From: Badhri Jagan Sridharan badhri@google.com
commit 286d9975a838d0a54da049765fa1d1fb96b89682 upstream.
usb_udc_connect_control(), soft_connect_store() and usb_gadget_deactivate() can potentially race against each other to invoke usb_gadget_connect()/usb_gadget_disconnect(). To prevent this, guard udc->started, gadget->allow_connect, gadget->deactivate and gadget->connect with connect_lock so that ->pullup() is only invoked when the gadget is bound, started and not deactivated. The routines 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.
An earlier version of this commit was reverted due to the crash reported in https://lore.kernel.org/all/ZF4BvgsOyoKxdPFF@francesco-nb.int.toradex.com/. commit 16737e78d190 ("usb: gadget: udc: core: Offload usb_udc_vbus_handler processing") addresses the crash reported.
Cc: stable@vger.kernel.org Fixes: 628ef0d273a6 ("usb: udc: add usb_udc_vbus_handler") Signed-off-by: Badhri Jagan Sridharan badhri@google.com Reviewed-by: Alan Stern stern@rowland.harvard.edu Message-ID: 20230609010227.978661-2-badhri@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/gadget/udc/core.c | 155 ++++++++++++++++++++++++++++-------------- 1 file changed, 106 insertions(+), 49 deletions(-)
--- a/drivers/usb/gadget/udc/core.c +++ b/drivers/usb/gadget/udc/core.c @@ -40,6 +40,11 @@ static struct bus_type gadget_bus_type; * @allow_connect: Indicates whether UDC is allowed to be pulled up. * Set/cleared by gadget_(un)bind_driver() after gadget driver is bound or * unbound. + * @connect_lock: protects udc->started, gadget->connect, + * gadget->allow_connect and gadget->deactivate. The routines + * usb_gadget_connect_locked(), usb_gadget_disconnect_locked(), + * usb_udc_connect_control_locked(), usb_gadget_udc_start_locked() and + * 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. @@ -53,6 +58,7 @@ struct usb_udc { bool started; bool allow_connect; struct work_struct vbus_work; + struct mutex connect_lock; };
static struct class *udc_class; @@ -665,17 +671,8 @@ 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) +static int usb_gadget_connect_locked(struct usb_gadget *gadget) + __must_hold(&gadget->udc->connect_lock) { int ret = 0;
@@ -684,10 +681,12 @@ int usb_gadget_connect(struct usb_gadget goto out; }
- if (gadget->deactivated || !gadget->udc->allow_connect) { + if (gadget->deactivated || !gadget->udc->allow_connect || !gadget->udc->started) { /* - * If gadget is deactivated we only save new state. - * Gadget will be connected automatically after activation. + * If the gadget isn't usable (because it is deactivated, + * unbound, or not yet started), we only save the new state. + * The gadget will be connected automatically when it is + * activated/bound/started. */ gadget->connected = true; goto out; @@ -702,22 +701,31 @@ 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); + +static int usb_gadget_disconnect_locked(struct usb_gadget *gadget) + __must_hold(&gadget->udc->connect_lock) { int ret = 0;
@@ -729,7 +737,7 @@ int usb_gadget_disconnect(struct usb_gad 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. @@ -752,6 +760,30 @@ 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);
/** @@ -769,13 +801,14 @@ int usb_gadget_deactivate(struct usb_gad { int ret = 0;
+ mutex_lock(&gadget->udc->connect_lock); if (gadget->deactivated) - goto out; + goto unlock;
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 @@ -785,7 +818,8 @@ int usb_gadget_deactivate(struct usb_gad } gadget->deactivated = true;
-out: +unlock: + mutex_unlock(&gadget->udc->connect_lock); trace_usb_gadget_deactivate(gadget, ret);
return ret; @@ -805,8 +839,9 @@ int usb_gadget_activate(struct usb_gadge { int ret = 0;
+ mutex_lock(&gadget->udc->connect_lock); if (!gadget->deactivated) - goto out; + goto unlock;
gadget->deactivated = false;
@@ -815,9 +850,11 @@ int usb_gadget_activate(struct usb_gadge * 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: +unlock: + mutex_unlock(&gadget->udc->connect_lock); trace_usb_gadget_activate(gadget, ret);
return ret; @@ -1056,19 +1093,22 @@ 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); + usb_gadget_connect_locked(udc->gadget); else - usb_gadget_disconnect(udc->gadget); + usb_gadget_disconnect_locked(udc->gadget); }
static void vbus_event_work(struct work_struct *work) { struct usb_udc *udc = container_of(work, struct usb_udc, vbus_work);
- usb_udc_connect_control(udc); + mutex_lock(&udc->connect_lock); + usb_udc_connect_control_locked(udc); + mutex_unlock(&udc->connect_lock); }
/** @@ -1117,7 +1157,7 @@ void usb_gadget_udc_reset(struct usb_gad 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 @@ -1128,8 +1168,11 @@ 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;
@@ -1146,7 +1189,7 @@ static inline int usb_gadget_udc_start(s }
/** - * 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 @@ -1155,8 +1198,11 @@ static inline int usb_gadget_udc_start(s * 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"); @@ -1315,6 +1361,7 @@ int usb_add_gadget(struct usb_gadget *ga
udc->gadget = gadget; gadget->udc = udc; + mutex_init(&udc->connect_lock);
udc->started = false;
@@ -1518,12 +1565,16 @@ static int gadget_bind_driver(struct 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); udc->allow_connect = true; - 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; @@ -1556,12 +1607,14 @@ static void gadget_unbind_driver(struct
udc->allow_connect = false; cancel_work_sync(&udc->vbus_work); - 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; @@ -1647,11 +1700,15 @@ static ssize_t soft_connect_store(struct }
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;