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[PATCH] USB: Limiting of resource use in skeleton driver 

this introduces limits whose lack in the skeleton driver someone recently
complained about.

Signed-off-by: Oliver Neukum <oliver@neukum.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Oliver Neukum 2005-12-21 19:27:29 +01:00 committed by Greg Kroah-Hartman
parent aafbf24a11
commit ff90651883
1 changed files with 18 additions and 7 deletions
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25
drivers/usb/usb-skeleton.c
View File

@ -39,10 +39,15 @@ MODULE_DEVICE_TABLE (usb, skel_table);
/* Get a minor range for your devices from the usb maintainer */
#define USB_SKEL_MINOR_BASE 192
/* our private defines. if this grows any larger, use your own .h file */
#define MAX_TRANSFER ( PAGE_SIZE - 512 )
#define WRITES_IN_FLIGHT 8
/* Structure to hold all of our device specific stuff */
struct usb_skel {
struct usb_device * udev; /* the usb device for this device */
struct usb_interface * interface; /* the interface for this device */
struct semaphore limit_sem; /* limiting the number of writes in progress */
unsigned char * bulk_in_buffer; /* the buffer to receive data */
size_t bulk_in_size; /* the size of the receive buffer */
__u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
@ -152,6 +157,7 @@ static void skel_write_bulk_callback(struct urb *urb, struct pt_regs *regs)
/* free up our allocated buffer */
usb_buffer_free(urb->dev, urb->transfer_buffer_length,
urb->transfer_buffer, urb->transfer_dma);
up(&dev->limit_sem);
}
static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
@ -160,6 +166,7 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
int retval = 0;
struct urb *urb = NULL;
char *buf = NULL;
size_t writesize = max(count, MAX_TRANSFER);
dev = (struct usb_skel *)file->private_data;
@ -167,6 +174,9 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
if (count == 0)
goto exit;
/* limit the number of URBs in flight to stop a user from using up all RAM */
down (&dev->limit_sem);
/* create a urb, and a buffer for it, and copy the data to the urb */
urb = usb_alloc_urb(0, GFP_KERNEL);
if (!urb) {
@ -174,13 +184,13 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
goto error;
}
buf = usb_buffer_alloc(dev->udev, count, GFP_KERNEL, &urb->transfer_dma);
buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
if (!buf) {
retval = -ENOMEM;
goto error;
}
if (copy_from_user(buf, user_buffer, count)) {
if (copy_from_user(buf, user_buffer, writesize)) {
retval = -EFAULT;
goto error;
}
@ -188,7 +198,7 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
/* initialize the urb properly */
usb_fill_bulk_urb(urb, dev->udev,
usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
buf, count, skel_write_bulk_callback, dev);
buf, writesize, skel_write_bulk_callback, dev);
urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
/* send the data out the bulk port */
@ -202,11 +212,12 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
usb_free_urb(urb);
exit:
return count;
return writesize;
error:
usb_buffer_free(dev->udev, count, buf, urb->transfer_dma);
usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
usb_free_urb(urb);
up(&dev->limit_sem);
return retval;
}
@ -238,13 +249,13 @@ static int skel_probe(struct usb_interface *interface, const struct usb_device_i
int retval = -ENOMEM;
/* allocate memory for our device state and initialize it */
dev = kmalloc(sizeof(*dev), GFP_KERNEL);
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (dev == NULL) {
err("Out of memory");
goto error;
}
memset(dev, 0x00, sizeof(*dev));
kref_init(&dev->kref);
sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
dev->udev = usb_get_dev(interface_to_usbdev(interface));
dev->interface = interface;