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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 374BEC433E0 for ; Wed, 17 Feb 2021 16:10:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B60C64E42 for ; Wed, 17 Feb 2021 16:10:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234030AbhBQQKi (ORCPT ); Wed, 17 Feb 2021 11:10:38 -0500 Received: from mx2.suse.de ([195.135.220.15]:35580 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234020AbhBQQK2 (ORCPT ); Wed, 17 Feb 2021 11:10:28 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1613578182; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=x3hBT9QaDaFA/EBlw1NkRQ4jKKS/PDh+tveWMhoehR8=; b=fUvXGBr7v3pLSvtoEaKwBotFOIaCOI48BXU14H7TxXg0jC6Mn+h+3dY5U+3osTVz7/h1E7 uQ4sE8pFvajvXNygtCAQBbftt5s7e+qk0ziF1VhAGzJlRlOAaPyA8RTCLHV5cyJz3MtrgX 3W1nuABGTJxKRqiUnDBpfrRnGw3sJCc= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 31464B944; Wed, 17 Feb 2021 16:09:42 +0000 (UTC) Date: Wed, 17 Feb 2021 17:09:41 +0100 From: Petr Mladek To: Chris Down Cc: linux-kernel@vger.kernel.org, Sergey Senozhatsky , John Ogness , Johannes Weiner , Andrew Morton , Steven Rostedt , Greg Kroah-Hartman , Kees Cook , kernel-team@fb.com Subject: Re: code style: Re: [PATCH v4] printk: Userspace format enumeration support Message-ID: References: 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 Tue 2021-02-16 17:27:08, Chris Down wrote: > Petr Mladek writes: > > > +/* > > > + * Stores .printk_fmt section boundaries for vmlinux and all loaded modules. > > > + * Add entries with store_printk_fmt_sec, remove entries with > > > + * remove_printk_fmt_sec. > > > + */ > > > +static DEFINE_HASHTABLE(printk_fmts_mod_sections, 8); > > > The hash table looks like an overkill. This is slow path. There are > > typically only tens of loaded modules. Even the module loader > > uses plain list for iterating the list of modules. > > I don't think it's overkill -- we have prod systems with hundreds. Hell, > even my laptop has over 150 loaded. If someone needs to walk all of the > files in debugfs, it seems unreasonable to do an O(n^2) walk when an O(n) > one would suffice. > > Unless you have a practical concern, I think this is a distinct case from > the module loader with its own unique requirements, so I'd prefer to use the > hash table. OK, it is true that the module API is either called with a particular struct module pointer. Or it has to iterate over all modules anyway, for example, when looking for a symbol. Well, do we need access to struct module at all? What about storing the pointer to struct pf_object into struct printk_fmt_sec *ps into the s->file->f_inode->i_private? Then we would not need any global list/table at all. > > > + > > > +/* Protects printk_fmts_mod_sections */ > > > +static DEFINE_MUTEX(printk_fmts_mutex); > > > > What is the rule for using "printk_fmts" and "printk_fmt", please? > > I can't find the system here ;-) > > > > Anyway, I would prefer to use "printk_fmt" everywhere. > > Or maybe even "pf_". > > pf_ sounds fine. :-) > > > > + > > > +static const char *ps_get_module_name(const struct printk_fmt_sec *ps); > > > +static int debugfs_pf_open(struct inode *inode, struct file *file); > > > > There are used many different: > > > > + shortcuts: fmt, fmts, ps, fmt_sec, dfs > > > > + styles/ordering: ps_get_module_name() vs. > > find_printk_fmt_sec() vs. > > printk_fmt_size() vs. > > debugfs_pf_open() > > > > It might be bearable because there is not much code. But it would > > still help a lot when we make it more consistent. Many subsystems > > prefer using a feature-specific prefix. > > > > It might be "printk_fmt_" or "pf_" [*] in this case. And we could use > > names like: > > > > + struct pf_object [**] > > + pf_get_object_name() > > + pf_find_object() > > + pf_fops, > > + pf_open() > > + pf_release() > > + pf_mutex, > > + pf_add_object() > > + pf_remove_object() > > + pf_module_notify > > Oh, I meant to change the name for v4 but neglected to do so. Sounds good, > will do. Thanks a lot. I am sorry that I ask you to do so many changes. I talked about the style early enough to make the review easy. Also I think that it is not ideal and annoing to do these mass changes and refactoring when the code is already reviewed, tested, and functional. Best Regards, Petr