From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88FDBC2D0A3 for ; Mon, 9 Nov 2020 12:47:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2569920789 for ; Mon, 9 Nov 2020 12:47:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604926055; bh=SIRMlvmwB2mNeabU8oM4DitYG6gk6nl+hbQznjihnKY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Qfi3UdlAzpqkQwAEOZQKFRK1gOHiLAvnJ2apUCIedN94S1hjgxxwv3kAelxG+Ix2n 1jwcStN80tOSbhl5/Hk3WUKklCb30d1YEoSCXTrlPH1WGPMPUskmG+mlVYijIBXZ0n iAoNV80PrnECaROunhrPrAPIElbxflzxezxCrakg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729697AbgKIMrb (ORCPT ); Mon, 9 Nov 2020 07:47:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:48920 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727311AbgKIMrE (ORCPT ); Mon, 9 Nov 2020 07:47:04 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C171D207BC; Mon, 9 Nov 2020 12:47:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604926022; bh=SIRMlvmwB2mNeabU8oM4DitYG6gk6nl+hbQznjihnKY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=IzfQu+yxsqxjOncONaSKv1vV7DLcRV+IXIVDsKUEsJCyv69xKzdO4EWxTJpyB7Y8u DOgVPVbDN0PEncLxZgWL+WGY0mpX3b0RK/DxaI2D9lopcVZDzz4U8PGl5TgQiVmr2w +QLwbg4n4OLPp/J9DHh3TIJwgW/ccx3vR7dhfol4= Date: Mon, 9 Nov 2020 13:48:01 +0100 From: Greg Kroah-Hartman To: Aisheng Dong Cc: Sudip Mukherjee , "Rafael J . Wysocki" , linux-kernel , Shawn Guo , Stephen Boyd Subject: Re: [PATCH RESEND] driver core: export device_is_bound() to fix build failure Message-ID: <20201109124801.GA1890488@kroah.com> References: <20201107224727.11015-1-sudipm.mukherjee@gmail.com> <20201108082317.GA40741@kroah.com> <20201109103703.GA1310551@kroah.com> <20201109114125.GC1769924@kroah.com> <20201109120512.GB1832201@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 09, 2020 at 12:26:55PM +0000, Aisheng Dong wrote: > > From: Greg Kroah-Hartman > > Sent: Monday, November 9, 2020 8:05 PM > > > > On Mon, Nov 09, 2020 at 11:55:46AM +0000, Aisheng Dong wrote: > > > > From: Greg Kroah-Hartman > > > > Sent: Monday, November 9, 2020 7:41 PM > > > > > > > > On Mon, Nov 09, 2020 at 10:57:05AM +0000, Aisheng Dong wrote: > > > > > Hi Greg, > > > > > > > > > > > From: Greg Kroah-Hartman > > > > > > Sent: Monday, November 9, 2020 6:37 PM > > > > > > Subject: Re: [PATCH RESEND] driver core: export > > > > > > device_is_bound() to fix build failure > > > > > > > > > > > > On Mon, Nov 09, 2020 at 10:14:46AM +0000, Sudip Mukherjee wrote: > > > > > > > Hi Greg, > > > > > > > > > > > > > > On Sun, Nov 8, 2020 at 8:23 AM Greg Kroah-Hartman > > > > > > > wrote: > > > > > > > > > > > > > > > > On Sat, Nov 07, 2020 at 10:47:27PM +0000, Sudip Mukherjee wrote: > > > > > > > > > When CONFIG_MXC_CLK_SCU is configured as 'm' the build > > > > > > > > > fails as it is unable to find device_is_bound(). The error being: > > > > > > > > > ERROR: modpost: "device_is_bound" > > [drivers/clk/imx/clk-imx-scu.ko] > > > > > > > > > undefined! > > > > > > > > > > > > > > > > > > Export the symbol so that the module finds it. > > > > > > > > > > > > > > > > > > Fixes: 77d8f3068c63 ("clk: imx: scu: add two cells binding > > > > > > > > > support") > > > > > > > > > Signed-off-by: Sudip Mukherjee > > > > > > > > > > > > > > > > > > --- > > > > > > > > > > > > > > > > > > resending with the Fixes: tag. > > > > > > > > > > > > > > > > > > drivers/base/dd.c | 1 + > > > > > > > > > 1 file changed, 1 insertion(+) > > > > > > > > > > > > > > > > > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c index > > > > > > > > > 148e81969e04..a796a57e5efb 100644 > > > > > > > > > --- a/drivers/base/dd.c > > > > > > > > > +++ b/drivers/base/dd.c > > > > > > > > > @@ -353,6 +353,7 @@ bool device_is_bound(struct device *dev) > > { > > > > > > > > > return dev->p && > > > > > > > > > klist_node_attached(&dev->p->knode_driver); > > > > > > > > > } > > > > > > > > > +EXPORT_SYMBOL(device_is_bound); > > > > > > > > > > > > > > > > EXPORT_SYMBOL_GPL() please, like all the other exports in this file. > > > > > > > > > > > > > > > > Also, wait, no, don't call this, are you sure you are > > > > > > > > calling it in a race-free way? And what branch/tree is the above > > commit in? > > > > > > > > > > > > > > I have not checked fully but since it is being called from > > > > > > > probe() I assume the lock will be held at that time. > > > > > > > > > > > > probe() should never call this function as it makes no sense at > > > > > > all at that point in time. The driver should be fixed. > > > > > > > > > > Would you suggest if any other API we can use to allow the driver > > > > > to know whether another device has been probed? > > > > > > > > There is none, sorry, as that just opens up way too many problems. > > > > > > > > > For imx scu driver in question, it has a special requirement that > > > > > it depends on scu power domain driver. However, there're a huge > > > > > number > > > > > (200+) of power domains for each device clock, we can't define > > > > > them all in DT > > > > for a single clock controller node. > > > > > > > > > > That's why we wanted to use device_is_bound() before to check if > > > > > scu power domain is ready or not to support defer probe. > > > > > > > > Use the device link functionality for this type of thing, that is > > > > what it was created for. > > > > > > > > > > Thanks for the suggestion. I will check it how to use. > > > BTW, I wonder if dev_driver_string() could be an optional solution > > > which seems a more simple way? > > > > Also, how do you really know you even have a valid pointer to that other device > > structure? How are you getting access to that? > > > > The rough idea is as follows. Not sure if those APIs are safe enough as there're > many users In kernel. > > pd_np = of_find_compatible_node(NULL, NULL, "fsl,scu-pd"); > pd_dev = of_find_device_by_node(pd_np); > if (!pd_dev || !dev_driver_string(&pd_dev->dev) || > strcmp(dev_driver_string(&pd_dev->dev), "imx-scu-pd")) { > of_node_put(pd_np); > return -EPROBE_DEFER; > } Ick, again, no, don't do that, you can not guarantee "names" of devices anywhere in the system, sorry. greg k-h