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authorOliver Neukum <oneukum@suse.com>2016-02-17 10:01:33 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-02-20 20:12:21 -0800
commit0ca10122ca08d21e375b8c85bd7b498b1aeaf55d (patch)
tree6464b5eed05796e90aee690b2c45574837629a72 /drivers/usb/misc
parent0a15e24c2740b7db99fbe21642b33a3028700225 (diff)
usb/misc/chaoskey: introduce an URB for asynchronous reads
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>
Diffstat (limited to 'drivers/usb/misc')
-rw-r--r--drivers/usb/misc/chaoskey.c86
1 files changed, 65 insertions, 21 deletions
diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c
index cb1c239cad72..76350e4ee807 100644
--- a/drivers/usb/misc/chaoskey.c
+++ b/drivers/usb/misc/chaoskey.c
@@ -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 @@ bail:
return read_count;
}
usb_dbg(dev->interface, "empty read, result %d", result);
+ if (result == -ETIMEDOUT)
+ result = -EAGAIN;
return result;
}