Skip to content

Commit

Permalink
usbdevfs: Use scatter-gather lists for large bulk transfers
Browse files Browse the repository at this point in the history 
When using urb->transfer_buffer we need to allocate physical contiguous buffers
for the entire transfer, which is pretty much guaranteed to fail with large
transfers.

Currently userspace works around this by breaking large transfers into multiple
urbs. For large bulk transfers this leads to all kind of complications.

This patch makes it possible for userspace to reliable submit large bulk
transfers to scatter-gather capable host controllers in one go, by using a
scatterlist to break the transfer up in managable chunks.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  • Loading branch information
Hans de Goede authored and Greg Kroah-Hartman committed Jul 6, 2012
1 parent 19181bc commit 3d97ff6
Show file tree
Hide file tree
Showing 2 changed files with 122 additions and 31 deletions.
152 changes: 121 additions & 31 deletions drivers/usb/core/devio.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,7 @@
#include <linux/notifier.h>
#include <linux/security.h>
#include <linux/user_namespace.h>
#include <linux/scatterlist.h>
#include <asm/uaccess.h>
#include <asm/byteorder.h>
#include <linux/moduleparam.h>
Expand All @@ -55,6 +56,7 @@

#define USB_MAXBUS 64
#define USB_DEVICE_MAX USB_MAXBUS * 128
#define USB_SG_SIZE 16384 /* split-size for large txs */

/* Mutual exclusion for removal, open, and release */
DEFINE_MUTEX(usbfs_mutex);
Expand Down Expand Up @@ -285,9 +287,16 @@ static struct async *alloc_async(unsigned int numisoframes)

static void free_async(struct async *as)
{
int i;

put_pid(as->pid);
if (as->cred)
put_cred(as->cred);
for (i = 0; i < as->urb->num_sgs; i++) {
if (sg_page(&as->urb->sg[i]))
kfree(sg_virt(&as->urb->sg[i]));
}
kfree(as->urb->sg);
kfree(as->urb->transfer_buffer);
kfree(as->urb->setup_packet);
usb_free_urb(as->urb);
Expand Down Expand Up @@ -388,6 +397,53 @@ static void snoop_urb(struct usb_device *udev,
}
}

static void snoop_urb_data(struct urb *urb, unsigned len)
{
int i, size;

if (!usbfs_snoop)
return;

if (urb->num_sgs == 0) {
print_hex_dump(KERN_DEBUG, "data: ", DUMP_PREFIX_NONE, 32, 1,
urb->transfer_buffer, len, 1);
return;
}

for (i = 0; i < urb->num_sgs && len; i++) {
size = (len > USB_SG_SIZE) ? USB_SG_SIZE : len;
print_hex_dump(KERN_DEBUG, "data: ", DUMP_PREFIX_NONE, 32, 1,
sg_virt(&urb->sg[i]), size, 1);
len -= size;
}
}

static int copy_urb_data_to_user(u8 __user *userbuffer, struct urb *urb)
{
unsigned i, len, size;

if (urb->number_of_packets > 0) /* Isochronous */
len = urb->transfer_buffer_length;
else /* Non-Isoc */
len = urb->actual_length;

if (urb->num_sgs == 0) {
if (copy_to_user(userbuffer, urb->transfer_buffer, len))
return -EFAULT;
return 0;
}

for (i = 0; i < urb->num_sgs && len; i++) {
size = (len > USB_SG_SIZE) ? USB_SG_SIZE : len;
if (copy_to_user(userbuffer, sg_virt(&urb->sg[i]), size))
return -EFAULT;
userbuffer += size;
len -= size;
}

return 0;
}

#define AS_CONTINUATION 1
#define AS_UNLINK 2

Expand Down Expand Up @@ -454,9 +510,10 @@ static void async_completed(struct urb *urb)
}
snoop(&urb->dev->dev, "urb complete\n");
snoop_urb(urb->dev, as->userurb, urb->pipe, urb->actual_length,
as->status, COMPLETE,
((urb->transfer_flags & URB_DIR_MASK) == USB_DIR_OUT) ?
NULL : urb->transfer_buffer, urb->actual_length);
as->status, COMPLETE, NULL, 0);
if ((urb->transfer_flags & URB_DIR_MASK) == USB_DIR_IN)
snoop_urb_data(urb, urb->actual_length);

if (as->status < 0 && as->bulk_addr && as->status != -ECONNRESET &&
as->status != -ENOENT)
cancel_bulk_urbs(ps, as->bulk_addr);
Expand Down Expand Up @@ -1114,8 +1171,8 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
struct async *as = NULL;
struct usb_ctrlrequest *dr = NULL;
unsigned int u, totlen, isofrmlen;
int ret, ifnum = -1;
int is_in;
int i, ret, is_in, num_sgs = 0, ifnum = -1;
void *buf;

if (uurb->flags & ~(USBDEVFS_URB_ISO_ASAP |
USBDEVFS_URB_SHORT_NOT_OK |
Expand Down Expand Up @@ -1199,6 +1256,9 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
goto interrupt_urb;
}
uurb->number_of_packets = 0;
num_sgs = DIV_ROUND_UP(uurb->buffer_length, USB_SG_SIZE);
if (num_sgs == 1 || num_sgs > ps->dev->bus->sg_tablesize)
num_sgs = 0;
break;

case USBDEVFS_URB_TYPE_INTERRUPT:
Expand Down Expand Up @@ -1255,26 +1315,67 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
ret = -ENOMEM;
goto error;
}
u += sizeof(struct async) + sizeof(struct urb) + uurb->buffer_length;

u += sizeof(struct async) + sizeof(struct urb) + uurb->buffer_length +
num_sgs * sizeof(struct scatterlist);
ret = usbfs_increase_memory_usage(u);
if (ret)
goto error;
as->mem_usage = u;

if (uurb->buffer_length > 0) {
if (num_sgs) {
as->urb->sg = kmalloc(num_sgs * sizeof(struct scatterlist),
GFP_KERNEL);
if (!as->urb->sg) {
ret = -ENOMEM;
goto error;
}
as->urb->num_sgs = num_sgs;
sg_init_table(as->urb->sg, as->urb->num_sgs);

totlen = uurb->buffer_length;
for (i = 0; i < as->urb->num_sgs; i++) {
u = (totlen > USB_SG_SIZE) ? USB_SG_SIZE : totlen;
buf = kmalloc(u, GFP_KERNEL);
if (!buf) {
ret = -ENOMEM;
goto error;
}
sg_set_buf(&as->urb->sg[i], buf, u);

if (!is_in) {
if (copy_from_user(buf, uurb->buffer, u)) {
ret = -EFAULT;
goto error;
}
}
totlen -= u;
}
} else if (uurb->buffer_length > 0) {
as->urb->transfer_buffer = kmalloc(uurb->buffer_length,
GFP_KERNEL);
if (!as->urb->transfer_buffer) {
ret = -ENOMEM;
goto error;
}
/* Isochronous input data may end up being discontiguous
* if some of the packets are short. Clear the buffer so
* that the gaps don't leak kernel data to userspace.
*/
if (is_in && uurb->type == USBDEVFS_URB_TYPE_ISO)

if (!is_in) {
if (copy_from_user(as->urb->transfer_buffer,
uurb->buffer,
uurb->buffer_length)) {
ret = -EFAULT;
goto error;
}
} else if (uurb->type == USBDEVFS_URB_TYPE_ISO) {
/*
* Isochronous input data may end up being
* discontiguous if some of the packets are short.
* Clear the buffer so that the gaps don't leak
* kernel data to userspace.
*/
memset(as->urb->transfer_buffer, 0,
uurb->buffer_length);
}
}
as->urb->dev = ps->dev;
as->urb->pipe = (uurb->type << 30) |
Expand Down Expand Up @@ -1328,17 +1429,12 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
as->pid = get_pid(task_pid(current));
as->cred = get_current_cred();
security_task_getsecid(current, &as->secid);
if (!is_in && uurb->buffer_length > 0) {
if (copy_from_user(as->urb->transfer_buffer, uurb->buffer,
uurb->buffer_length)) {
ret = -EFAULT;
goto error;
}
}
snoop_urb(ps->dev, as->userurb, as->urb->pipe,
as->urb->transfer_buffer_length, 0, SUBMIT,
is_in ? NULL : as->urb->transfer_buffer,
uurb->buffer_length);
NULL, 0);
if (!is_in)
snoop_urb_data(as->urb, as->urb->transfer_buffer_length);

async_newpending(as);

if (usb_endpoint_xfer_bulk(&ep->desc)) {
Expand Down Expand Up @@ -1433,11 +1529,7 @@ static int processcompl(struct async *as, void __user * __user *arg)
unsigned int i;

if (as->userbuffer && urb->actual_length) {
if (urb->number_of_packets > 0) /* Isochronous */
i = urb->transfer_buffer_length;
else /* Non-Isoc */
i = urb->actual_length;
if (copy_to_user(as->userbuffer, urb->transfer_buffer, i))
if (copy_urb_data_to_user(as->userbuffer, urb))
goto err_out;
}
if (put_user(as->status, &userurb->status))
Expand Down Expand Up @@ -1605,11 +1697,7 @@ static int processcompl_compat(struct async *as, void __user * __user *arg)
unsigned int i;

if (as->userbuffer && urb->actual_length) {
if (urb->number_of_packets > 0) /* Isochronous */
i = urb->transfer_buffer_length;
else /* Non-Isoc */
i = urb->actual_length;
if (copy_to_user(as->userbuffer, urb->transfer_buffer, i))
if (copy_urb_data_to_user(as->userbuffer, urb))
return -EFAULT;
}
if (put_user(as->status, &userurb->status))
Expand Down Expand Up @@ -1831,6 +1919,8 @@ static int proc_get_capabilities(struct dev_state *ps, void __user *arg)
caps = USBDEVFS_CAP_ZERO_PACKET | USBDEVFS_CAP_NO_PACKET_SIZE_LIM;
if (!ps->dev->bus->no_stop_on_short)
caps |= USBDEVFS_CAP_BULK_CONTINUATION;
if (ps->dev->bus->sg_tablesize)
caps |= USBDEVFS_CAP_BULK_SCATTER_GATHER;

if (put_user(caps, (__u32 __user *)arg))
return -EFAULT;
Expand Down
1 change: 1 addition & 0 deletions include/linux/usbdevice_fs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -129,6 +129,7 @@ struct usbdevfs_hub_portinfo {
#define USBDEVFS_CAP_ZERO_PACKET 0x01
#define USBDEVFS_CAP_BULK_CONTINUATION 0x02
#define USBDEVFS_CAP_NO_PACKET_SIZE_LIM 0x04
#define USBDEVFS_CAP_BULK_SCATTER_GATHER 0x08

#ifdef __KERNEL__
#ifdef CONFIG_COMPAT
Expand Down

0 comments on commit 3d97ff6

Please sign in to comment.