From patchwork Thu Jun 1 03:10:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Badhri Jagan Sridharan X-Patchwork-Id: 13262953 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE1AAC7EE23 for ; Thu, 1 Jun 2023 03:11:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229689AbjFADLH (ORCPT ); Wed, 31 May 2023 23:11:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230450AbjFADKn (ORCPT ); Wed, 31 May 2023 23:10:43 -0400 Received: from mail-pf1-x44a.google.com (mail-pf1-x44a.google.com [IPv6:2607:f8b0:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BCB77132 for ; Wed, 31 May 2023 20:10:32 -0700 (PDT) Received: by mail-pf1-x44a.google.com with SMTP id d2e1a72fcca58-64fa459504aso183777b3a.2 for ; Wed, 31 May 2023 20:10:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1685589032; x=1688181032; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=KsoozzYRQMf4DTV7Un2XyzrXR0h8VX0m8PvEcef8Os8=; b=s2eFhbqh/2IvjRDc8KIQSPuyQ6J5ZwW6l9E9NLOIq2GqpuBSxF5zR3tJ4DUtDZbq87 i8NjCRnLuA8HhVvGyEAuljqvZKl4QLR534im67oIaxyvyaRhfgKtzhD6mp/cmaKBPgD7 BdE0KyGvHhzFzcXLlSiqY87LHCK+nw/5V/UkyMXDdszMA6QYmViodVoywZoKKv4FaSHK 8P4Az9kMhMT+Cef6upLNNnBbkrum5bUTS96nXAJRIj32XiQfr7l/8BZIVFSgV26D0CM1 9ZwyY2EqJCwJGu7q0n9oppIUAg2u/LpEYEphkJY0HknoNYy14lgZMq+cjlwxQ3WbOqSy mB6A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685589032; x=1688181032; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=KsoozzYRQMf4DTV7Un2XyzrXR0h8VX0m8PvEcef8Os8=; b=aXYqLOYUMca+GYY4lUWypK3KR2jUk49dh50ldbw4rH8jbfmRpYY158YqAcNweV7LDw 8f+bPy6SJo3cYc8SJBRHcqFtiEa9Ur0L16wLAp7idlw6fre0tXxw3kQiapLrt29W+dEf T6x43aFBigLuUXtmmB77XCeIvdU9kQr6yTSeU3cAlITqrDa9vSM8WH6a+tx0WVDEwpJa +lxjKsso+3A4aKGV3nfs0Jn+Rg/7Z8Xv+fe7iIvT01D+6qwE1pxLXaJ1C5TLoTmryK7i F8FedO286hRuDtAU06v+m9llqNNclejqevvRoN0quHelqEQuyo7pla+DFl5wk7jw/P11 MUzQ== X-Gm-Message-State: AC+VfDy2+qqCIuHAfyonybvcVI7y2Vr6QR7LPprHFUOHaBk4G9Gv4YQu VB8xXFEKl7JEup+YQ6SIyBJ3mIRAXZA= X-Google-Smtp-Source: ACHHUZ7gv15vVvyt6AVxuBSl9wTIMQpxfH74C6zdoIq2tFxEAibMRAr0HV3DTIHnYZbc04YsHoQptbR6ok8= X-Received: from badhri.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:6442]) (user=badhri job=sendgmr) by 2002:a63:5946:0:b0:52c:b362:1895 with SMTP id j6-20020a635946000000b0052cb3621895mr1439104pgm.3.1685589032185; Wed, 31 May 2023 20:10:32 -0700 (PDT) Date: Thu, 1 Jun 2023 03:10:27 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.41.0.rc0.172.g3f132b7071-goog Message-ID: <20230601031028.544244-1-badhri@google.com> Subject: [PATCH v6 1/2] usb: gadget: udc: core: Offload usb_udc_vbus_handler processing From: Badhri Jagan Sridharan To: gregkh@linuxfoundation.org, stern@rowland.harvard.edu, colin.i.king@gmail.com, xuetao09@huawei.com, quic_eserrao@quicinc.com, water.zhangjiantao@huawei.com, peter.chen@freescale.com, balbi@ti.com, francesco@dolcini.it, alistair@alistair23.me, stephan@gerhold.net, bagasdotme@gmail.com, luca@z3ntu.xyz Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Badhri Jagan Sridharan Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org usb_udc_vbus_handler() can be invoked from interrupt context by irq handlers of the gadget drivers, however, usb_udc_connect_control() has to run in non-atomic context due to the following: a. Some of the gadget driver implementations expect the ->pullup callback to be invoked in non-atomic context. b. usb_gadget_disconnect() acquires udc_lock which is a mutex. Hence offload invocation of usb_udc_connect_control() to workqueue. UDC should not be pulled up unless gadget driver is bound. The new flag "allow_connect" is now set by gadget_bind_driver() and cleared by gadget_unbind_driver(). This prevents work item to pull up the gadget even if queued when the gadget driver is already unbound. Cc: stable@vger.kernel.org Fixes: 1016fc0c096c ("USB: gadget: Fix obscure lockdep violation for udc_mutex") Signed-off-by: Badhri Jagan Sridharan Reviewed-by: Alan Stern --- 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. Changes since v3: ** Made a minor cleanup which I missed to do in v3 in * usb_udc_vbus_handler(). Changes since v4: - Addressing Alan Stern's comments: ** usb_udc_vbus_handler() now offloads invocation of usb_udc_connect_control() * from workqueue. ** Dropped vbus_events list as this was redundant. Updating to the * latest value is suffice Changes since v5: - Addressing Alan Stern's comments: ** Squashed allow_connect logic to this patch. ** Fixed comment length to wrap at 76 ** Cancelling vbus_work in del_gadget() --- drivers/usb/gadget/udc/core.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) base-commit: 922c0cb578ac9104a22c11a093cc1e0575c35a39 diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c index 52e6d2e84e35..d2e4f78c53e3 100644 --- a/drivers/usb/gadget/udc/core.c +++ b/drivers/usb/gadget/udc/core.c @@ -37,6 +37,9 @@ static const 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. + * @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. * * This represents the internal data structure which is used by the UDC-class * to hold information about udc driver and gadget together. @@ -48,6 +51,8 @@ struct usb_udc { struct list_head list; bool vbus; bool started; + bool allow_connect; + struct work_struct vbus_work; }; static struct class *udc_class; @@ -706,7 +711,7 @@ int usb_gadget_connect(struct usb_gadget *gadget) goto out; } - if (gadget->deactivated) { + if (gadget->deactivated || !gadget->udc->allow_connect) { /* * If gadget is deactivated we only save new state. * Gadget will be connected automatically after activation. @@ -1086,6 +1091,13 @@ static void usb_udc_connect_control(struct usb_udc *udc) usb_gadget_disconnect(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); +} + /** * usb_udc_vbus_handler - updates the udc core vbus status, and try to * connect or disconnect gadget @@ -1094,6 +1106,14 @@ static void usb_udc_connect_control(struct usb_udc *udc) * * The udc driver calls it when it wants to connect or disconnect gadget * according to vbus status. + * + * This function can be invoked from interrupt context by irq handlers of + * the gadget drivers, however, usb_udc_connect_control() has to run in + * non-atomic context due to the following: + * a. Some of the gadget driver implementations expect the ->pullup + * callback to be invoked in non-atomic context. + * b. usb_gadget_disconnect() acquires udc_lock which is a mutex. + * Hence offload invocation of usb_udc_connect_control() to workqueue. */ void usb_udc_vbus_handler(struct usb_gadget *gadget, bool status) { @@ -1101,7 +1121,7 @@ void usb_udc_vbus_handler(struct usb_gadget *gadget, bool status) if (udc) { udc->vbus = status; - usb_udc_connect_control(udc); + schedule_work(&udc->vbus_work); } } EXPORT_SYMBOL_GPL(usb_udc_vbus_handler); @@ -1328,6 +1348,7 @@ int usb_add_gadget(struct usb_gadget *gadget) mutex_lock(&udc_lock); list_add_tail(&udc->list, &udc_list); mutex_unlock(&udc_lock); + INIT_WORK(&udc->vbus_work, vbus_event_work); ret = device_add(&udc->dev); if (ret) @@ -1459,6 +1480,7 @@ void usb_del_gadget(struct usb_gadget *gadget) flush_work(&gadget->work); device_del(&gadget->dev); ida_free(&gadget_id_numbers, gadget->id_number); + cancel_work_sync(&udc->vbus_work); device_unregister(&udc->dev); } EXPORT_SYMBOL_GPL(usb_del_gadget); @@ -1527,6 +1549,7 @@ static int gadget_bind_driver(struct device *dev) if (ret) goto err_start; usb_gadget_enable_async_callbacks(udc); + udc->allow_connect = true; usb_udc_connect_control(udc); kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE); @@ -1558,6 +1581,8 @@ static void gadget_unbind_driver(struct device *dev) kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE); + udc->allow_connect = false; + cancel_work_sync(&udc->vbus_work); usb_gadget_disconnect(gadget); usb_gadget_disable_async_callbacks(udc); if (gadget->irq)