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=-6.7 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1, USER_IN_DEF_DKIM_WL autolearn=no 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 9E7F3C3A59B for ; Fri, 30 Aug 2019 23:37:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6625A23430 for ; Fri, 30 Aug 2019 23:37:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="soGYPU2c" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728437AbfH3XhT (ORCPT ); Fri, 30 Aug 2019 19:37:19 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:40700 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728395AbfH3XhR (ORCPT ); Fri, 30 Aug 2019 19:37:17 -0400 Received: by mail-pf1-f196.google.com with SMTP id w16so5562116pfn.7 for ; Fri, 30 Aug 2019 16:37:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=YFTK9l48HgFlEfO2ql+ojPVP+yldR+Yv79LTZZYwKgY=; b=soGYPU2cXZVyEmSQrFtuZNhQ1j3VNFQJMN2wp6q10eDbyQfq8hQxHBrRL9izb5VZc7 eXz9edafaF8M5TP3yZDWnF/EopxRz3g049UVV70/TcDbaTn7hb/UPjz/+MZfQytEb1uZ 6fZJdK0Tb23JLwQfd75dCGUeOSFrXwTJHGoIhgOQTqk7qBps4c97F1zxF3bzcd3C4P4S W7a9gItWvAaWjNjTvYc4CAgY5SzR76Vbl4xd6NMvw2s709Vt5MwB+9P2bntXaec82+2j FeBKCuzpLjxYNBLJfz65j7bebXt50JjCPXpXHC3sbb0BehhwQwo1wN2hTsTsr9+cg+5l NyDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=YFTK9l48HgFlEfO2ql+ojPVP+yldR+Yv79LTZZYwKgY=; b=dS+bkm6ip2KUHk/+VKgvG0mur5oXb+X+g9lacRrpi7Z2/FWNq6dtCMMX7/pY3j8Wvp pdtMka0Jx3JWnSSd3XxmhvX3wCA+biaBjKM/hSinW6Y6XUfuu1TN3E9kIu/DBVDYFNEJ iFIsJ7AnLBeleYpOUwBpW0jkcn13TM/eiXFTZBSUvf584MxoeeDB1OLyz1vCvSpOarFq QhjaIVxncvIunmzRHa1LjMevVbdk68c3cPKtgVvRnbaSW0GH1CKjsE+pjsTKGWpY2ujY AFXiA3F/awpal3MWe6XPRsipQysRtTcnf2YMZsLJGTvx4o0JubnDxnh+F7sf0x62QNzp SaVw== X-Gm-Message-State: APjAAAUnrO/f1v/Nb/QVrWols3nBvZvSHYmli7jehrqGcxjK9e2WZbmt KddKS9Kl2UcYLqB2y2CuahWVpw== X-Google-Smtp-Source: APXvYqw6w0Q4kDWY2duwjPimT9htv/UJFgKQCmcAUtnMSA/hgFu1PLvccl2u2lz0C3vbaaQrSHrzOg== X-Received: by 2002:a63:d002:: with SMTP id z2mr15369704pgf.364.1567208236014; Fri, 30 Aug 2019 16:37:16 -0700 (PDT) Received: from google.com ([2620:15c:2cb:1:e90c:8e54:c2b4:29e7]) by smtp.gmail.com with ESMTPSA id x22sm14444793pfo.180.2019.08.30.16.37.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Aug 2019 16:37:15 -0700 (PDT) Date: Fri, 30 Aug 2019 16:37:10 -0700 From: Brendan Higgins To: Tim.Bird@sony.com Cc: joe@perches.com, shuah@kernel.org, sergey.senozhatsky.work@gmail.com, kunit-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, frowand.list@gmail.com, sboyd@kernel.org, pmladek@suse.com, sergey.senozhatsky@gmail.com, rostedt@goodmis.org, rdunlap@infradead.org, sfr@canb.auug.org.au Subject: Re: [PATCH v2] kunit: fix failure to build without printk Message-ID: <20190830233710.GA101591@google.com> References: <20190828093143.163302-1-brendanhiggins@google.com> <20190828094929.GA14038@jagdpanzerIV> <8b2d63bf-56cd-e8f5-e8ee-2891c2c1be8f@kernel.org> <20190830183821.GA30306@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 30, 2019 at 11:22:43PM +0000, Tim.Bird@sony.com wrote: > > -----Original Message----- > > From: Brendan Higgins > > > > On Fri, Aug 30, 2019 at 3:46 PM Joe Perches wrote: > > > > > > On Fri, 2019-08-30 at 21:58 +0000, Tim.Bird@sony.com wrote: > > > > > From: Joe Perches > > > [] > > > > IMHO %pV should be avoided if possible. Just because people are > > > > doing it doesn't mean it should be used when it is not necessary. > > > > > > Well, as the guy that created %pV, I of course > > > have a different opinion. > > > > > > > > then wouldn't it be easier to pass in the > > > > > > kernel level as a separate parameter and then strip off all printk > > > > > > headers like this: > > > > > > > > > > Depends on whether or not you care for overall > > > > > object size. Consolidated formats with the > > > > > embedded KERN_ like suggested are smaller > > > > > overall object size. > > > > > > > > This is an argument I can agree with. I'm generally in favor of > > > > things that lessen kernel size creep. :-) > > > > > > As am I. > > > > Sorry, to be clear, we are talking about the object size penalty due > > to adding a single parameter to a function. Is that right? > > Not exactly. The argument is that pre-pending the different KERN_LEVEL > strings onto format strings can result in several versions of nearly identical strings > being compiled into the object file. By parameterizing this (that is, adding > '%s' into the format string, and putting the level into the string as an argument), > it prevents this duplication of format strings. > > I haven't seen the data on duplication of format strings, and how much this > affects it, but little things can add up. Whether it matters in this case depends > on whether the format strings that kunit uses are also used elsewhere in the kernel, > and whether these same format strings are used with multiple kernel message levels. > -- Tim I thought this portion of the discussion was about whether Joe's version of kunit_printk was better or my critique of his version of kunit_printk: Joe's: > > > > -void kunit_printk(const char *level, > > > > - const struct kunit *test, > > > > - const char *fmt, ...) > > > > +void kunit_printk(const struct kunit *test, const char *fmt, ...) > > > > { > > > > + char lvl[PRINTK_MAX_SINGLE_HEADER_LEN + 1] = "\0"; > > > > struct va_format vaf; > > > > va_list args; > > > > + int kern_level; > > > > > > > > va_start(args, fmt); > > > > > > > > + while ((kern_level = printk_get_level(fmt)) != 0) { > > > > + size_t size = printk_skip_level(fmt) - fmt; > > > > + > > > > + if (kern_level >= '0' && kern_level <= '7') { > > > > + memcpy(lvl, fmt, size); > > > > + lvl[size] = '\0'; > > > > + } > > > > + fmt += size; > > > > + } > > > > + > > > > vaf.fmt = fmt; > > > > vaf.va = &args; > > > > > > > > - kunit_vprintk(test, level, &vaf); > > > > + printk("%s\t# %s %pV\n", lvl, test->name, &vaf); > > > > > > > > va_end(args); > > > > } Mine: > void kunit_printk(const char *level, > const struct kunit *test, > const char *fmt, ...) > { > struct va_format vaf; > va_list args; > > va_start(args, fmt); > > + fmt = printk_skip_headers(fmt); > + > vaf.fmt = fmt; > vaf.va = &args; > > - kunit_vprintk(test, level, &vaf); > + printk("%s\t# %s %pV\n", level, test->name, &vaf); > > va_end(args); > } I thought you and Joe were arguing that "Joe's" resulted in a smaller object size than "Mine" (not to be confused with the actual patch I presented here, which is what Sergey suggested I do on a different thread). I really don't feel strongly about what Sergey suggested I do (which is what this patch originally introduced), versus, what Joe suggested, versus what I suggested in response to Joe (or any of the things suggested on other threads). I just want to pick one, fix the breakage in linux-next, and move on with my life. Cheers