From patchwork Thu Jun 8 20:45:15 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: 690831 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 79D28C7EE25 for ; Thu, 8 Jun 2023 20:45:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236509AbjFHUpZ (ORCPT ); Thu, 8 Jun 2023 16:45:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46888 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233520AbjFHUpY (ORCPT ); Thu, 8 Jun 2023 16:45:24 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B364D2D74 for ; Thu, 8 Jun 2023 13:45:21 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-568ab5c813eso13948147b3.2 for ; Thu, 08 Jun 2023 13:45:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1686257121; x=1688849121; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=vnoG17X4SR0Yr68DnHAZRjmH2ycNdwkX85eHutCEXPA=; b=UN/Iuh6A4ZSn2Srw/iO2/QubYI3z1NBUEPCiOwH2gXvKtbxgDMkJwJQ3fcr7lYMaS6 LRgUsrWvSHO13NXiH9E6FCY713p0mH4UD6phKd3HXqJm2EK1H6v4xP2sMNG0LkiHtk+i qdc2rvtqxhBrZt/vAZwTWMBKfQ/RLOzYINvXt795GjADbOfcB3Ly37ZVYeuBZDz4R7qO LENlFPhFhtZtw1uGFcNraCjatKtaQ8LVu81LBVrP9XK2PoiMxOQU+D62A1+LG842jH7D JCOU50sAWOiqTrv+RhqLhyXFYi2p3ZHBLG+b+Xb9fGNURYbw3afAIrJdf9EOkkyc3b6t 13yg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1686257121; x=1688849121; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=vnoG17X4SR0Yr68DnHAZRjmH2ycNdwkX85eHutCEXPA=; b=G1d3oWG/PEVIxKEEdN1DT/chciNaa3+HzX6Kjsw36M8dMlGqpPx4nivNNFAqn9tqaY NtWk36ZmX2O/NNs8Aka1iyDLqz0tDYrVEf1tDafRwjYmFYY7tv0p3uPujaulErhA5ftM +8196It9AnonPxUqX+WpA/kkJ9Qbu5l1aGC3pYJDnCCc3d7qL3TpXxFcjVJlcn8WeYn/ lOJ9nzSaO1q3YZwFcWEDInKOr+ybzc0sphHDmiC8mTY9KPR6vKZEJ28nKPVWLX00L3BK WWsRAIE2wImqKc7w5pTgfLts8ZZTppcCvSO3GG1S0URvTRHzwZ4t6iRtUth5drz+AgzW 7e/g== X-Gm-Message-State: AC+VfDyYrUge1E9hztLYBoDqrvRV6W3nxWcMiHA3w5lsO07dt0YLR3qh YOBwFZf9hlB5WIDY+G3BIIY426NFUBE= X-Google-Smtp-Source: ACHHUZ7uhwjynCVEVzqwdWP8vaJWg7hx84JcFomCDllbBtoGac7XAtCG6fQcADbdP5cT0fgiYf6v3PXmguI= X-Received: from badhri.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:6442]) (user=badhri job=sendgmr) by 2002:a81:a7c9:0:b0:569:8603:577 with SMTP id e192-20020a81a7c9000000b0056986030577mr505740ywh.4.1686257120940; Thu, 08 Jun 2023 13:45:20 -0700 (PDT) Date: Thu, 8 Jun 2023 20:45:15 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.41.0.162.gfafddb0af9-goog Message-ID: <20230608204517.105396-1-badhri@google.com> Subject: [PATCH v7 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() Changes since v6: - Added reviewed by tag --- drivers/usb/gadget/udc/core.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) base-commit: d37537a1f7cf09e304fe7993cb5e732534a0fb22 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)