hollalinux
/
linux-sg2042
mirror of https://github.com/sophgo/linux-riscv.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

USB: fix skeleton driver 

compilation of the skeleton driver is currently broken. It doesn't compile.
So while I am it:

- fix typo
- add comments to answer common questions
- actually allow autosuspend in the driver struct
- increase paralellism by restricting code under locks

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Oliver Neukum 2007-03-01 14:31:02 +01:00 committed by Greg Kroah-Hartman
parent 08a78cbb41
commit ba35e02bdc
1 changed files with 20 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
drivers/usb/usb-skeleton.c
View File

@ -40,12 +40,16 @@ MODULE_DEVICE_TABLE(usb, skel_table);
/* our private defines. if this grows any larger, use your own .h file */
#define MAX_TRANSFER (PAGE_SIZE - 512)
/* MAX_TRANSFER is chosen so that the VM is not stressed by
allocations > PAGE_SIZE and the number of packets in a page
is an integer 512 is the largest possible packet on EHCI */
#define WRITES_IN_FLIGHT 8
/* arbitrarily chosen */
/* Structure to hold all of our device specific stuff */
struct usb_skel {
struct usb_device *dev; /* the usb device for this device */
struct usb_interface *interface; /* the interface for this device */
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 */
@ -201,12 +205,6 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
goto exit;
}
mutex_lock(&dev->io_mutex);
if (!dev->interface) { /* disconnect() was called */
retval = -ENODEV;
goto error;
}
/* create a urb, and a buffer for it, and copy the data to the urb */
urb = usb_alloc_urb(0, GFP_KERNEL);
if (!urb) {
@ -225,6 +223,14 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
goto error;
}
/* this lock makes sure we don't submit URBs to gone devices */
mutex_lock(&dev->io_mutex);
if (!dev->interface) { /* disconnect() was called */
mutex_unlock(&dev->io_mutex);
retval = -ENODEV;
goto error;
}
/* initialize the urb properly */
usb_fill_bulk_urb(urb, dev->udev,
usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
@ -233,6 +239,7 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
/* send the data out the bulk port */
retval = usb_submit_urb(urb, GFP_KERNEL);
mutex_unlock(&dev->io_mutex);
if (retval) {
err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
goto error;
@ -241,7 +248,7 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou
/* release our reference to this urb, the USB core will eventually free it entirely */
usb_free_urb(urb);
mutex_unlock(&dev->io_mutex);
return writesize;
error:
@ -249,7 +256,6 @@ error:
usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
usb_free_urb(urb);
}
mutex_unlock(&dev->io_mutex);
up(&dev->limit_sem);
exit:
@ -344,6 +350,7 @@ static int skel_probe(struct usb_interface *interface, const struct usb_device_i
error:
if (dev)
/* this frees allocated memory */
kref_put(&dev->kref, skel_delete);
return retval;
}
@ -361,13 +368,14 @@ static void skel_disconnect(struct usb_interface *interface)
/* give back our minor */
usb_deregister_dev(interface, &skel_class);
unlock_kernel();
/* prevent more I/O from starting */
mutex_lock(&dev->io_mutex);
dev->interface = NULL;
mutex_unlock(&dev->io_mutex);
unlock_kernel();
/* decrement our usage count */
kref_put(&dev->kref, skel_delete);
@ -380,6 +388,7 @@ static struct usb_driver skel_driver = {
.probe = skel_probe,
.disconnect = skel_disconnect,
.id_table = skel_table,
.supports_autosuspend = 1,
};
static int __init usb_skel_init(void)