michael Sweet