Re: [PATCH] usb:musb:musb_host: Handle highmem in PIO mode

From: Alan Stern
Date: Thu Aug 02 2012 - 10:48:22 EST


On Thu, 2 Aug 2012, Virupax Sadashivpetimath wrote:

> In case of USB bulk transfer, when himem page
> is received, the usb_sg_init function sets the
> urb transfer buffer to NULL. When such URB
> transfer is handled, kernel crashes in PIO mode.
> Handle this by mapping the highmem buffer in PIO mode.


> --- a/include/linux/usb.h
> +++ b/include/linux/usb.h
> @@ -21,6 +21,7 @@
> #include <linux/sched.h> /* for current && schedule_timeout */
> #include <linux/mutex.h> /* for struct mutex */
> #include <linux/pm_runtime.h> /* for runtime PM */
> +#include <linux/scatterlist.h>
>
> struct usb_device;
> struct usb_driver;
> @@ -1309,6 +1310,7 @@ struct urb {
> usb_complete_t complete; /* (in) completion routine */
> struct usb_iso_packet_descriptor iso_frame_desc[0];
> /* (in) ISO ONLY */
> + struct sg_mapping_iter sg_miter; /* handling highmem data in PIO mode */
> };

This is unacceptable. Fields like this should be stored in the
URB's hcpriv structure, not in the URB itself.

Alan Stern

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