chipidea udc calls usb_udc_vbus_handler from udc_start gadget ops causing a deadlock. Avoid this by offloading usb_udc_vbus_handler processing.
============================================ WARNING: possible recursive locking detected 640-rc1-000-devel-00005-gcda3c69ebc14 #1 Not tainted -------------------------------------------
CPU0 ---- lock(&udc->connect_lock); lock(&udc->connect_lock);
DEADLOCK
stack backtrace: CPU: 1 PID: 566 Comm: echo Not tainted 640-rc1-000-devel-00005-gcda3c69ebc14 #1 Hardware name: Freescale iMX7 Dual (Device Tree) unwind_backtrace from show_stack+0x10/0x14 show_stack from dump_stack_lvl+0x70/0xb0 dump_stack_lvl from __lock_acquire+0x924/0x22c4 __lock_acquire from lock_acquire+0x100/0x370 lock_acquire from __mutex_lock+0xa8/0xfb4 __mutex_lock from mutex_lock_nested+0x1c/0x24 mutex_lock_nested from usb_udc_vbus_handler+0x1c/0x60 usb_udc_vbus_handler from ci_udc_start+0x74/0x9c ci_udc_start from gadget_bind_driver+0x130/0x230 gadget_bind_driver from really_probe+0xd8/0x3fc really_probe from __driver_probe_device+0x94/0x1f0 __driver_probe_device from driver_probe_device+0x2c/0xc4 driver_probe_device from __driver_attach+0x114/0x1cc __driver_attach from bus_for_each_dev+0x7c/0xcc bus_for_each_dev from bus_add_driver+0xd4/0x200 bus_add_driver from driver_register+0x7c/0x114 driver_register from usb_gadget_register_driver_owner+0x40/0xe0 usb_gadget_register_driver_owner from gadget_dev_desc_UDC_store+0xd4/0x110 gadget_dev_desc_UDC_store from configfs_write_iter+0xac/0x118 configfs_write_iter from vfs_write+0x1b4/0x40c vfs_write from ksys_write+0x70/0xf8 ksys_write from ret_fast_syscall+0x0/0x1c
Fixes: 0db213ea8eed ("Revert "Revert "usb: gadget: udc: core: Prevent redundant calls to pullup""") Cc: stable@vger.kernel.org Reported-by: Stephan Gerhold stephan@gerhold.net Closes: https://lore.kernel.org/all/ZF4bMptC3Lf2Hnee@gerhold.net/ Reported-by: Francesco Dolcini francesco.dolcini@toradex.com Closes: https://lore.kernel.org/all/ZF4BvgsOyoKxdPFF@francesco-nb.int.toradex.com/ Reported-by: Alistair alistair@alistair23.me Closes: https://lore.kernel.org/lkml/0cf8c588b701d7cf25ffe1a9217b81716e6a5c51.camel@... Signed-off-by: Badhri Jagan Sridharan badhri@google.com --- Changes since v1: - Address Alan Stern's comment on usb_udc_vbus_handler invocation from atomic context: * vbus_events_lock is now a spinlock and allocations in * usb_udc_vbus_handler are atomic now.
Changes since v2: - Addressing Alan Stern's comments: ** connect_lock is now held by callers of * usb_gadget_pullup_update_locked() and gadget_(un)bind_driver() does * notdirectly hold the lock.
** Both usb_gadget_(dis)connect() and usb_udc_vbus_handler() would * set/clear udc->vbus and invoke usb_gadget_pullup_update_locked.
** Add "unbinding" to prevent new connections after the gadget is being * unbound. --- drivers/usb/gadget/udc/core.c | 269 ++++++++++++++++------------------ 1 file changed, 124 insertions(+), 145 deletions(-)
diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c index 4641153e9706..2aa914a0a195 100644 --- a/drivers/usb/gadget/udc/core.c +++ b/drivers/usb/gadget/udc/core.c @@ -38,9 +38,10 @@ static const struct bus_type gadget_bus_type; * 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. + * functions. usb_gadget_pullup_update_locked called with this lock held. + * @vbus_events: list head for processing vbus updates on usb_udc_vbus_handler. + * @vbus_events_lock: protects vbus_events list + * @vbus_work: work item that invokes usb_gadget_pullup_update_locked. * * This represents the internal data structure which is used by the UDC-class * to hold information about udc driver and gadget together. @@ -53,6 +54,20 @@ struct usb_udc { bool vbus; bool started; struct mutex connect_lock; + struct list_head vbus_events; + spinlock_t vbus_events_lock; + struct work_struct vbus_work; + bool unbinding; +}; + +/** + * struct vbus_event - used to notify vbus updates posted through usb_udc_vbus_handler. + * @vbus_on: true when vbus is on. false other wise. + * @node: list node for maintaining a list of pending updates to be processed. + */ +struct vbus_event { + bool vbus_on; + struct list_head node; };
static struct class *udc_class; @@ -693,40 +708,46 @@ int usb_gadget_vbus_disconnect(struct usb_gadget *gadget) EXPORT_SYMBOL_GPL(usb_gadget_vbus_disconnect);
/* Internal version of usb_gadget_connect needs to be called with connect_lock held. */ -static int usb_gadget_connect_locked(struct usb_gadget *gadget) +static int usb_gadget_pullup_update_locked(struct usb_gadget *gadget) __must_hold(&gadget->udc->connect_lock) { int ret = 0; + bool connect = !gadget->deactivated && gadget->udc->started && gadget->udc->vbus && + !gadget->udc->unbinding;
if (!gadget->ops->pullup) { ret = -EOPNOTSUPP; goto out; }
- if (gadget->connected) - goto out; - - 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; + if (connect != gadget->connected) { + ret = gadget->ops->pullup(gadget, connect); + if (!ret) + gadget->connected = connect; + mutex_lock(&udc_lock); + if (!connect) + gadget->udc->driver->disconnect(gadget); + mutex_unlock(&udc_lock); }
- ret = gadget->ops->pullup(gadget, 1); - if (!ret) - gadget->connected = 1; - out: trace_usb_gadget_connect(gadget, ret);
return ret; }
+static int usb_gadget_set_vbus(struct usb_gadget *gadget, bool vbus) +{ + int ret; + + mutex_lock(&gadget->udc->connect_lock); + gadget->udc->vbus = vbus; + ret = usb_gadget_pullup_update_locked(gadget); + mutex_unlock(&gadget->udc->connect_lock); + + return ret; +} + /** * usb_gadget_connect - software-controlled connect to USB host * @gadget:the peripheral being connected @@ -739,56 +760,10 @@ static int usb_gadget_connect_locked(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; + return usb_gadget_set_vbus(gadget, true); } 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; - - if (!gadget->ops->pullup) { - ret = -EOPNOTSUPP; - goto out; - } - - if (!gadget->connected) - goto out; - - 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; - } - - ret = gadget->ops->pullup(gadget, 0); - if (!ret) - gadget->connected = 0; - - mutex_lock(&udc_lock); - if (gadget->udc->driver) - gadget->udc->driver->disconnect(gadget); - mutex_unlock(&udc_lock); - -out: - trace_usb_gadget_disconnect(gadget, ret); - - return ret; -} - /** * usb_gadget_disconnect - software-controlled disconnect from USB host * @gadget:the peripheral being disconnected @@ -803,16 +778,22 @@ static int usb_gadget_disconnect_locked(struct usb_gadget *gadget) * Returns zero on success, else negative errno. */ int usb_gadget_disconnect(struct usb_gadget *gadget) +{ + return usb_gadget_set_vbus(gadget, false); +} +EXPORT_SYMBOL_GPL(usb_gadget_disconnect); + +static int usb_gadget_set_deactivate(struct usb_gadget *gadget, bool deactivate) { int ret;
mutex_lock(&gadget->udc->connect_lock); - ret = usb_gadget_disconnect_locked(gadget); + gadget->deactivated = deactivate; + ret = usb_gadget_pullup_update_locked(gadget); mutex_unlock(&gadget->udc->connect_lock);
return ret; } -EXPORT_SYMBOL_GPL(usb_gadget_disconnect);
/** * usb_gadget_deactivate - deactivate function which is not ready to work @@ -829,26 +810,7 @@ int usb_gadget_deactivate(struct usb_gadget *gadget) { int ret = 0;
- if (gadget->deactivated) - goto out; - - mutex_lock(&gadget->udc->connect_lock); - if (gadget->connected) { - ret = usb_gadget_disconnect_locked(gadget); - if (ret) - goto unlock; - - /* - * If gadget was being connected before deactivation, we want - * to reconnect it in usb_gadget_activate(). - */ - gadget->connected = true; - } - gadget->deactivated = true; - -unlock: - mutex_unlock(&gadget->udc->connect_lock); -out: + ret = usb_gadget_set_deactivate(gadget, true); trace_usb_gadget_deactivate(gadget, ret);
return ret; @@ -868,21 +830,7 @@ int usb_gadget_activate(struct usb_gadget *gadget) { int ret = 0;
- if (!gadget->deactivated) - goto out; - - mutex_lock(&gadget->udc->connect_lock); - gadget->deactivated = false; - - /* - * If gadget has been connected before deactivation, or became connected - * while it was being deactivated, we call usb_gadget_connect(). - */ - if (gadget->connected) - ret = usb_gadget_connect_locked(gadget); - mutex_unlock(&gadget->udc->connect_lock); - -out: + ret = usb_gadget_set_deactivate(gadget, false); trace_usb_gadget_activate(gadget, ret);
return ret; @@ -1121,13 +1069,28 @@ EXPORT_SYMBOL_GPL(usb_gadget_set_state);
/* ------------------------------------------------------------------------- */
-/* Acquire connect_lock before calling this function. */ -static void usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock) +static void vbus_event_work(struct work_struct *work) { - if (udc->vbus && udc->started) - usb_gadget_connect_locked(udc->gadget); - else - usb_gadget_disconnect_locked(udc->gadget); + struct vbus_event *event, *n; + struct usb_udc *udc = container_of(work, struct usb_udc, vbus_work); + unsigned long flags; + + spin_lock_irqsave(&udc->vbus_events_lock, flags); + list_for_each_entry_safe(event, n, &udc->vbus_events, node) { + list_del(&event->node); + /* OK to drop the lock here as it suffice to syncrhronize udc->vbus_events node + * retrieval and deletion against usb_udc_vbus_handler. usb_udc_vbus_handler does + * list_add_tail so n would be the same even if the lock is dropped. + */ + spin_unlock_irqrestore(&udc->vbus_events_lock, flags); + mutex_lock(&udc->connect_lock); + udc->vbus = event->vbus_on; + usb_gadget_pullup_update_locked(udc->gadget); + kfree(event); + mutex_unlock(&udc->connect_lock); + spin_lock_irqsave(&udc->vbus_events_lock, flags); + } + spin_unlock_irqrestore(&udc->vbus_events_lock, flags); }
/** @@ -1141,14 +1104,26 @@ static void usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc */ void usb_udc_vbus_handler(struct usb_gadget *gadget, bool status) { - struct usb_udc *udc = gadget->udc; + struct usb_udc *udc; + struct vbus_event *vbus_event; + unsigned long flags;
- mutex_lock(&udc->connect_lock); - if (udc) { - udc->vbus = status; - usb_udc_connect_control_locked(udc); + //mutex_lock(&udc_lock); + if (!gadget || !gadget->udc) { + //mutex_unlock(&udc_lock); + return; } - mutex_unlock(&udc->connect_lock); + udc = gadget->udc; + + vbus_event = kzalloc(sizeof(*vbus_event), GFP_ATOMIC); + if (!vbus_event) + return; + + spin_lock_irqsave(&udc->vbus_events_lock, flags); + vbus_event->vbus_on = status; + list_add_tail(&vbus_event->node, &udc->vbus_events); + spin_unlock_irqrestore(&udc->vbus_events_lock, flags); + schedule_work(&udc->vbus_work); } EXPORT_SYMBOL_GPL(usb_udc_vbus_handler);
@@ -1170,7 +1145,7 @@ void usb_gadget_udc_reset(struct usb_gadget *gadget, EXPORT_SYMBOL_GPL(usb_gadget_udc_reset);
/** - * usb_gadget_udc_start_locked - tells usb device controller to start up + * usb_gadget_udc_start - 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 @@ -1181,11 +1156,8 @@ 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_locked(struct usb_udc *udc) - __must_hold(&udc->connect_lock) +static inline int usb_gadget_udc_start(struct usb_udc *udc) { int ret;
@@ -1194,15 +1166,17 @@ static inline int usb_gadget_udc_start_locked(struct usb_udc *udc) return -EBUSY; }
+ mutex_lock(&udc->connect_lock); ret = udc->gadget->ops->udc_start(udc->gadget, udc->driver); if (!ret) udc->started = true; + mutex_unlock(&udc->connect_lock);
return ret; }
/** - * usb_gadget_udc_stop_locked - tells usb device controller we don't need it anymore + * usb_gadget_udc_stop - 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 @@ -1211,19 +1185,18 @@ static inline int usb_gadget_udc_start_locked(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_locked(struct usb_udc *udc) - __must_hold(&udc->connect_lock) +static inline void usb_gadget_udc_stop(struct usb_udc *udc) { if (!udc->started) { dev_err(&udc->dev, "UDC had already stopped\n"); return; }
+ mutex_lock(&udc->connect_lock); udc->gadget->ops->udc_stop(udc->gadget); udc->started = false; + mutex_unlock(&udc->connect_lock); }
/** @@ -1362,6 +1335,7 @@ int usb_add_gadget(struct usb_gadget *gadget) if (!udc) goto error;
+ udc->unbinding = true; device_initialize(&udc->dev); udc->dev.release = usb_udc_release; udc->dev.class = udc_class; @@ -1375,6 +1349,9 @@ int usb_add_gadget(struct usb_gadget *gadget) udc->gadget = gadget; gadget->udc = udc; mutex_init(&udc->connect_lock); + INIT_LIST_HEAD(&udc->vbus_events); + spin_lock_init(&udc->vbus_events_lock); + INIT_WORK(&udc->vbus_work, vbus_event_work);
udc->started = false;
@@ -1474,6 +1451,17 @@ char *usb_get_gadget_udc_name(void) } EXPORT_SYMBOL_GPL(usb_get_gadget_udc_name);
+static int usb_gadget_set_unbinding(struct usb_udc *udc, bool status) +{ + int ret; + + mutex_lock(&udc->connect_lock); + udc->unbinding = status; + ret = usb_gadget_pullup_update_locked(udc->gadget); + mutex_unlock(&udc->connect_lock); + + return ret; +} /** * usb_add_gadget_udc - adds a new gadget to the udc class driver list * @parent: the parent device to this udc. Usually the controller @@ -1576,15 +1564,11 @@ static int gadget_bind_driver(struct device *dev) if (ret) goto err_bind;
- mutex_lock(&udc->connect_lock); - ret = usb_gadget_udc_start_locked(udc); - if (ret) { - mutex_unlock(&udc->connect_lock); + ret = usb_gadget_udc_start(udc); + if (ret) goto err_start; - } usb_gadget_enable_async_callbacks(udc); - usb_udc_connect_control_locked(udc); - mutex_unlock(&udc->connect_lock); + usb_gadget_set_unbinding(udc, false);
kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE); return 0; @@ -1615,14 +1599,13 @@ static void gadget_unbind_driver(struct device *dev)
kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
- mutex_lock(&udc->connect_lock); - usb_gadget_disconnect_locked(gadget); + usb_gadget_set_unbinding(udc, true); + cancel_work_sync(&udc->vbus_work); usb_gadget_disable_async_callbacks(udc); if (gadget->irq) synchronize_irq(gadget->irq); udc->driver->unbind(gadget); - usb_gadget_udc_stop_locked(udc); - mutex_unlock(&udc->connect_lock); + usb_gadget_udc_stop(udc);
mutex_lock(&udc_lock); driver->is_bound = false; @@ -1708,15 +1691,11 @@ static ssize_t soft_connect_store(struct device *dev, }
if (sysfs_streq(buf, "connect")) { - mutex_lock(&udc->connect_lock); - usb_gadget_udc_start_locked(udc); - usb_gadget_connect_locked(udc->gadget); - mutex_unlock(&udc->connect_lock); + usb_gadget_udc_start(udc); + usb_udc_vbus_handler(udc->gadget, true); } else if (sysfs_streq(buf, "disconnect")) { - mutex_lock(&udc->connect_lock); - usb_gadget_disconnect_locked(udc->gadget); - usb_gadget_udc_stop_locked(udc); - mutex_unlock(&udc->connect_lock); + usb_udc_vbus_handler(udc->gadget, false); + usb_gadget_udc_stop(udc); } else { dev_err(dev, "unsupported command '%s'\n", buf); ret = -EINVAL;