[PATCH v3 0/1] usb: gadget: add raw-gadget interface

[PATCH v3 0/1] usb: gadget: add raw-gadget interface

[Andrey Konovalov]

This patchset (currently a single patch) adds a new userspace interface
for the USB Gadget subsystem called USB Raw Gadget (I don't mind changing
the name to something else if there are better ideas). This is what
currently being used to enable coverage-buided USB fuzzing with syzkaller:

https://github.com/google/syzkaller/blob/master/docs/linux/external_fuzzing_usb.md

Initially I was using GadgetFS (together with the Dummy HCD/UDC module)
to perform emulation of USB devices for fuzzing, but later switched to a
custom written interface. The incentive to implement a different interface
was to provide a somewhat raw and direct access to the USB Gadget layer
for the userspace, where every USB request is passed to the userspace to
get a response. See documentation for the list of differences between
Raw Gadget and GadgetFS.

This patchset has been pushed to the public Linux kernel Gerrit instance:

https://linux-review.googlesource.com/c/linux/kernel/git/torvalds/linux/+/2144

Changes v2 -> v3:
- Updated device path in documentation.
- Changed usb_raw_init struct layout to make it the same for 32 bit compat
  mode.
- Added compat_ioctl to raw_fops.
- Changed raw_ioctl_init() to return EINVAL for invalid USB speeds, except
  for USB_SPEED_UNKNOWN, which defaults to USB_SPEED_HIGH.
- Reject endpoints with maxpacket = 0 in raw_ioctl_ep_enable().

Changes v1 -> v2:
- Moved raw.c to legacy/.
- Changed uapi header to use __u* types.
- Switched from debugfs entry to a misc device.
- Changed raw_dev from refcount to kref.
- Moved UDC_NAME_LENGTH_MAX to uapi headers.
- Used usb_endpoint_type() and usb_endpoint_dir_in/out() functions instead
  of open coding them.
- Added "WITH Linux-syscall-note" to SPDX id in the uapi header.
- Removed pr_err() if case dev_new() fails.
- Reduced the number of debugging messages.

Andrey Konovalov (1):
  usb: gadget: add raw-gadget interface

 Documentation/usb/index.rst         |    1 +
 Documentation/usb/raw-gadget.rst    |   59 ++
 drivers/usb/gadget/legacy/Kconfig   |    8 +
 drivers/usb/gadget/legacy/Makefile  |    1 +
 drivers/usb/gadget/legacy/raw.c     | 1070 +++++++++++++++++++++++++++
 include/uapi/linux/usb/raw_gadget.h |  167 +++++
 6 files changed, 1306 insertions(+)
 create mode 100644 Documentation/usb/raw-gadget.rst
 create mode 100644 drivers/usb/gadget/legacy/raw.c
 create mode 100644 include/uapi/linux/usb/raw_gadget.h

-- 
2.24.1.735.g03f4e72817-goog

[PATCH v3 1/1] usb: gadget: add raw-gadget interface

[Andrey Konovalov]

USB Raw Gadget is a kernel module that provides a userspace interface for
the USB Gadget subsystem. Essentially it allows to emulate USB devices
from userspace. Enabled with CONFIG_USB_RAW_GADGET. Raw Gadget is
currently a strictly debugging feature and shouldn't be used in
production.

Raw Gadget is similar to GadgetFS, but provides a more low-level and
direct access to the USB Gadget layer for the userspace. The key
differences are:

1. Every USB request is passed to the userspace to get a response, while
   GadgetFS responds to some USB requests internally based on the provided
   descriptors. However note, that the UDC driver might respond to some
   requests on its own and never forward them to the Gadget layer.

2. GadgetFS performs some sanity checks on the provided USB descriptors,
   while Raw Gadget allows you to provide arbitrary data as responses to
   USB requests.

3. Raw Gadget provides a way to select a UDC device/driver to bind to,
   while GadgetFS currently binds to the first available UDC.

4. Raw Gadget uses predictable endpoint names (handles) across different
   UDCs (as long as UDCs have enough endpoints of each required transfer
   type).

5. Raw Gadget has ioctl-based interface instead of a filesystem-based one.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 Documentation/usb/index.rst         |    1 +
 Documentation/usb/raw-gadget.rst    |   59 ++
 drivers/usb/gadget/legacy/Kconfig   |    8 +
 drivers/usb/gadget/legacy/Makefile  |    1 +
 drivers/usb/gadget/legacy/raw.c     | 1070 +++++++++++++++++++++++++++
 include/uapi/linux/usb/raw_gadget.h |  167 +++++
 6 files changed, 1306 insertions(+)
 create mode 100644 Documentation/usb/raw-gadget.rst
 create mode 100644 drivers/usb/gadget/legacy/raw.c
 create mode 100644 include/uapi/linux/usb/raw_gadget.h

diff --git a/Documentation/usb/index.rst b/Documentation/usb/index.rst
index e55386a4abfb..90310e2a0c1f 100644
--- a/Documentation/usb/index.rst
+++ b/Documentation/usb/index.rst
@@ -22,6 +22,7 @@ USB support
     misc_usbsevseg
     mtouchusb
     ohci
+    raw-gadget
     rio
     usbip_protocol
     usbmon
diff --git a/Documentation/usb/raw-gadget.rst b/Documentation/usb/raw-gadget.rst
new file mode 100644
index 000000000000..cbedf5451ed3
--- /dev/null
+++ b/Documentation/usb/raw-gadget.rst
@@ -0,0 +1,59 @@
+==============
+USB Raw Gadget
+==============
+
+USB Raw Gadget is a kernel module that provides a userspace interface for
+the USB Gadget subsystem. Essentially it allows to emulate USB devices
+from userspace. Enabled with CONFIG_USB_RAW_GADGET. Raw Gadget is
+currently a strictly debugging feature and shouldn't be used in
+production, use GadgetFS instead.
+
+Comparison to GadgetFS
+~~~~~~~~~~~~~~~~~~~~~~
+
+Raw Gadget is similar to GadgetFS, but provides a more low-level and
+direct access to the USB Gadget layer for the userspace. The key
+differences are:
+
+1. Every USB request is passed to the userspace to get a response, while
+   GadgetFS responds to some USB requests internally based on the provided
+   descriptors. However note, that the UDC driver might respond to some
+   requests on its own and never forward them to the Gadget layer.
+
+2. GadgetFS performs some sanity checks on the provided USB descriptors,
+   while Raw Gadget allows you to provide arbitrary data as responses to
+   USB requests.
+
+3. Raw Gadget provides a way to select a UDC device/driver to bind to,
+   while GadgetFS currently binds to the first available UDC.
+
+4. Raw Gadget uses predictable endpoint names (handles) across different
+   UDCs (as long as UDCs have enough endpoints of each required transfer
+   type).
+
+5. Raw Gadget has ioctl-based interface instead of a filesystem-based one.
+
+Userspace interface
+~~~~~~~~~~~~~~~~~~~
+
+To create a Raw Gadget instance open /dev/raw-gadget. Multiple raw-gadget
+instances (bound to different UDCs) can be used at the same time. The
+interaction with the opened file happens through the ioctl() calls, see
+comments in include/uapi/linux/usb/raw_gadget.h for details.
+
+The typical usage of Raw Gadget looks like:
+
+1. Open Raw Gadget instance via /dev/raw-gadget.
+2. Initialize the instance via USB_RAW_IOCTL_INIT.
+3. Launch the instance with USB_RAW_IOCTL_RUN.
+4. In a loop issue USB_RAW_IOCTL_EVENT_FETCH calls to receive events from
+   Raw Gadget and react to those depending on what kind of USB device
+   needs to be emulated.
+
+Potential future improvements
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+- Implement ioctl's for setting/clearing halt status on endpoints.
+
+- Reporting more events (suspend, resume, etc.) through
+  USB_RAW_IOCTL_EVENT_FETCH.
diff --git a/drivers/usb/gadget/legacy/Kconfig b/drivers/usb/gadget/legacy/Kconfig
index 119a4e47681f..8c947edf7515 100644
--- a/drivers/usb/gadget/legacy/Kconfig
+++ b/drivers/usb/gadget/legacy/Kconfig
@@ -489,3 +489,11 @@ config USB_G_WEBCAM
 
 	  Say "y" to link the driver statically, or "m" to build a
 	  dynamically linked module called "g_webcam".
+
+config USB_RAW_GADGET
+	tristate "USB Raw Gadget"
+	help
+	  USB Raw Gadget is a kernel module that provides a userspace interface
+	  for the USB Gadget subsystem. Essentially it allows to emulate USB
+	  devices from userspace. See Documentation/usb/raw-gadget.rst for
+	  details.
diff --git a/drivers/usb/gadget/legacy/Makefile b/drivers/usb/gadget/legacy/Makefile
index abd0c3e66a05..799feefeee58 100644
--- a/drivers/usb/gadget/legacy/Makefile
+++ b/drivers/usb/gadget/legacy/Makefile
@@ -43,3 +43,4 @@ obj-$(CONFIG_USB_G_WEBCAM)	+= g_webcam.o
 obj-$(CONFIG_USB_G_NCM)		+= g_ncm.o
 obj-$(CONFIG_USB_G_ACM_MS)	+= g_acm_ms.o
 obj-$(CONFIG_USB_GADGET_TARGET)	+= tcm_usb_gadget.o
+obj-$(CONFIG_USB_RAW_GADGET)	+= raw.o
diff --git a/drivers/usb/gadget/legacy/raw.c b/drivers/usb/gadget/legacy/raw.c
new file mode 100644
index 000000000000..fcfa2ebc103e
--- /dev/null
+++ b/drivers/usb/gadget/legacy/raw.c
@@ -0,0 +1,1070 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * USB Raw Gadget driver.
+ * See Documentation/usb/raw-gadget.rst for more details.
+ *
+ * Andrey Konovalov <andreyknvl@gmail.com>
+ */
+
+#define pr_fmt(fmt) "raw: %s: " fmt, __func__
+
+#include <linux/compiler.h>
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/kref.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/semaphore.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/wait.h>
+
+#include <linux/usb.h>
+#include <linux/usb/ch9.h>
+#include <linux/usb/ch11.h>
+#include <linux/usb/gadget.h>
+
+#include <uapi/linux/usb/raw_gadget.h>
+
+#define	DRIVER_DESC "USB Raw Gadget"
+#define DRIVER_NAME "raw-gadget"
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_AUTHOR("Andrey Konovalov");
+MODULE_LICENSE("GPL");
+
+/*----------------------------------------------------------------------*/
+
+#define RAW_EVENT_QUEUE_SIZE	128
+
+struct raw_event_queue {
+	spinlock_t		lock;
+	struct semaphore	sema;
+	struct usb_raw_event	*events[RAW_EVENT_QUEUE_SIZE];
+	int			size;
+};
+
+static void raw_event_queue_init(struct raw_event_queue *queue)
+{
+	spin_lock_init(&queue->lock);
+	sema_init(&queue->sema, 0);
+	queue->size = 0;
+}
+
+static int raw_event_queue_add(struct raw_event_queue *queue,
+	enum usb_raw_event_type type, size_t length, const void *data)
+{
+	unsigned long flags;
+	struct usb_raw_event *event;
+
+	spin_lock_irqsave(&queue->lock, flags);
+	if (queue->size >= RAW_EVENT_QUEUE_SIZE) {
+		pr_err("too many events\n");
+		spin_unlock_irqrestore(&queue->lock, flags);
+		return -ENOMEM;
+	}
+	event = kmalloc(sizeof(*event) + length, GFP_ATOMIC);
+	if (!event) {
+		spin_unlock_irqrestore(&queue->lock, flags);
+		return -ENOMEM;
+	}
+	event->type = type;
+	event->length = length;
+	if (event->length)
+		memcpy(&event->data[0], data, length);
+	queue->events[queue->size] = event;
+	queue->size++;
+	up(&queue->sema);
+	spin_unlock_irqrestore(&queue->lock, flags);
+	return 0;
+}
+
+static struct usb_raw_event *raw_event_queue_fetch(
+				struct raw_event_queue *queue)
+{
+	unsigned long flags;
+	struct usb_raw_event *event;
+
+	if (down_interruptible(&queue->sema))
+		return NULL;
+	spin_lock_irqsave(&queue->lock, flags);
+	if (WARN_ON(!queue->size))
+		return NULL;
+	event = queue->events[0];
+	queue->size--;
+	memmove(&queue->events[0], &queue->events[1],
+			queue->size * sizeof(queue->events[0]));
+	spin_unlock_irqrestore(&queue->lock, flags);
+	return event;
+}
+
+static void raw_event_queue_destroy(struct raw_event_queue *queue)
+{
+	int i;
+
+	for (i = 0; i < queue->size; i++)
+		kfree(queue->events[i]);
+	queue->size = 0;
+}
+
+/*----------------------------------------------------------------------*/
+
+struct raw_dev;
+
+#define USB_RAW_MAX_ENDPOINTS 32
+
+enum ep_state {
+	STATE_EP_DISABLED,
+	STATE_EP_ENABLED,
+};
+
+struct raw_ep {
+	struct raw_dev		*dev;
+	enum ep_state		state;
+	struct usb_ep		*ep;
+	struct usb_request	*req;
+	bool			urb_queued;
+	bool			disabling;
+	ssize_t			status;
+};
+
+enum dev_state {
+	STATE_DEV_INVALID = 0,
+	STATE_DEV_OPENED,
+	STATE_DEV_INITIALIZED,
+	STATE_DEV_RUNNING,
+	STATE_DEV_CLOSED,
+	STATE_DEV_FAILED
+};
+
+struct raw_dev {
+	struct kref			count;
+	spinlock_t			lock;
+
+	const char			*udc_name;
+	struct usb_gadget_driver	driver;
+
+	/* Protected by lock: */
+	enum dev_state			state;
+	bool				gadget_registered;
+	struct usb_gadget		*gadget;
+	struct usb_request		*req;
+	bool				ep0_in_pending;
+	bool				ep0_out_pending;
+	bool				ep0_urb_queued;
+	ssize_t				ep0_status;
+	struct raw_ep			eps[USB_RAW_MAX_ENDPOINTS];
+
+	struct completion		ep0_done;
+	struct raw_event_queue		queue;
+};
+
+static struct raw_dev *dev_new(void)
+{
+	struct raw_dev *dev;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return NULL;
+	/* Matches kref_put() in raw_release(). */
+	kref_init(&dev->count);
+	spin_lock_init(&dev->lock);
+	init_completion(&dev->ep0_done);
+	raw_event_queue_init(&dev->queue);
+	return dev;
+}
+
+static void dev_free(struct kref *kref)
+{
+	struct raw_dev *dev = container_of(kref, struct raw_dev, count);
+	int i;
+
+	kfree(dev->udc_name);
+	kfree(dev->driver.udc_name);
+	if (dev->req) {
+		if (dev->ep0_urb_queued)
+			usb_ep_dequeue(dev->gadget->ep0, dev->req);
+		usb_ep_free_request(dev->gadget->ep0, dev->req);
+	}
+	raw_event_queue_destroy(&dev->queue);
+	for (i = 0; i < USB_RAW_MAX_ENDPOINTS; i++) {
+		if (dev->eps[i].state != STATE_EP_ENABLED)
+			continue;
+		usb_ep_disable(dev->eps[i].ep);
+		usb_ep_free_request(dev->eps[i].ep, dev->eps[i].req);
+		kfree(dev->eps[i].ep->desc);
+		dev->eps[i].state = STATE_EP_DISABLED;
+	}
+	kfree(dev);
+}
+
+/*----------------------------------------------------------------------*/
+
+static int raw_queue_event(struct raw_dev *dev,
+	enum usb_raw_event_type type, size_t length, const void *data)
+{
+	int ret = 0;
+	unsigned long flags;
+
+	ret = raw_event_queue_add(&dev->queue, type, length, data);
+	if (ret < 0) {
+		spin_lock_irqsave(&dev->lock, flags);
+		dev->state = STATE_DEV_FAILED;
+		spin_unlock_irqrestore(&dev->lock, flags);
+	}
+	return ret;
+}
+
+static void gadget_ep0_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct raw_dev *dev = req->context;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (req->status)
+		dev->ep0_status = req->status;
+	else
+		dev->ep0_status = req->actual;
+	if (dev->ep0_in_pending)
+		dev->ep0_in_pending = false;
+	else
+		dev->ep0_out_pending = false;
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	complete(&dev->ep0_done);
+}
+
+static int gadget_bind(struct usb_gadget *gadget,
+			struct usb_gadget_driver *driver)
+{
+	int ret = 0;
+	struct raw_dev *dev = container_of(driver, struct raw_dev, driver);
+	struct usb_request *req;
+	unsigned long flags;
+
+	if (strcmp(gadget->name, dev->udc_name) != 0)
+		return -ENODEV;
+
+	set_gadget_data(gadget, dev);
+	req = usb_ep_alloc_request(gadget->ep0, GFP_KERNEL);
+	if (!req) {
+		pr_err("usb_ep_alloc_request failed\n");
+		set_gadget_data(gadget, NULL);
+		return -ENOMEM;
+	}
+
+	spin_lock_irqsave(&dev->lock, flags);
+	dev->req = req;
+	dev->req->context = dev;
+	dev->req->complete = gadget_ep0_complete;
+	dev->gadget = gadget;
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	/* Matches kref_put() in gadget_unbind(). */
+	kref_get(&dev->count);
+
+	ret = raw_queue_event(dev, USB_RAW_EVENT_CONNECT, 0, NULL);
+	if (ret < 0)
+		pr_err("failed to queue event\n");
+
+	return ret;
+}
+
+static void gadget_unbind(struct usb_gadget *gadget)
+{
+	struct raw_dev *dev = get_gadget_data(gadget);
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	set_gadget_data(gadget, NULL);
+	spin_unlock_irqrestore(&dev->lock, flags);
+	/* Matches kref_get() in gadget_bind(). */
+	kref_put(&dev->count, dev_free);
+}
+
+static int gadget_setup(struct usb_gadget *gadget,
+			const struct usb_ctrlrequest *ctrl)
+{
+	int ret = 0;
+	struct raw_dev *dev = get_gadget_data(gadget);
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->state != STATE_DEV_RUNNING) {
+		pr_err("ignoring, device is not running\n");
+		ret = -ENODEV;
+		goto out_unlock;
+	}
+	if (dev->ep0_in_pending || dev->ep0_out_pending) {
+		pr_debug("stalling, already have pending request\n");
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+	if ((ctrl->bRequestType & USB_DIR_IN) && ctrl->wLength)
+		dev->ep0_in_pending = true;
+	else
+		dev->ep0_out_pending = true;
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	ret = raw_queue_event(dev, USB_RAW_EVENT_CONTROL, sizeof(*ctrl), ctrl);
+	if (ret < 0)
+		pr_err("failed to queue event\n");
+	goto out;
+
+out_unlock:
+	spin_unlock_irqrestore(&dev->lock, flags);
+out:
+	return ret;
+}
+
+/* These are currently ununsed but present in case UDC driver requires them. */
+static void gadget_disconnect(struct usb_gadget *gadget) { }
+static void gadget_suspend(struct usb_gadget *gadget) { }
+static void gadget_resume(struct usb_gadget *gadget) { }
+static void gadget_reset(struct usb_gadget *gadget) { }
+
+/*----------------------------------------------------------------------*/
+
+static int raw_open(struct inode *inode, struct file *fd)
+{
+	struct raw_dev *dev;
+
+	dev = dev_new();
+	if (!dev) {
+		pr_err("failed to created device");
+		return -ENOMEM;
+	}
+	fd->private_data = dev;
+	dev->state = STATE_DEV_OPENED;
+	return 0;
+}
+
+static int raw_release(struct inode *inode, struct file *fd)
+{
+	int ret = 0;
+	struct raw_dev *dev = fd->private_data;
+	unsigned long flags;
+	bool unregister = false;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	dev->state = STATE_DEV_CLOSED;
+	if (!dev->gadget) {
+		spin_unlock_irqrestore(&dev->lock, flags);
+		goto out_put;
+	}
+	if (dev->gadget_registered)
+		unregister = true;
+	dev->gadget_registered = false;
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	if (unregister) {
+		ret = usb_gadget_unregister_driver(&dev->driver);
+		WARN_ON(ret != 0);
+		/* Matches kref_get() in raw_ioctl_run(). */
+		kref_put(&dev->count, dev_free);
+	}
+
+out_put:
+	/* Matches dev_new() in raw_open(). */
+	kref_put(&dev->count, dev_free);
+	return ret;
+}
+
+/*----------------------------------------------------------------------*/
+
+static int raw_ioctl_init(struct raw_dev *dev, unsigned long value)
+{
+	int ret = 0;
+	struct usb_raw_init arg;
+	char *udc_driver_name;
+	char *udc_device_name;
+	unsigned long flags;
+
+	ret = copy_from_user(&arg, (void __user *)value, sizeof(arg));
+	if (ret)
+		return ret;
+
+	switch (arg.speed) {
+	case USB_SPEED_UNKNOWN:
+		arg.speed = USB_SPEED_HIGH;
+		break;
+	case USB_SPEED_LOW:
+	case USB_SPEED_FULL:
+	case USB_SPEED_HIGH:
+	case USB_SPEED_SUPER:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	udc_driver_name = kmalloc(UDC_NAME_LENGTH_MAX, GFP_KERNEL);
+	if (!udc_driver_name)
+		return -ENOMEM;
+	ret = strscpy(udc_driver_name, &arg.driver_name[0],
+				UDC_NAME_LENGTH_MAX);
+	if (ret < 0) {
+		kfree(udc_driver_name);
+		return ret;
+	}
+	ret = 0;
+
+	udc_device_name = kmalloc(UDC_NAME_LENGTH_MAX, GFP_KERNEL);
+	if (!udc_device_name) {
+		kfree(udc_driver_name);
+		return -ENOMEM;
+	}
+	ret = strscpy(udc_device_name, &arg.device_name[0],
+				UDC_NAME_LENGTH_MAX);
+	if (ret < 0) {
+		kfree(udc_driver_name);
+		kfree(udc_device_name);
+		return ret;
+	}
+	ret = 0;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->state != STATE_DEV_OPENED) {
+		pr_debug("fail, device is not opened\n");
+		kfree(udc_driver_name);
+		kfree(udc_device_name);
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+	dev->udc_name = udc_driver_name;
+
+	dev->driver.function = DRIVER_DESC;
+	dev->driver.max_speed = arg.speed;
+	dev->driver.setup = gadget_setup;
+	dev->driver.disconnect = gadget_disconnect;
+	dev->driver.bind = gadget_bind;
+	dev->driver.unbind = gadget_unbind;
+	dev->driver.suspend = gadget_suspend;
+	dev->driver.resume = gadget_resume;
+	dev->driver.reset = gadget_reset;
+	dev->driver.driver.name = DRIVER_NAME;
+	dev->driver.udc_name = udc_device_name;
+	dev->driver.match_existing_only = 1;
+
+	dev->state = STATE_DEV_INITIALIZED;
+
+out_unlock:
+	spin_unlock_irqrestore(&dev->lock, flags);
+	return ret;
+}
+
+static int raw_ioctl_run(struct raw_dev *dev, unsigned long value)
+{
+	int ret = 0;
+	unsigned long flags;
+
+	if (value)
+		return -EINVAL;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->state != STATE_DEV_INITIALIZED) {
+		pr_debug("fail, device is not initialized\n");
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	ret = usb_gadget_probe_driver(&dev->driver);
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (ret) {
+		pr_err("fail, usb_gadget_probe_driver returned %d\n", ret);
+		dev->state = STATE_DEV_FAILED;
+		goto out_unlock;
+	}
+	dev->gadget_registered = true;
+	dev->state = STATE_DEV_RUNNING;
+	/* Matches kref_put() in raw_release(). */
+	kref_get(&dev->count);
+
+out_unlock:
+	spin_unlock_irqrestore(&dev->lock, flags);
+	return ret;
+}
+
+static int raw_ioctl_event_fetch(struct raw_dev *dev, unsigned long value)
+{
+	int ret = 0;
+	struct usb_raw_event arg;
+	unsigned long flags;
+	struct usb_raw_event *event;
+	uint32_t length;
+
+	ret = copy_from_user(&arg, (void __user *)value, sizeof(arg));
+	if (ret)
+		return ret;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->state != STATE_DEV_RUNNING) {
+		pr_debug("fail, device is not running\n");
+		spin_unlock_irqrestore(&dev->lock, flags);
+		return -EINVAL;
+	}
+	if (!dev->gadget) {
+		pr_debug("fail, gadget is not bound\n");
+		spin_unlock_irqrestore(&dev->lock, flags);
+		return -EBUSY;
+	}
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	event = raw_event_queue_fetch(&dev->queue);
+	if (!event) {
+		pr_debug("event fetching interrupted\n");
+		return -EINTR;
+	}
+	length = min(arg.length, event->length);
+	ret = copy_to_user((void __user *)value, event,
+				sizeof(*event) + length);
+	return ret;
+}
+
+static void *raw_alloc_io_data(struct usb_raw_ep_io *io, void __user *ptr,
+				bool get_from_user)
+{
+	int ret;
+	void *data;
+
+	ret = copy_from_user(io, ptr, sizeof(*io));
+	if (ret)
+		return ERR_PTR(ret);
+	if (io->ep >= USB_RAW_MAX_ENDPOINTS)
+		return ERR_PTR(-EINVAL);
+	if (!usb_raw_io_flags_valid(io->flags))
+		return ERR_PTR(-EINVAL);
+	if (io->length > PAGE_SIZE)
+		return ERR_PTR(-EINVAL);
+	if (get_from_user)
+		data = memdup_user(ptr + sizeof(*io), io->length);
+	else {
+		data = kmalloc(io->length, GFP_KERNEL);
+		if (!data)
+			data = ERR_PTR(-ENOMEM);
+	}
+	return data;
+}
+
+static int raw_process_ep0_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
+				void *data, bool in)
+{
+	int ret = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->state != STATE_DEV_RUNNING) {
+		pr_debug("fail, device is not running\n");
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+	if (!dev->gadget) {
+		pr_debug("fail, gadget is not bound\n");
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+	if (dev->ep0_urb_queued) {
+		pr_debug("fail, urb already queued\n");
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+	if ((in && !dev->ep0_in_pending) ||
+			(!in && !dev->ep0_out_pending)) {
+		pr_debug("fail, wrong direction\n");
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+	if (WARN_ON(in && dev->ep0_out_pending)) {
+		ret = -ENODEV;
+		dev->state = STATE_DEV_FAILED;
+		goto out_done;
+	}
+	if (WARN_ON(!in && dev->ep0_in_pending)) {
+		ret = -ENODEV;
+		dev->state = STATE_DEV_FAILED;
+		goto out_done;
+	}
+
+	dev->req->buf = data;
+	dev->req->length = io->length;
+	dev->req->zero = usb_raw_io_flags_zero(io->flags);
+	dev->ep0_urb_queued = true;
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	ret = usb_ep_queue(dev->gadget->ep0, dev->req, GFP_ATOMIC);
+	if (ret) {
+		pr_err("fail, usb_ep_queue returned %d\n", ret);
+		spin_lock_irqsave(&dev->lock, flags);
+		dev->state = STATE_DEV_FAILED;
+		goto out_done;
+	}
+
+	ret = wait_for_completion_interruptible(&dev->ep0_done);
+	if (ret) {
+		pr_debug("wait interrupted\n");
+		usb_ep_dequeue(dev->gadget->ep0, dev->req);
+		wait_for_completion(&dev->ep0_done);
+		spin_lock_irqsave(&dev->lock, flags);
+		goto out_done;
+	}
+
+	spin_lock_irqsave(&dev->lock, flags);
+	ret = dev->ep0_status;
+
+out_done:
+	dev->ep0_urb_queued = false;
+out_unlock:
+	spin_unlock_irqrestore(&dev->lock, flags);
+	return ret;
+}
+
+static int raw_ioctl_ep0_write(struct raw_dev *dev, unsigned long value)
+{
+	int ret = 0;
+	void *data;
+	struct usb_raw_ep_io io;
+
+	data = raw_alloc_io_data(&io, (void __user *)value, true);
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+	ret = raw_process_ep0_io(dev, &io, data, true);
+	kfree(data);
+	return ret;
+}
+
+static int raw_ioctl_ep0_read(struct raw_dev *dev, unsigned long value)
+{
+	int ret = 0;
+	void *data;
+	struct usb_raw_ep_io io;
+	unsigned int length;
+
+	data = raw_alloc_io_data(&io, (void __user *)value, false);
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+	ret = raw_process_ep0_io(dev, &io, data, false);
+	if (ret < 0) {
+		kfree(data);
+		return ret;
+	}
+	length = min(io.length, (unsigned int)ret);
+	ret = copy_to_user((void __user *)(value + sizeof(io)), data, length);
+	kfree(data);
+	return ret;
+}
+
+static bool check_ep_caps(struct usb_ep *ep,
+				struct usb_endpoint_descriptor *desc)
+{
+	switch (usb_endpoint_type(desc)) {
+	case USB_ENDPOINT_XFER_ISOC:
+		if (!ep->caps.type_iso)
+			return false;
+		break;
+	case USB_ENDPOINT_XFER_BULK:
+		if (!ep->caps.type_bulk)
+			return false;
+		break;
+	case USB_ENDPOINT_XFER_INT:
+		if (!ep->caps.type_int)
+			return false;
+		break;
+	default:
+		return false;
+	}
+
+	if (usb_endpoint_dir_in(desc) && !ep->caps.dir_in)
+		return false;
+	if (usb_endpoint_dir_out(desc) && !ep->caps.dir_out)
+		return false;
+
+	return true;
+}
+
+static int raw_ioctl_ep_enable(struct raw_dev *dev, unsigned long value)
+{
+	int ret = 0, i;
+	unsigned long flags;
+	struct usb_endpoint_descriptor *desc;
+	struct usb_ep *ep = NULL;
+
+	desc = memdup_user((void __user *)value, sizeof(*desc));
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
+	/*
+	 * Endpoints with a maxpacket length of 0 can cause crashes in UDC
+	 * drivers.
+	 */
+	if (usb_endpoint_maxp(desc) == 0) {
+		kfree(desc);
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->state != STATE_DEV_RUNNING) {
+		pr_debug("fail, device is not running\n");
+		ret = -EINVAL;
+		goto out_free;
+	}
+	if (!dev->gadget) {
+		pr_debug("fail, gadget is not bound\n");
+		ret = -EBUSY;
+		goto out_free;
+	}
+
+	for (i = 0; i < USB_RAW_MAX_ENDPOINTS; i++) {
+		if (dev->eps[i].state == STATE_EP_ENABLED)
+			continue;
+		break;
+	}
+	if (i == USB_RAW_MAX_ENDPOINTS) {
+		pr_debug("fail, no device endpoints available\n");
+		ret = -EBUSY;
+		goto out_free;
+	}
+
+	gadget_for_each_ep(ep, dev->gadget) {
+		if (ep->enabled)
+			continue;
+		if (!check_ep_caps(ep, desc))
+			continue;
+		ep->desc = desc;
+		ret = usb_ep_enable(ep);
+		if (ret < 0) {
+			pr_err("fail, usb_ep_enable returned %d\n", ret);
+			goto out_free;
+		}
+		dev->eps[i].req = usb_ep_alloc_request(ep, GFP_ATOMIC);
+		if (!dev->eps[i].req) {
+			pr_err("fail, usb_ep_alloc_request failed\n");
+			usb_ep_disable(ep);
+			ret = -ENOMEM;
+			goto out_free;
+		}
+		dev->eps[i].ep = ep;
+		dev->eps[i].state = STATE_EP_ENABLED;
+		ep->driver_data = &dev->eps[i];
+		ret = i;
+		goto out_unlock;
+	}
+
+	pr_debug("fail, no gadget endpoints available\n");
+	ret = -EBUSY;
+
+out_free:
+	kfree(desc);
+out_unlock:
+	spin_unlock_irqrestore(&dev->lock, flags);
+	return ret;
+}
+
+static int raw_ioctl_ep_disable(struct raw_dev *dev, unsigned long value)
+{
+	int ret = 0, i = value;
+	unsigned long flags;
+	const void *desc;
+
+	if (i < 0 || i >= USB_RAW_MAX_ENDPOINTS)
+		return -EINVAL;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->state != STATE_DEV_RUNNING) {
+		pr_debug("fail, device is not running\n");
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+	if (!dev->gadget) {
+		pr_debug("fail, gadget is not bound\n");
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+	if (dev->eps[i].state != STATE_EP_ENABLED) {
+		pr_debug("fail, endpoint is not enabled\n");
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+	if (dev->eps[i].disabling) {
+		pr_debug("fail, disable already in progress\n");
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+	dev->eps[i].disabling = true;
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	usb_ep_disable(dev->eps[i].ep);
+
+	spin_lock_irqsave(&dev->lock, flags);
+	usb_ep_free_request(dev->eps[i].ep, dev->eps[i].req);
+	desc = dev->eps[i].ep->desc;
+	dev->eps[i].ep = NULL;
+	dev->eps[i].state = STATE_EP_DISABLED;
+	kfree(desc);
+	dev->eps[i].disabling = false;
+
+out_unlock:
+	spin_unlock_irqrestore(&dev->lock, flags);
+	return ret;
+}
+
+static void gadget_ep_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct raw_ep *r_ep = (struct raw_ep *)ep->driver_data;
+	struct raw_dev *dev = r_ep->dev;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (req->status)
+		r_ep->status = req->status;
+	else
+		r_ep->status = req->actual;
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	complete((struct completion *)req->context);
+}
+
+static int raw_process_ep_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
+				void *data, bool in)
+{
+	int ret = 0;
+	unsigned long flags;
+	struct raw_ep *ep = &dev->eps[io->ep];
+	DECLARE_COMPLETION_ONSTACK(done);
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->state != STATE_DEV_RUNNING) {
+		pr_debug("fail, device is not running\n");
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+	if (!dev->gadget) {
+		pr_debug("fail, gadget is not bound\n");
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+	if (ep->state != STATE_EP_ENABLED) {
+		pr_debug("fail, endpoint is not enabled\n");
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+	if (ep->disabling) {
+		pr_debug("fail, endpoint is being disabled\n");
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+	if (ep->urb_queued) {
+		pr_debug("fail, urb already queued\n");
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+	if ((in && !ep->ep->caps.dir_in) || (!in && ep->ep->caps.dir_in)) {
+		pr_debug("fail, wrong direction\n");
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	ep->dev = dev;
+	ep->req->context = &done;
+	ep->req->complete = gadget_ep_complete;
+	ep->req->buf = data;
+	ep->req->length = io->length;
+	ep->req->zero = usb_raw_io_flags_zero(io->flags);
+	ep->urb_queued = true;
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	ret = usb_ep_queue(ep->ep, ep->req, GFP_ATOMIC);
+	if (ret) {
+		pr_err("fail, usb_ep_queue returned %d\n", ret);
+		spin_lock_irqsave(&dev->lock, flags);
+		dev->state = STATE_DEV_FAILED;
+		goto out_done;
+	}
+
+	ret = wait_for_completion_interruptible(&done);
+	if (ret) {
+		pr_debug("wait interrupted\n");
+		usb_ep_dequeue(ep->ep, ep->req);
+		wait_for_completion(&done);
+		spin_lock_irqsave(&dev->lock, flags);
+		goto out_done;
+	}
+
+	spin_lock_irqsave(&dev->lock, flags);
+	ret = ep->status;
+
+out_done:
+	ep->urb_queued = false;
+out_unlock:
+	spin_unlock_irqrestore(&dev->lock, flags);
+	return ret;
+}
+
+static int raw_ioctl_ep_write(struct raw_dev *dev, unsigned long value)
+{
+	int ret = 0;
+	char *data;
+	struct usb_raw_ep_io io;
+
+	data = raw_alloc_io_data(&io, (void __user *)value, true);
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+	ret = raw_process_ep_io(dev, &io, data, true);
+	kfree(data);
+	return ret;
+}
+
+static int raw_ioctl_ep_read(struct raw_dev *dev, unsigned long value)
+{
+	int ret = 0;
+	char *data;
+	struct usb_raw_ep_io io;
+	unsigned int length;
+
+	data = raw_alloc_io_data(&io, (void __user *)value, false);
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+	ret = raw_process_ep_io(dev, &io, data, false);
+	if (ret < 0) {
+		kfree(data);
+		return ret;
+	}
+	length = min(io.length, (unsigned int)ret);
+	ret = copy_to_user((void __user *)(value + sizeof(io)), data, length);
+	kfree(data);
+	return ret;
+}
+
+static int raw_ioctl_configure(struct raw_dev *dev, unsigned long value)
+{
+	int ret = 0;
+	unsigned long flags;
+
+	if (value)
+		return -EINVAL;
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->state != STATE_DEV_RUNNING) {
+		pr_debug("fail, device is not running\n");
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+	if (!dev->gadget) {
+		pr_debug("fail, gadget is not bound\n");
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+	usb_gadget_set_state(dev->gadget, USB_STATE_CONFIGURED);
+
+out_unlock:
+	spin_unlock_irqrestore(&dev->lock, flags);
+	return ret;
+}
+
+static int raw_ioctl_vbus_draw(struct raw_dev *dev, unsigned long value)
+{
+	int ret = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+	if (dev->state != STATE_DEV_RUNNING) {
+		pr_debug("fail, device is not running\n");
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+	if (!dev->gadget) {
+		pr_debug("fail, gadget is not bound\n");
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+	usb_gadget_vbus_draw(dev->gadget, 2 * value);
+
+out_unlock:
+	spin_unlock_irqrestore(&dev->lock, flags);
+	return ret;
+}
+
+static long raw_ioctl(struct file *fd, unsigned int cmd, unsigned long value)
+{
+	struct raw_dev *dev = fd->private_data;
+	int ret = 0;
+
+	if (!dev)
+		return -EBUSY;
+
+	switch (cmd) {
+	case USB_RAW_IOCTL_INIT:
+		ret = raw_ioctl_init(dev, value);
+		break;
+	case USB_RAW_IOCTL_RUN:
+		ret = raw_ioctl_run(dev, value);
+		break;
+	case USB_RAW_IOCTL_EVENT_FETCH:
+		ret = raw_ioctl_event_fetch(dev, value);
+		break;
+	case USB_RAW_IOCTL_EP0_WRITE:
+		ret = raw_ioctl_ep0_write(dev, value);
+		break;
+	case USB_RAW_IOCTL_EP0_READ:
+		ret = raw_ioctl_ep0_read(dev, value);
+		break;
+	case USB_RAW_IOCTL_EP_ENABLE:
+		ret = raw_ioctl_ep_enable(dev, value);
+		break;
+	case USB_RAW_IOCTL_EP_DISABLE:
+		ret = raw_ioctl_ep_disable(dev, value);
+		break;
+	case USB_RAW_IOCTL_EP_WRITE:
+		ret = raw_ioctl_ep_write(dev, value);
+		break;
+	case USB_RAW_IOCTL_EP_READ:
+		ret = raw_ioctl_ep_read(dev, value);
+		break;
+	case USB_RAW_IOCTL_CONFIGURE:
+		ret = raw_ioctl_configure(dev, value);
+		break;
+	case USB_RAW_IOCTL_VBUS_DRAW:
+		ret = raw_ioctl_vbus_draw(dev, value);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+/*----------------------------------------------------------------------*/
+
+static const struct file_operations raw_fops = {
+	.open =			raw_open,
+	.unlocked_ioctl =	raw_ioctl,
+	.compat_ioctl =		raw_ioctl,
+	.release =		raw_release,
+	.llseek =		no_llseek,
+};
+
+static struct miscdevice raw_device = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "raw-gadget",
+	.fops = &raw_fops,
+};
+
+static int __init raw_init(void)
+{
+	int rv;
+
+	rv = misc_register(&raw_device);
+	if (rv) {
+		pr_err("failed to register raw-gadget device with %d\n", rv);
+		return rv;
+	}
+	return 0;
+}
+
+static void __exit raw_exit(void)
+{
+	misc_deregister(&raw_device);
+}
+
+module_init(raw_init);
+module_exit(raw_exit);
diff --git a/include/uapi/linux/usb/raw_gadget.h b/include/uapi/linux/usb/raw_gadget.h
new file mode 100644
index 000000000000..c84ad6d9e81c
--- /dev/null
+++ b/include/uapi/linux/usb/raw_gadget.h
@@ -0,0 +1,167 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * USB Raw Gadget driver.
+ *
+ * See Documentation/usb/raw-gadget.rst for more details.
+ */
+
+#ifndef _UAPI__LINUX_USB_RAW_GADGET_H
+#define _UAPI__LINUX_USB_RAW_GADGET_H
+
+#include <asm/ioctl.h>
+#include <linux/types.h>
+#include <linux/usb/ch9.h>
+
+/* Maximum length of driver_name/device_name in the usb_raw_init struct. */
+#define UDC_NAME_LENGTH_MAX 128
+
+/*
+ * struct usb_raw_init - argument for USB_RAW_IOCTL_INIT ioctl.
+ * @speed: The speed of the emulated USB device, takes the same values as
+ *     the usb_device_speed enum: USB_SPEED_FULL, USB_SPEED_HIGH, etc.
+ * @driver_name: The name of the UDC driver.
+ * @device_name: The name of a UDC instance.
+ *
+ * The last two fields identify a UDC the gadget driver should bind to.
+ * For example, Dummy UDC has "dummy_udc" as its driver_name and "dummy_udc.N"
+ * as its device_name, where N in the index of the Dummy UDC instance.
+ * At the same time the dwc2 driver that is used on Raspberry Pi Zero, has
+ * "20980000.usb" as both driver_name and device_name.
+ */
+struct usb_raw_init {
+	__u8	driver_name[UDC_NAME_LENGTH_MAX];
+	__u8	device_name[UDC_NAME_LENGTH_MAX];
+	__u8	speed;
+};
+
+/* The type of event fetched with the USB_RAW_IOCTL_EVENT_FETCH ioctl. */
+enum usb_raw_event_type {
+	USB_RAW_EVENT_INVALID,
+
+	/* This event is queued when the driver has bound to a UDC. */
+	USB_RAW_EVENT_CONNECT,
+
+	/* This event is queued when a new control request arrived to ep0. */
+	USB_RAW_EVENT_CONTROL,
+
+	/* The list might grow in the future. */
+};
+
+/*
+ * struct usb_raw_event - argument for USB_RAW_IOCTL_EVENT_FETCH ioctl.
+ * @type: The type of the fetched event.
+ * @length: Length of the data buffer. Updated by the driver and set to the
+ *     actual length of the fetched event data.
+ * @data: A buffer to store the fetched event data.
+ *
+ * Currently the fetched data buffer is empty for USB_RAW_EVENT_CONNECT,
+ * and contains struct usb_ctrlrequest for USB_RAW_EVENT_CONTROL.
+ */
+struct usb_raw_event {
+	__u32		type;
+	__u32		length;
+	__u8		data[0];
+};
+
+#define USB_RAW_IO_FLAGS_ZERO	0x0001
+#define USB_RAW_IO_FLAGS_MASK	0x0001
+
+static int usb_raw_io_flags_valid(__u16 flags)
+{
+	return (flags & ~USB_RAW_IO_FLAGS_MASK) == 0;
+}
+
+static int usb_raw_io_flags_zero(__u16 flags)
+{
+	return (flags & USB_RAW_IO_FLAGS_ZERO);
+}
+
+/*
+ * struct usb_raw_ep_io - argument for USB_RAW_IOCTL_EP0/EP_WRITE/READ ioctls.
+ * @ep: Endpoint handle as returned by USB_RAW_IOCTL_EP_ENABLE for
+ *     USB_RAW_IOCTL_EP_WRITE/READ. Ignored for USB_RAW_IOCTL_EP0_WRITE/READ.
+ * @flags: When USB_RAW_IO_FLAGS_ZERO is specified, the zero flag is set on
+ *     the submitted USB request, see include/linux/usb/gadget.h for details.
+ * @length: Length of data.
+ * @data: Data to send for USB_RAW_IOCTL_EP0/EP_WRITE. Buffer to store received
+ *     data for USB_RAW_IOCTL_EP0/EP_READ.
+ */
+struct usb_raw_ep_io {
+	__u16		ep;
+	__u16		flags;
+	__u32		length;
+	__u8		data[0];
+};
+
+/*
+ * Initializes a Raw Gadget instance.
+ * Accepts a pointer to the usb_raw_init struct as an argument.
+ * Returns 0 on success or negative error code on failure.
+ */
+#define USB_RAW_IOCTL_INIT		_IOW('U', 0, struct usb_raw_init)
+
+/*
+ * Instructs Raw Gadget to bind to a UDC and start emulating a USB device.
+ * Returns 0 on success or negative error code on failure.
+ */
+#define USB_RAW_IOCTL_RUN		_IO('U', 1)
+
+/*
+ * A blocking ioctl that waits for an event and returns fetched event data to
+ * the user.
+ * Accepts a pointer to the usb_raw_event struct.
+ * Returns 0 on success or negative error code on failure.
+ */
+#define USB_RAW_IOCTL_EVENT_FETCH	_IOR('U', 2, struct usb_raw_event)
+
+/*
+ * Queues an IN (OUT for READ) urb as a response to the last control request
+ * received on endpoint 0, provided that was an IN (OUT for READ) request and
+ * waits until the urb is completed. Copies received data to user for READ.
+ * Accepts a pointer to the usb_raw_ep_io struct as an argument.
+ * Returns length of trasferred data on success or negative error code on
+ * failure.
+ */
+#define USB_RAW_IOCTL_EP0_WRITE		_IOW('U', 3, struct usb_raw_ep_io)
+#define USB_RAW_IOCTL_EP0_READ		_IOWR('U', 4, struct usb_raw_ep_io)
+
+/*
+ * Finds an endpoint that supports the transfer type specified in the
+ * descriptor and enables it.
+ * Accepts a pointer to the usb_endpoint_descriptor struct as an argument.
+ * Returns enabled endpoint handle on success or negative error code on failure.
+ */
+#define USB_RAW_IOCTL_EP_ENABLE		_IOW('U', 5, struct usb_endpoint_descriptor)
+
+/* Disables specified endpoint.
+ * Accepts endpoint handle as an argument.
+ * Returns 0 on success or negative error code on failure.
+ */
+#define USB_RAW_IOCTL_EP_DISABLE	_IOW('U', 6, __u32)
+
+/*
+ * Queues an IN (OUT for READ) urb as a response to the last control request
+ * received on endpoint usb_raw_ep_io.ep, provided that was an IN (OUT for READ)
+ * request and waits until the urb is completed. Copies received data to user
+ * for READ.
+ * Accepts a pointer to the usb_raw_ep_io struct as an argument.
+ * Returns length of trasferred data on success or negative error code on
+ * failure.
+ */
+#define USB_RAW_IOCTL_EP_WRITE		_IOW('U', 7, struct usb_raw_ep_io)
+#define USB_RAW_IOCTL_EP_READ		_IOWR('U', 8, struct usb_raw_ep_io)
+
+/*
+ * Switches the gadget into the configured state.
+ * Returns 0 on success or negative error code on failure.
+ */
+#define USB_RAW_IOCTL_CONFIGURE		_IO('U', 9)
+
+/*
+ * Constrains UDC VBUS power usage.
+ * Accepts current limit in 2 mA units as an argument.
+ * Returns 0 on success or negative error code on failure.
+ */
+#define USB_RAW_IOCTL_VBUS_DRAW		_IOW('U', 10, __u32)
+
+#endif /* _UAPI__LINUX_USB_RAW_GADGET_H */
-- 
2.24.1.735.g03f4e72817-goog

Re: [PATCH v3 1/1] usb: gadget: add raw-gadget interface

[Greg Kroah-Hartman]

On Wed, Dec 11, 2019 at 07:02:41PM +0100, Andrey Konovalov wrote:
> USB Raw Gadget is a kernel module that provides a userspace interface for
> the USB Gadget subsystem. Essentially it allows to emulate USB devices
> from userspace. Enabled with CONFIG_USB_RAW_GADGET. Raw Gadget is
> currently a strictly debugging feature and shouldn't be used in
> production.
> 
> Raw Gadget is similar to GadgetFS, but provides a more low-level and
> direct access to the USB Gadget layer for the userspace. The key
> differences are:
> 
> 1. Every USB request is passed to the userspace to get a response, while
>    GadgetFS responds to some USB requests internally based on the provided
>    descriptors. However note, that the UDC driver might respond to some
>    requests on its own and never forward them to the Gadget layer.
> 
> 2. GadgetFS performs some sanity checks on the provided USB descriptors,
>    while Raw Gadget allows you to provide arbitrary data as responses to
>    USB requests.
> 
> 3. Raw Gadget provides a way to select a UDC device/driver to bind to,
>    while GadgetFS currently binds to the first available UDC.
> 
> 4. Raw Gadget uses predictable endpoint names (handles) across different
>    UDCs (as long as UDCs have enough endpoints of each required transfer
>    type).
> 
> 5. Raw Gadget has ioctl-based interface instead of a filesystem-based one.

Looks good to me, only minor comments below.

> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
>  Documentation/usb/index.rst         |    1 +
>  Documentation/usb/raw-gadget.rst    |   59 ++
>  drivers/usb/gadget/legacy/Kconfig   |    8 +
>  drivers/usb/gadget/legacy/Makefile  |    1 +
>  drivers/usb/gadget/legacy/raw.c     | 1070 +++++++++++++++++++++++++++
>  include/uapi/linux/usb/raw_gadget.h |  167 +++++
>  6 files changed, 1306 insertions(+)
>  create mode 100644 Documentation/usb/raw-gadget.rst
>  create mode 100644 drivers/usb/gadget/legacy/raw.c
>  create mode 100644 include/uapi/linux/usb/raw_gadget.h
> 
> diff --git a/Documentation/usb/index.rst b/Documentation/usb/index.rst
> index e55386a4abfb..90310e2a0c1f 100644
> --- a/Documentation/usb/index.rst
> +++ b/Documentation/usb/index.rst
> @@ -22,6 +22,7 @@ USB support
>      misc_usbsevseg
>      mtouchusb
>      ohci
> +    raw-gadget
>      rio
>      usbip_protocol
>      usbmon
> diff --git a/Documentation/usb/raw-gadget.rst b/Documentation/usb/raw-gadget.rst
> new file mode 100644
> index 000000000000..cbedf5451ed3
> --- /dev/null
> +++ b/Documentation/usb/raw-gadget.rst
> @@ -0,0 +1,59 @@
> +==============
> +USB Raw Gadget
> +==============
> +
> +USB Raw Gadget is a kernel module that provides a userspace interface for
> +the USB Gadget subsystem. Essentially it allows to emulate USB devices
> +from userspace. Enabled with CONFIG_USB_RAW_GADGET. Raw Gadget is
> +currently a strictly debugging feature and shouldn't be used in
> +production, use GadgetFS instead.
> +
> +Comparison to GadgetFS
> +~~~~~~~~~~~~~~~~~~~~~~
> +
> +Raw Gadget is similar to GadgetFS, but provides a more low-level and
> +direct access to the USB Gadget layer for the userspace. The key
> +differences are:
> +
> +1. Every USB request is passed to the userspace to get a response, while
> +   GadgetFS responds to some USB requests internally based on the provided
> +   descriptors. However note, that the UDC driver might respond to some
> +   requests on its own and never forward them to the Gadget layer.
> +
> +2. GadgetFS performs some sanity checks on the provided USB descriptors,
> +   while Raw Gadget allows you to provide arbitrary data as responses to
> +   USB requests.
> +
> +3. Raw Gadget provides a way to select a UDC device/driver to bind to,
> +   while GadgetFS currently binds to the first available UDC.
> +
> +4. Raw Gadget uses predictable endpoint names (handles) across different
> +   UDCs (as long as UDCs have enough endpoints of each required transfer
> +   type).
> +
> +5. Raw Gadget has ioctl-based interface instead of a filesystem-based one.
> +
> +Userspace interface
> +~~~~~~~~~~~~~~~~~~~
> +
> +To create a Raw Gadget instance open /dev/raw-gadget. Multiple raw-gadget
> +instances (bound to different UDCs) can be used at the same time. The
> +interaction with the opened file happens through the ioctl() calls, see
> +comments in include/uapi/linux/usb/raw_gadget.h for details.
> +
> +The typical usage of Raw Gadget looks like:
> +
> +1. Open Raw Gadget instance via /dev/raw-gadget.
> +2. Initialize the instance via USB_RAW_IOCTL_INIT.
> +3. Launch the instance with USB_RAW_IOCTL_RUN.
> +4. In a loop issue USB_RAW_IOCTL_EVENT_FETCH calls to receive events from
> +   Raw Gadget and react to those depending on what kind of USB device
> +   needs to be emulated.
> +
> +Potential future improvements
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +- Implement ioctl's for setting/clearing halt status on endpoints.
> +
> +- Reporting more events (suspend, resume, etc.) through
> +  USB_RAW_IOCTL_EVENT_FETCH.
> diff --git a/drivers/usb/gadget/legacy/Kconfig b/drivers/usb/gadget/legacy/Kconfig
> index 119a4e47681f..8c947edf7515 100644
> --- a/drivers/usb/gadget/legacy/Kconfig
> +++ b/drivers/usb/gadget/legacy/Kconfig
> @@ -489,3 +489,11 @@ config USB_G_WEBCAM
>  
>  	  Say "y" to link the driver statically, or "m" to build a
>  	  dynamically linked module called "g_webcam".
> +
> +config USB_RAW_GADGET
> +	tristate "USB Raw Gadget"
> +	help
> +	  USB Raw Gadget is a kernel module that provides a userspace interface
> +	  for the USB Gadget subsystem. Essentially it allows to emulate USB
> +	  devices from userspace. See Documentation/usb/raw-gadget.rst for
> +	  details.

No help text saying what the module name would be if selected as one?


> diff --git a/drivers/usb/gadget/legacy/Makefile b/drivers/usb/gadget/legacy/Makefile
> index abd0c3e66a05..799feefeee58 100644
> --- a/drivers/usb/gadget/legacy/Makefile
> +++ b/drivers/usb/gadget/legacy/Makefile
> @@ -43,3 +43,4 @@ obj-$(CONFIG_USB_G_WEBCAM)	+= g_webcam.o
>  obj-$(CONFIG_USB_G_NCM)		+= g_ncm.o
>  obj-$(CONFIG_USB_G_ACM_MS)	+= g_acm_ms.o
>  obj-$(CONFIG_USB_GADGET_TARGET)	+= tcm_usb_gadget.o
> +obj-$(CONFIG_USB_RAW_GADGET)	+= raw.o

raw.ko?  I think we already have a raw.ko in the kernel, shouldn't this
be usb_raw_gadget.ko or something?

Yeah, we do, look at drivers/char/raw.c.  This needs to be changed,
I can't take it as-is otherwise the builders will croak on it.

> diff --git a/drivers/usb/gadget/legacy/raw.c b/drivers/usb/gadget/legacy/raw.c
> new file mode 100644
> index 000000000000..fcfa2ebc103e
> --- /dev/null
> +++ b/drivers/usb/gadget/legacy/raw.c
> @@ -0,0 +1,1070 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * USB Raw Gadget driver.
> + * See Documentation/usb/raw-gadget.rst for more details.
> + *
> + * Andrey Konovalov <andreyknvl@gmail.com>
> + */
> +
> +#define pr_fmt(fmt) "raw: %s: " fmt, __func__

"raw gadget"?

This a driver, why do you ever need to do a pr_* call and not a dev_*
instead?

> +
> +#include <linux/compiler.h>
> +#include <linux/debugfs.h>
> +#include <linux/delay.h>
> +#include <linux/kref.h>
> +#include <linux/miscdevice.h>
> +#include <linux/module.h>
> +#include <linux/semaphore.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <linux/uaccess.h>
> +#include <linux/wait.h>
> +
> +#include <linux/usb.h>
> +#include <linux/usb/ch9.h>
> +#include <linux/usb/ch11.h>
> +#include <linux/usb/gadget.h>
> +
> +#include <uapi/linux/usb/raw_gadget.h>
> +
> +#define	DRIVER_DESC "USB Raw Gadget"
> +#define DRIVER_NAME "raw-gadget"

You only use this in one place.  You can use it in the definition of the
misc driver name also, right?


> +
> +MODULE_DESCRIPTION(DRIVER_DESC);
> +MODULE_AUTHOR("Andrey Konovalov");
> +MODULE_LICENSE("GPL");
> +
> +/*----------------------------------------------------------------------*/
> +
> +#define RAW_EVENT_QUEUE_SIZE	128
> +
> +struct raw_event_queue {
> +	spinlock_t		lock;
> +	struct semaphore	sema;

Two locks for the same structure?  That feels "wrong".  Why is this?
document the heck out of it if it is required please.

> +	struct usb_raw_event	*events[RAW_EVENT_QUEUE_SIZE];
> +	int			size;
> +};
> +
> +static void raw_event_queue_init(struct raw_event_queue *queue)
> +{
> +	spin_lock_init(&queue->lock);
> +	sema_init(&queue->sema, 0);
> +	queue->size = 0;
> +}
> +
> +static int raw_event_queue_add(struct raw_event_queue *queue,
> +	enum usb_raw_event_type type, size_t length, const void *data)
> +{
> +	unsigned long flags;
> +	struct usb_raw_event *event;
> +
> +	spin_lock_irqsave(&queue->lock, flags);
> +	if (queue->size >= RAW_EVENT_QUEUE_SIZE) {
> +		pr_err("too many events\n");

What can someone do with this error?

dev_err() to show exactly where it came from?

> +		spin_unlock_irqrestore(&queue->lock, flags);
> +		return -ENOMEM;
> +	}
> +	event = kmalloc(sizeof(*event) + length, GFP_ATOMIC);
> +	if (!event) {
> +		spin_unlock_irqrestore(&queue->lock, flags);
> +		return -ENOMEM;
> +	}
> +	event->type = type;
> +	event->length = length;
> +	if (event->length)
> +		memcpy(&event->data[0], data, length);
> +	queue->events[queue->size] = event;
> +	queue->size++;
> +	up(&queue->sema);
> +	spin_unlock_irqrestore(&queue->lock, flags);
> +	return 0;
> +}
> +
> +static struct usb_raw_event *raw_event_queue_fetch(
> +				struct raw_event_queue *queue)
> +{
> +	unsigned long flags;
> +	struct usb_raw_event *event;
> +
> +	if (down_interruptible(&queue->sema))
> +		return NULL;
> +	spin_lock_irqsave(&queue->lock, flags);

You just locked twice?

> +	if (WARN_ON(!queue->size))
> +		return NULL;

It's as if you want to trigger syzbot :)

Just log it and return an error.

> +	event = queue->events[0];
> +	queue->size--;
> +	memmove(&queue->events[0], &queue->events[1],
> +			queue->size * sizeof(queue->events[0]));
> +	spin_unlock_irqrestore(&queue->lock, flags);
> +	return event;
> +}
> +
> +static void raw_event_queue_destroy(struct raw_event_queue *queue)
> +{
> +	int i;
> +
> +	for (i = 0; i < queue->size; i++)
> +		kfree(queue->events[i]);
> +	queue->size = 0;

No locking needed?

> +}
> +
> +/*----------------------------------------------------------------------*/
> +
> +struct raw_dev;
> +
> +#define USB_RAW_MAX_ENDPOINTS 32
> +
> +enum ep_state {
> +	STATE_EP_DISABLED,
> +	STATE_EP_ENABLED,
> +};
> +
> +struct raw_ep {
> +	struct raw_dev		*dev;
> +	enum ep_state		state;
> +	struct usb_ep		*ep;
> +	struct usb_request	*req;
> +	bool			urb_queued;
> +	bool			disabling;
> +	ssize_t			status;
> +};
> +
> +enum dev_state {
> +	STATE_DEV_INVALID = 0,
> +	STATE_DEV_OPENED,
> +	STATE_DEV_INITIALIZED,
> +	STATE_DEV_RUNNING,
> +	STATE_DEV_CLOSED,
> +	STATE_DEV_FAILED
> +};
> +
> +struct raw_dev {
> +	struct kref			count;
> +	spinlock_t			lock;
> +
> +	const char			*udc_name;
> +	struct usb_gadget_driver	driver;

A dev embeds a driver?

Not a pointer?

But you have a kref, so the reference count of this object is there,
right?

> +
> +	/* Protected by lock: */
> +	enum dev_state			state;
> +	bool				gadget_registered;
> +	struct usb_gadget		*gadget;
> +	struct usb_request		*req;
> +	bool				ep0_in_pending;
> +	bool				ep0_out_pending;
> +	bool				ep0_urb_queued;
> +	ssize_t				ep0_status;
> +	struct raw_ep			eps[USB_RAW_MAX_ENDPOINTS];
> +
> +	struct completion		ep0_done;
> +	struct raw_event_queue		queue;

No pointer to your misc device?  I think you need that for logging.

> +};
> +
> +static struct raw_dev *dev_new(void)
> +{
> +	struct raw_dev *dev;
> +
> +	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> +	if (!dev)
> +		return NULL;
> +	/* Matches kref_put() in raw_release(). */
> +	kref_init(&dev->count);
> +	spin_lock_init(&dev->lock);
> +	init_completion(&dev->ep0_done);
> +	raw_event_queue_init(&dev->queue);
> +	return dev;
> +}
> +
> +static void dev_free(struct kref *kref)
> +{
> +	struct raw_dev *dev = container_of(kref, struct raw_dev, count);
> +	int i;
> +
> +	kfree(dev->udc_name);
> +	kfree(dev->driver.udc_name);
> +	if (dev->req) {
> +		if (dev->ep0_urb_queued)
> +			usb_ep_dequeue(dev->gadget->ep0, dev->req);
> +		usb_ep_free_request(dev->gadget->ep0, dev->req);
> +	}
> +	raw_event_queue_destroy(&dev->queue);
> +	for (i = 0; i < USB_RAW_MAX_ENDPOINTS; i++) {
> +		if (dev->eps[i].state != STATE_EP_ENABLED)
> +			continue;
> +		usb_ep_disable(dev->eps[i].ep);
> +		usb_ep_free_request(dev->eps[i].ep, dev->eps[i].req);
> +		kfree(dev->eps[i].ep->desc);
> +		dev->eps[i].state = STATE_EP_DISABLED;
> +	}
> +	kfree(dev);
> +}
> +
> +/*----------------------------------------------------------------------*/
> +
> +static int raw_queue_event(struct raw_dev *dev,
> +	enum usb_raw_event_type type, size_t length, const void *data)
> +{
> +	int ret = 0;
> +	unsigned long flags;
> +
> +	ret = raw_event_queue_add(&dev->queue, type, length, data);
> +	if (ret < 0) {
> +		spin_lock_irqsave(&dev->lock, flags);
> +		dev->state = STATE_DEV_FAILED;
> +		spin_unlock_irqrestore(&dev->lock, flags);
> +	}
> +	return ret;
> +}
> +
> +static void gadget_ep0_complete(struct usb_ep *ep, struct usb_request *req)
> +{
> +	struct raw_dev *dev = req->context;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (req->status)
> +		dev->ep0_status = req->status;
> +	else
> +		dev->ep0_status = req->actual;
> +	if (dev->ep0_in_pending)
> +		dev->ep0_in_pending = false;
> +	else
> +		dev->ep0_out_pending = false;
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +
> +	complete(&dev->ep0_done);
> +}
> +
> +static int gadget_bind(struct usb_gadget *gadget,
> +			struct usb_gadget_driver *driver)
> +{
> +	int ret = 0;
> +	struct raw_dev *dev = container_of(driver, struct raw_dev, driver);
> +	struct usb_request *req;
> +	unsigned long flags;
> +
> +	if (strcmp(gadget->name, dev->udc_name) != 0)
> +		return -ENODEV;
> +
> +	set_gadget_data(gadget, dev);
> +	req = usb_ep_alloc_request(gadget->ep0, GFP_KERNEL);
> +	if (!req) {
> +		pr_err("usb_ep_alloc_request failed\n");
> +		set_gadget_data(gadget, NULL);
> +		return -ENOMEM;
> +	}
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	dev->req = req;
> +	dev->req->context = dev;
> +	dev->req->complete = gadget_ep0_complete;
> +	dev->gadget = gadget;
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +
> +	/* Matches kref_put() in gadget_unbind(). */
> +	kref_get(&dev->count);
> +
> +	ret = raw_queue_event(dev, USB_RAW_EVENT_CONNECT, 0, NULL);
> +	if (ret < 0)
> +		pr_err("failed to queue event\n");
> +
> +	return ret;
> +}
> +
> +static void gadget_unbind(struct usb_gadget *gadget)
> +{
> +	struct raw_dev *dev = get_gadget_data(gadget);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	set_gadget_data(gadget, NULL);
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +	/* Matches kref_get() in gadget_bind(). */
> +	kref_put(&dev->count, dev_free);

What protects the kref from being called 'put' twice on the same
pointer at the same time?  There should be some lock somewhere, right?


> +}
> +
> +static int gadget_setup(struct usb_gadget *gadget,
> +			const struct usb_ctrlrequest *ctrl)
> +{
> +	int ret = 0;
> +	struct raw_dev *dev = get_gadget_data(gadget);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (dev->state != STATE_DEV_RUNNING) {
> +		pr_err("ignoring, device is not running\n");
> +		ret = -ENODEV;
> +		goto out_unlock;
> +	}
> +	if (dev->ep0_in_pending || dev->ep0_out_pending) {
> +		pr_debug("stalling, already have pending request\n");
> +		ret = -EBUSY;
> +		goto out_unlock;
> +	}
> +	if ((ctrl->bRequestType & USB_DIR_IN) && ctrl->wLength)
> +		dev->ep0_in_pending = true;
> +	else
> +		dev->ep0_out_pending = true;
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +
> +	ret = raw_queue_event(dev, USB_RAW_EVENT_CONTROL, sizeof(*ctrl), ctrl);
> +	if (ret < 0)
> +		pr_err("failed to queue event\n");
> +	goto out;
> +
> +out_unlock:
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +out:
> +	return ret;
> +}
> +
> +/* These are currently ununsed but present in case UDC driver requires them. */
> +static void gadget_disconnect(struct usb_gadget *gadget) { }
> +static void gadget_suspend(struct usb_gadget *gadget) { }
> +static void gadget_resume(struct usb_gadget *gadget) { }
> +static void gadget_reset(struct usb_gadget *gadget) { }
> +
> +/*----------------------------------------------------------------------*/
> +
> +static int raw_open(struct inode *inode, struct file *fd)
> +{
> +	struct raw_dev *dev;
> +
> +	dev = dev_new();
> +	if (!dev) {
> +		pr_err("failed to created device");

You should have access to your misc device here, so dev_err()?

> +		return -ENOMEM;
> +	}
> +	fd->private_data = dev;
> +	dev->state = STATE_DEV_OPENED;
> +	return 0;
> +}
> +
> +static int raw_release(struct inode *inode, struct file *fd)
> +{
> +	int ret = 0;
> +	struct raw_dev *dev = fd->private_data;
> +	unsigned long flags;
> +	bool unregister = false;
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	dev->state = STATE_DEV_CLOSED;
> +	if (!dev->gadget) {
> +		spin_unlock_irqrestore(&dev->lock, flags);
> +		goto out_put;
> +	}
> +	if (dev->gadget_registered)
> +		unregister = true;
> +	dev->gadget_registered = false;
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +
> +	if (unregister) {
> +		ret = usb_gadget_unregister_driver(&dev->driver);
> +		WARN_ON(ret != 0);

you want to crash?  :)

> +		/* Matches kref_get() in raw_ioctl_run(). */
> +		kref_put(&dev->count, dev_free);
> +	}
> +
> +out_put:
> +	/* Matches dev_new() in raw_open(). */
> +	kref_put(&dev->count, dev_free);
> +	return ret;
> +}
> +
> +/*----------------------------------------------------------------------*/
> +
> +static int raw_ioctl_init(struct raw_dev *dev, unsigned long value)
> +{
> +	int ret = 0;
> +	struct usb_raw_init arg;
> +	char *udc_driver_name;
> +	char *udc_device_name;
> +	unsigned long flags;
> +
> +	ret = copy_from_user(&arg, (void __user *)value, sizeof(arg));
> +	if (ret)
> +		return ret;
> +
> +	switch (arg.speed) {
> +	case USB_SPEED_UNKNOWN:
> +		arg.speed = USB_SPEED_HIGH;
> +		break;
> +	case USB_SPEED_LOW:
> +	case USB_SPEED_FULL:
> +	case USB_SPEED_HIGH:
> +	case USB_SPEED_SUPER:
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	udc_driver_name = kmalloc(UDC_NAME_LENGTH_MAX, GFP_KERNEL);
> +	if (!udc_driver_name)
> +		return -ENOMEM;
> +	ret = strscpy(udc_driver_name, &arg.driver_name[0],
> +				UDC_NAME_LENGTH_MAX);
> +	if (ret < 0) {
> +		kfree(udc_driver_name);
> +		return ret;
> +	}
> +	ret = 0;
> +
> +	udc_device_name = kmalloc(UDC_NAME_LENGTH_MAX, GFP_KERNEL);
> +	if (!udc_device_name) {
> +		kfree(udc_driver_name);
> +		return -ENOMEM;
> +	}
> +	ret = strscpy(udc_device_name, &arg.device_name[0],
> +				UDC_NAME_LENGTH_MAX);
> +	if (ret < 0) {
> +		kfree(udc_driver_name);
> +		kfree(udc_device_name);
> +		return ret;
> +	}
> +	ret = 0;
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (dev->state != STATE_DEV_OPENED) {
> +		pr_debug("fail, device is not opened\n");

dev_dbg().

> +		kfree(udc_driver_name);
> +		kfree(udc_device_name);
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +	dev->udc_name = udc_driver_name;
> +
> +	dev->driver.function = DRIVER_DESC;
> +	dev->driver.max_speed = arg.speed;
> +	dev->driver.setup = gadget_setup;
> +	dev->driver.disconnect = gadget_disconnect;
> +	dev->driver.bind = gadget_bind;
> +	dev->driver.unbind = gadget_unbind;
> +	dev->driver.suspend = gadget_suspend;
> +	dev->driver.resume = gadget_resume;
> +	dev->driver.reset = gadget_reset;
> +	dev->driver.driver.name = DRIVER_NAME;
> +	dev->driver.udc_name = udc_device_name;
> +	dev->driver.match_existing_only = 1;
> +
> +	dev->state = STATE_DEV_INITIALIZED;
> +
> +out_unlock:
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +	return ret;
> +}
> +
> +static int raw_ioctl_run(struct raw_dev *dev, unsigned long value)
> +{
> +	int ret = 0;
> +	unsigned long flags;
> +
> +	if (value)
> +		return -EINVAL;
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (dev->state != STATE_DEV_INITIALIZED) {
> +		pr_debug("fail, device is not initialized\n");

dev_dbg()

> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +
> +	ret = usb_gadget_probe_driver(&dev->driver);
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (ret) {
> +		pr_err("fail, usb_gadget_probe_driver returned %d\n", ret);

dev_err()

same goes for everywhere, no need for any pr_* calls in this driver.

> +		dev->state = STATE_DEV_FAILED;
> +		goto out_unlock;
> +	}
> +	dev->gadget_registered = true;
> +	dev->state = STATE_DEV_RUNNING;
> +	/* Matches kref_put() in raw_release(). */
> +	kref_get(&dev->count);
> +
> +out_unlock:
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +	return ret;
> +}
> +
> +static int raw_ioctl_event_fetch(struct raw_dev *dev, unsigned long value)
> +{
> +	int ret = 0;
> +	struct usb_raw_event arg;
> +	unsigned long flags;
> +	struct usb_raw_event *event;
> +	uint32_t length;
> +
> +	ret = copy_from_user(&arg, (void __user *)value, sizeof(arg));
> +	if (ret)
> +		return ret;
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (dev->state != STATE_DEV_RUNNING) {
> +		pr_debug("fail, device is not running\n");
> +		spin_unlock_irqrestore(&dev->lock, flags);
> +		return -EINVAL;
> +	}
> +	if (!dev->gadget) {
> +		pr_debug("fail, gadget is not bound\n");
> +		spin_unlock_irqrestore(&dev->lock, flags);
> +		return -EBUSY;
> +	}
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +
> +	event = raw_event_queue_fetch(&dev->queue);
> +	if (!event) {
> +		pr_debug("event fetching interrupted\n");
> +		return -EINTR;
> +	}
> +	length = min(arg.length, event->length);
> +	ret = copy_to_user((void __user *)value, event,
> +				sizeof(*event) + length);
> +	return ret;
> +}
> +
> +static void *raw_alloc_io_data(struct usb_raw_ep_io *io, void __user *ptr,
> +				bool get_from_user)
> +{
> +	int ret;
> +	void *data;
> +
> +	ret = copy_from_user(io, ptr, sizeof(*io));
> +	if (ret)
> +		return ERR_PTR(ret);
> +	if (io->ep >= USB_RAW_MAX_ENDPOINTS)
> +		return ERR_PTR(-EINVAL);
> +	if (!usb_raw_io_flags_valid(io->flags))
> +		return ERR_PTR(-EINVAL);
> +	if (io->length > PAGE_SIZE)
> +		return ERR_PTR(-EINVAL);
> +	if (get_from_user)
> +		data = memdup_user(ptr + sizeof(*io), io->length);
> +	else {
> +		data = kmalloc(io->length, GFP_KERNEL);
> +		if (!data)
> +			data = ERR_PTR(-ENOMEM);
> +	}
> +	return data;
> +}
> +
> +static int raw_process_ep0_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
> +				void *data, bool in)
> +{
> +	int ret = 0;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (dev->state != STATE_DEV_RUNNING) {
> +		pr_debug("fail, device is not running\n");
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +	if (!dev->gadget) {
> +		pr_debug("fail, gadget is not bound\n");
> +		ret = -EBUSY;
> +		goto out_unlock;
> +	}
> +	if (dev->ep0_urb_queued) {
> +		pr_debug("fail, urb already queued\n");
> +		ret = -EBUSY;
> +		goto out_unlock;
> +	}
> +	if ((in && !dev->ep0_in_pending) ||
> +			(!in && !dev->ep0_out_pending)) {
> +		pr_debug("fail, wrong direction\n");
> +		ret = -EBUSY;
> +		goto out_unlock;
> +	}
> +	if (WARN_ON(in && dev->ep0_out_pending)) {
> +		ret = -ENODEV;
> +		dev->state = STATE_DEV_FAILED;
> +		goto out_done;
> +	}
> +	if (WARN_ON(!in && dev->ep0_in_pending)) {
> +		ret = -ENODEV;
> +		dev->state = STATE_DEV_FAILED;
> +		goto out_done;
> +	}
> +
> +	dev->req->buf = data;
> +	dev->req->length = io->length;
> +	dev->req->zero = usb_raw_io_flags_zero(io->flags);
> +	dev->ep0_urb_queued = true;
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +
> +	ret = usb_ep_queue(dev->gadget->ep0, dev->req, GFP_ATOMIC);
> +	if (ret) {
> +		pr_err("fail, usb_ep_queue returned %d\n", ret);
> +		spin_lock_irqsave(&dev->lock, flags);
> +		dev->state = STATE_DEV_FAILED;
> +		goto out_done;
> +	}
> +
> +	ret = wait_for_completion_interruptible(&dev->ep0_done);
> +	if (ret) {
> +		pr_debug("wait interrupted\n");
> +		usb_ep_dequeue(dev->gadget->ep0, dev->req);
> +		wait_for_completion(&dev->ep0_done);
> +		spin_lock_irqsave(&dev->lock, flags);
> +		goto out_done;
> +	}
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	ret = dev->ep0_status;
> +
> +out_done:
> +	dev->ep0_urb_queued = false;
> +out_unlock:
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +	return ret;
> +}
> +
> +static int raw_ioctl_ep0_write(struct raw_dev *dev, unsigned long value)
> +{
> +	int ret = 0;
> +	void *data;
> +	struct usb_raw_ep_io io;
> +
> +	data = raw_alloc_io_data(&io, (void __user *)value, true);
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +	ret = raw_process_ep0_io(dev, &io, data, true);
> +	kfree(data);
> +	return ret;
> +}
> +
> +static int raw_ioctl_ep0_read(struct raw_dev *dev, unsigned long value)
> +{
> +	int ret = 0;
> +	void *data;
> +	struct usb_raw_ep_io io;
> +	unsigned int length;
> +
> +	data = raw_alloc_io_data(&io, (void __user *)value, false);
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +	ret = raw_process_ep0_io(dev, &io, data, false);
> +	if (ret < 0) {
> +		kfree(data);
> +		return ret;
> +	}
> +	length = min(io.length, (unsigned int)ret);
> +	ret = copy_to_user((void __user *)(value + sizeof(io)), data, length);
> +	kfree(data);
> +	return ret;
> +}
> +
> +static bool check_ep_caps(struct usb_ep *ep,
> +				struct usb_endpoint_descriptor *desc)
> +{
> +	switch (usb_endpoint_type(desc)) {
> +	case USB_ENDPOINT_XFER_ISOC:
> +		if (!ep->caps.type_iso)
> +			return false;
> +		break;
> +	case USB_ENDPOINT_XFER_BULK:
> +		if (!ep->caps.type_bulk)
> +			return false;
> +		break;
> +	case USB_ENDPOINT_XFER_INT:
> +		if (!ep->caps.type_int)
> +			return false;
> +		break;
> +	default:
> +		return false;
> +	}
> +
> +	if (usb_endpoint_dir_in(desc) && !ep->caps.dir_in)
> +		return false;
> +	if (usb_endpoint_dir_out(desc) && !ep->caps.dir_out)
> +		return false;
> +
> +	return true;
> +}
> +
> +static int raw_ioctl_ep_enable(struct raw_dev *dev, unsigned long value)
> +{
> +	int ret = 0, i;
> +	unsigned long flags;
> +	struct usb_endpoint_descriptor *desc;
> +	struct usb_ep *ep = NULL;
> +
> +	desc = memdup_user((void __user *)value, sizeof(*desc));
> +	if (IS_ERR(desc))
> +		return PTR_ERR(desc);
> +
> +	/*
> +	 * Endpoints with a maxpacket length of 0 can cause crashes in UDC
> +	 * drivers.
> +	 */
> +	if (usb_endpoint_maxp(desc) == 0) {
> +		kfree(desc);
> +		return -EINVAL;
> +	}
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (dev->state != STATE_DEV_RUNNING) {
> +		pr_debug("fail, device is not running\n");
> +		ret = -EINVAL;
> +		goto out_free;
> +	}
> +	if (!dev->gadget) {
> +		pr_debug("fail, gadget is not bound\n");
> +		ret = -EBUSY;
> +		goto out_free;
> +	}
> +
> +	for (i = 0; i < USB_RAW_MAX_ENDPOINTS; i++) {
> +		if (dev->eps[i].state == STATE_EP_ENABLED)
> +			continue;
> +		break;
> +	}
> +	if (i == USB_RAW_MAX_ENDPOINTS) {
> +		pr_debug("fail, no device endpoints available\n");
> +		ret = -EBUSY;
> +		goto out_free;
> +	}
> +
> +	gadget_for_each_ep(ep, dev->gadget) {
> +		if (ep->enabled)
> +			continue;
> +		if (!check_ep_caps(ep, desc))
> +			continue;
> +		ep->desc = desc;
> +		ret = usb_ep_enable(ep);
> +		if (ret < 0) {
> +			pr_err("fail, usb_ep_enable returned %d\n", ret);
> +			goto out_free;
> +		}
> +		dev->eps[i].req = usb_ep_alloc_request(ep, GFP_ATOMIC);
> +		if (!dev->eps[i].req) {
> +			pr_err("fail, usb_ep_alloc_request failed\n");
> +			usb_ep_disable(ep);
> +			ret = -ENOMEM;
> +			goto out_free;
> +		}
> +		dev->eps[i].ep = ep;
> +		dev->eps[i].state = STATE_EP_ENABLED;
> +		ep->driver_data = &dev->eps[i];
> +		ret = i;
> +		goto out_unlock;
> +	}
> +
> +	pr_debug("fail, no gadget endpoints available\n");
> +	ret = -EBUSY;
> +
> +out_free:
> +	kfree(desc);
> +out_unlock:
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +	return ret;
> +}
> +
> +static int raw_ioctl_ep_disable(struct raw_dev *dev, unsigned long value)
> +{
> +	int ret = 0, i = value;
> +	unsigned long flags;
> +	const void *desc;
> +
> +	if (i < 0 || i >= USB_RAW_MAX_ENDPOINTS)
> +		return -EINVAL;
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (dev->state != STATE_DEV_RUNNING) {
> +		pr_debug("fail, device is not running\n");
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +	if (!dev->gadget) {
> +		pr_debug("fail, gadget is not bound\n");
> +		ret = -EBUSY;
> +		goto out_unlock;
> +	}
> +	if (dev->eps[i].state != STATE_EP_ENABLED) {
> +		pr_debug("fail, endpoint is not enabled\n");
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +	if (dev->eps[i].disabling) {
> +		pr_debug("fail, disable already in progress\n");
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +	dev->eps[i].disabling = true;
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +
> +	usb_ep_disable(dev->eps[i].ep);
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	usb_ep_free_request(dev->eps[i].ep, dev->eps[i].req);
> +	desc = dev->eps[i].ep->desc;
> +	dev->eps[i].ep = NULL;
> +	dev->eps[i].state = STATE_EP_DISABLED;
> +	kfree(desc);
> +	dev->eps[i].disabling = false;
> +
> +out_unlock:
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +	return ret;
> +}
> +
> +static void gadget_ep_complete(struct usb_ep *ep, struct usb_request *req)
> +{
> +	struct raw_ep *r_ep = (struct raw_ep *)ep->driver_data;
> +	struct raw_dev *dev = r_ep->dev;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (req->status)
> +		r_ep->status = req->status;
> +	else
> +		r_ep->status = req->actual;
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +
> +	complete((struct completion *)req->context);
> +}
> +
> +static int raw_process_ep_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
> +				void *data, bool in)
> +{
> +	int ret = 0;
> +	unsigned long flags;
> +	struct raw_ep *ep = &dev->eps[io->ep];
> +	DECLARE_COMPLETION_ONSTACK(done);
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (dev->state != STATE_DEV_RUNNING) {
> +		pr_debug("fail, device is not running\n");
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +	if (!dev->gadget) {
> +		pr_debug("fail, gadget is not bound\n");
> +		ret = -EBUSY;
> +		goto out_unlock;
> +	}
> +	if (ep->state != STATE_EP_ENABLED) {
> +		pr_debug("fail, endpoint is not enabled\n");
> +		ret = -EBUSY;
> +		goto out_unlock;
> +	}
> +	if (ep->disabling) {
> +		pr_debug("fail, endpoint is being disabled\n");
> +		ret = -EBUSY;
> +		goto out_unlock;
> +	}
> +	if (ep->urb_queued) {
> +		pr_debug("fail, urb already queued\n");
> +		ret = -EBUSY;
> +		goto out_unlock;
> +	}
> +	if ((in && !ep->ep->caps.dir_in) || (!in && ep->ep->caps.dir_in)) {
> +		pr_debug("fail, wrong direction\n");
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +
> +	ep->dev = dev;
> +	ep->req->context = &done;
> +	ep->req->complete = gadget_ep_complete;
> +	ep->req->buf = data;
> +	ep->req->length = io->length;
> +	ep->req->zero = usb_raw_io_flags_zero(io->flags);
> +	ep->urb_queued = true;
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +
> +	ret = usb_ep_queue(ep->ep, ep->req, GFP_ATOMIC);
> +	if (ret) {
> +		pr_err("fail, usb_ep_queue returned %d\n", ret);
> +		spin_lock_irqsave(&dev->lock, flags);
> +		dev->state = STATE_DEV_FAILED;
> +		goto out_done;
> +	}
> +
> +	ret = wait_for_completion_interruptible(&done);
> +	if (ret) {
> +		pr_debug("wait interrupted\n");
> +		usb_ep_dequeue(ep->ep, ep->req);
> +		wait_for_completion(&done);
> +		spin_lock_irqsave(&dev->lock, flags);
> +		goto out_done;
> +	}
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	ret = ep->status;
> +
> +out_done:
> +	ep->urb_queued = false;
> +out_unlock:
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +	return ret;
> +}
> +
> +static int raw_ioctl_ep_write(struct raw_dev *dev, unsigned long value)
> +{
> +	int ret = 0;
> +	char *data;
> +	struct usb_raw_ep_io io;
> +
> +	data = raw_alloc_io_data(&io, (void __user *)value, true);
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +	ret = raw_process_ep_io(dev, &io, data, true);
> +	kfree(data);
> +	return ret;
> +}
> +
> +static int raw_ioctl_ep_read(struct raw_dev *dev, unsigned long value)
> +{
> +	int ret = 0;
> +	char *data;
> +	struct usb_raw_ep_io io;
> +	unsigned int length;
> +
> +	data = raw_alloc_io_data(&io, (void __user *)value, false);
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +	ret = raw_process_ep_io(dev, &io, data, false);
> +	if (ret < 0) {
> +		kfree(data);
> +		return ret;
> +	}
> +	length = min(io.length, (unsigned int)ret);
> +	ret = copy_to_user((void __user *)(value + sizeof(io)), data, length);
> +	kfree(data);
> +	return ret;
> +}
> +
> +static int raw_ioctl_configure(struct raw_dev *dev, unsigned long value)
> +{
> +	int ret = 0;
> +	unsigned long flags;
> +
> +	if (value)
> +		return -EINVAL;
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (dev->state != STATE_DEV_RUNNING) {
> +		pr_debug("fail, device is not running\n");
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +	if (!dev->gadget) {
> +		pr_debug("fail, gadget is not bound\n");
> +		ret = -EBUSY;
> +		goto out_unlock;
> +	}
> +	usb_gadget_set_state(dev->gadget, USB_STATE_CONFIGURED);
> +
> +out_unlock:
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +	return ret;
> +}
> +
> +static int raw_ioctl_vbus_draw(struct raw_dev *dev, unsigned long value)
> +{
> +	int ret = 0;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dev->lock, flags);
> +	if (dev->state != STATE_DEV_RUNNING) {
> +		pr_debug("fail, device is not running\n");
> +		ret = -EINVAL;
> +		goto out_unlock;
> +	}
> +	if (!dev->gadget) {
> +		pr_debug("fail, gadget is not bound\n");
> +		ret = -EBUSY;
> +		goto out_unlock;
> +	}
> +	usb_gadget_vbus_draw(dev->gadget, 2 * value);
> +
> +out_unlock:
> +	spin_unlock_irqrestore(&dev->lock, flags);
> +	return ret;
> +}
> +
> +static long raw_ioctl(struct file *fd, unsigned int cmd, unsigned long value)
> +{
> +	struct raw_dev *dev = fd->private_data;
> +	int ret = 0;
> +
> +	if (!dev)
> +		return -EBUSY;
> +
> +	switch (cmd) {
> +	case USB_RAW_IOCTL_INIT:
> +		ret = raw_ioctl_init(dev, value);
> +		break;
> +	case USB_RAW_IOCTL_RUN:
> +		ret = raw_ioctl_run(dev, value);
> +		break;
> +	case USB_RAW_IOCTL_EVENT_FETCH:
> +		ret = raw_ioctl_event_fetch(dev, value);
> +		break;
> +	case USB_RAW_IOCTL_EP0_WRITE:
> +		ret = raw_ioctl_ep0_write(dev, value);
> +		break;
> +	case USB_RAW_IOCTL_EP0_READ:
> +		ret = raw_ioctl_ep0_read(dev, value);
> +		break;
> +	case USB_RAW_IOCTL_EP_ENABLE:
> +		ret = raw_ioctl_ep_enable(dev, value);
> +		break;
> +	case USB_RAW_IOCTL_EP_DISABLE:
> +		ret = raw_ioctl_ep_disable(dev, value);
> +		break;
> +	case USB_RAW_IOCTL_EP_WRITE:
> +		ret = raw_ioctl_ep_write(dev, value);
> +		break;
> +	case USB_RAW_IOCTL_EP_READ:
> +		ret = raw_ioctl_ep_read(dev, value);
> +		break;
> +	case USB_RAW_IOCTL_CONFIGURE:
> +		ret = raw_ioctl_configure(dev, value);
> +		break;
> +	case USB_RAW_IOCTL_VBUS_DRAW:
> +		ret = raw_ioctl_vbus_draw(dev, value);
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +	return ret;
> +}
> +
> +/*----------------------------------------------------------------------*/
> +
> +static const struct file_operations raw_fops = {
> +	.open =			raw_open,
> +	.unlocked_ioctl =	raw_ioctl,
> +	.compat_ioctl =		raw_ioctl,
> +	.release =		raw_release,
> +	.llseek =		no_llseek,
> +};
> +
> +static struct miscdevice raw_device = {
> +	.minor = MISC_DYNAMIC_MINOR,
> +	.name = "raw-gadget",

DRIVER_NAME?

> +	.fops = &raw_fops,
> +};
> +
> +static int __init raw_init(void)
> +{
> +	int rv;
> +
> +	rv = misc_register(&raw_device);
> +	if (rv) {
> +		pr_err("failed to register raw-gadget device with %d\n", rv);
> +		return rv;
> +	}
> +	return 0;
> +}
> +
> +static void __exit raw_exit(void)
> +{
> +	misc_deregister(&raw_device);
> +}
> +
> +module_init(raw_init);
> +module_exit(raw_exit);

module_misc_device()?  :)

Looks good.

thanks,

greg k-h

Re: [PATCH v3 1/1] usb: gadget: add raw-gadget interface

[Andrey Konovalov]

On Wed, Dec 18, 2019 at 2:23 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Wed, Dec 11, 2019 at 07:02:41PM +0100, Andrey Konovalov wrote:
> > USB Raw Gadget is a kernel module that provides a userspace interface for
> > the USB Gadget subsystem. Essentially it allows to emulate USB devices
> > from userspace. Enabled with CONFIG_USB_RAW_GADGET. Raw Gadget is
> > currently a strictly debugging feature and shouldn't be used in
> > production.
> >
> > Raw Gadget is similar to GadgetFS, but provides a more low-level and
> > direct access to the USB Gadget layer for the userspace. The key
> > differences are:
> >
> > 1. Every USB request is passed to the userspace to get a response, while
> >    GadgetFS responds to some USB requests internally based on the provided
> >    descriptors. However note, that the UDC driver might respond to some
> >    requests on its own and never forward them to the Gadget layer.
> >
> > 2. GadgetFS performs some sanity checks on the provided USB descriptors,
> >    while Raw Gadget allows you to provide arbitrary data as responses to
> >    USB requests.
> >
> > 3. Raw Gadget provides a way to select a UDC device/driver to bind to,
> >    while GadgetFS currently binds to the first available UDC.
> >
> > 4. Raw Gadget uses predictable endpoint names (handles) across different
> >    UDCs (as long as UDCs have enough endpoints of each required transfer
> >    type).
> >
> > 5. Raw Gadget has ioctl-based interface instead of a filesystem-based one.
>
> Looks good to me, only minor comments below.

Great, thanks!

About reworking the logging to use dev_err/dbg(): can I pass the
global miscdevice struct into those macros? Or should I pass a pointer
to this struct into all of the functions that print log messages? The
latter seems unnecessarily complex, unless there's a reason to do
that.

For the rest of the comments please see below.

>
> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > ---
> >  Documentation/usb/index.rst         |    1 +
> >  Documentation/usb/raw-gadget.rst    |   59 ++
> >  drivers/usb/gadget/legacy/Kconfig   |    8 +
> >  drivers/usb/gadget/legacy/Makefile  |    1 +
> >  drivers/usb/gadget/legacy/raw.c     | 1070 +++++++++++++++++++++++++++
> >  include/uapi/linux/usb/raw_gadget.h |  167 +++++
> >  6 files changed, 1306 insertions(+)
> >  create mode 100644 Documentation/usb/raw-gadget.rst
> >  create mode 100644 drivers/usb/gadget/legacy/raw.c
> >  create mode 100644 include/uapi/linux/usb/raw_gadget.h
> >
> > diff --git a/Documentation/usb/index.rst b/Documentation/usb/index.rst
> > index e55386a4abfb..90310e2a0c1f 100644
> > --- a/Documentation/usb/index.rst
> > +++ b/Documentation/usb/index.rst
> > @@ -22,6 +22,7 @@ USB support
> >      misc_usbsevseg
> >      mtouchusb
> >      ohci
> > +    raw-gadget
> >      rio
> >      usbip_protocol
> >      usbmon
> > diff --git a/Documentation/usb/raw-gadget.rst b/Documentation/usb/raw-gadget.rst
> > new file mode 100644
> > index 000000000000..cbedf5451ed3
> > --- /dev/null
> > +++ b/Documentation/usb/raw-gadget.rst
> > @@ -0,0 +1,59 @@
> > +==============
> > +USB Raw Gadget
> > +==============
> > +
> > +USB Raw Gadget is a kernel module that provides a userspace interface for
> > +the USB Gadget subsystem. Essentially it allows to emulate USB devices
> > +from userspace. Enabled with CONFIG_USB_RAW_GADGET. Raw Gadget is
> > +currently a strictly debugging feature and shouldn't be used in
> > +production, use GadgetFS instead.
> > +
> > +Comparison to GadgetFS
> > +~~~~~~~~~~~~~~~~~~~~~~
> > +
> > +Raw Gadget is similar to GadgetFS, but provides a more low-level and
> > +direct access to the USB Gadget layer for the userspace. The key
> > +differences are:
> > +
> > +1. Every USB request is passed to the userspace to get a response, while
> > +   GadgetFS responds to some USB requests internally based on the provided
> > +   descriptors. However note, that the UDC driver might respond to some
> > +   requests on its own and never forward them to the Gadget layer.
> > +
> > +2. GadgetFS performs some sanity checks on the provided USB descriptors,
> > +   while Raw Gadget allows you to provide arbitrary data as responses to
> > +   USB requests.
> > +
> > +3. Raw Gadget provides a way to select a UDC device/driver to bind to,
> > +   while GadgetFS currently binds to the first available UDC.
> > +
> > +4. Raw Gadget uses predictable endpoint names (handles) across different
> > +   UDCs (as long as UDCs have enough endpoints of each required transfer
> > +   type).
> > +
> > +5. Raw Gadget has ioctl-based interface instead of a filesystem-based one.
> > +
> > +Userspace interface
> > +~~~~~~~~~~~~~~~~~~~
> > +
> > +To create a Raw Gadget instance open /dev/raw-gadget. Multiple raw-gadget
> > +instances (bound to different UDCs) can be used at the same time. The
> > +interaction with the opened file happens through the ioctl() calls, see
> > +comments in include/uapi/linux/usb/raw_gadget.h for details.
> > +
> > +The typical usage of Raw Gadget looks like:
> > +
> > +1. Open Raw Gadget instance via /dev/raw-gadget.
> > +2. Initialize the instance via USB_RAW_IOCTL_INIT.
> > +3. Launch the instance with USB_RAW_IOCTL_RUN.
> > +4. In a loop issue USB_RAW_IOCTL_EVENT_FETCH calls to receive events from
> > +   Raw Gadget and react to those depending on what kind of USB device
> > +   needs to be emulated.
> > +
> > +Potential future improvements
> > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > +
> > +- Implement ioctl's for setting/clearing halt status on endpoints.
> > +
> > +- Reporting more events (suspend, resume, etc.) through
> > +  USB_RAW_IOCTL_EVENT_FETCH.
> > diff --git a/drivers/usb/gadget/legacy/Kconfig b/drivers/usb/gadget/legacy/Kconfig
> > index 119a4e47681f..8c947edf7515 100644
> > --- a/drivers/usb/gadget/legacy/Kconfig
> > +++ b/drivers/usb/gadget/legacy/Kconfig
> > @@ -489,3 +489,11 @@ config USB_G_WEBCAM
> >
> >         Say "y" to link the driver statically, or "m" to build a
> >         dynamically linked module called "g_webcam".
> > +
> > +config USB_RAW_GADGET
> > +     tristate "USB Raw Gadget"
> > +     help
> > +       USB Raw Gadget is a kernel module that provides a userspace interface
> > +       for the USB Gadget subsystem. Essentially it allows to emulate USB
> > +       devices from userspace. See Documentation/usb/raw-gadget.rst for
> > +       details.
>
> No help text saying what the module name would be if selected as one?

Will add in v4.

>
>
> > diff --git a/drivers/usb/gadget/legacy/Makefile b/drivers/usb/gadget/legacy/Makefile
> > index abd0c3e66a05..799feefeee58 100644
> > --- a/drivers/usb/gadget/legacy/Makefile
> > +++ b/drivers/usb/gadget/legacy/Makefile
> > @@ -43,3 +43,4 @@ obj-$(CONFIG_USB_G_WEBCAM)  += g_webcam.o
> >  obj-$(CONFIG_USB_G_NCM)              += g_ncm.o
> >  obj-$(CONFIG_USB_G_ACM_MS)   += g_acm_ms.o
> >  obj-$(CONFIG_USB_GADGET_TARGET)      += tcm_usb_gadget.o
> > +obj-$(CONFIG_USB_RAW_GADGET) += raw.o
>
> raw.ko?  I think we already have a raw.ko in the kernel, shouldn't this
> be usb_raw_gadget.ko or something?
>
> Yeah, we do, look at drivers/char/raw.c.  This needs to be changed,
> I can't take it as-is otherwise the builders will croak on it.

OK, I think raw_gadget.ko is short enough and unique. Will change it in in v4.

>
> > diff --git a/drivers/usb/gadget/legacy/raw.c b/drivers/usb/gadget/legacy/raw.c
> > new file mode 100644
> > index 000000000000..fcfa2ebc103e
> > --- /dev/null
> > +++ b/drivers/usb/gadget/legacy/raw.c
> > @@ -0,0 +1,1070 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * USB Raw Gadget driver.
> > + * See Documentation/usb/raw-gadget.rst for more details.
> > + *
> > + * Andrey Konovalov <andreyknvl@gmail.com>
> > + */
> > +
> > +#define pr_fmt(fmt) "raw: %s: " fmt, __func__
>
> "raw gadget"?
>
> This a driver, why do you ever need to do a pr_* call and not a dev_*
> instead?
>
> > +
> > +#include <linux/compiler.h>
> > +#include <linux/debugfs.h>
> > +#include <linux/delay.h>
> > +#include <linux/kref.h>
> > +#include <linux/miscdevice.h>
> > +#include <linux/module.h>
> > +#include <linux/semaphore.h>
> > +#include <linux/sched.h>
> > +#include <linux/slab.h>
> > +#include <linux/uaccess.h>
> > +#include <linux/wait.h>
> > +
> > +#include <linux/usb.h>
> > +#include <linux/usb/ch9.h>
> > +#include <linux/usb/ch11.h>
> > +#include <linux/usb/gadget.h>
> > +
> > +#include <uapi/linux/usb/raw_gadget.h>
> > +
> > +#define      DRIVER_DESC "USB Raw Gadget"
> > +#define DRIVER_NAME "raw-gadget"
>
> You only use this in one place.  You can use it in the definition of the
> misc driver name also, right?

Yes, will do in v4.

>
>
> > +
> > +MODULE_DESCRIPTION(DRIVER_DESC);
> > +MODULE_AUTHOR("Andrey Konovalov");
> > +MODULE_LICENSE("GPL");
> > +
> > +/*----------------------------------------------------------------------*/
> > +
> > +#define RAW_EVENT_QUEUE_SIZE 128
> > +
> > +struct raw_event_queue {
> > +     spinlock_t              lock;
> > +     struct semaphore        sema;
>
> Two locks for the same structure?  That feels "wrong".  Why is this?
> document the heck out of it if it is required please.

raw_event_queue_fetch() can be called concurrently, so there we first
check that there's at least one event queued by decrementing the
semaphore, and then take the lock to protect queue struct fields. Does
this make sense?

I'll add comment explaining that in v4.

>
> > +     struct usb_raw_event    *events[RAW_EVENT_QUEUE_SIZE];
> > +     int                     size;
> > +};
> > +
> > +static void raw_event_queue_init(struct raw_event_queue *queue)
> > +{
> > +     spin_lock_init(&queue->lock);
> > +     sema_init(&queue->sema, 0);
> > +     queue->size = 0;
> > +}
> > +
> > +static int raw_event_queue_add(struct raw_event_queue *queue,
> > +     enum usb_raw_event_type type, size_t length, const void *data)
> > +{
> > +     unsigned long flags;
> > +     struct usb_raw_event *event;
> > +
> > +     spin_lock_irqsave(&queue->lock, flags);
> > +     if (queue->size >= RAW_EVENT_QUEUE_SIZE) {
> > +             pr_err("too many events\n");
>
> What can someone do with this error?

Hm, I guess we better change this to WARN_ON(), since if this is
triggered, there's probably a flaw in raw gadget that we want to
detect and get fixed.

>
> dev_err() to show exactly where it came from?
>
> > +             spin_unlock_irqrestore(&queue->lock, flags);
> > +             return -ENOMEM;
> > +     }
> > +     event = kmalloc(sizeof(*event) + length, GFP_ATOMIC);
> > +     if (!event) {
> > +             spin_unlock_irqrestore(&queue->lock, flags);
> > +             return -ENOMEM;
> > +     }
> > +     event->type = type;
> > +     event->length = length;
> > +     if (event->length)
> > +             memcpy(&event->data[0], data, length);
> > +     queue->events[queue->size] = event;
> > +     queue->size++;
> > +     up(&queue->sema);
> > +     spin_unlock_irqrestore(&queue->lock, flags);
> > +     return 0;
> > +}
> > +
> > +static struct usb_raw_event *raw_event_queue_fetch(
> > +                             struct raw_event_queue *queue)
> > +{
> > +     unsigned long flags;
> > +     struct usb_raw_event *event;
> > +
> > +     if (down_interruptible(&queue->sema))
> > +             return NULL;
> > +     spin_lock_irqsave(&queue->lock, flags);
>
> You just locked twice?

See the explanation above.

>
> > +     if (WARN_ON(!queue->size))
> > +             return NULL;
>
> It's as if you want to trigger syzbot :)
>
> Just log it and return an error.

We do want to trigger syzbot here =) Same as with the upper bound, if
this is hit, there's probably a flaw in raw gadget that we want to
detect and get fixed.

>
> > +     event = queue->events[0];
> > +     queue->size--;
> > +     memmove(&queue->events[0], &queue->events[1],
> > +                     queue->size * sizeof(queue->events[0]));
> > +     spin_unlock_irqrestore(&queue->lock, flags);
> > +     return event;
> > +}
> > +
> > +static void raw_event_queue_destroy(struct raw_event_queue *queue)
> > +{
> > +     int i;
> > +
> > +     for (i = 0; i < queue->size; i++)
> > +             kfree(queue->events[i]);
> > +     queue->size = 0;
>
> No locking needed?

No. This is called from dev_free(), which is only called when all
references go away, so there are no concurrent accesses.

>
> > +}
> > +
> > +/*----------------------------------------------------------------------*/
> > +
> > +struct raw_dev;
> > +
> > +#define USB_RAW_MAX_ENDPOINTS 32
> > +
> > +enum ep_state {
> > +     STATE_EP_DISABLED,
> > +     STATE_EP_ENABLED,
> > +};
> > +
> > +struct raw_ep {
> > +     struct raw_dev          *dev;
> > +     enum ep_state           state;
> > +     struct usb_ep           *ep;
> > +     struct usb_request      *req;
> > +     bool                    urb_queued;
> > +     bool                    disabling;
> > +     ssize_t                 status;
> > +};
> > +
> > +enum dev_state {
> > +     STATE_DEV_INVALID = 0,
> > +     STATE_DEV_OPENED,
> > +     STATE_DEV_INITIALIZED,
> > +     STATE_DEV_RUNNING,
> > +     STATE_DEV_CLOSED,
> > +     STATE_DEV_FAILED
> > +};
> > +
> > +struct raw_dev {
> > +     struct kref                     count;
> > +     spinlock_t                      lock;
> > +
> > +     const char                      *udc_name;
> > +     struct usb_gadget_driver        driver;
>
> A dev embeds a driver?
>
> Not a pointer?
>
> But you have a kref, so the reference count of this object is there,
> right?

I didn't get this comment, could you elaborate? I can make it a
pointer, but for each raw_dev we have a unique usb_gadget_driver
instance, so embedding it as is is simpler.

>
> > +
> > +     /* Protected by lock: */
> > +     enum dev_state                  state;
> > +     bool                            gadget_registered;
> > +     struct usb_gadget               *gadget;
> > +     struct usb_request              *req;
> > +     bool                            ep0_in_pending;
> > +     bool                            ep0_out_pending;
> > +     bool                            ep0_urb_queued;
> > +     ssize_t                         ep0_status;
> > +     struct raw_ep                   eps[USB_RAW_MAX_ENDPOINTS];
> > +
> > +     struct completion               ep0_done;
> > +     struct raw_event_queue          queue;
>
> No pointer to your misc device?  I think you need that for logging.
>
> > +};
> > +
> > +static struct raw_dev *dev_new(void)
> > +{
> > +     struct raw_dev *dev;
> > +
> > +     dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> > +     if (!dev)
> > +             return NULL;
> > +     /* Matches kref_put() in raw_release(). */
> > +     kref_init(&dev->count);
> > +     spin_lock_init(&dev->lock);
> > +     init_completion(&dev->ep0_done);
> > +     raw_event_queue_init(&dev->queue);
> > +     return dev;
> > +}
> > +
> > +static void dev_free(struct kref *kref)
> > +{
> > +     struct raw_dev *dev = container_of(kref, struct raw_dev, count);
> > +     int i;
> > +
> > +     kfree(dev->udc_name);
> > +     kfree(dev->driver.udc_name);
> > +     if (dev->req) {
> > +             if (dev->ep0_urb_queued)
> > +                     usb_ep_dequeue(dev->gadget->ep0, dev->req);
> > +             usb_ep_free_request(dev->gadget->ep0, dev->req);
> > +     }
> > +     raw_event_queue_destroy(&dev->queue);
> > +     for (i = 0; i < USB_RAW_MAX_ENDPOINTS; i++) {
> > +             if (dev->eps[i].state != STATE_EP_ENABLED)
> > +                     continue;
> > +             usb_ep_disable(dev->eps[i].ep);
> > +             usb_ep_free_request(dev->eps[i].ep, dev->eps[i].req);
> > +             kfree(dev->eps[i].ep->desc);
> > +             dev->eps[i].state = STATE_EP_DISABLED;
> > +     }
> > +     kfree(dev);
> > +}
> > +
> > +/*----------------------------------------------------------------------*/
> > +
> > +static int raw_queue_event(struct raw_dev *dev,
> > +     enum usb_raw_event_type type, size_t length, const void *data)
> > +{
> > +     int ret = 0;
> > +     unsigned long flags;
> > +
> > +     ret = raw_event_queue_add(&dev->queue, type, length, data);
> > +     if (ret < 0) {
> > +             spin_lock_irqsave(&dev->lock, flags);
> > +             dev->state = STATE_DEV_FAILED;
> > +             spin_unlock_irqrestore(&dev->lock, flags);
> > +     }
> > +     return ret;
> > +}
> > +
> > +static void gadget_ep0_complete(struct usb_ep *ep, struct usb_request *req)
> > +{
> > +     struct raw_dev *dev = req->context;
> > +     unsigned long flags;
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (req->status)
> > +             dev->ep0_status = req->status;
> > +     else
> > +             dev->ep0_status = req->actual;
> > +     if (dev->ep0_in_pending)
> > +             dev->ep0_in_pending = false;
> > +     else
> > +             dev->ep0_out_pending = false;
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +
> > +     complete(&dev->ep0_done);
> > +}
> > +
> > +static int gadget_bind(struct usb_gadget *gadget,
> > +                     struct usb_gadget_driver *driver)
> > +{
> > +     int ret = 0;
> > +     struct raw_dev *dev = container_of(driver, struct raw_dev, driver);
> > +     struct usb_request *req;
> > +     unsigned long flags;
> > +
> > +     if (strcmp(gadget->name, dev->udc_name) != 0)
> > +             return -ENODEV;
> > +
> > +     set_gadget_data(gadget, dev);
> > +     req = usb_ep_alloc_request(gadget->ep0, GFP_KERNEL);
> > +     if (!req) {
> > +             pr_err("usb_ep_alloc_request failed\n");
> > +             set_gadget_data(gadget, NULL);
> > +             return -ENOMEM;
> > +     }
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     dev->req = req;
> > +     dev->req->context = dev;
> > +     dev->req->complete = gadget_ep0_complete;
> > +     dev->gadget = gadget;
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +
> > +     /* Matches kref_put() in gadget_unbind(). */
> > +     kref_get(&dev->count);
> > +
> > +     ret = raw_queue_event(dev, USB_RAW_EVENT_CONNECT, 0, NULL);
> > +     if (ret < 0)
> > +             pr_err("failed to queue event\n");
> > +
> > +     return ret;
> > +}
> > +
> > +static void gadget_unbind(struct usb_gadget *gadget)
> > +{
> > +     struct raw_dev *dev = get_gadget_data(gadget);
> > +     unsigned long flags;
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     set_gadget_data(gadget, NULL);
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +     /* Matches kref_get() in gadget_bind(). */
> > +     kref_put(&dev->count, dev_free);
>
> What protects the kref from being called 'put' twice on the same
> pointer at the same time?  There should be some lock somewhere, right?

Hm, kref_put() does refcount_dec_and_test(), which in turns calls
atomic_dec_and_test(), so this is protected against concurrent puts
(which is the whole idea of kref?), and no locking is needed. Unless I
misunderstand something.

>
>
> > +}
> > +
> > +static int gadget_setup(struct usb_gadget *gadget,
> > +                     const struct usb_ctrlrequest *ctrl)
> > +{
> > +     int ret = 0;
> > +     struct raw_dev *dev = get_gadget_data(gadget);
> > +     unsigned long flags;
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (dev->state != STATE_DEV_RUNNING) {
> > +             pr_err("ignoring, device is not running\n");
> > +             ret = -ENODEV;
> > +             goto out_unlock;
> > +     }
> > +     if (dev->ep0_in_pending || dev->ep0_out_pending) {
> > +             pr_debug("stalling, already have pending request\n");
> > +             ret = -EBUSY;
> > +             goto out_unlock;
> > +     }
> > +     if ((ctrl->bRequestType & USB_DIR_IN) && ctrl->wLength)
> > +             dev->ep0_in_pending = true;
> > +     else
> > +             dev->ep0_out_pending = true;
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +
> > +     ret = raw_queue_event(dev, USB_RAW_EVENT_CONTROL, sizeof(*ctrl), ctrl);
> > +     if (ret < 0)
> > +             pr_err("failed to queue event\n");
> > +     goto out;
> > +
> > +out_unlock:
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +out:
> > +     return ret;
> > +}
> > +
> > +/* These are currently ununsed but present in case UDC driver requires them. */
> > +static void gadget_disconnect(struct usb_gadget *gadget) { }
> > +static void gadget_suspend(struct usb_gadget *gadget) { }
> > +static void gadget_resume(struct usb_gadget *gadget) { }
> > +static void gadget_reset(struct usb_gadget *gadget) { }
> > +
> > +/*----------------------------------------------------------------------*/
> > +
> > +static int raw_open(struct inode *inode, struct file *fd)
> > +{
> > +     struct raw_dev *dev;
> > +
> > +     dev = dev_new();
> > +     if (!dev) {
> > +             pr_err("failed to created device");
>
> You should have access to your misc device here, so dev_err()?
>
> > +             return -ENOMEM;
> > +     }
> > +     fd->private_data = dev;
> > +     dev->state = STATE_DEV_OPENED;
> > +     return 0;
> > +}
> > +
> > +static int raw_release(struct inode *inode, struct file *fd)
> > +{
> > +     int ret = 0;
> > +     struct raw_dev *dev = fd->private_data;
> > +     unsigned long flags;
> > +     bool unregister = false;
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     dev->state = STATE_DEV_CLOSED;
> > +     if (!dev->gadget) {
> > +             spin_unlock_irqrestore(&dev->lock, flags);
> > +             goto out_put;
> > +     }
> > +     if (dev->gadget_registered)
> > +             unregister = true;
> > +     dev->gadget_registered = false;
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +
> > +     if (unregister) {
> > +             ret = usb_gadget_unregister_driver(&dev->driver);
> > +             WARN_ON(ret != 0);
>
> you want to crash?  :)

No reason to crash here I guess :) Will remove in v4.

>
> > +             /* Matches kref_get() in raw_ioctl_run(). */
> > +             kref_put(&dev->count, dev_free);
> > +     }
> > +
> > +out_put:
> > +     /* Matches dev_new() in raw_open(). */
> > +     kref_put(&dev->count, dev_free);
> > +     return ret;
> > +}
> > +
> > +/*----------------------------------------------------------------------*/
> > +
> > +static int raw_ioctl_init(struct raw_dev *dev, unsigned long value)
> > +{
> > +     int ret = 0;
> > +     struct usb_raw_init arg;
> > +     char *udc_driver_name;
> > +     char *udc_device_name;
> > +     unsigned long flags;
> > +
> > +     ret = copy_from_user(&arg, (void __user *)value, sizeof(arg));
> > +     if (ret)
> > +             return ret;
> > +
> > +     switch (arg.speed) {
> > +     case USB_SPEED_UNKNOWN:
> > +             arg.speed = USB_SPEED_HIGH;
> > +             break;
> > +     case USB_SPEED_LOW:
> > +     case USB_SPEED_FULL:
> > +     case USB_SPEED_HIGH:
> > +     case USB_SPEED_SUPER:
> > +             break;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +
> > +     udc_driver_name = kmalloc(UDC_NAME_LENGTH_MAX, GFP_KERNEL);
> > +     if (!udc_driver_name)
> > +             return -ENOMEM;
> > +     ret = strscpy(udc_driver_name, &arg.driver_name[0],
> > +                             UDC_NAME_LENGTH_MAX);
> > +     if (ret < 0) {
> > +             kfree(udc_driver_name);
> > +             return ret;
> > +     }
> > +     ret = 0;
> > +
> > +     udc_device_name = kmalloc(UDC_NAME_LENGTH_MAX, GFP_KERNEL);
> > +     if (!udc_device_name) {
> > +             kfree(udc_driver_name);
> > +             return -ENOMEM;
> > +     }
> > +     ret = strscpy(udc_device_name, &arg.device_name[0],
> > +                             UDC_NAME_LENGTH_MAX);
> > +     if (ret < 0) {
> > +             kfree(udc_driver_name);
> > +             kfree(udc_device_name);
> > +             return ret;
> > +     }
> > +     ret = 0;
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (dev->state != STATE_DEV_OPENED) {
> > +             pr_debug("fail, device is not opened\n");
>
> dev_dbg().
>
> > +             kfree(udc_driver_name);
> > +             kfree(udc_device_name);
> > +             ret = -EINVAL;
> > +             goto out_unlock;
> > +     }
> > +     dev->udc_name = udc_driver_name;
> > +
> > +     dev->driver.function = DRIVER_DESC;
> > +     dev->driver.max_speed = arg.speed;
> > +     dev->driver.setup = gadget_setup;
> > +     dev->driver.disconnect = gadget_disconnect;
> > +     dev->driver.bind = gadget_bind;
> > +     dev->driver.unbind = gadget_unbind;
> > +     dev->driver.suspend = gadget_suspend;
> > +     dev->driver.resume = gadget_resume;
> > +     dev->driver.reset = gadget_reset;
> > +     dev->driver.driver.name = DRIVER_NAME;
> > +     dev->driver.udc_name = udc_device_name;
> > +     dev->driver.match_existing_only = 1;
> > +
> > +     dev->state = STATE_DEV_INITIALIZED;
> > +
> > +out_unlock:
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +     return ret;
> > +}
> > +
> > +static int raw_ioctl_run(struct raw_dev *dev, unsigned long value)
> > +{
> > +     int ret = 0;
> > +     unsigned long flags;
> > +
> > +     if (value)
> > +             return -EINVAL;
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (dev->state != STATE_DEV_INITIALIZED) {
> > +             pr_debug("fail, device is not initialized\n");
>
> dev_dbg()
>
> > +             ret = -EINVAL;
> > +             goto out_unlock;
> > +     }
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +
> > +     ret = usb_gadget_probe_driver(&dev->driver);
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (ret) {
> > +             pr_err("fail, usb_gadget_probe_driver returned %d\n", ret);
>
> dev_err()
>
> same goes for everywhere, no need for any pr_* calls in this driver.
>
> > +             dev->state = STATE_DEV_FAILED;
> > +             goto out_unlock;
> > +     }
> > +     dev->gadget_registered = true;
> > +     dev->state = STATE_DEV_RUNNING;
> > +     /* Matches kref_put() in raw_release(). */
> > +     kref_get(&dev->count);
> > +
> > +out_unlock:
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +     return ret;
> > +}
> > +
> > +static int raw_ioctl_event_fetch(struct raw_dev *dev, unsigned long value)
> > +{
> > +     int ret = 0;
> > +     struct usb_raw_event arg;
> > +     unsigned long flags;
> > +     struct usb_raw_event *event;
> > +     uint32_t length;
> > +
> > +     ret = copy_from_user(&arg, (void __user *)value, sizeof(arg));
> > +     if (ret)
> > +             return ret;
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (dev->state != STATE_DEV_RUNNING) {
> > +             pr_debug("fail, device is not running\n");
> > +             spin_unlock_irqrestore(&dev->lock, flags);
> > +             return -EINVAL;
> > +     }
> > +     if (!dev->gadget) {
> > +             pr_debug("fail, gadget is not bound\n");
> > +             spin_unlock_irqrestore(&dev->lock, flags);
> > +             return -EBUSY;
> > +     }
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +
> > +     event = raw_event_queue_fetch(&dev->queue);
> > +     if (!event) {
> > +             pr_debug("event fetching interrupted\n");
> > +             return -EINTR;
> > +     }
> > +     length = min(arg.length, event->length);
> > +     ret = copy_to_user((void __user *)value, event,
> > +                             sizeof(*event) + length);
> > +     return ret;
> > +}
> > +
> > +static void *raw_alloc_io_data(struct usb_raw_ep_io *io, void __user *ptr,
> > +                             bool get_from_user)
> > +{
> > +     int ret;
> > +     void *data;
> > +
> > +     ret = copy_from_user(io, ptr, sizeof(*io));
> > +     if (ret)
> > +             return ERR_PTR(ret);
> > +     if (io->ep >= USB_RAW_MAX_ENDPOINTS)
> > +             return ERR_PTR(-EINVAL);
> > +     if (!usb_raw_io_flags_valid(io->flags))
> > +             return ERR_PTR(-EINVAL);
> > +     if (io->length > PAGE_SIZE)
> > +             return ERR_PTR(-EINVAL);
> > +     if (get_from_user)
> > +             data = memdup_user(ptr + sizeof(*io), io->length);
> > +     else {
> > +             data = kmalloc(io->length, GFP_KERNEL);
> > +             if (!data)
> > +                     data = ERR_PTR(-ENOMEM);
> > +     }
> > +     return data;
> > +}
> > +
> > +static int raw_process_ep0_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
> > +                             void *data, bool in)
> > +{
> > +     int ret = 0;
> > +     unsigned long flags;
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (dev->state != STATE_DEV_RUNNING) {
> > +             pr_debug("fail, device is not running\n");
> > +             ret = -EINVAL;
> > +             goto out_unlock;
> > +     }
> > +     if (!dev->gadget) {
> > +             pr_debug("fail, gadget is not bound\n");
> > +             ret = -EBUSY;
> > +             goto out_unlock;
> > +     }
> > +     if (dev->ep0_urb_queued) {
> > +             pr_debug("fail, urb already queued\n");
> > +             ret = -EBUSY;
> > +             goto out_unlock;
> > +     }
> > +     if ((in && !dev->ep0_in_pending) ||
> > +                     (!in && !dev->ep0_out_pending)) {
> > +             pr_debug("fail, wrong direction\n");
> > +             ret = -EBUSY;
> > +             goto out_unlock;
> > +     }
> > +     if (WARN_ON(in && dev->ep0_out_pending)) {
> > +             ret = -ENODEV;
> > +             dev->state = STATE_DEV_FAILED;
> > +             goto out_done;
> > +     }
> > +     if (WARN_ON(!in && dev->ep0_in_pending)) {
> > +             ret = -ENODEV;
> > +             dev->state = STATE_DEV_FAILED;
> > +             goto out_done;
> > +     }
> > +
> > +     dev->req->buf = data;
> > +     dev->req->length = io->length;
> > +     dev->req->zero = usb_raw_io_flags_zero(io->flags);
> > +     dev->ep0_urb_queued = true;
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +
> > +     ret = usb_ep_queue(dev->gadget->ep0, dev->req, GFP_ATOMIC);
> > +     if (ret) {
> > +             pr_err("fail, usb_ep_queue returned %d\n", ret);
> > +             spin_lock_irqsave(&dev->lock, flags);
> > +             dev->state = STATE_DEV_FAILED;
> > +             goto out_done;
> > +     }
> > +
> > +     ret = wait_for_completion_interruptible(&dev->ep0_done);
> > +     if (ret) {
> > +             pr_debug("wait interrupted\n");
> > +             usb_ep_dequeue(dev->gadget->ep0, dev->req);
> > +             wait_for_completion(&dev->ep0_done);
> > +             spin_lock_irqsave(&dev->lock, flags);
> > +             goto out_done;
> > +     }
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     ret = dev->ep0_status;
> > +
> > +out_done:
> > +     dev->ep0_urb_queued = false;
> > +out_unlock:
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +     return ret;
> > +}
> > +
> > +static int raw_ioctl_ep0_write(struct raw_dev *dev, unsigned long value)
> > +{
> > +     int ret = 0;
> > +     void *data;
> > +     struct usb_raw_ep_io io;
> > +
> > +     data = raw_alloc_io_data(&io, (void __user *)value, true);
> > +     if (IS_ERR(data))
> > +             return PTR_ERR(data);
> > +     ret = raw_process_ep0_io(dev, &io, data, true);
> > +     kfree(data);
> > +     return ret;
> > +}
> > +
> > +static int raw_ioctl_ep0_read(struct raw_dev *dev, unsigned long value)
> > +{
> > +     int ret = 0;
> > +     void *data;
> > +     struct usb_raw_ep_io io;
> > +     unsigned int length;
> > +
> > +     data = raw_alloc_io_data(&io, (void __user *)value, false);
> > +     if (IS_ERR(data))
> > +             return PTR_ERR(data);
> > +     ret = raw_process_ep0_io(dev, &io, data, false);
> > +     if (ret < 0) {
> > +             kfree(data);
> > +             return ret;
> > +     }
> > +     length = min(io.length, (unsigned int)ret);
> > +     ret = copy_to_user((void __user *)(value + sizeof(io)), data, length);
> > +     kfree(data);
> > +     return ret;
> > +}
> > +
> > +static bool check_ep_caps(struct usb_ep *ep,
> > +                             struct usb_endpoint_descriptor *desc)
> > +{
> > +     switch (usb_endpoint_type(desc)) {
> > +     case USB_ENDPOINT_XFER_ISOC:
> > +             if (!ep->caps.type_iso)
> > +                     return false;
> > +             break;
> > +     case USB_ENDPOINT_XFER_BULK:
> > +             if (!ep->caps.type_bulk)
> > +                     return false;
> > +             break;
> > +     case USB_ENDPOINT_XFER_INT:
> > +             if (!ep->caps.type_int)
> > +                     return false;
> > +             break;
> > +     default:
> > +             return false;
> > +     }
> > +
> > +     if (usb_endpoint_dir_in(desc) && !ep->caps.dir_in)
> > +             return false;
> > +     if (usb_endpoint_dir_out(desc) && !ep->caps.dir_out)
> > +             return false;
> > +
> > +     return true;
> > +}
> > +
> > +static int raw_ioctl_ep_enable(struct raw_dev *dev, unsigned long value)
> > +{
> > +     int ret = 0, i;
> > +     unsigned long flags;
> > +     struct usb_endpoint_descriptor *desc;
> > +     struct usb_ep *ep = NULL;
> > +
> > +     desc = memdup_user((void __user *)value, sizeof(*desc));
> > +     if (IS_ERR(desc))
> > +             return PTR_ERR(desc);
> > +
> > +     /*
> > +      * Endpoints with a maxpacket length of 0 can cause crashes in UDC
> > +      * drivers.
> > +      */
> > +     if (usb_endpoint_maxp(desc) == 0) {
> > +             kfree(desc);
> > +             return -EINVAL;
> > +     }
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (dev->state != STATE_DEV_RUNNING) {
> > +             pr_debug("fail, device is not running\n");
> > +             ret = -EINVAL;
> > +             goto out_free;
> > +     }
> > +     if (!dev->gadget) {
> > +             pr_debug("fail, gadget is not bound\n");
> > +             ret = -EBUSY;
> > +             goto out_free;
> > +     }
> > +
> > +     for (i = 0; i < USB_RAW_MAX_ENDPOINTS; i++) {
> > +             if (dev->eps[i].state == STATE_EP_ENABLED)
> > +                     continue;
> > +             break;
> > +     }
> > +     if (i == USB_RAW_MAX_ENDPOINTS) {
> > +             pr_debug("fail, no device endpoints available\n");
> > +             ret = -EBUSY;
> > +             goto out_free;
> > +     }
> > +
> > +     gadget_for_each_ep(ep, dev->gadget) {
> > +             if (ep->enabled)
> > +                     continue;
> > +             if (!check_ep_caps(ep, desc))
> > +                     continue;
> > +             ep->desc = desc;
> > +             ret = usb_ep_enable(ep);
> > +             if (ret < 0) {
> > +                     pr_err("fail, usb_ep_enable returned %d\n", ret);
> > +                     goto out_free;
> > +             }
> > +             dev->eps[i].req = usb_ep_alloc_request(ep, GFP_ATOMIC);
> > +             if (!dev->eps[i].req) {
> > +                     pr_err("fail, usb_ep_alloc_request failed\n");
> > +                     usb_ep_disable(ep);
> > +                     ret = -ENOMEM;
> > +                     goto out_free;
> > +             }
> > +             dev->eps[i].ep = ep;
> > +             dev->eps[i].state = STATE_EP_ENABLED;
> > +             ep->driver_data = &dev->eps[i];
> > +             ret = i;
> > +             goto out_unlock;
> > +     }
> > +
> > +     pr_debug("fail, no gadget endpoints available\n");
> > +     ret = -EBUSY;
> > +
> > +out_free:
> > +     kfree(desc);
> > +out_unlock:
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +     return ret;
> > +}
> > +
> > +static int raw_ioctl_ep_disable(struct raw_dev *dev, unsigned long value)
> > +{
> > +     int ret = 0, i = value;
> > +     unsigned long flags;
> > +     const void *desc;
> > +
> > +     if (i < 0 || i >= USB_RAW_MAX_ENDPOINTS)
> > +             return -EINVAL;
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (dev->state != STATE_DEV_RUNNING) {
> > +             pr_debug("fail, device is not running\n");
> > +             ret = -EINVAL;
> > +             goto out_unlock;
> > +     }
> > +     if (!dev->gadget) {
> > +             pr_debug("fail, gadget is not bound\n");
> > +             ret = -EBUSY;
> > +             goto out_unlock;
> > +     }
> > +     if (dev->eps[i].state != STATE_EP_ENABLED) {
> > +             pr_debug("fail, endpoint is not enabled\n");
> > +             ret = -EINVAL;
> > +             goto out_unlock;
> > +     }
> > +     if (dev->eps[i].disabling) {
> > +             pr_debug("fail, disable already in progress\n");
> > +             ret = -EINVAL;
> > +             goto out_unlock;
> > +     }
> > +     dev->eps[i].disabling = true;
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +
> > +     usb_ep_disable(dev->eps[i].ep);
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     usb_ep_free_request(dev->eps[i].ep, dev->eps[i].req);
> > +     desc = dev->eps[i].ep->desc;
> > +     dev->eps[i].ep = NULL;
> > +     dev->eps[i].state = STATE_EP_DISABLED;
> > +     kfree(desc);
> > +     dev->eps[i].disabling = false;
> > +
> > +out_unlock:
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +     return ret;
> > +}
> > +
> > +static void gadget_ep_complete(struct usb_ep *ep, struct usb_request *req)
> > +{
> > +     struct raw_ep *r_ep = (struct raw_ep *)ep->driver_data;
> > +     struct raw_dev *dev = r_ep->dev;
> > +     unsigned long flags;
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (req->status)
> > +             r_ep->status = req->status;
> > +     else
> > +             r_ep->status = req->actual;
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +
> > +     complete((struct completion *)req->context);
> > +}
> > +
> > +static int raw_process_ep_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
> > +                             void *data, bool in)
> > +{
> > +     int ret = 0;
> > +     unsigned long flags;
> > +     struct raw_ep *ep = &dev->eps[io->ep];
> > +     DECLARE_COMPLETION_ONSTACK(done);
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (dev->state != STATE_DEV_RUNNING) {
> > +             pr_debug("fail, device is not running\n");
> > +             ret = -EINVAL;
> > +             goto out_unlock;
> > +     }
> > +     if (!dev->gadget) {
> > +             pr_debug("fail, gadget is not bound\n");
> > +             ret = -EBUSY;
> > +             goto out_unlock;
> > +     }
> > +     if (ep->state != STATE_EP_ENABLED) {
> > +             pr_debug("fail, endpoint is not enabled\n");
> > +             ret = -EBUSY;
> > +             goto out_unlock;
> > +     }
> > +     if (ep->disabling) {
> > +             pr_debug("fail, endpoint is being disabled\n");
> > +             ret = -EBUSY;
> > +             goto out_unlock;
> > +     }
> > +     if (ep->urb_queued) {
> > +             pr_debug("fail, urb already queued\n");
> > +             ret = -EBUSY;
> > +             goto out_unlock;
> > +     }
> > +     if ((in && !ep->ep->caps.dir_in) || (!in && ep->ep->caps.dir_in)) {
> > +             pr_debug("fail, wrong direction\n");
> > +             ret = -EINVAL;
> > +             goto out_unlock;
> > +     }
> > +
> > +     ep->dev = dev;
> > +     ep->req->context = &done;
> > +     ep->req->complete = gadget_ep_complete;
> > +     ep->req->buf = data;
> > +     ep->req->length = io->length;
> > +     ep->req->zero = usb_raw_io_flags_zero(io->flags);
> > +     ep->urb_queued = true;
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +
> > +     ret = usb_ep_queue(ep->ep, ep->req, GFP_ATOMIC);
> > +     if (ret) {
> > +             pr_err("fail, usb_ep_queue returned %d\n", ret);
> > +             spin_lock_irqsave(&dev->lock, flags);
> > +             dev->state = STATE_DEV_FAILED;
> > +             goto out_done;
> > +     }
> > +
> > +     ret = wait_for_completion_interruptible(&done);
> > +     if (ret) {
> > +             pr_debug("wait interrupted\n");
> > +             usb_ep_dequeue(ep->ep, ep->req);
> > +             wait_for_completion(&done);
> > +             spin_lock_irqsave(&dev->lock, flags);
> > +             goto out_done;
> > +     }
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     ret = ep->status;
> > +
> > +out_done:
> > +     ep->urb_queued = false;
> > +out_unlock:
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +     return ret;
> > +}
> > +
> > +static int raw_ioctl_ep_write(struct raw_dev *dev, unsigned long value)
> > +{
> > +     int ret = 0;
> > +     char *data;
> > +     struct usb_raw_ep_io io;
> > +
> > +     data = raw_alloc_io_data(&io, (void __user *)value, true);
> > +     if (IS_ERR(data))
> > +             return PTR_ERR(data);
> > +     ret = raw_process_ep_io(dev, &io, data, true);
> > +     kfree(data);
> > +     return ret;
> > +}
> > +
> > +static int raw_ioctl_ep_read(struct raw_dev *dev, unsigned long value)
> > +{
> > +     int ret = 0;
> > +     char *data;
> > +     struct usb_raw_ep_io io;
> > +     unsigned int length;
> > +
> > +     data = raw_alloc_io_data(&io, (void __user *)value, false);
> > +     if (IS_ERR(data))
> > +             return PTR_ERR(data);
> > +     ret = raw_process_ep_io(dev, &io, data, false);
> > +     if (ret < 0) {
> > +             kfree(data);
> > +             return ret;
> > +     }
> > +     length = min(io.length, (unsigned int)ret);
> > +     ret = copy_to_user((void __user *)(value + sizeof(io)), data, length);
> > +     kfree(data);
> > +     return ret;
> > +}
> > +
> > +static int raw_ioctl_configure(struct raw_dev *dev, unsigned long value)
> > +{
> > +     int ret = 0;
> > +     unsigned long flags;
> > +
> > +     if (value)
> > +             return -EINVAL;
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (dev->state != STATE_DEV_RUNNING) {
> > +             pr_debug("fail, device is not running\n");
> > +             ret = -EINVAL;
> > +             goto out_unlock;
> > +     }
> > +     if (!dev->gadget) {
> > +             pr_debug("fail, gadget is not bound\n");
> > +             ret = -EBUSY;
> > +             goto out_unlock;
> > +     }
> > +     usb_gadget_set_state(dev->gadget, USB_STATE_CONFIGURED);
> > +
> > +out_unlock:
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +     return ret;
> > +}
> > +
> > +static int raw_ioctl_vbus_draw(struct raw_dev *dev, unsigned long value)
> > +{
> > +     int ret = 0;
> > +     unsigned long flags;
> > +
> > +     spin_lock_irqsave(&dev->lock, flags);
> > +     if (dev->state != STATE_DEV_RUNNING) {
> > +             pr_debug("fail, device is not running\n");
> > +             ret = -EINVAL;
> > +             goto out_unlock;
> > +     }
> > +     if (!dev->gadget) {
> > +             pr_debug("fail, gadget is not bound\n");
> > +             ret = -EBUSY;
> > +             goto out_unlock;
> > +     }
> > +     usb_gadget_vbus_draw(dev->gadget, 2 * value);
> > +
> > +out_unlock:
> > +     spin_unlock_irqrestore(&dev->lock, flags);
> > +     return ret;
> > +}
> > +
> > +static long raw_ioctl(struct file *fd, unsigned int cmd, unsigned long value)
> > +{
> > +     struct raw_dev *dev = fd->private_data;
> > +     int ret = 0;
> > +
> > +     if (!dev)
> > +             return -EBUSY;
> > +
> > +     switch (cmd) {
> > +     case USB_RAW_IOCTL_INIT:
> > +             ret = raw_ioctl_init(dev, value);
> > +             break;
> > +     case USB_RAW_IOCTL_RUN:
> > +             ret = raw_ioctl_run(dev, value);
> > +             break;
> > +     case USB_RAW_IOCTL_EVENT_FETCH:
> > +             ret = raw_ioctl_event_fetch(dev, value);
> > +             break;
> > +     case USB_RAW_IOCTL_EP0_WRITE:
> > +             ret = raw_ioctl_ep0_write(dev, value);
> > +             break;
> > +     case USB_RAW_IOCTL_EP0_READ:
> > +             ret = raw_ioctl_ep0_read(dev, value);
> > +             break;
> > +     case USB_RAW_IOCTL_EP_ENABLE:
> > +             ret = raw_ioctl_ep_enable(dev, value);
> > +             break;
> > +     case USB_RAW_IOCTL_EP_DISABLE:
> > +             ret = raw_ioctl_ep_disable(dev, value);
> > +             break;
> > +     case USB_RAW_IOCTL_EP_WRITE:
> > +             ret = raw_ioctl_ep_write(dev, value);
> > +             break;
> > +     case USB_RAW_IOCTL_EP_READ:
> > +             ret = raw_ioctl_ep_read(dev, value);
> > +             break;
> > +     case USB_RAW_IOCTL_CONFIGURE:
> > +             ret = raw_ioctl_configure(dev, value);
> > +             break;
> > +     case USB_RAW_IOCTL_VBUS_DRAW:
> > +             ret = raw_ioctl_vbus_draw(dev, value);
> > +             break;
> > +     default:
> > +             ret = -EINVAL;
> > +     }
> > +
> > +     return ret;
> > +}
> > +
> > +/*----------------------------------------------------------------------*/
> > +
> > +static const struct file_operations raw_fops = {
> > +     .open =                 raw_open,
> > +     .unlocked_ioctl =       raw_ioctl,
> > +     .compat_ioctl =         raw_ioctl,
> > +     .release =              raw_release,
> > +     .llseek =               no_llseek,
> > +};
> > +
> > +static struct miscdevice raw_device = {
> > +     .minor = MISC_DYNAMIC_MINOR,
> > +     .name = "raw-gadget",
>
> DRIVER_NAME?

Will do in v4.

>
> > +     .fops = &raw_fops,
> > +};
> > +
> > +static int __init raw_init(void)
> > +{
> > +     int rv;
> > +
> > +     rv = misc_register(&raw_device);
> > +     if (rv) {
> > +             pr_err("failed to register raw-gadget device with %d\n", rv);
> > +             return rv;
> > +     }
> > +     return 0;
> > +}
> > +
> > +static void __exit raw_exit(void)
> > +{
> > +     misc_deregister(&raw_device);
> > +}
> > +
> > +module_init(raw_init);
> > +module_exit(raw_exit);
>
> module_misc_device()?  :)

Will do in v4.

Thanks!

Re: [PATCH v3 1/1] usb: gadget: add raw-gadget interface

[Greg Kroah-Hartman]

On Wed, Dec 18, 2019 at 06:28:19PM +0100, Andrey Konovalov wrote:
> On Wed, Dec 18, 2019 at 2:23 PM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Wed, Dec 11, 2019 at 07:02:41PM +0100, Andrey Konovalov wrote:
> > > USB Raw Gadget is a kernel module that provides a userspace interface for
> > > the USB Gadget subsystem. Essentially it allows to emulate USB devices
> > > from userspace. Enabled with CONFIG_USB_RAW_GADGET. Raw Gadget is
> > > currently a strictly debugging feature and shouldn't be used in
> > > production.
> > >
> > > Raw Gadget is similar to GadgetFS, but provides a more low-level and
> > > direct access to the USB Gadget layer for the userspace. The key
> > > differences are:
> > >
> > > 1. Every USB request is passed to the userspace to get a response, while
> > >    GadgetFS responds to some USB requests internally based on the provided
> > >    descriptors. However note, that the UDC driver might respond to some
> > >    requests on its own and never forward them to the Gadget layer.
> > >
> > > 2. GadgetFS performs some sanity checks on the provided USB descriptors,
> > >    while Raw Gadget allows you to provide arbitrary data as responses to
> > >    USB requests.
> > >
> > > 3. Raw Gadget provides a way to select a UDC device/driver to bind to,
> > >    while GadgetFS currently binds to the first available UDC.
> > >
> > > 4. Raw Gadget uses predictable endpoint names (handles) across different
> > >    UDCs (as long as UDCs have enough endpoints of each required transfer
> > >    type).
> > >
> > > 5. Raw Gadget has ioctl-based interface instead of a filesystem-based one.
> >
> > Looks good to me, only minor comments below.
> 
> Great, thanks!
> 
> About reworking the logging to use dev_err/dbg(): can I pass the
> global miscdevice struct into those macros? Or should I pass a pointer
> to this struct into all of the functions that print log messages? The
> latter seems unnecessarily complex, unless there's a reason to do
> that.

Ah, you are right, you only have one misc device here.  No, that's not
good, but you can use it for some messages (your ioctl errors), but
ideally you will have a struct device somewhere for each of the
"instances" you create, right?  That is what you should use for that.

> > > +struct raw_dev {
> > > +     struct kref                     count;
> > > +     spinlock_t                      lock;
> > > +
> > > +     const char                      *udc_name;
> > > +     struct usb_gadget_driver        driver;
> >
> > A dev embeds a driver?
> >
> > Not a pointer?
> >
> > But you have a kref, so the reference count of this object is there,
> > right?
> 
> I didn't get this comment, could you elaborate? I can make it a
> pointer, but for each raw_dev we have a unique usb_gadget_driver
> instance, so embedding it as is is simpler.

Ok, that's fine.  But it feels odd creating a driver dynamically to me,
but it should work (as you show.)  It doesn't give you something to use
for the dev_* messages directly, ah, but you do have something:

> > > +
> > > +     /* Protected by lock: */
> > > +     enum dev_state                  state;
> > > +     bool                            gadget_registered;
> > > +     struct usb_gadget               *gadget;

There, use that pointer for your dev_* messages, and you should be fine.

> > > +static void gadget_unbind(struct usb_gadget *gadget)
> > > +{
> > > +     struct raw_dev *dev = get_gadget_data(gadget);
> > > +     unsigned long flags;
> > > +
> > > +     spin_lock_irqsave(&dev->lock, flags);
> > > +     set_gadget_data(gadget, NULL);
> > > +     spin_unlock_irqrestore(&dev->lock, flags);
> > > +     /* Matches kref_get() in gadget_bind(). */
> > > +     kref_put(&dev->count, dev_free);
> >
> > What protects the kref from being called 'put' twice on the same
> > pointer at the same time?  There should be some lock somewhere, right?
> 
> Hm, kref_put() does refcount_dec_and_test(), which in turns calls
> atomic_dec_and_test(), so this is protected against concurrent puts
> (which is the whole idea of kref?), and no locking is needed. Unless I
> misunderstand something.

It's late, but there should be some lock somewhere to prevent a race
around this type of thing.  That's why we have kref_put_mutex() and
kref_put_lock().

Odds are you are fine here, but just something to be aware of...

thanks,

greg k-h

Re: [PATCH v3 1/1] usb: gadget: add raw-gadget interface

[Andrey Konovalov]

On Wed, Dec 18, 2019 at 7:19 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Wed, Dec 18, 2019 at 06:28:19PM +0100, Andrey Konovalov wrote:
> > On Wed, Dec 18, 2019 at 2:23 PM Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Wed, Dec 11, 2019 at 07:02:41PM +0100, Andrey Konovalov wrote:
> > > > USB Raw Gadget is a kernel module that provides a userspace interface for
> > > > the USB Gadget subsystem. Essentially it allows to emulate USB devices
> > > > from userspace. Enabled with CONFIG_USB_RAW_GADGET. Raw Gadget is
> > > > currently a strictly debugging feature and shouldn't be used in
> > > > production.
> > > >
> > > > Raw Gadget is similar to GadgetFS, but provides a more low-level and
> > > > direct access to the USB Gadget layer for the userspace. The key
> > > > differences are:
> > > >
> > > > 1. Every USB request is passed to the userspace to get a response, while
> > > >    GadgetFS responds to some USB requests internally based on the provided
> > > >    descriptors. However note, that the UDC driver might respond to some
> > > >    requests on its own and never forward them to the Gadget layer.
> > > >
> > > > 2. GadgetFS performs some sanity checks on the provided USB descriptors,
> > > >    while Raw Gadget allows you to provide arbitrary data as responses to
> > > >    USB requests.
> > > >
> > > > 3. Raw Gadget provides a way to select a UDC device/driver to bind to,
> > > >    while GadgetFS currently binds to the first available UDC.
> > > >
> > > > 4. Raw Gadget uses predictable endpoint names (handles) across different
> > > >    UDCs (as long as UDCs have enough endpoints of each required transfer
> > > >    type).
> > > >
> > > > 5. Raw Gadget has ioctl-based interface instead of a filesystem-based one.
> > >
> > > Looks good to me, only minor comments below.
> >
> > Great, thanks!
> >
> > About reworking the logging to use dev_err/dbg(): can I pass the
> > global miscdevice struct into those macros? Or should I pass a pointer
> > to this struct into all of the functions that print log messages? The
> > latter seems unnecessarily complex, unless there's a reason to do
> > that.
>
> Ah, you are right, you only have one misc device here.  No, that's not
> good, but you can use it for some messages (your ioctl errors), but
> ideally you will have a struct device somewhere for each of the
> "instances" you create, right?  That is what you should use for that.

OK, I think I got the idea. Will do in v4.

>
> > > > +struct raw_dev {
> > > > +     struct kref                     count;
> > > > +     spinlock_t                      lock;
> > > > +
> > > > +     const char                      *udc_name;
> > > > +     struct usb_gadget_driver        driver;
> > >
> > > A dev embeds a driver?
> > >
> > > Not a pointer?
> > >
> > > But you have a kref, so the reference count of this object is there,
> > > right?
> >
> > I didn't get this comment, could you elaborate? I can make it a
> > pointer, but for each raw_dev we have a unique usb_gadget_driver
> > instance, so embedding it as is is simpler.
>
> Ok, that's fine.  But it feels odd creating a driver dynamically to me,
> but it should work (as you show.)  It doesn't give you something to use
> for the dev_* messages directly, ah, but you do have something:
>
> > > > +
> > > > +     /* Protected by lock: */
> > > > +     enum dev_state                  state;
> > > > +     bool                            gadget_registered;
> > > > +     struct usb_gadget               *gadget;
>
> There, use that pointer for your dev_* messages, and you should be fine.
>
> > > > +static void gadget_unbind(struct usb_gadget *gadget)
> > > > +{
> > > > +     struct raw_dev *dev = get_gadget_data(gadget);
> > > > +     unsigned long flags;
> > > > +
> > > > +     spin_lock_irqsave(&dev->lock, flags);
> > > > +     set_gadget_data(gadget, NULL);
> > > > +     spin_unlock_irqrestore(&dev->lock, flags);
> > > > +     /* Matches kref_get() in gadget_bind(). */
> > > > +     kref_put(&dev->count, dev_free);
> > >
> > > What protects the kref from being called 'put' twice on the same
> > > pointer at the same time?  There should be some lock somewhere, right?
> >
> > Hm, kref_put() does refcount_dec_and_test(), which in turns calls
> > atomic_dec_and_test(), so this is protected against concurrent puts
> > (which is the whole idea of kref?), and no locking is needed. Unless I
> > misunderstand something.
>
> It's late, but there should be some lock somewhere to prevent a race
> around this type of thing.  That's why we have kref_put_mutex() and
> kref_put_lock().
>
> Odds are you are fine here, but just something to be aware of...

Ah, I see. So AFAIU kref_put_lock/mutex() are meant to be used in
cases when there might be a concurrent user that doesn't have the
reference counter incremented, but holds the lock? We don't do this
kind of stuff here.

Re: [PATCH v3 1/1] usb: gadget: add raw-gadget interface

[Greg Kroah-Hartman]

On Wed, Dec 18, 2019 at 08:22:47PM +0100, Andrey Konovalov wrote:
> > > > > +static void gadget_unbind(struct usb_gadget *gadget)
> > > > > +{
> > > > > +     struct raw_dev *dev = get_gadget_data(gadget);
> > > > > +     unsigned long flags;
> > > > > +
> > > > > +     spin_lock_irqsave(&dev->lock, flags);
> > > > > +     set_gadget_data(gadget, NULL);
> > > > > +     spin_unlock_irqrestore(&dev->lock, flags);
> > > > > +     /* Matches kref_get() in gadget_bind(). */
> > > > > +     kref_put(&dev->count, dev_free);
> > > >
> > > > What protects the kref from being called 'put' twice on the same
> > > > pointer at the same time?  There should be some lock somewhere, right?
> > >
> > > Hm, kref_put() does refcount_dec_and_test(), which in turns calls
> > > atomic_dec_and_test(), so this is protected against concurrent puts
> > > (which is the whole idea of kref?), and no locking is needed. Unless I
> > > misunderstand something.
> >
> > It's late, but there should be some lock somewhere to prevent a race
> > around this type of thing.  That's why we have kref_put_mutex() and
> > kref_put_lock().
> >
> > Odds are you are fine here, but just something to be aware of...
> 
> Ah, I see. So AFAIU kref_put_lock/mutex() are meant to be used in
> cases when there might be a concurrent user that doesn't have the
> reference counter incremented, but holds the lock? We don't do this
> kind of stuff here.

Ok, as long as there is a lock somewhere preventing this type of thing
from happening.  Last time I looked at this, it took me and 2 grad
students an hour with a whiteboard to work it all out.  Which is why the
lock variants are there now :)

thanks,

greg k-h