From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.14]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8109A227E8B; Thu, 13 Feb 2025 11:25:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.14 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739445944; cv=none; b=HZnIhc1EZgKhSfkVRlT6dyEvEiug+oBPXJ628G/nEAEUcXWfDTPeiE+G6fPelzfcWf4aYcHsEZlyTpaV65FwX1m0rLnu7ZszChH5gb8nNNMvJDlPM+RDUxEiL5OPeqKYeASzoa2rV2D5CnkX0YnnahiD0I9hw9Sz3DciJZcmV80= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739445944; c=relaxed/simple; bh=EVAUuBDBMmfoOHTQ3D16fxtASQyPWClWKsW6lBNhEzg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=b/qCESuG1ZM8kQCVIgjesPwRNF20LWxao5ph4RSkmujTJG5mai0eHk1QsDTewmOopUVfeHnwirl0BzWx5CP7UkiO6mbTkmL/qg31YlC5OK5kNp63MEBRoK8oJA/RF3nF9Hms1+2/Pkv058p7J+SVrZuclHVj0JCoCCCjyF0EA0M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Rc5YUrNt; arc=none smtp.client-ip=198.175.65.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Rc5YUrNt" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1739445943; x=1770981943; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=EVAUuBDBMmfoOHTQ3D16fxtASQyPWClWKsW6lBNhEzg=; b=Rc5YUrNtSUxrPBtbJB2wQdLrnQpyYWvzOqxx1I9Za4CZpiTKdfdLywTE OHU8pSGumQhBq3fERmj1NBBkb3QqBE3cmV8lUmu5tm85owNJ/Ip/r8+06 4dd2q9ZazkHbRzj5Tpgog6Lj8h//DGxJB9Hq6ZQo7+x6ALn5gD7wZ4nig fu5bzlgUdgScH2L3Bw37uiEHPfR8xYPQNxR02RvU3ZCDqghWR3xQUN/FQ Q6AN/er2gJ7J3lZ7kTWT9KpBuuOUeEt6kzj4x5tRqR/BezMLFSLN9bGKd gew0A/KAZAVtVs36fs3s4hBMycfEVZ6WpXw3iwzCI4cZVv/KzE95soDcx A==; X-CSE-ConnectionGUID: f7hjgxBeRjCiItQq7oYKqQ== X-CSE-MsgGUID: zU49gNWfTeWfOB+tmEI/fQ== X-IronPort-AV: E=McAfee;i="6700,10204,11343"; a="43911389" X-IronPort-AV: E=Sophos;i="6.13,282,1732608000"; d="scan'208";a="43911389" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Feb 2025 03:25:42 -0800 X-CSE-ConnectionGUID: eASTbBQoRtKW+uWVNLxbOA== X-CSE-MsgGUID: e7u4gQZ2Rn6BPVjTgQ5C7Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,224,1728975600"; d="scan'208";a="112951902" Received: from kuha.fi.intel.com ([10.237.72.152]) by orviesa010.jf.intel.com with SMTP; 13 Feb 2025 03:25:39 -0800 Received: by kuha.fi.intel.com (sSMTP sendmail emulation); Thu, 13 Feb 2025 13:25:38 +0200 Date: Thu, 13 Feb 2025 13:25:38 +0200 From: Heikki Krogerus To: Elson Roy Serrao Cc: gregkh@linuxfoundation.org, xu.yang_2@nxp.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2] usb: roles: set switch registered flag early on Message-ID: References: <20250206193950.22421-1-quic_eserrao@quicinc.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250206193950.22421-1-quic_eserrao@quicinc.com> On Thu, Feb 06, 2025 at 11:39:50AM -0800, Elson Roy Serrao wrote: > The role switch registration and set_role() can happen in parallel as they > are invoked independent of each other. There is a possibility that a driver > might spend significant amount of time in usb_role_switch_register() API > due to the presence of time intensive operations like component_add() > which operate under common mutex. This leads to a time window after > allocating the switch and before setting the registered flag where the set > role notifications are dropped. Below timeline summarizes this behavior > > Thread1 | Thread2 > usb_role_switch_register() | > | | > ---> allocate switch | > | | > ---> component_add() | usb_role_switch_set_role() > | | | > | | --> Drop role notifications > | | since sw->registered > | | flag is not set. > | | > --->Set registered flag.| > > To avoid this, set the registered flag early on in the switch register > API. > > Fixes: b787a3e78175 ("usb: roles: don't get/set_role() when usb_role_switch is unregistered") > cc: stable@vger.kernel.org > Signed-off-by: Elson Roy Serrao Reviewed-by: Heikki Krogerus > --- > Changes in v2: > - Set the switch registered flag from the get-go as suggested by > Heikki. > - Modified subject line and commit next as per the new logic. > - Link to v1: https://lore.kernel.org/all/20250127230715.6142-1-quic_eserrao@quicinc.com/ > > drivers/usb/roles/class.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c > index c58a12c147f4..30482d4cf826 100644 > --- a/drivers/usb/roles/class.c > +++ b/drivers/usb/roles/class.c > @@ -387,8 +387,11 @@ usb_role_switch_register(struct device *parent, > dev_set_name(&sw->dev, "%s-role-switch", > desc->name ? desc->name : dev_name(parent)); > > + sw->registered = true; > + > ret = device_register(&sw->dev); > if (ret) { > + sw->registered = false; > put_device(&sw->dev); > return ERR_PTR(ret); > } > @@ -399,8 +402,6 @@ usb_role_switch_register(struct device *parent, > dev_warn(&sw->dev, "failed to add component\n"); > } > > - sw->registered = true; > - > /* TODO: Symlinks for the host port and the device controller. */ > > return sw; > -- > 2.17.1 -- heikki