usb: gadget: udc: core: Invoke usb_gadget_connect only when started

usb_udc_connect_control does not check to see if the udc has already
been started. This causes gadget->ops->pullup to be called through
usb_gadget_connect when invoked from usb_udc_vbus_handler even before
usb_gadget_udc_start is called. Guard this by checking for udc->started
in usb_udc_connect_control before invoking usb_gadget_connect.

Guarding udc->vbus, udc->started, gadget->connect, gadget->deactivate
related functions with connect_lock. usb_gadget_connect_locked,
usb_gadget_disconnect_locked, usb_udc_connect_control_locked,
usb_gadget_udc_start_locked, usb_gadget_udc_stop_locked are called with
this lock held as they can be simulataneously invoked from different code
paths.

Adding an additional check to make sure udc is started(udc->started)
before pullup callback is invoked.

Fixes: 628ef0d273a6 ("usb: udc: add usb_udc_vbus_handler")
Cc: stable@vger.kernel.org
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Link: https://lore.kernel.org/r/20230407030741.3163220-1-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 3dcbba7..af92c2e 100644 (file)
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -37,6 +37,10 @@ static struct bus_type gadget_bus_type;
  * @vbus: for udcs who care about vbus status, this value is real vbus status;
  * for udcs who do not care about vbus status, this value is always true
  * @started: the UDC's started state. True if the UDC had started.
+ * @connect_lock: protects udc->vbus, udc->started, gadget->connect, gadget->deactivate related
+ * functions. usb_gadget_connect_locked, usb_gadget_disconnect_locked,
+ * usb_udc_connect_control_locked, usb_gadget_udc_start_locked, usb_gadget_udc_stop_locked are
+ * called with this lock held.
  *
  * This represents the internal data structure which is used by the UDC-class
  * to hold information about udc driver and gadget together.
@@ -48,6 +52,7 @@ struct usb_udc {
        struct list_head                list;
        bool                            vbus;
        bool                            started;
+       struct mutex                    connect_lock;
 };
 
 static struct class *udc_class;
@@ -687,17 +692,9 @@ out:
 }
 EXPORT_SYMBOL_GPL(usb_gadget_vbus_disconnect);
 
-/**
- * usb_gadget_connect - software-controlled connect to USB host
- * @gadget:the peripheral being connected
- *
- * Enables the D+ (or potentially D-) pullup.  The host will start
- * enumerating this gadget when the pullup is active and a VBUS session
- * is active (the link is powered).
- *
- * Returns zero on success, else negative errno.
- */
-int usb_gadget_connect(struct usb_gadget *gadget)
+/* Internal version of usb_gadget_connect needs to be called with connect_lock held. */
+static int usb_gadget_connect_locked(struct usb_gadget *gadget)
+       __must_hold(&gadget->udc->connect_lock)
 {
        int ret = 0;
 
@@ -706,10 +703,12 @@ int usb_gadget_connect(struct usb_gadget *gadget)
                goto out;
        }
 
-       if (gadget->deactivated) {
+       if (gadget->deactivated || !gadget->udc->started) {
                /*
                 * If gadget is deactivated we only save new state.
                 * Gadget will be connected automatically after activation.
+                *
+                * udc first needs to be started before gadget can be pulled up.
                 */
                gadget->connected = true;
                goto out;
@@ -724,22 +723,32 @@ out:
 
        return ret;
 }
-EXPORT_SYMBOL_GPL(usb_gadget_connect);
 
 /**
- * usb_gadget_disconnect - software-controlled disconnect from USB host
- * @gadget:the peripheral being disconnected
- *
- * Disables the D+ (or potentially D-) pullup, which the host may see
- * as a disconnect (when a VBUS session is active).  Not all systems
- * support software pullup controls.
+ * usb_gadget_connect - software-controlled connect to USB host
+ * @gadget:the peripheral being connected
  *
- * Following a successful disconnect, invoke the ->disconnect() callback
- * for the current gadget driver so that UDC drivers don't need to.
+ * Enables the D+ (or potentially D-) pullup.  The host will start
+ * enumerating this gadget when the pullup is active and a VBUS session
+ * is active (the link is powered).
  *
  * Returns zero on success, else negative errno.
  */
-int usb_gadget_disconnect(struct usb_gadget *gadget)
+int usb_gadget_connect(struct usb_gadget *gadget)
+{
+       int ret;
+
+       mutex_lock(&gadget->udc->connect_lock);
+       ret = usb_gadget_connect_locked(gadget);
+       mutex_unlock(&gadget->udc->connect_lock);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(usb_gadget_connect);
+
+/* Internal version of usb_gadget_disconnect needs to be called with connect_lock held. */
+static int usb_gadget_disconnect_locked(struct usb_gadget *gadget)
+       __must_hold(&gadget->udc->connect_lock)
 {
        int ret = 0;
 
@@ -751,10 +760,12 @@ int usb_gadget_disconnect(struct usb_gadget *gadget)
        if (!gadget->connected)
                goto out;
 
-       if (gadget->deactivated) {
+       if (gadget->deactivated || !gadget->udc->started) {
                /*
                 * If gadget is deactivated we only save new state.
                 * Gadget will stay disconnected after activation.
+                *
+                * udc should have been started before gadget being pulled down.
                 */
                gadget->connected = false;
                goto out;
@@ -774,6 +785,30 @@ out:
 
        return ret;
 }
+
+/**
+ * usb_gadget_disconnect - software-controlled disconnect from USB host
+ * @gadget:the peripheral being disconnected
+ *
+ * Disables the D+ (or potentially D-) pullup, which the host may see
+ * as a disconnect (when a VBUS session is active).  Not all systems
+ * support software pullup controls.
+ *
+ * Following a successful disconnect, invoke the ->disconnect() callback
+ * for the current gadget driver so that UDC drivers don't need to.
+ *
+ * Returns zero on success, else negative errno.
+ */
+int usb_gadget_disconnect(struct usb_gadget *gadget)
+{
+       int ret;
+
+       mutex_lock(&gadget->udc->connect_lock);
+       ret = usb_gadget_disconnect_locked(gadget);
+       mutex_unlock(&gadget->udc->connect_lock);
+
+       return ret;
+}
 EXPORT_SYMBOL_GPL(usb_gadget_disconnect);
 
 /**
@@ -794,10 +829,11 @@ int usb_gadget_deactivate(struct usb_gadget *gadget)
        if (gadget->deactivated)
                goto out;
 
+       mutex_lock(&gadget->udc->connect_lock);
        if (gadget->connected) {
-               ret = usb_gadget_disconnect(gadget);
+               ret = usb_gadget_disconnect_locked(gadget);
                if (ret)
-                       goto out;
+                       goto unlock;
 
                /*
                 * If gadget was being connected before deactivation, we want
@@ -807,6 +843,8 @@ int usb_gadget_deactivate(struct usb_gadget *gadget)
        }
        gadget->deactivated = true;
 
+unlock:
+       mutex_unlock(&gadget->udc->connect_lock);
 out:
        trace_usb_gadget_deactivate(gadget, ret);
 
@@ -830,6 +868,7 @@ int usb_gadget_activate(struct usb_gadget *gadget)
        if (!gadget->deactivated)
                goto out;
 
+       mutex_lock(&gadget->udc->connect_lock);
        gadget->deactivated = false;
 
        /*
@@ -837,7 +876,8 @@ int usb_gadget_activate(struct usb_gadget *gadget)
         * while it was being deactivated, we call usb_gadget_connect().
         */
        if (gadget->connected)
-               ret = usb_gadget_connect(gadget);
+               ret = usb_gadget_connect_locked(gadget);
+       mutex_unlock(&gadget->udc->connect_lock);
 
 out:
        trace_usb_gadget_activate(gadget, ret);
@@ -1078,12 +1118,13 @@ EXPORT_SYMBOL_GPL(usb_gadget_set_state);
 
 /* ------------------------------------------------------------------------- */
 
-static void usb_udc_connect_control(struct usb_udc *udc)
+/* Acquire connect_lock before calling this function. */
+static void usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock)
 {
-       if (udc->vbus)
-               usb_gadget_connect(udc->gadget);
+       if (udc->vbus && udc->started)
+               usb_gadget_connect_locked(udc->gadget);
        else
-               usb_gadget_disconnect(udc->gadget);
+               usb_gadget_disconnect_locked(udc->gadget);
 }
 
 /**
@@ -1099,10 +1140,12 @@ void usb_udc_vbus_handler(struct usb_gadget *gadget, bool status)
 {
        struct usb_udc *udc = gadget->udc;
 
+       mutex_lock(&udc->connect_lock);
        if (udc) {
                udc->vbus = status;
-               usb_udc_connect_control(udc);
+               usb_udc_connect_control_locked(udc);
        }
+       mutex_unlock(&udc->connect_lock);
 }
 EXPORT_SYMBOL_GPL(usb_udc_vbus_handler);
 
@@ -1124,7 +1167,7 @@ void usb_gadget_udc_reset(struct usb_gadget *gadget,
 EXPORT_SYMBOL_GPL(usb_gadget_udc_reset);
 
 /**
- * usb_gadget_udc_start - tells usb device controller to start up
+ * usb_gadget_udc_start_locked - tells usb device controller to start up
  * @udc: The UDC to be started
  *
  * This call is issued by the UDC Class driver when it's about
@@ -1135,8 +1178,11 @@ EXPORT_SYMBOL_GPL(usb_gadget_udc_reset);
  * necessary to have it powered on.
  *
  * Returns zero on success, else negative errno.
+ *
+ * Caller should acquire connect_lock before invoking this function.
  */
-static inline int usb_gadget_udc_start(struct usb_udc *udc)
+static inline int usb_gadget_udc_start_locked(struct usb_udc *udc)
+       __must_hold(&udc->connect_lock)
 {
        int ret;
 
@@ -1153,7 +1199,7 @@ static inline int usb_gadget_udc_start(struct usb_udc *udc)
 }
 
 /**
- * usb_gadget_udc_stop - tells usb device controller we don't need it anymore
+ * usb_gadget_udc_stop_locked - tells usb device controller we don't need it anymore
  * @udc: The UDC to be stopped
  *
  * This call is issued by the UDC Class driver after calling
@@ -1162,8 +1208,11 @@ static inline int usb_gadget_udc_start(struct usb_udc *udc)
  * The details are implementation specific, but it can go as
  * far as powering off UDC completely and disable its data
  * line pullups.
+ *
+ * Caller should acquire connect lock before invoking this function.
  */
-static inline void usb_gadget_udc_stop(struct usb_udc *udc)
+static inline void usb_gadget_udc_stop_locked(struct usb_udc *udc)
+       __must_hold(&udc->connect_lock)
 {
        if (!udc->started) {
                dev_err(&udc->dev, "UDC had already stopped\n");
@@ -1322,6 +1371,7 @@ int usb_add_gadget(struct usb_gadget *gadget)
 
        udc->gadget = gadget;
        gadget->udc = udc;
+       mutex_init(&udc->connect_lock);
 
        udc->started = false;
 
@@ -1523,11 +1573,15 @@ static int gadget_bind_driver(struct device *dev)
        if (ret)
                goto err_bind;
 
-       ret = usb_gadget_udc_start(udc);
-       if (ret)
+       mutex_lock(&udc->connect_lock);
+       ret = usb_gadget_udc_start_locked(udc);
+       if (ret) {
+               mutex_unlock(&udc->connect_lock);
                goto err_start;
+       }
        usb_gadget_enable_async_callbacks(udc);
-       usb_udc_connect_control(udc);
+       usb_udc_connect_control_locked(udc);
+       mutex_unlock(&udc->connect_lock);
 
        kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
        return 0;
@@ -1558,12 +1612,14 @@ static void gadget_unbind_driver(struct device *dev)
 
        kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
 
-       usb_gadget_disconnect(gadget);
+       mutex_lock(&udc->connect_lock);
+       usb_gadget_disconnect_locked(gadget);
        usb_gadget_disable_async_callbacks(udc);
        if (gadget->irq)
                synchronize_irq(gadget->irq);
        udc->driver->unbind(gadget);
-       usb_gadget_udc_stop(udc);
+       usb_gadget_udc_stop_locked(udc);
+       mutex_unlock(&udc->connect_lock);
 
        mutex_lock(&udc_lock);
        driver->is_bound = false;
@@ -1649,11 +1705,15 @@ static ssize_t soft_connect_store(struct device *dev,
        }
 
        if (sysfs_streq(buf, "connect")) {
-               usb_gadget_udc_start(udc);
-               usb_gadget_connect(udc->gadget);
+               mutex_lock(&udc->connect_lock);
+               usb_gadget_udc_start_locked(udc);
+               usb_gadget_connect_locked(udc->gadget);
+               mutex_unlock(&udc->connect_lock);
        } else if (sysfs_streq(buf, "disconnect")) {
-               usb_gadget_disconnect(udc->gadget);
-               usb_gadget_udc_stop(udc);
+               mutex_lock(&udc->connect_lock);
+               usb_gadget_disconnect_locked(udc->gadget);
+               usb_gadget_udc_stop_locked(udc);
+               mutex_unlock(&udc->connect_lock);
        } else {
                dev_err(dev, "unsupported command '%s'\n", buf);
                ret = -EINVAL;