From: Oliver Neukum <[EMAIL PROTECTED]>
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 <[EMAIL PROTECTED]>
Signed-off-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>
---
drivers/usb/usb-skeleton.c | 31 ++++++++++++++++++++-----------
1 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c
index 46929a1..962b28c 100644
--- a/drivers/usb/usb-skeleton.c
+++ b/drivers/usb/usb-skeleton.c
@@ -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)
--
1.5.1.2
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