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=-10.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 754D9C433FF for ; Tue, 13 Aug 2019 15:26:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4691D2184D for ; Tue, 13 Aug 2019 15:26:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565709961; bh=SucDibVqB1Y6XJo22ADJTrZr/i/5Mo/9zkyEYvRtiyo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=k8Z/xwsxgKF6JJicsKQKP4q7H1gX/t3jSKSGy+Pp/zLt1TZwwog6BNjiuMZARaje7 WkPgySPo3AVBH/ifQLwD3GT+4sk2+tawpzuk7hx3hmg000KEo3Tt4zpn1Q6+s8DcIY W47we0uLz7oCctj77ewPmPwSJUPeY1QPmjB5N5Og= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727177AbfHMP0B (ORCPT ); Tue, 13 Aug 2019 11:26:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:37354 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727035AbfHMP0A (ORCPT ); Tue, 13 Aug 2019 11:26:00 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 F20FA20663; Tue, 13 Aug 2019 15:25:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565709959; bh=SucDibVqB1Y6XJo22ADJTrZr/i/5Mo/9zkyEYvRtiyo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WDUzqsDwCUvJpPnUro5nrw2rYkWOE7CzVwQ6FTy1etS8EF51sHnkhLMPEqq0ROv4s zElsbAeuayJ7FJRXjRLsTGwhN3xN60ua/oV5CdMCYcFDyCPSZzAY+LdX2vCNO2Ooxf CYV16DXHVpzI/PVCFeMioa0zcbPqdhPHd9ogqzfo= Date: Tue, 13 Aug 2019 17:25:56 +0200 From: Greg Kroah-Hartman To: Joel Fernandes Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, kbuild test robot , Josh Triplett , Lai Jiangshan , linux-doc@vger.kernel.org, Mathieu Desnoyers , "Paul E. McKenney" , "Rafael J. Wysocki" , rcu@vger.kernel.org, Steven Rostedt Subject: Re: [PATCH v2] driver/core: Fix build error when SRCU and lockdep disabled Message-ID: <20190813152556.GA26138@kroah.com> References: <20190812214918.101756-1-joel@joelfernandes.org> <20190813060540.GE6670@kroah.com> <20190813133905.GA258732@google.com> <20190813134014.GB258732@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190813134014.GB258732@google.com> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Tue, Aug 13, 2019 at 09:40:14AM -0400, Joel Fernandes wrote: > On Tue, Aug 13, 2019 at 09:39:05AM -0400, Joel Fernandes wrote: > [snip] > > > > drivers/base/core.c | 4 +++- > > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/base/core.c b/drivers/base/core.c > > > > index 32cf83d1c744..c22271577c84 100644 > > > > --- a/drivers/base/core.c > > > > +++ b/drivers/base/core.c > > > > @@ -97,10 +97,12 @@ void device_links_read_unlock(int not_used) > > > > up_read(&device_links_lock); > > > > } > > > > > > > > +#ifdef CONFIG_DEBUG_LOCK_ALLOC > > > > int device_links_read_lock_held(void) > > > > { > > > > - return lock_is_held(&device_links_lock); > > > > + return lock_is_held(&(device_links_lock.dep_map)); > > > > } > > > > +#endif > > > > > > I don't know what the original code looks like here, but I'm guessing > > > that some .h file will need to be fixed up as you are just preventing > > > this function from ever being present without that option enabled? > > > > No, it doesn't. I already thought about that and it is not an issue. I know > > this may be confusing because the patch I am fixing is not yet in mainline > > but in -rcu dev branch, however I did CC you on that RCU patch before but > > understandably it is not in the series so it was harder to review. > > > > Let me explain, the lock checking facility that this patch uses is here: > > https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?h=dev&id=28875945ba98d1b47a8a706812b6494d165bb0a0 > > > > If you see, the CONFIG_PROVE_RCU_LIST defines an alternate __list_check_rcu() > > which is just a NOOP if CONFIG_PROVE_RCU_LIST=n. > > > > CONFIG_PROVE_RCU_LIST depends on CONFIG_PROVE_RCU which is def_bool on > > CONFIG_PROVE_LOCKING which selects CONFIG_DEBUG_LOCK_ALLOC. > > > > So there cannot be a scenario where CONFIG_PROVE_RCU_LIST is enabled but > > CONFIG_DEBUG_LOCK_ALLOC is disabled. > > > > To verify this, one could clone the RCU tree's dev branch and do this: > > > > Initially PROVE_RCU_LIST is not in config: > > > > joelaf@joelaf:~/repo/linux-master$ grep -i prove_rcu .config > > > > Neither is DEBUG_LOCK_ALLOC: > > > > joelaf@joelaf:~/repo/linux-master$ grep -i debug_lock .config > > # CONFIG_DEBUG_LOCK_ALLOC is not set > > > > Enable all configs: > > joelaf@joelaf:~/repo/linux-master$ ./scripts/config -e CONFIG_RCU_EXPERT > > joelaf@joelaf:~/repo/linux-master$ ./scripts/config -e CONFIG_PROVE_LOCKING > > joelaf@joelaf:~/repo/linux-master$ ./scripts/config -e CONFIG_PROVE_RCU > > joelaf@joelaf:~/repo/linux-master$ ./scripts/config -e CONFIG_PROVE_RCU_LIST > > joelaf@joelaf:~/repo/linux-master$ make olddefconfig > > > > DEBUG_LOCK_ALLOC shows up: > > > > joelaf@joelaf:~/repo/linux-master$ grep -i debug_lock_all .config > > CONFIG_DEBUG_LOCK_ALLOC=y > > > > So does PROVE_RCU options: > > joelaf@joelaf:~/repo/linux-master$ grep -i prove_rcu .config > > CONFIG_PROVE_RCU=y > > CONFIG_PROVE_RCU_LIST=y > > > > Now, force disable DEBUG_LOCK_ALLOC: > > > > joelaf@joelaf:~/repo/linux-master$ ./scripts/config -d CONFIG_DEBUG_LOCK_ALLOC > > > > joelaf@joelaf:~/repo/linux-master$ make olddefconfig > > > > Options are still enabled: > > > > joelaf@joelaf:~/repo/linux-master$ grep -i debug_lock .config > > CONFIG_DEBUG_LOCK_ALLOC=y > > joelaf@joelaf:~/repo/linux-master$ grep -i prove_rcu .config > > CONFIG_PROVE_RCU=y > > CONFIG_PROVE_RCU_LIST=y > > Also, appreciate if you could Ack the fix ;-) (assuming the newlines in > commit message are fixed). I don't know enough here to ack it, given that I can't even remember the original patch... If you think it's ok, that's fine with me, you can deal with the fallout if it fails later :) thanks, greg k-h