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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 A8524C3A5A3 for ; Tue, 27 Aug 2019 22:55:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 73D6922CED for ; Tue, 27 Aug 2019 22:55:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566946528; bh=KNwArzVbNm8E/1uMq4N2WCFYXTVjp5rzpzUHm185bIg=; h=Subject:To:Cc:References:From:Date:In-Reply-To:List-ID:From; b=zkYUmS9S904R662dnJJhrguy7jjlGILBYXrMT3IGDj2Np/UaaMcZPEKvatgSMZwYu 1sRuGdX+KYdBS/Pd+VkY66Gnnu08CG7MppZGjgh/1KWvVJXq7LjcOBXPCko18oht6F VlckOoaXHH/HH04XxNNdZ2WEFVOQYm/c/D0ZjDaQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726078AbfH0WzY (ORCPT ); Tue, 27 Aug 2019 18:55:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:37396 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725835AbfH0WzX (ORCPT ); Tue, 27 Aug 2019 18:55:23 -0400 Received: from [192.168.1.112] (c-24-9-64-241.hsd1.co.comcast.net [24.9.64.241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 401C2217F5; Tue, 27 Aug 2019 22:55:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566946522; bh=KNwArzVbNm8E/1uMq4N2WCFYXTVjp5rzpzUHm185bIg=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=0Ri5y9DtZ6EwxRD84fFUzn9ouh1+D+xrBUkHCnkf+RGms/JIW1n3lbZpNjyz/dXDX lpGAIUgaQAyC7NrhyM56tpF5k6D4WguZrLIwerhB3tviHK60OgG9k1cPbVepSbzYjG q55XH/5YxHoZeZm2/jwVL8E/knU6InIoz8d74SAs= Subject: Re: [PATCH v1] kunit: fix failure to build without printk To: Brendan Higgins Cc: kunit-dev@googlegroups.com, Linux Kernel Mailing List , "open list:KERNEL SELFTEST FRAMEWORK" , Frank Rowand , Stephen Boyd , Randy Dunlap , Stephen Rothwell , shuah References: <20190827174932.44177-1-brendanhiggins@google.com> <10b44374-829d-0daa-8fb0-4450582cb40c@kernel.org> From: shuah Message-ID: <559233b8-cd29-189a-e63b-0f46ea9b6f83@kernel.org> Date: Tue, 27 Aug 2019 16:55:21 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On 8/27/19 4:16 PM, Brendan Higgins wrote: > On Tue, Aug 27, 2019 at 3:00 PM shuah wrote: >> >> On 8/27/19 3:36 PM, Brendan Higgins wrote: >>> On Tue, Aug 27, 2019 at 2:09 PM Brendan Higgins >>> wrote: >>>> >>>> On Tue, Aug 27, 2019 at 2:03 PM Brendan Higgins >>>> wrote: >>>>> >>>>> On Tue, Aug 27, 2019 at 1:21 PM shuah wrote: >>>>>> >>>>>> On 8/27/19 11:49 AM, Brendan Higgins wrote: >>>>>>> Previously KUnit assumed that printk would always be present, which is >>>>>>> not a valid assumption to make. Fix that by ifdefing out functions which >>>>>>> directly depend on printk core functions similar to what dev_printk >>>>>>> does. >>>>>>> >>>>>>> Reported-by: Randy Dunlap >>>>>>> Link: https://lore.kernel.org/linux-kselftest/0352fae9-564f-4a97-715a-fabe016259df@kernel.org/T/#t >>>>>>> Cc: Stephen Rothwell >>>>>>> Signed-off-by: Brendan Higgins >>>>>>> --- >>>>>>> include/kunit/test.h | 7 +++++++ >>>>>>> kunit/test.c | 41 ++++++++++++++++++++++++----------------- >>>>>>> 2 files changed, 31 insertions(+), 17 deletions(-) >>>>>>> >>>>>>> diff --git a/include/kunit/test.h b/include/kunit/test.h >>>>>>> index 8b7eb03d4971..339af5f95c4a 100644 >>>>>>> --- a/include/kunit/test.h >>>>>>> +++ b/include/kunit/test.h >>>>>>> @@ -339,9 +339,16 @@ static inline void *kunit_kzalloc(struct kunit *test, size_t size, gfp_t gfp) >>>>> [...] >>>>>> Okay after reviewing this, I am not sure why you need to do all >>>>>> this. >>>>>> >>>>>> Why can't you just change the root function that throws the warn: >>>>>> >>>>>> static int kunit_vprintk_emit(int level, const char *fmt, va_list args) >>>>>> { >>>>>> return vprintk_emit(0, level, NULL, 0, fmt, args); >>>>>> } >>>>>> >>>>>> You aren'r really doing anything extra here, other than calling >>>>>> vprintk_emit() >>>>> >>>>> Yeah, I did that a while ago. I think it was a combination of trying >>>>> to avoid an extra layer of adding and then removing the log level, and >>>>> that's what dev_printk and friends did. >>>>> >>>>> But I think you are probably right. It's a lot of maintenance overhead >>>>> to get rid of that. Probably best to just use what the printk people >>>>> have. >>>>> >>>>>> Unless I am missing something, can't you solve this problem by including >>>>>> printk.h and let it handle the !CONFIG_PRINTK case? >>>>> >>>>> Randy, I hope you don't mind, but I am going to ask you to re-ack my >>>>> next revision since it basically addresses the problem in a totally >>>>> different way. >>>> >>>> Actually, scratch that. Checkpatch doesn't like me calling printk >>>> without using a KERN_. >>>> >>>> Now that I am thinking back to when I wrote this. I think it also >>>> might not like using a dynamic KERN_ either (printk("%s my >>>> message", KERN_INFO)). >>>> >>>> I am going to have to do some more investigation. >>> >>> Alright, I am pretty sure it is safe to do printk("%smessage", KERN_); >>> >>> Looking at the printk implementation, it appears to do the format >>> before it checks the log level: >>> >>> https://elixir.bootlin.com/linux/v5.2.10/source/kernel/printk/printk.c#L1907 >>> >>> So I am pretty sure we can do it either with the vprintk_emit or with printk. >> >> Let me see if we are on the same page first. I am asking if you can >> just include printk.h for vprintk_emit() define for both CONFIG_PRINTK >> and !CONFIG_PRINTK cases. > > Ah sorry, I misunderstood you. > > No, that doesn't work. I tried including linux/printk.h, and I get the > same error. > > The reason for this is that vprintk_emit() is only defined when CONFIG_PRINTK=y: > This is the real problem here. printk.h defines several for !CONFIG_PRINTK case. > https://elixir.bootlin.com/linux/latest/ident/vprintk_emit > >> I am not asking you to use printk() in place of vprintk_emit(). >> It is perfectly fine to use vprintk_emit() > > Okay, cool. > >>> >>> So it appears that we have to weigh the following trade-offs: >>> >>> Using vprintk_emit: >>> >>> Pros: >>> - That's what dev_printk uses. >> >> Not sure what you mean by this. I am suggesting if you can just >> call vprintk_emit() and include printk.h and not have to ifdef >> around all the other callers of kunit_vprintk_emit() > > Oh, I was just saying that I heavily based my implementation of > kunit_printk on dev_printk. So I have a high degree of confidence that > it is okay to use it the way that I am using it. > >> Yes. There is the other issue of why do you need the complexity >> of having kunit_vprintk_emit() at all. > > Right, and the problem with the alternative, is there is no good > kernel API for logging with the log level set dynamically. printk > prefers to have it as a string prefix on the format string, but I > cannot do that because I need to add my own prefix to the format > string. > > So, I guess I should just go ahead and address the earlier comments on > this patch? > So what does your code do in the case of !CONFIG_PRINTK. From my read of it, it returns 0 from kunit_printk_emit(0 from my read of it. What I am saying is this is a lot of indirection instead of fixing the leaf function which is kunit_vprintk_emit(). +#else /* CONFIG_PRINTK */ +static inline int kunit_printk_emit(int level, const char *fmt, ...) +{ + return 0; +} +#endif /* CONFIG_PRINTK */ Does the following work? #if defined CONFIG_PRINTK static int kunit_vprintk_emit(int level, const char *fmt, va_list args) { return vprintk_emit(0, level, NULL, 0, fmt, args); } #else static int kunit_vprintk_emit(int level, const char *fmt, va_list args) { return 0; } #endif I think the real problem is in the printk.h with its missing define for vprintk_emit() for !CONFIG_PRINTK case. There seem to only one call for this in drivers/base/core.c in CONFIG_PRINTK path. Unless I am totally missing some context for why there is no stub for vprintk_emit() for !CONFIG_PRINTK case thanks, -- Shuah