From patchwork Wed May 31 04:02:01 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: 687664 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 F07D9C77B73 for ; Wed, 31 May 2023 04:02:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234030AbjEaECL (ORCPT ); Wed, 31 May 2023 00:02:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232344AbjEaECJ (ORCPT ); Wed, 31 May 2023 00:02:09 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 04A6BFC for ; Tue, 30 May 2023 21:02:08 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-ba81b37d9d2so9689858276.3 for ; Tue, 30 May 2023 21:02:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1685505727; x=1688097727; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=FRShDzU+m20ot9o4O+80g75qyx0AzeQfhVYqf4ZY7r8=; b=Ql0coGq15Pj7nTlxZq2f/RivqyjWmPolPYZ2HZFcuekbbm33jfO2dDe82WO2v1/qbk /0rAWbwAhOEAeLqo+DBjfOUetbwAHYSr6SCT7UNmRnoKrZhODAzGy6rozWxzB0GFfoeK LDoujjTAbvrWNyIgH5c/Pg613GMixADgkWZf5GXNLKoofc9DJ5AkH5wzAL4ppeN/yd+t jXSLlKA9RdamVar9TI4EUuLsUSNbXVZbkRRlZQXHZ5/1cF7c2TQfTlUVFQWn+Knn4T5T b93NBITM+3BHDI02S2hws83FjuuCzNBdhptgbJvPXHSzwhPWaFmO42Jl5l5KXThnr0Xz FRaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685505727; x=1688097727; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=FRShDzU+m20ot9o4O+80g75qyx0AzeQfhVYqf4ZY7r8=; b=RZ0Uod//ZDyS7wcl90kzqrbMbR28E9WUXm2oBoh2zwvYwG766DaCWFjZVMs+b3nmgo l9vnsEtugeWC+8XMKVHMZJr0ail+k4nhndRJKF8yVsniR2p+H72cOi7lnzfjsbCdET7d I08PzU9FBQgaV9ygnIKM1GtnZxE6aHc72zJprGdVS6B24mymPpoXbRVZaMQO2AlYHol0 kaf7wrWM12BKtj2JTZH90ErsyOYzwUBTaTcUfGrm0xg814FIJ4RIPOAhMxwRY+jRwp86 tIFii2mcDufTA5TGko6zN56hNZKTFGAbBIHe08WgCNgRykeAmKofBJRB0oOYRNwAy4Gb jQoA== X-Gm-Message-State: AC+VfDwQaMcCvGTwa11AL744nj13nQ9J0C6YdVJb6BOzzO2Yoi9y+dOp mKosmIAMIdAUwPkSVdqb5+tXWmuxgCk= X-Google-Smtp-Source: ACHHUZ4ub/AbluMPbZht6ZvhJeeDHG3ymN5X09VDEgsrBNofrc3dYiieroVxZdqj+lnI/TXtJaCBv3cEWgk= X-Received: from badhri.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:6442]) (user=badhri job=sendgmr) by 2002:a5b:14f:0:b0:bac:faf4:78fd with SMTP id c15-20020a5b014f000000b00bacfaf478fdmr1794911ybp.7.1685505727275; Tue, 30 May 2023 21:02:07 -0700 (PDT) Date: Wed, 31 May 2023 04:02:01 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.41.0.rc0.172.g3f132b7071-goog Message-ID: <20230531040203.19295-1-badhri@google.com> Subject: [PATCH v5 1/3] 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. Cc: stable@vger.kernel.org Fixes: 1016fc0c096c ("USB: gadget: Fix obscure lockdep violation for udc_mutex") Signed-off-by: Badhri Jagan Sridharan --- 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 --- drivers/usb/gadget/udc/core.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) base-commit: 046895105d9666ab56e86ce8dd9786f8003125c6 diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c index 52e6d2e84e35..44a9f32679b5 100644 --- a/drivers/usb/gadget/udc/core.c +++ b/drivers/usb/gadget/udc/core.c @@ -48,6 +48,7 @@ struct usb_udc { struct list_head list; bool vbus; bool started; + struct work_struct vbus_work; }; static struct class *udc_class; @@ -1086,6 +1087,13 @@ 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 +1102,13 @@ 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 +1116,7 @@ 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 +1343,7 @@ 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) @@ -1558,6 +1574,7 @@ static void gadget_unbind_driver(struct device *dev) kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE); + cancel_work_sync(&udc->vbus_work); usb_gadget_disconnect(gadget); usb_gadget_disable_async_callbacks(udc); if (gadget->irq)