[PATCHv3 0/5] usb/gadget: independent registration of gadgets and gadget drivers

[PATCHv3 0/5] usb/gadget: independent registration of gadgets and gadget drivers

[Ruslan Bilovol]

This patchset adds independent registration of gadgets
and gadget drivers to udc-core. This is very useful for
built-in modules into kernel case since it's possible
situation that gadget driver is probing at a time
when no gadgets are registered in udc-core.
In this case instead of silently failing without
of any attempt to recover, with independent registration
of gadgets and gadget drivers there is no matter
in which order gadgets and gadget drivers are
probed/registered.

This patch has side-effect on gadget drivers that had
__init/__exit attributes on some paths like bind/unbind
and (since bind/unbind may happen at any time) should
not use them now. This is covered by forth patch

=====================
v3:
 - addressed Alan's comments - now UDC name and pending
   gadget drivers list is a part of struct usb_gadget_driver.
 - removed usb_udc_attach_driver() function that became unused
   and not needed now

v2:
 - changed first patch to have only deferred probe part
   (because Gadget Bus seems to be better variant when
   some more complicated behavior will be required)
 - rebased to latest 'next' branch of Felipe Balbi's tree


Ruslan Bilovol (5):
  usb: gadget: bind UDC by name passed via usb_gadget_driver structure
  usb: gadge: configfs: pass UDC name via usb_gadget_driver struct
  usb: gadget: udc-core: remove unused usb_udc_attach_driver()
  usb: gadget: legacy: don't use __init/__exit attributes for
    bind/unbind path
  usb: gadget: udc-core: independent registration of gadgets and gadget
    drivers

 drivers/usb/gadget/configfs.c            | 27 +++++-----
 drivers/usb/gadget/legacy/acm_ms.c       |  6 +--
 drivers/usb/gadget/legacy/audio.c        |  6 +--
 drivers/usb/gadget/legacy/cdc2.c         |  6 +--
 drivers/usb/gadget/legacy/dbgp.c         |  2 +-
 drivers/usb/gadget/legacy/ether.c        |  8 +--
 drivers/usb/gadget/legacy/gmidi.c        |  6 +--
 drivers/usb/gadget/legacy/hid.c          |  6 +--
 drivers/usb/gadget/legacy/mass_storage.c |  4 +-
 drivers/usb/gadget/legacy/multi.c        | 16 +++---
 drivers/usb/gadget/legacy/ncm.c          |  6 +--
 drivers/usb/gadget/legacy/nokia.c        |  6 +--
 drivers/usb/gadget/legacy/printer.c      |  6 +--
 drivers/usb/gadget/legacy/serial.c       |  2 +-
 drivers/usb/gadget/legacy/webcam.c       |  4 +-
 drivers/usb/gadget/legacy/zero.c         |  2 +-
 drivers/usb/gadget/udc/udc-core.c        | 88 +++++++++++++++++++-------------
 include/linux/usb/gadget.h               |  8 ++-
 18 files changed, 116 insertions(+), 93 deletions(-)

-- 
1.9.1

[PATCHv3 1/5] usb: gadget: bind UDC by name passed via usb_gadget_driver structure

[Ruslan Bilovol]

Introduce new 'udc_name' member to usb_gadget_driver structure.
The 'udc_name' is a name of UDC that usb_gadget_driver should
be bound to. If udc_name is NULL, it will be bound to any
available UDC.

Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
---
 drivers/usb/gadget/udc/udc-core.c | 25 ++++++++++++++++++++-----
 include/linux/usb/gadget.h        |  4 ++++
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
index 5a81cb0..e1079e08 100644
--- a/drivers/usb/gadget/udc/udc-core.c
+++ b/drivers/usb/gadget/udc/udc-core.c
@@ -440,21 +440,36 @@ EXPORT_SYMBOL_GPL(usb_udc_attach_driver);
 int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
 {
 	struct usb_udc		*udc = NULL;
-	int			ret;
+	int			ret = -ENODEV;
 
 	if (!driver || !driver->bind || !driver->setup)
 		return -EINVAL;
 
 	mutex_lock(&udc_lock);
-	list_for_each_entry(udc, &udc_list, list) {
-		/* For now we take the first one */
-		if (!udc->driver)
+	if (driver->udc_name) {
+		list_for_each_entry(udc, &udc_list, list) {
+			ret = strcmp(driver->udc_name, dev_name(&udc->dev));
+			if (!ret)
+				break;
+		}
+		if (ret)
+			ret = -ENODEV;
+		else if (udc->driver)
+			ret = -EBUSY;
+		else
 			goto found;
+	} else {
+		list_for_each_entry(udc, &udc_list, list) {
+			/* For now we take the first one */
+			if (!udc->driver)
+				goto found;
+		}
+		ret = -ENODEV;
 	}
 
 	pr_debug("couldn't find an available UDC\n");
 	mutex_unlock(&udc_lock);
-	return -ENODEV;
+	return ret;
 found:
 	ret = udc_bind_to_driver(udc, driver);
 	mutex_unlock(&udc_lock);
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index e2f00fd..3e7aab1 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -821,6 +821,8 @@ static inline int usb_gadget_disconnect(struct usb_gadget *gadget)
  * @reset: Invoked on USB bus reset. It is mandatory for all gadget drivers
  *	and should be called in_interrupt.
  * @driver: Driver model state for this driver.
+ * @udc_name: A name of UDC this driver should be bound to. If udc_name is NULL,
+ * 	this driver will be bound to any available UDC.
  *
  * Devices are disabled till a gadget driver successfully bind()s, which
  * means the driver will handle setup() requests needed to enumerate (and
@@ -881,6 +883,8 @@ struct usb_gadget_driver {
 
 	/* FIXME support safe rmmod */
 	struct device_driver	driver;
+
+	char			*udc_name;
 };
 
 
-- 
1.9.1

[PATCHv3 2/5] usb: gadge: configfs: pass UDC name via usb_gadget_driver struct

[Ruslan Bilovol]

Now when udc-core supports binding to specific UDC by passing
its name via 'udc_name' member of usb_gadget_driver struct,
switch to this generic approach.

Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
---
 drivers/usb/gadget/configfs.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 7564814..b6aae63 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -54,7 +54,6 @@ struct gadget_info {
 	struct list_head string_list;
 	struct list_head available_func;
 
-	const char *udc_name;
 #ifdef CONFIG_USB_OTG
 	struct usb_otg_descriptor otg;
 #endif
@@ -230,21 +229,21 @@ static ssize_t gadget_dev_desc_bcdUSB_store(struct gadget_info *gi,
 
 static ssize_t gadget_dev_desc_UDC_show(struct gadget_info *gi, char *page)
 {
-	return sprintf(page, "%s\n", gi->udc_name ?: "");
+	return sprintf(page, "%s\n", gi->composite.gadget_driver.udc_name ?: "");
 }
 
 static int unregister_gadget(struct gadget_info *gi)
 {
 	int ret;
 
-	if (!gi->udc_name)
+	if (!gi->composite.gadget_driver.udc_name)
 		return -ENODEV;
 
 	ret = usb_gadget_unregister_driver(&gi->composite.gadget_driver);
 	if (ret)
 		return ret;
-	kfree(gi->udc_name);
-	gi->udc_name = NULL;
+	kfree(gi->composite.gadget_driver.udc_name);
+	gi->composite.gadget_driver.udc_name = NULL;
 	return 0;
 }
 
@@ -267,14 +266,16 @@ static ssize_t gadget_dev_desc_UDC_store(struct gadget_info *gi,
 		if (ret)
 			goto err;
 	} else {
-		if (gi->udc_name) {
+		if (gi->composite.gadget_driver.udc_name) {
 			ret = -EBUSY;
 			goto err;
 		}
-		ret = usb_udc_attach_driver(name, &gi->composite.gadget_driver);
-		if (ret)
+		gi->composite.gadget_driver.udc_name = name;
+		ret = usb_gadget_probe_driver(&gi->composite.gadget_driver);
+		if (ret) {
+			gi->composite.gadget_driver.udc_name = NULL;
 			goto err;
-		gi->udc_name = name;
+		}
 	}
 	mutex_unlock(&gi->lock);
 	return len;
@@ -438,9 +439,9 @@ static int config_usb_cfg_unlink(
 	 * remove the function.
 	 */
 	mutex_lock(&gi->lock);
-	if (gi->udc_name)
+	if (gi->composite.gadget_driver.udc_name)
 		unregister_gadget(gi);
-	WARN_ON(gi->udc_name);
+	WARN_ON(gi->composite.gadget_driver.udc_name);
 
 	list_for_each_entry(f, &cfg->func_list, list) {
 		if (f->fi == fi) {
@@ -917,10 +918,10 @@ static int os_desc_unlink(struct config_item *os_desc_ci,
 	struct usb_composite_dev *cdev = &gi->cdev;
 
 	mutex_lock(&gi->lock);
-	if (gi->udc_name)
+	if (gi->composite.gadget_driver.udc_name)
 		unregister_gadget(gi);
 	cdev->os_desc_config = NULL;
-	WARN_ON(gi->udc_name);
+	WARN_ON(gi->composite.gadget_driver.udc_name);
 	mutex_unlock(&gi->lock);
 	return 0;
 }
-- 
1.9.1

[PATCHv3 3/5] usb: gadget: udc-core: remove unused usb_udc_attach_driver()

[Ruslan Bilovol]

Now when last user of usb_udc_attach_driver() is switched
to passing UDC name via usb_gadget_driver struct, it's safe
to remove this function

Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
---
 drivers/usb/gadget/udc/udc-core.c | 26 --------------------------
 include/linux/usb/gadget.h        |  2 --
 2 files changed, 28 deletions(-)

diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
index e1079e08..a960f3f 100644
--- a/drivers/usb/gadget/udc/udc-core.c
+++ b/drivers/usb/gadget/udc/udc-core.c
@@ -411,32 +411,6 @@ err1:
 	return ret;
 }
 
-int usb_udc_attach_driver(const char *name, struct usb_gadget_driver *driver)
-{
-	struct usb_udc *udc = NULL;
-	int ret = -ENODEV;
-
-	mutex_lock(&udc_lock);
-	list_for_each_entry(udc, &udc_list, list) {
-		ret = strcmp(name, dev_name(&udc->dev));
-		if (!ret)
-			break;
-	}
-	if (ret) {
-		ret = -ENODEV;
-		goto out;
-	}
-	if (udc->driver) {
-		ret = -EBUSY;
-		goto out;
-	}
-	ret = udc_bind_to_driver(udc, driver);
-out:
-	mutex_unlock(&udc_lock);
-	return ret;
-}
-EXPORT_SYMBOL_GPL(usb_udc_attach_driver);
-
 int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
 {
 	struct usb_udc		*udc = NULL;
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 3e7aab1..6070e8d 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -930,8 +930,6 @@ extern int usb_add_gadget_udc_release(struct device *parent,
 		struct usb_gadget *gadget, void (*release)(struct device *dev));
 extern int usb_add_gadget_udc(struct device *parent, struct usb_gadget *gadget);
 extern void usb_del_gadget_udc(struct usb_gadget *gadget);
-extern int usb_udc_attach_driver(const char *name,
-		struct usb_gadget_driver *driver);
 
 /*-------------------------------------------------------------------------*/
 
-- 
1.9.1

[PATCHv3 4/5] usb: gadget: legacy: don't use __init/__exit attributes for bind/unbind path

[Ruslan Bilovol]

In order to prepare to independent gadgets and
gadget drivers registration in udc-core, some of the
functions can't have __init/__exit attributes (almost
only bind/unbind callbacks are affected)

Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
---
 drivers/usb/gadget/legacy/acm_ms.c       |  6 +++---
 drivers/usb/gadget/legacy/audio.c        |  6 +++---
 drivers/usb/gadget/legacy/cdc2.c         |  6 +++---
 drivers/usb/gadget/legacy/dbgp.c         |  2 +-
 drivers/usb/gadget/legacy/ether.c        |  8 ++++----
 drivers/usb/gadget/legacy/gmidi.c        |  6 +++---
 drivers/usb/gadget/legacy/hid.c          |  6 +++---
 drivers/usb/gadget/legacy/mass_storage.c |  4 ++--
 drivers/usb/gadget/legacy/multi.c        | 16 ++++++++--------
 drivers/usb/gadget/legacy/ncm.c          |  6 +++---
 drivers/usb/gadget/legacy/nokia.c        |  6 +++---
 drivers/usb/gadget/legacy/printer.c      |  6 +++---
 drivers/usb/gadget/legacy/serial.c       |  2 +-
 drivers/usb/gadget/legacy/webcam.c       |  4 ++--
 drivers/usb/gadget/legacy/zero.c         |  2 +-
 15 files changed, 43 insertions(+), 43 deletions(-)

diff --git a/drivers/usb/gadget/legacy/acm_ms.c b/drivers/usb/gadget/legacy/acm_ms.c
index c30b7b5..3a48aab 100644
--- a/drivers/usb/gadget/legacy/acm_ms.c
+++ b/drivers/usb/gadget/legacy/acm_ms.c
@@ -121,7 +121,7 @@ static struct usb_function *f_msg;
 /*
  * We _always_ have both ACM and mass storage functions.
  */
-static int __init acm_ms_do_config(struct usb_configuration *c)
+static int acm_ms_do_config(struct usb_configuration *c)
 {
 	struct fsg_opts *opts;
 	int	status;
@@ -174,7 +174,7 @@ static struct usb_configuration acm_ms_config_driver = {
 
 /*-------------------------------------------------------------------------*/
 
-static int __init acm_ms_bind(struct usb_composite_dev *cdev)
+static int acm_ms_bind(struct usb_composite_dev *cdev)
 {
 	struct usb_gadget	*gadget = cdev->gadget;
 	struct fsg_opts		*opts;
@@ -249,7 +249,7 @@ fail_get_msg:
 	return status;
 }
 
-static int __exit acm_ms_unbind(struct usb_composite_dev *cdev)
+static int acm_ms_unbind(struct usb_composite_dev *cdev)
 {
 	usb_put_function(f_msg);
 	usb_put_function_instance(fi_msg);
diff --git a/drivers/usb/gadget/legacy/audio.c b/drivers/usb/gadget/legacy/audio.c
index f46a395..ba95518 100644
--- a/drivers/usb/gadget/legacy/audio.c
+++ b/drivers/usb/gadget/legacy/audio.c
@@ -167,7 +167,7 @@ static const struct usb_descriptor_header *otg_desc[] = {
 
 /*-------------------------------------------------------------------------*/
 
-static int __init audio_do_config(struct usb_configuration *c)
+static int audio_do_config(struct usb_configuration *c)
 {
 	int status;
 
@@ -216,7 +216,7 @@ static struct usb_configuration audio_config_driver = {
 
 /*-------------------------------------------------------------------------*/
 
-static int __init audio_bind(struct usb_composite_dev *cdev)
+static int audio_bind(struct usb_composite_dev *cdev)
 {
 #ifndef CONFIG_GADGET_UAC1
 	struct f_uac2_opts	*uac2_opts;
@@ -276,7 +276,7 @@ fail:
 	return status;
 }
 
-static int __exit audio_unbind(struct usb_composite_dev *cdev)
+static int audio_unbind(struct usb_composite_dev *cdev)
 {
 #ifdef CONFIG_GADGET_UAC1
 	if (!IS_ERR_OR_NULL(f_uac1))
diff --git a/drivers/usb/gadget/legacy/cdc2.c b/drivers/usb/gadget/legacy/cdc2.c
index 2e85d94..8d1985c 100644
--- a/drivers/usb/gadget/legacy/cdc2.c
+++ b/drivers/usb/gadget/legacy/cdc2.c
@@ -104,7 +104,7 @@ static struct usb_function_instance *fi_ecm;
 /*
  * We _always_ have both CDC ECM and CDC ACM functions.
  */
-static int __init cdc_do_config(struct usb_configuration *c)
+static int cdc_do_config(struct usb_configuration *c)
 {
 	int	status;
 
@@ -153,7 +153,7 @@ static struct usb_configuration cdc_config_driver = {
 
 /*-------------------------------------------------------------------------*/
 
-static int __init cdc_bind(struct usb_composite_dev *cdev)
+static int cdc_bind(struct usb_composite_dev *cdev)
 {
 	struct usb_gadget	*gadget = cdev->gadget;
 	struct f_ecm_opts	*ecm_opts;
@@ -211,7 +211,7 @@ fail:
 	return status;
 }
 
-static int __exit cdc_unbind(struct usb_composite_dev *cdev)
+static int cdc_unbind(struct usb_composite_dev *cdev)
 {
 	usb_put_function(f_acm);
 	usb_put_function_instance(fi_serial);
diff --git a/drivers/usb/gadget/legacy/dbgp.c b/drivers/usb/gadget/legacy/dbgp.c
index 633683a..7c42b01 100644
--- a/drivers/usb/gadget/legacy/dbgp.c
+++ b/drivers/usb/gadget/legacy/dbgp.c
@@ -284,7 +284,7 @@ fail_1:
 	return -ENODEV;
 }
 
-static int __init dbgp_bind(struct usb_gadget *gadget,
+static int dbgp_bind(struct usb_gadget *gadget,
 		struct usb_gadget_driver *driver)
 {
 	int err, stp;
diff --git a/drivers/usb/gadget/legacy/ether.c b/drivers/usb/gadget/legacy/ether.c
index c5fdc61..4283969 100644
--- a/drivers/usb/gadget/legacy/ether.c
+++ b/drivers/usb/gadget/legacy/ether.c
@@ -222,7 +222,7 @@ static struct usb_function *f_rndis;
  * the first one present.  That's to make Microsoft's drivers happy,
  * and to follow DOCSIS 1.0 (cable modem standard).
  */
-static int __init rndis_do_config(struct usb_configuration *c)
+static int rndis_do_config(struct usb_configuration *c)
 {
 	int status;
 
@@ -264,7 +264,7 @@ MODULE_PARM_DESC(use_eem, "use CDC EEM mode");
 /*
  * We _always_ have an ECM, CDC Subset, or EEM configuration.
  */
-static int __init eth_do_config(struct usb_configuration *c)
+static int eth_do_config(struct usb_configuration *c)
 {
 	int status = 0;
 
@@ -318,7 +318,7 @@ static struct usb_configuration eth_config_driver = {
 
 /*-------------------------------------------------------------------------*/
 
-static int __init eth_bind(struct usb_composite_dev *cdev)
+static int eth_bind(struct usb_composite_dev *cdev)
 {
 	struct usb_gadget	*gadget = cdev->gadget;
 	struct f_eem_opts	*eem_opts = NULL;
@@ -447,7 +447,7 @@ fail:
 	return status;
 }
 
-static int __exit eth_unbind(struct usb_composite_dev *cdev)
+static int eth_unbind(struct usb_composite_dev *cdev)
 {
 	if (has_rndis()) {
 		usb_put_function(f_rndis);
diff --git a/drivers/usb/gadget/legacy/gmidi.c b/drivers/usb/gadget/legacy/gmidi.c
index e02a095..c098281 100644
--- a/drivers/usb/gadget/legacy/gmidi.c
+++ b/drivers/usb/gadget/legacy/gmidi.c
@@ -118,7 +118,7 @@ static struct usb_gadget_strings *dev_strings[] = {
 static struct usb_function_instance *fi_midi;
 static struct usb_function *f_midi;
 
-static int __exit midi_unbind(struct usb_composite_dev *dev)
+static int midi_unbind(struct usb_composite_dev *dev)
 {
 	usb_put_function(f_midi);
 	usb_put_function_instance(fi_midi);
@@ -133,7 +133,7 @@ static struct usb_configuration midi_config = {
 	.MaxPower	= CONFIG_USB_GADGET_VBUS_DRAW,
 };
 
-static int __init midi_bind_config(struct usb_configuration *c)
+static int midi_bind_config(struct usb_configuration *c)
 {
 	int status;
 
@@ -150,7 +150,7 @@ static int __init midi_bind_config(struct usb_configuration *c)
 	return 0;
 }
 
-static int __init midi_bind(struct usb_composite_dev *cdev)
+static int midi_bind(struct usb_composite_dev *cdev)
 {
 	struct f_midi_opts *midi_opts;
 	int status;
diff --git a/drivers/usb/gadget/legacy/hid.c b/drivers/usb/gadget/legacy/hid.c
index 614b06d..11de01b 100644
--- a/drivers/usb/gadget/legacy/hid.c
+++ b/drivers/usb/gadget/legacy/hid.c
@@ -106,7 +106,7 @@ static struct usb_gadget_strings *dev_strings[] = {
 
 /****************************** Configurations ******************************/
 
-static int __init do_config(struct usb_configuration *c)
+static int do_config(struct usb_configuration *c)
 {
 	struct hidg_func_node *e, *n;
 	int status = 0;
@@ -147,7 +147,7 @@ static struct usb_configuration config_driver = {
 
 /****************************** Gadget Bind ******************************/
 
-static int __init hid_bind(struct usb_composite_dev *cdev)
+static int hid_bind(struct usb_composite_dev *cdev)
 {
 	struct usb_gadget *gadget = cdev->gadget;
 	struct list_head *tmp;
@@ -205,7 +205,7 @@ put:
 	return status;
 }
 
-static int __exit hid_unbind(struct usb_composite_dev *cdev)
+static int hid_unbind(struct usb_composite_dev *cdev)
 {
 	struct hidg_func_node *n;
 
diff --git a/drivers/usb/gadget/legacy/mass_storage.c b/drivers/usb/gadget/legacy/mass_storage.c
index 8e27a8c..d169d43 100644
--- a/drivers/usb/gadget/legacy/mass_storage.c
+++ b/drivers/usb/gadget/legacy/mass_storage.c
@@ -130,7 +130,7 @@ static int msg_thread_exits(struct fsg_common *common)
 	return 0;
 }
 
-static int __init msg_do_config(struct usb_configuration *c)
+static int msg_do_config(struct usb_configuration *c)
 {
 	struct fsg_opts *opts;
 	int ret;
@@ -170,7 +170,7 @@ static struct usb_configuration msg_config_driver = {
 
 /****************************** Gadget Bind ******************************/
 
-static int __init msg_bind(struct usb_composite_dev *cdev)
+static int msg_bind(struct usb_composite_dev *cdev)
 {
 	static const struct fsg_operations ops = {
 		.thread_exits = msg_thread_exits,
diff --git a/drivers/usb/gadget/legacy/multi.c b/drivers/usb/gadget/legacy/multi.c
index 39d27bb..4a4a1a1 100644
--- a/drivers/usb/gadget/legacy/multi.c
+++ b/drivers/usb/gadget/legacy/multi.c
@@ -149,7 +149,7 @@ static struct usb_function *f_acm_rndis;
 static struct usb_function *f_rndis;
 static struct usb_function *f_msg_rndis;
 
-static __init int rndis_do_config(struct usb_configuration *c)
+static int rndis_do_config(struct usb_configuration *c)
 {
 	struct fsg_opts *fsg_opts;
 	int ret;
@@ -206,7 +206,7 @@ err_func_rndis:
 	return ret;
 }
 
-static __ref int rndis_config_register(struct usb_composite_dev *cdev)
+static int rndis_config_register(struct usb_composite_dev *cdev)
 {
 	static struct usb_configuration config = {
 		.bConfigurationValue	= MULTI_RNDIS_CONFIG_NUM,
@@ -221,7 +221,7 @@ static __ref int rndis_config_register(struct usb_composite_dev *cdev)
 
 #else
 
-static __ref int rndis_config_register(struct usb_composite_dev *cdev)
+static int rndis_config_register(struct usb_composite_dev *cdev)
 {
 	return 0;
 }
@@ -237,7 +237,7 @@ static struct usb_function *f_acm_multi;
 static struct usb_function *f_ecm;
 static struct usb_function *f_msg_multi;
 
-static __init int cdc_do_config(struct usb_configuration *c)
+static int cdc_do_config(struct usb_configuration *c)
 {
 	struct fsg_opts *fsg_opts;
 	int ret;
@@ -295,7 +295,7 @@ err_func_ecm:
 	return ret;
 }
 
-static __ref int cdc_config_register(struct usb_composite_dev *cdev)
+static int cdc_config_register(struct usb_composite_dev *cdev)
 {
 	static struct usb_configuration config = {
 		.bConfigurationValue	= MULTI_CDC_CONFIG_NUM,
@@ -310,7 +310,7 @@ static __ref int cdc_config_register(struct usb_composite_dev *cdev)
 
 #else
 
-static __ref int cdc_config_register(struct usb_composite_dev *cdev)
+static int cdc_config_register(struct usb_composite_dev *cdev)
 {
 	return 0;
 }
@@ -321,7 +321,7 @@ static __ref int cdc_config_register(struct usb_composite_dev *cdev)
 
 /****************************** Gadget Bind ******************************/
 
-static int __ref multi_bind(struct usb_composite_dev *cdev)
+static int multi_bind(struct usb_composite_dev *cdev)
 {
 	struct usb_gadget *gadget = cdev->gadget;
 #ifdef CONFIG_USB_G_MULTI_CDC
@@ -466,7 +466,7 @@ fail:
 	return status;
 }
 
-static int __exit multi_unbind(struct usb_composite_dev *cdev)
+static int multi_unbind(struct usb_composite_dev *cdev)
 {
 #ifdef CONFIG_USB_G_MULTI_CDC
 	usb_put_function(f_msg_multi);
diff --git a/drivers/usb/gadget/legacy/ncm.c b/drivers/usb/gadget/legacy/ncm.c
index e90e23d..fb14e0c 100644
--- a/drivers/usb/gadget/legacy/ncm.c
+++ b/drivers/usb/gadget/legacy/ncm.c
@@ -107,7 +107,7 @@ static struct usb_function *f_ncm;
 
 /*-------------------------------------------------------------------------*/
 
-static int __init ncm_do_config(struct usb_configuration *c)
+static int ncm_do_config(struct usb_configuration *c)
 {
 	int status;
 
@@ -143,7 +143,7 @@ static struct usb_configuration ncm_config_driver = {
 
 /*-------------------------------------------------------------------------*/
 
-static int __init gncm_bind(struct usb_composite_dev *cdev)
+static int gncm_bind(struct usb_composite_dev *cdev)
 {
 	struct usb_gadget	*gadget = cdev->gadget;
 	struct f_ncm_opts	*ncm_opts;
@@ -186,7 +186,7 @@ fail:
 	return status;
 }
 
-static int __exit gncm_unbind(struct usb_composite_dev *cdev)
+static int gncm_unbind(struct usb_composite_dev *cdev)
 {
 	if (!IS_ERR_OR_NULL(f_ncm))
 		usb_put_function(f_ncm);
diff --git a/drivers/usb/gadget/legacy/nokia.c b/drivers/usb/gadget/legacy/nokia.c
index 9b8fd70..7ad8398 100644
--- a/drivers/usb/gadget/legacy/nokia.c
+++ b/drivers/usb/gadget/legacy/nokia.c
@@ -118,7 +118,7 @@ static struct usb_function_instance *fi_obex1;
 static struct usb_function_instance *fi_obex2;
 static struct usb_function_instance *fi_phonet;
 
-static int __init nokia_bind_config(struct usb_configuration *c)
+static int nokia_bind_config(struct usb_configuration *c)
 {
 	struct usb_function *f_acm;
 	struct usb_function *f_phonet = NULL;
@@ -224,7 +224,7 @@ err_get_acm:
 	return status;
 }
 
-static int __init nokia_bind(struct usb_composite_dev *cdev)
+static int nokia_bind(struct usb_composite_dev *cdev)
 {
 	struct usb_gadget	*gadget = cdev->gadget;
 	int			status;
@@ -307,7 +307,7 @@ err_usb:
 	return status;
 }
 
-static int __exit nokia_unbind(struct usb_composite_dev *cdev)
+static int nokia_unbind(struct usb_composite_dev *cdev)
 {
 	if (!IS_ERR_OR_NULL(f_obex1_cfg2))
 		usb_put_function(f_obex1_cfg2);
diff --git a/drivers/usb/gadget/legacy/printer.c b/drivers/usb/gadget/legacy/printer.c
index 9054598..da2a89b 100644
--- a/drivers/usb/gadget/legacy/printer.c
+++ b/drivers/usb/gadget/legacy/printer.c
@@ -1034,7 +1034,7 @@ unknown:
 	return value;
 }
 
-static int __init printer_func_bind(struct usb_configuration *c,
+static int printer_func_bind(struct usb_configuration *c,
 		struct usb_function *f)
 {
 	struct printer_dev *dev = container_of(f, struct printer_dev, function);
@@ -1162,7 +1162,7 @@ static struct usb_configuration printer_cfg_driver = {
 	.bmAttributes		= USB_CONFIG_ATT_ONE | USB_CONFIG_ATT_SELFPOWER,
 };
 
-static int __init printer_bind_config(struct usb_configuration *c)
+static int printer_bind_config(struct usb_configuration *c)
 {
 	struct usb_gadget	*gadget = c->cdev->gadget;
 	struct printer_dev	*dev;
@@ -1284,7 +1284,7 @@ static int printer_unbind(struct usb_composite_dev *cdev)
 	return 0;
 }
 
-static int __init printer_bind(struct usb_composite_dev *cdev)
+static int printer_bind(struct usb_composite_dev *cdev)
 {
 	int ret;
 
diff --git a/drivers/usb/gadget/legacy/serial.c b/drivers/usb/gadget/legacy/serial.c
index 1f5f978..812780f 100644
--- a/drivers/usb/gadget/legacy/serial.c
+++ b/drivers/usb/gadget/legacy/serial.c
@@ -174,7 +174,7 @@ out:
 	return ret;
 }
 
-static int __init gs_bind(struct usb_composite_dev *cdev)
+static int gs_bind(struct usb_composite_dev *cdev)
 {
 	int			status;
 
diff --git a/drivers/usb/gadget/legacy/webcam.c b/drivers/usb/gadget/legacy/webcam.c
index 04a3da2..d200ab4 100644
--- a/drivers/usb/gadget/legacy/webcam.c
+++ b/drivers/usb/gadget/legacy/webcam.c
@@ -334,7 +334,7 @@ static const struct uvc_descriptor_header * const uvc_ss_streaming_cls[] = {
  * USB configuration
  */
 
-static int __init
+static int
 webcam_config_bind(struct usb_configuration *c)
 {
 	int status = 0;
@@ -368,7 +368,7 @@ webcam_unbind(struct usb_composite_dev *cdev)
 	return 0;
 }
 
-static int __init
+static int
 webcam_bind(struct usb_composite_dev *cdev)
 {
 	struct f_uvc_opts *uvc_opts;
diff --git a/drivers/usb/gadget/legacy/zero.c b/drivers/usb/gadget/legacy/zero.c
index ff97ac9..f805bc2 100644
--- a/drivers/usb/gadget/legacy/zero.c
+++ b/drivers/usb/gadget/legacy/zero.c
@@ -289,7 +289,7 @@ static struct usb_function_instance *func_inst_lb;
 module_param_named(qlen, gzero_options.qlen, uint, S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(qlen, "depth of loopback queue");
 
-static int __init zero_bind(struct usb_composite_dev *cdev)
+static int zero_bind(struct usb_composite_dev *cdev)
 {
 	struct f_ss_opts	*ss_opts;
 	struct f_lb_opts	*lb_opts;
-- 
1.9.1

[PATCHv3 5/5] usb: gadget: udc-core: independent registration of gadgets and gadget drivers

[Ruslan Bilovol]

Change behavior during registration of gadgets and
gadget drivers in udc-core. Instead of previous
approach when for successful probe of usb gadget driver
at least one usb gadget should be already registered
use another one where gadget drivers and gadgets
can be registered in udc-core independently.

Independent registration of gadgets and gadget drivers
is useful for built-in into kernel gadget and gadget
driver case - because it's possible that gadget is
really probed only on late_init stage (due to deferred
probe) whereas gadget driver's probe is silently failed
on module_init stage due to no any UDC added.

Also it is useful for modules case - now there is no
difference what module to insert first: gadget module
or gadget driver one.

Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
---
 drivers/usb/gadget/udc/udc-core.c | 51 ++++++++++++++++++++++++++++++---------
 include/linux/usb/gadget.h        |  2 ++
 2 files changed, 42 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
index a960f3f..9e82497 100644
--- a/drivers/usb/gadget/udc/udc-core.c
+++ b/drivers/usb/gadget/udc/udc-core.c
@@ -48,8 +48,11 @@ struct usb_udc {
 
 static struct class *udc_class;
 static LIST_HEAD(udc_list);
+static LIST_HEAD(gadget_driver_pending_list);
 static DEFINE_MUTEX(udc_lock);
 
+static int udc_bind_to_driver(struct usb_udc *udc,
+					struct usb_gadget_driver *driver);
 /* ------------------------------------------------------------------------- */
 
 #ifdef	CONFIG_HAS_DMA
@@ -243,6 +246,7 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
 		void (*release)(struct device *dev))
 {
 	struct usb_udc		*udc;
+	struct usb_gadget_driver *pgadget;
 	int			ret = -ENOMEM;
 
 	udc = kzalloc(sizeof(*udc), GFP_KERNEL);
@@ -288,6 +292,18 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
 
 	usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);
 
+	/* pick up one of pending gadget drivers */
+	list_for_each_entry(pgadget, &gadget_driver_pending_list, pending) {
+		if (!pgadget->udc_name || strcmp(pgadget->udc_name,
+						dev_name(&udc->dev)) == 0) {
+			ret = udc_bind_to_driver(udc, pgadget);
+			if (ret)
+				goto err4;
+			list_del(&pgadget->pending);
+			break;
+		}
+	}
+
 	mutex_unlock(&udc_lock);
 
 	return 0;
@@ -364,10 +380,11 @@ found:
 	dev_vdbg(gadget->dev.parent, "unregistering gadget\n");
 
 	list_del(&udc->list);
-	mutex_unlock(&udc_lock);
-
-	if (udc->driver)
+	if (udc->driver) {
+		list_add(&udc->driver->pending, &gadget_driver_pending_list);
 		usb_gadget_remove_driver(udc);
+	}
+	mutex_unlock(&udc_lock);
 
 	kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
 	flush_work(&gadget->work);
@@ -426,24 +443,26 @@ int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
 			if (!ret)
 				break;
 		}
-		if (ret)
-			ret = -ENODEV;
-		else if (udc->driver)
-			ret = -EBUSY;
-		else
+		if (!ret && udc->driver) {
+			mutex_unlock(&udc_lock);
+			return -EBUSY;
+		} else if (!ret) {
 			goto found;
+		}
 	} else {
 		list_for_each_entry(udc, &udc_list, list) {
 			/* For now we take the first one */
 			if (!udc->driver)
 				goto found;
 		}
-		ret = -ENODEV;
 	}
 
-	pr_debug("couldn't find an available UDC\n");
+	list_add_tail(&driver->pending, &gadget_driver_pending_list);
+	pr_info("udc-core: couldn't find an available UDC "
+			"- added [%s] to list of pending drivers\n",
+			driver->function);
 	mutex_unlock(&udc_lock);
-	return ret;
+	return 0;
 found:
 	ret = udc_bind_to_driver(udc, driver);
 	mutex_unlock(&udc_lock);
@@ -469,6 +488,16 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
 			break;
 		}
 
+	if (ret) {
+		struct usb_gadget_driver *tmp;
+
+		list_for_each_entry(tmp, &gadget_driver_pending_list, pending)
+			if (tmp == driver) {
+				list_del(&driver->pending);
+				ret = 0;
+				break;
+			}
+	}
 	mutex_unlock(&udc_lock);
 	return ret;
 }
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 6070e8d..3878425 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -823,6 +823,7 @@ static inline int usb_gadget_disconnect(struct usb_gadget *gadget)
  * @driver: Driver model state for this driver.
  * @udc_name: A name of UDC this driver should be bound to. If udc_name is NULL,
  * 	this driver will be bound to any available UDC.
+ * @pending: UDC core private data used for deferred probe of this driver.
  *
  * Devices are disabled till a gadget driver successfully bind()s, which
  * means the driver will handle setup() requests needed to enumerate (and
@@ -885,6 +886,7 @@ struct usb_gadget_driver {
 	struct device_driver	driver;
 
 	char			*udc_name;
+	struct list_head	pending;
 };
 
 
-- 
1.9.1

Re: [PATCHv3 5/5] usb: gadget: udc-core: independent registration of gadgets and gadget drivers

[Alan Stern]

On Tue, 17 Feb 2015, Ruslan Bilovol wrote:

> Change behavior during registration of gadgets and
> gadget drivers in udc-core. Instead of previous
> approach when for successful probe of usb gadget driver
> at least one usb gadget should be already registered
> use another one where gadget drivers and gadgets
> can be registered in udc-core independently.
> 
> Independent registration of gadgets and gadget drivers
> is useful for built-in into kernel gadget and gadget
> driver case - because it's possible that gadget is
> really probed only on late_init stage (due to deferred
> probe) whereas gadget driver's probe is silently failed
> on module_init stage due to no any UDC added.
> 
> Also it is useful for modules case - now there is no
> difference what module to insert first: gadget module
> or gadget driver one.
> 
> Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
> ---
>  drivers/usb/gadget/udc/udc-core.c | 51 ++++++++++++++++++++++++++++++---------
>  include/linux/usb/gadget.h        |  2 ++
>  2 files changed, 42 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
> index a960f3f..9e82497 100644
> --- a/drivers/usb/gadget/udc/udc-core.c
> +++ b/drivers/usb/gadget/udc/udc-core.c
> @@ -48,8 +48,11 @@ struct usb_udc {
>  
>  static struct class *udc_class;
>  static LIST_HEAD(udc_list);
> +static LIST_HEAD(gadget_driver_pending_list);
>  static DEFINE_MUTEX(udc_lock);
>  
> +static int udc_bind_to_driver(struct usb_udc *udc,
> +					struct usb_gadget_driver *driver);

Strange indentation, not at all like the other continuation lines in 
this source file.

Also, there should be a blank line here, as in the original file.

>  /* ------------------------------------------------------------------------- */
>  
>  #ifdef	CONFIG_HAS_DMA
> @@ -243,6 +246,7 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
>  		void (*release)(struct device *dev))
>  {
>  	struct usb_udc		*udc;
> +	struct usb_gadget_driver *pgadget;

Don't call it "pgadget".  None of the other pointer variables in this 
file have an extra "p" added to the beginnings of their names.

>  	int			ret = -ENOMEM;
>  
>  	udc = kzalloc(sizeof(*udc), GFP_KERNEL);
> @@ -288,6 +292,18 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
>  
>  	usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);
>  
> +	/* pick up one of pending gadget drivers */
> +	list_for_each_entry(pgadget, &gadget_driver_pending_list, pending) {
> +		if (!pgadget->udc_name || strcmp(pgadget->udc_name,
> +						dev_name(&udc->dev)) == 0) {
> +			ret = udc_bind_to_driver(udc, pgadget);

Are you sure it's safe to call this routine while holding the udc_lock 
mutex?

> +			if (ret)
> +				goto err4;
> +			list_del(&pgadget->pending);

Use list_del_init().

> +			break;
> +		}
> +	}
> +
>  	mutex_unlock(&udc_lock);
>  
>  	return 0;
> @@ -364,10 +380,11 @@ found:
>  	dev_vdbg(gadget->dev.parent, "unregistering gadget\n");
>  
>  	list_del(&udc->list);
> -	mutex_unlock(&udc_lock);
> -
> -	if (udc->driver)
> +	if (udc->driver) {
> +		list_add(&udc->driver->pending, &gadget_driver_pending_list);
>  		usb_gadget_remove_driver(udc);

Are you sure it's safe to call this routine while holding the udc_lock
mutex?

> +	}
> +	mutex_unlock(&udc_lock);
>  
>  	kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
>  	flush_work(&gadget->work);
> @@ -426,24 +443,26 @@ int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
>  			if (!ret)
>  				break;
>  		}
> -		if (ret)
> -			ret = -ENODEV;
> -		else if (udc->driver)
> -			ret = -EBUSY;
> -		else
> +		if (!ret && udc->driver) {
> +			mutex_unlock(&udc_lock);
> +			return -EBUSY;

This is a judgement call.  It might be better to return 0 and add the 
gadget driver to the pending list.

> +		} else if (!ret) {
>  			goto found;
> +		}
>  	} else {
>  		list_for_each_entry(udc, &udc_list, list) {
>  			/* For now we take the first one */
>  			if (!udc->driver)
>  				goto found;
>  		}
> -		ret = -ENODEV;
>  	}
>  
> -	pr_debug("couldn't find an available UDC\n");
> +	list_add_tail(&driver->pending, &gadget_driver_pending_list);
> +	pr_info("udc-core: couldn't find an available UDC "
> +			"- added [%s] to list of pending drivers\n",
> +			driver->function);
>  	mutex_unlock(&udc_lock);
> -	return ret;
> +	return 0;
>  found:

Call list_init(&driver->pending) here.  Or at the start of this 
routine, if you prefer.

>  	ret = udc_bind_to_driver(udc, driver);
>  	mutex_unlock(&udc_lock);
> @@ -469,6 +488,16 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
>  			break;
>  		}
>  
> +	if (ret) {
> +		struct usb_gadget_driver *tmp;
> +
> +		list_for_each_entry(tmp, &gadget_driver_pending_list, pending)
> +			if (tmp == driver) {
> +				list_del(&driver->pending);
> +				ret = 0;
> +				break;
> +			}
> +	}

If you add the list_init and list_del_init above, this loop won't be 
needed.  You can just call list_del.

Alan Stern

Re: [PATCHv3 1/5] usb: gadget: bind UDC by name passed via usb_gadget_driver structure

[Sergei Shtylyov]

Hello.

On 2/18/2015 12:17 AM, Ruslan Bilovol wrote:

> Introduce new 'udc_name' member to usb_gadget_driver structure.
> The 'udc_name' is a name of UDC that usb_gadget_driver should
> be bound to. If udc_name is NULL, it will be bound to any
> available UDC.

> Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
> ---
>   drivers/usb/gadget/udc/udc-core.c | 25 ++++++++++++++++++++-----
>   include/linux/usb/gadget.h        |  4 ++++
>   2 files changed, 24 insertions(+), 5 deletions(-)

> diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
> index 5a81cb0..e1079e08 100644
> --- a/drivers/usb/gadget/udc/udc-core.c
> +++ b/drivers/usb/gadget/udc/udc-core.c
> @@ -440,21 +440,36 @@ EXPORT_SYMBOL_GPL(usb_udc_attach_driver);
>   int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
>   {
>   	struct usb_udc		*udc = NULL;
> -	int			ret;
> +	int			ret = -ENODEV;
>
>   	if (!driver || !driver->bind || !driver->setup)
>   		return -EINVAL;
>
>   	mutex_lock(&udc_lock);
> -	list_for_each_entry(udc, &udc_list, list) {
> -		/* For now we take the first one */
> -		if (!udc->driver)
> +	if (driver->udc_name) {
> +		list_for_each_entry(udc, &udc_list, list) {
> +			ret = strcmp(driver->udc_name, dev_name(&udc->dev));
> +			if (!ret)
> +				break;
> +		}
> +		if (ret)
> +			ret = -ENODEV;
> +		else if (udc->driver)
> +			ret = -EBUSY;
> +		else
>   			goto found;
> +	} else {
> +		list_for_each_entry(udc, &udc_list, list) {
> +			/* For now we take the first one */
> +			if (!udc->driver)
> +				goto found;
> +		}
> +		ret = -ENODEV;

    Already assigned the same value by the initializer.

>   	}
>
>   	pr_debug("couldn't find an available UDC\n");
>   	mutex_unlock(&udc_lock);
> -	return -ENODEV;
> +	return ret;
>   found:
>   	ret = udc_bind_to_driver(udc, driver);
>   	mutex_unlock(&udc_lock);
[...]

WBR, Sergei

Re: [PATCHv3 5/5] usb: gadget: udc-core: independent registration of gadgets and gadget drivers

[Ruslan Bilovol]

Hi Alan,

On Tue, Feb 17, 2015 at 11:51 PM, Alan Stern <stern@rowland.harvard.edu> wrote:
> On Tue, 17 Feb 2015, Ruslan Bilovol wrote:
>
>> Change behavior during registration of gadgets and
>> gadget drivers in udc-core. Instead of previous
>> approach when for successful probe of usb gadget driver
>> at least one usb gadget should be already registered
>> use another one where gadget drivers and gadgets
>> can be registered in udc-core independently.
>>
>> Independent registration of gadgets and gadget drivers
>> is useful for built-in into kernel gadget and gadget
>> driver case - because it's possible that gadget is
>> really probed only on late_init stage (due to deferred
>> probe) whereas gadget driver's probe is silently failed
>> on module_init stage due to no any UDC added.
>>
>> Also it is useful for modules case - now there is no
>> difference what module to insert first: gadget module
>> or gadget driver one.
>>
>> Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
>> ---
>>  drivers/usb/gadget/udc/udc-core.c | 51 ++++++++++++++++++++++++++++++---------
>>  include/linux/usb/gadget.h        |  2 ++
>>  2 files changed, 42 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
>> index a960f3f..9e82497 100644
>> --- a/drivers/usb/gadget/udc/udc-core.c
>> +++ b/drivers/usb/gadget/udc/udc-core.c
>> @@ -48,8 +48,11 @@ struct usb_udc {
>>
>>  static struct class *udc_class;
>>  static LIST_HEAD(udc_list);
>> +static LIST_HEAD(gadget_driver_pending_list);
>>  static DEFINE_MUTEX(udc_lock);
>>
>> +static int udc_bind_to_driver(struct usb_udc *udc,
>> +                                     struct usb_gadget_driver *driver);
>
> Strange indentation, not at all like the other continuation lines in
> this source file.
>
> Also, there should be a blank line here, as in the original file.

Will fix it

>
>>  /* ------------------------------------------------------------------------- */
>>
>>  #ifdef       CONFIG_HAS_DMA
>> @@ -243,6 +246,7 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
>>               void (*release)(struct device *dev))
>>  {
>>       struct usb_udc          *udc;
>> +     struct usb_gadget_driver *pgadget;
>
> Don't call it "pgadget".  None of the other pointer variables in this
> file have an extra "p" added to the beginnings of their names.

It seems this name is confusing (it is intended to have "pending
gadget" meaning). Will change it in next patch version

>
>>       int                     ret = -ENOMEM;
>>
>>       udc = kzalloc(sizeof(*udc), GFP_KERNEL);
>> @@ -288,6 +292,18 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
>>
>>       usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);
>>
>> +     /* pick up one of pending gadget drivers */
>> +     list_for_each_entry(pgadget, &gadget_driver_pending_list, pending) {
>> +             if (!pgadget->udc_name || strcmp(pgadget->udc_name,
>> +                                             dev_name(&udc->dev)) == 0) {
>> +                     ret = udc_bind_to_driver(udc, pgadget);
>
> Are you sure it's safe to call this routine while holding the udc_lock
> mutex?

Yes, it's safe here, in the only place where it was used before
this routine is also called while holding the udc_lock mutex
(see usb_gadget_probe_driver)

>
>> +                     if (ret)
>> +                             goto err4;
>> +                     list_del(&pgadget->pending);
>
> Use list_del_init().
>
>> +                     break;
>> +             }
>> +     }
>> +
>>       mutex_unlock(&udc_lock);
>>
>>       return 0;
>> @@ -364,10 +380,11 @@ found:
>>       dev_vdbg(gadget->dev.parent, "unregistering gadget\n");
>>
>>       list_del(&udc->list);
>> -     mutex_unlock(&udc_lock);
>> -
>> -     if (udc->driver)
>> +     if (udc->driver) {
>> +             list_add(&udc->driver->pending, &gadget_driver_pending_list);
>>               usb_gadget_remove_driver(udc);
>
> Are you sure it's safe to call this routine while holding the udc_lock
> mutex?

Should not be any issue here but it's possible to prevent this, will do it
in next patch version

>
>> +     }
>> +     mutex_unlock(&udc_lock);
>>
>>       kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
>>       flush_work(&gadget->work);
>> @@ -426,24 +443,26 @@ int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
>>                       if (!ret)
>>                               break;
>>               }
>> -             if (ret)
>> -                     ret = -ENODEV;
>> -             else if (udc->driver)
>> -                     ret = -EBUSY;
>> -             else
>> +             if (!ret && udc->driver) {
>> +                     mutex_unlock(&udc_lock);
>> +                     return -EBUSY;
>
> This is a judgement call.  It might be better to return 0 and add the
> gadget driver to the pending list.

Yes, that makes sense, will change it

>
>> +             } else if (!ret) {
>>                       goto found;
>> +             }
>>       } else {
>>               list_for_each_entry(udc, &udc_list, list) {
>>                       /* For now we take the first one */
>>                       if (!udc->driver)
>>                               goto found;
>>               }
>> -             ret = -ENODEV;
>>       }
>>
>> -     pr_debug("couldn't find an available UDC\n");
>> +     list_add_tail(&driver->pending, &gadget_driver_pending_list);
>> +     pr_info("udc-core: couldn't find an available UDC "
>> +                     "- added [%s] to list of pending drivers\n",
>> +                     driver->function);
>>       mutex_unlock(&udc_lock);
>> -     return ret;
>> +     return 0;
>>  found:
>
> Call list_init(&driver->pending) here.  Or at the start of this
> routine, if you prefer.
>
>>       ret = udc_bind_to_driver(udc, driver);
>>       mutex_unlock(&udc_lock);
>> @@ -469,6 +488,16 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
>>                       break;
>>               }
>>
>> +     if (ret) {
>> +             struct usb_gadget_driver *tmp;
>> +
>> +             list_for_each_entry(tmp, &gadget_driver_pending_list, pending)
>> +                     if (tmp == driver) {
>> +                             list_del(&driver->pending);
>> +                             ret = 0;
>> +                             break;
>> +                     }
>> +     }
>
> If you add the list_init and list_del_init above, this loop won't be
> needed.  You can just call list_del.

I disagree with this. This function is externally visible and we can't
guarantee that some buggy code will not call it with uninitialized
'pending' list_head. For example, if it never called usb_gadget_probe_driver()
but calls usb_gadget_unregister_driver().
As per my opinion it's better to check it and return -ENODEV rather than
fail on deleting of uninitialized list_head. In this case adding the list_init
and list_del_init above is not needed.

Best regards,
Ruslan

Re: [PATCHv3 1/5] usb: gadget: bind UDC by name passed via usb_gadget_driver structure

[Ruslan Bilovol]

Hi Sergei,

On Wed, Feb 18, 2015 at 2:05 PM, Sergei Shtylyov
<sergei.shtylyov@cogentembedded.com> wrote:
> Hello.
>
> On 2/18/2015 12:17 AM, Ruslan Bilovol wrote:
>
>> Introduce new 'udc_name' member to usb_gadget_driver structure.
>> The 'udc_name' is a name of UDC that usb_gadget_driver should
>> be bound to. If udc_name is NULL, it will be bound to any
>> available UDC.
>
>
>> Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
>> ---
>>   drivers/usb/gadget/udc/udc-core.c | 25 ++++++++++++++++++++-----
>>   include/linux/usb/gadget.h        |  4 ++++
>>   2 files changed, 24 insertions(+), 5 deletions(-)
>
>
>> diff --git a/drivers/usb/gadget/udc/udc-core.c
>> b/drivers/usb/gadget/udc/udc-core.c
>> index 5a81cb0..e1079e08 100644
>> --- a/drivers/usb/gadget/udc/udc-core.c
>> +++ b/drivers/usb/gadget/udc/udc-core.c
>> @@ -440,21 +440,36 @@ EXPORT_SYMBOL_GPL(usb_udc_attach_driver);
>>   int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
>>   {
>>         struct usb_udc          *udc = NULL;
>> -       int                     ret;
>> +       int                     ret = -ENODEV;
>>
>>         if (!driver || !driver->bind || !driver->setup)
>>                 return -EINVAL;
>>
>>         mutex_lock(&udc_lock);
>> -       list_for_each_entry(udc, &udc_list, list) {
>> -               /* For now we take the first one */
>> -               if (!udc->driver)
>> +       if (driver->udc_name) {
>> +               list_for_each_entry(udc, &udc_list, list) {
>> +                       ret = strcmp(driver->udc_name,
>> dev_name(&udc->dev));
>> +                       if (!ret)
>> +                               break;
>> +               }
>> +               if (ret)
>> +                       ret = -ENODEV;
>> +               else if (udc->driver)
>> +                       ret = -EBUSY;
>> +               else
>>                         goto found;
>> +       } else {
>> +               list_for_each_entry(udc, &udc_list, list) {
>> +                       /* For now we take the first one */
>> +                       if (!udc->driver)
>> +                               goto found;
>> +               }
>> +               ret = -ENODEV;
>
>
>    Already assigned the same value by the initializer.

Thanks for pointing to this, will be fixed in next patch version

>
>>         }
>>
>>         pr_debug("couldn't find an available UDC\n");
>>         mutex_unlock(&udc_lock);
>> -       return -ENODEV;
>> +       return ret;
>>   found:
>>         ret = udc_bind_to_driver(udc, driver);
>>         mutex_unlock(&udc_lock);
>
> [...]
>
> WBR, Sergei
>


Best regards,
Ruslan

Re: [PATCHv3 5/5] usb: gadget: udc-core: independent registration of gadgets and gadget drivers

[Alan Stern]

On Wed, 11 Mar 2015, Ruslan Bilovol wrote:

> Hi Alan,

Hello.

> > If you add the list_init and list_del_init above, this loop won't be
> > needed.  You can just call list_del.
> 
> I disagree with this. This function is externally visible and we can't
> guarantee that some buggy code will not call it with uninitialized
> 'pending' list_head. For example, if it never called usb_gadget_probe_driver()
> but calls usb_gadget_unregister_driver().
> As per my opinion it's better to check it and return -ENODEV rather than
> fail on deleting of uninitialized list_head. In this case adding the list_init
> and list_del_init above is not needed.

No, that is not the approach used in the rest of the kernel.  We _want_
to know about bugs, so we can fix them.  If you silently return -ENODEV
then nobody will realize anything is wrong, but a big fat WARN or OOPS
caused by an uninitialized list_head will draw people's attention very
quickly.

Alan Stern

Re: [PATCHv3 5/5] usb: gadget: udc-core: independent registration of gadgets and gadget drivers

[Felipe Balbi]

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Hi,

On Wed, Mar 11, 2015 at 02:21:38AM +0200, Ruslan Bilovol wrote:
> >> @@ -469,6 +488,16 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
> >>                       break;
> >>               }
> >>
> >> +     if (ret) {
> >> +             struct usb_gadget_driver *tmp;
> >> +
> >> +             list_for_each_entry(tmp, &gadget_driver_pending_list, pending)
> >> +                     if (tmp == driver) {
> >> +                             list_del(&driver->pending);
> >> +                             ret = 0;
> >> +                             break;
> >> +                     }
> >> +     }
> >
> > If you add the list_init and list_del_init above, this loop won't be
> > needed.  You can just call list_del.
> 
> I disagree with this. This function is externally visible and we can't
> guarantee that some buggy code will not call it with uninitialized
> 'pending' list_head. For example, if it never called usb_gadget_probe_driver()
> but calls usb_gadget_unregister_driver().

those cases deserve to suffer a really painfull and horrible death by
means of a kernel oops ;-) Sure, defensive programming and all, but at
some point we need to consider certain cases ridiculous and just not do
anything about them, so people know that they need more coffee and
attention while writing code.

-- 
balbi

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