Hi,
this introduces limits whose lack in the skeleton driver someone recently
complained about.
Regards
Oliver
Signed-off-by: Oliver Neukum <[EMAIL PROTECTED]>
--- a/drivers/usb/usb-skeleton.c 2005-12-04 06:10:42.000000000 +0100
+++ b/drivers/usb/usb-skeleton.c 2005-12-17 23:31:43.000000000 +0100
@@ -39,10 +39,15 @@
/* 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 @@
/* 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 @@
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 @@
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 @@
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 @@
/* 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 @@
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 @@
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;
-------------------------------------------------------
This SF.net email is sponsored by: Splunk Inc. Do you grep through log files
for problems? Stop! Download the new AJAX search engine that makes
searching your log files as easy as surfing the web. DOWNLOAD SPLUNK!
http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click
_______________________________________________
linux-usb-devel@lists.sourceforge.net
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
