From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.24]) (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 7A1C31E4A4; Mon, 18 Dec 2023 17:23:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=gmail.com X-IronPort-AV: E=McAfee;i="6600,9927,10928"; a="398319087" X-IronPort-AV: E=Sophos;i="6.04,286,1695711600"; d="scan'208";a="398319087" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Dec 2023 09:23:28 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10928"; a="919334061" X-IronPort-AV: E=Sophos;i="6.04,286,1695711600"; d="scan'208";a="919334061" Received: from smile.fi.intel.com ([10.237.72.54]) by fmsmga001.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Dec 2023 09:23:26 -0800 Received: from andy by smile.fi.intel.com with local (Exim 4.97) (envelope-from ) id 1rFHKt-0000000725r-1PQS; Mon, 18 Dec 2023 19:23:23 +0200 Date: Mon, 18 Dec 2023 19:23:23 +0200 From: Andy Shevchenko To: Nick Desaulniers Cc: Tanzir Hasan , Kees Cook , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, Nick DeSaulniers , Andrew Morton , llvm@lists.linux.dev, Al Viro Subject: Re: [PATCH v2 1/2] sh: Added kernel.h to word-at-a-time Message-ID: References: <20231214-libstringheader-v2-0-0f195dcff204@google.com> <20231214-libstringheader-v2-1-0f195dcff204@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo On Mon, Dec 18, 2023 at 08:57:59AM -0800, Nick Desaulniers wrote: > On Fri, Dec 15, 2023 at 11:09 AM Andy Shevchenko > wrote: > > On Fri, Dec 15, 2023 at 8:31 PM Tanzir Hasan wrote: > > > On Fri, Dec 15, 2023 at 8:04 AM Andy Shevchenko wrote: > > >> On Thu, Dec 14, 2023 at 09:06:12PM +0000, tanzirh@google.com wrote: ... > > >> > +#include > > >> > > >> I highly discourage from doing that. Instead, split what is needed to > > >> the separate (new) header and include that one. > > > > > > > > > I think it would make the most sense to do this in a separate patch. > > > What word-at-a-time.h needs from kernel.h is REPEAT_BYTE and to my knowledge, > > > almost every other version of word-at-a-time.h includes kernel.h gets this by > > > including kernel.h. A future change could be removing REPEAT_BYTE > > > out of kernel.h > > > > Just create a patch that either moves that macro (along with upper_*() > > and lower_*() APIs) to a more distinguishable header > > (maybe bytes.h or words.h or wordpart.h, etc) and use it in your case > > and fix others. > > Andy, > These are good suggestions and we should do them... > > ...and Tanzir only has 3 weeks left of his internship. I don't want > him to get bogged down chasing build regressions from modifying the > headers themselves. I think what's best for him from here through the > remainder of his internship is to stay focused on applying suggestions > from IWYU to just modify the #include list of .c files, and not start > splitting .h files. Splitting the .h files will be the next step, and > is made easier by having the codebase not have so many indirect > includes (via IWYU), but we need time to soak header changes, and time > Tanzir does not have. Please can we keep the suggestions focused on > whether the modifications to the header includes (and the tangential > cleanups) are correct? Understood. Can we add a comment like /* FIXME: replace with a proper header to avoid dependency hell */ #include ? > While REPEAT_BYTE has a manageable number of users, upper_* and > lower_* have significantly more; I worry about moving those causing > regressions. If you look at how I did similar in the past, I back included new header into kernel.h. Not the pretty solution, but allows to split in the new code. > We can move them, but such changes would need significantly more soak time s/significantly// But I got your point, see above. > than this series IMO. Tanzir is also working on statistical analysis; I > suspect if he analyzes include/linux/kernel.h, he can comment on whether the > usage of REPEAT_BYTE is correlated with the usage of upper_* and lower_* in > order to inform whether they should be grouped together or not. -- With Best Regards, Andy Shevchenko