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Commit 1129d270 authored by Mateusz Berezecki's avatar Mateusz Berezecki Committed by Greg Kroah-Hartman
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USB: Increase usbfs transfer limit 



Promote a variable keeping track of USB transfer memory usage to a
wider data type and allow for higher bandwidth transfers from a large
number of USB devices connected to a single host.

Signed-off-by: default avatarMateusz Berezecki <mateuszb@fastmail.fm>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 444d9309

drivers/usb/core/devio.c

+16 −27
Original line number Diff line number Diff line
@@ -134,42 +134,35 @@ enum snoop_when { 
#define USB_DEVICE_DEV		MKDEV(USB_DEVICE_MAJOR, 0)



/* Limit on the total amount of memory we can allocate for transfers */

static unsigned usbfs_memory_mb = 16;

static u32 usbfs_memory_mb = 16;

module_param(usbfs_memory_mb, uint, 0644);

MODULE_PARM_DESC(usbfs_memory_mb,

		"maximum MB allowed for usbfs buffers (0 = no limit)");



/* Hard limit, necessary to avoid arithmetic overflow */

#define USBFS_XFER_MAX		(UINT_MAX / 2 - 1000000)



static atomic_t usbfs_memory_usage;	/* Total memory currently allocated */

static atomic64_t usbfs_memory_usage;	/* Total memory currently allocated */



/* Check whether it's okay to allocate more memory for a transfer */

static int usbfs_increase_memory_usage(unsigned amount)

static int usbfs_increase_memory_usage(u64 amount)

{

	unsigned lim;

	u64 lim;



	/*

	 * Convert usbfs_memory_mb to bytes, avoiding overflows.

	 * 0 means use the hard limit (effectively unlimited).

	 */

	lim = ACCESS_ONCE(usbfs_memory_mb);

	if (lim == 0 || lim > (USBFS_XFER_MAX >> 20))

		lim = USBFS_XFER_MAX;

	else

	lim <<= 20;



	atomic_add(amount, &usbfs_memory_usage);

	if (atomic_read(&usbfs_memory_usage) <= lim)

		return 0;

	atomic_sub(amount, &usbfs_memory_usage);

	atomic64_add(amount, &usbfs_memory_usage);



	if (lim > 0 && atomic64_read(&usbfs_memory_usage) > lim) {

		atomic64_sub(amount, &usbfs_memory_usage);

		return -ENOMEM;

	}



	return 0;

}



/* Memory for a transfer is being deallocated */

static void usbfs_decrease_memory_usage(unsigned amount)

static void usbfs_decrease_memory_usage(u64 amount)

{

	atomic_sub(amount, &usbfs_memory_usage);

	atomic64_sub(amount, &usbfs_memory_usage);

}



static int connected(struct usb_dev_state *ps)
@@ -1191,7 +1184,7 @@ static int proc_bulk(struct usb_dev_state *ps, void __user *arg) 
	if (!usb_maxpacket(dev, pipe, !(bulk.ep & USB_DIR_IN)))

		return -EINVAL;

	len1 = bulk.len;

	if (len1 >= USBFS_XFER_MAX)

	if (len1 >= (INT_MAX - sizeof(struct urb)))

		return -EINVAL;

	ret = usbfs_increase_memory_usage(len1 + sizeof(struct urb));

	if (ret)
@@ -1584,10 +1577,6 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb 
		return -EINVAL;

	}



	if (uurb->buffer_length >= USBFS_XFER_MAX) {

		ret = -EINVAL;

		goto error;

	}

	if (uurb->buffer_length > 0 &&

			!access_ok(is_in ? VERIFY_WRITE : VERIFY_READ,

				uurb->buffer, uurb->buffer_length)) {