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usb/misc/chaoskey: introduce an URB for asynchronous reads

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To allow for and clean handling of signals an URB is introduced.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Oliver Neukum 2016-02-17 10:01:33 -08:00 committed by Greg Kroah-Hartman
parent 0a15e24c27
commit 0ca10122ca
1 changed files with 65 additions and 21 deletions
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86
drivers/usb/misc/chaoskey.c
View file

@ -73,6 +73,8 @@ static const struct usb_device_id chaoskey_table[] = {
};
MODULE_DEVICE_TABLE(usb, chaoskey_table);
static void chaos_read_callback(struct urb *urb);
/* Driver-local specific stuff */
struct chaoskey {
struct usb_interface *interface;
@ -80,7 +82,8 @@ struct chaoskey {
struct mutex lock;
struct mutex rng_lock;
int open; /* open count */
int present; /* device not disconnected */
bool present; /* device not disconnected */
bool reading; /* ongoing IO */
int size; /* size of buf */
int valid; /* bytes of buf read */
int used; /* bytes of buf consumed */
@ -88,6 +91,7 @@ struct chaoskey {
struct hwrng hwrng; /* Embedded struct for hwrng */
int hwrng_registered; /* registered with hwrng API */
wait_queue_head_t wait_q; /* for timeouts */
struct urb *urb; /* for performing IO */
char *buf;
};
@ -95,6 +99,7 @@ static void chaoskey_free(struct chaoskey *dev)
{
if (dev) {
usb_dbg(dev->interface, "free");
usb_free_urb(dev->urb);
kfree(dev->name);
kfree(dev->buf);
kfree(dev);
@ -151,6 +156,19 @@ static int chaoskey_probe(struct usb_interface *interface,
if (dev->buf == NULL)
goto out;
dev->urb = usb_alloc_urb(0, GFP_KERNEL);
if (!dev->urb)
goto out;
usb_fill_bulk_urb(dev->urb,
udev,
usb_rcvbulkpipe(udev, in_ep),
dev->buf,
size,
chaos_read_callback,
dev);
/* Construct a name using the product and serial values. Each
* device needs a unique name for the hwrng code
*/
@ -237,6 +255,7 @@ static void chaoskey_disconnect(struct usb_interface *interface)
mutex_lock(&dev->lock);
dev->present = 0;
usb_poison_urb(dev->urb);
if (!dev->open) {
mutex_unlock(&dev->lock);
@ -311,14 +330,33 @@ static int chaoskey_release(struct inode *inode, struct file *file)
return 0;
}
static void chaos_read_callback(struct urb *urb)
{
struct chaoskey *dev = urb->context;
int status = urb->status;
usb_dbg(dev->interface, "callback status (%d)", status);
if (status == 0)
dev->valid = urb->actual_length;
else
dev->valid = 0;
dev->used = 0;
/* must be seen first before validity is announced */
smp_wmb();
dev->reading = false;
wake_up(&dev->wait_q);
}
/* Fill the buffer. Called with dev->lock held
*/
static int _chaoskey_fill(struct chaoskey *dev)
{
DEFINE_WAIT(wait);
int result;
int this_read;
struct usb_device *udev = interface_to_usbdev(dev->interface);
usb_dbg(dev->interface, "fill");
@ -343,21 +381,31 @@ static int _chaoskey_fill(struct chaoskey *dev)
return result;
}
result = usb_bulk_msg(udev,
usb_rcvbulkpipe(udev, dev->in_ep),
dev->buf, dev->size, &this_read,
NAK_TIMEOUT);
dev->reading = true;
result = usb_submit_urb(dev->urb, GFP_KERNEL);
if (result < 0) {
result = usb_translate_errors(result);
dev->reading = false;
goto out;
}
result = wait_event_interruptible_timeout(
dev->wait_q,
!dev->reading,
NAK_TIMEOUT);
if (result < 0)
goto out;
if (result == 0)
result = -ETIMEDOUT;
else
result = dev->valid;
out:
/* Let the device go back to sleep eventually */
usb_autopm_put_interface(dev->interface);
if (result == 0) {
dev->valid = this_read;
dev->used = 0;
}
usb_dbg(dev->interface, "bulk_msg result %d this_read %d",
result, this_read);
usb_dbg(dev->interface, "read %d bytes", dev->valid);
return result;
}
@ -395,13 +443,7 @@ static ssize_t chaoskey_read(struct file *file,
goto bail;
if (dev->valid == dev->used) {
result = _chaoskey_fill(dev);
if (result) {
mutex_unlock(&dev->lock);
goto bail;
}
/* Read returned zero bytes */
if (dev->used == dev->valid) {
if (result < 0) {
mutex_unlock(&dev->lock);
goto bail;
}
@ -435,6 +477,8 @@ static ssize_t chaoskey_read(struct file *file,
return read_count;
}
usb_dbg(dev->interface, "empty read, result %d", result);
if (result == -ETIMEDOUT)
result = -EAGAIN;
return result;
}