From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from jpms-ob01.noc.sony.co.jp (jpms-ob01.noc.sony.co.jp [211.125.140.164]) (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 87BB01DF75B; Sat, 23 May 2026 03:34:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=211.125.140.164 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779507273; cv=none; b=W6KytM0CbxybhV8p/OTjNkVX4pVyykPm2VKKSQXlv4049k84xoRZ0QzG3Adi49pL2h2q787JwScvEgdXz5R0NmAqIIFUK5AU1H5VB7zn3BeuiHIifukPFyFGZABAJFy2LeU1rfrHY16lroQACe8tF6aIKyvix89N1ljp4ShJINA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779507273; c=relaxed/simple; bh=yAHUx9qOBhWRWLyWrle1ZFuyeDrR76+YVL2i8bDyMoE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NLNukVwwmjayymS/d02t0DUTL69Art6lSKxBxHmqvnI+ZV4FNznJ5HfZqIAyHv80KMUceDBZf5eaeYvRox+IOvgmoC2l7Eo1H1Pf6J9y2zJ4J4rKmY0Guj9RLi75ukl1K3b0F03K14iyLkxELxsltPfIGOiVtSKqFUhXhKxwoCg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sony.com; spf=pass smtp.mailfrom=sony.com; dkim=pass (2048-bit key) header.d=sony.com header.i=@sony.com header.b=CJ34+Ekr; arc=none smtp.client-ip=211.125.140.164 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sony.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sony.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=sony.com header.i=@sony.com header.b="CJ34+Ekr" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sony.com; s=s1jp; t=1779507271; x=1811043271; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=/PI3FmT1/Yi4DE7+lMDULD4fdLB7X6k2BakvtD3RsQA=; b=CJ34+EkrdvS8TLCU1GMDd9XiSFGc42qAwqqAJzakA6x4hxJES5TQTyDH AauetdpPKtrS0L9E/8IAFRpjLmGFEX2ivinNIgEnITZbPDqOFC60TVrZU VsvwAsd3ogR5zeVXjHGgfsIedMFgAw/hcnnrxvJWSB+13XodZyPHKk2k5 NTEDv819lDKG4a+6NCVw0O+/+tRczdM+eTNzo5Fw2NYxk8vopj/RFOd9V grTsucMJB+xgLR4dqU7TEgEh4cDzlj6hQuqV5iYDFL/9XgIgsBY2NQ8Zr +hu7RoXUOmnz25Mn5u/iL/bxnPhm7ZKWc3Au2qlssP/pw7jKXp1k/Tb3H A==; X-CSE-ConnectionGUID: W/RIScbkTxKp9xbcw93A8A== X-CSE-MsgGUID: SSH56JXnQYyCD+s9Irbv0w== Received: from unknown (HELO jpmta-ob1.noc.sony.co.jp) ([IPv6:2001:cf8:0:6e7::6]) by jpms-ob01.noc.sony.co.jp with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 May 2026 12:24:20 +0900 X-CSE-ConnectionGUID: O/SdfXAXTci1J18nuI/Q/A== X-CSE-MsgGUID: JQfr130jQ/m+0PdF94fS/g== X-IronPort-AV: E=Sophos;i="6.24,163,1774278000"; d="scan'208";a="639353636" Received: from unknown (HELO JPC00244420) ([IPv6:2001:cf8:1:573:0:dddd:6b3e:119e]) by jpmta-ob1.noc.sony.co.jp with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 May 2026 12:24:18 +0900 Date: Sat, 23 May 2026 12:24:18 +0900 From: Shashank Balaji To: Petr Pavlu Cc: Suzuki K Poulose , James Clark , Alexander Shishkin , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Miguel Ojeda , Boqun Feng , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Jonathan Corbet , Shuah Khan , Luis Chamberlain , Daniel Gomez , Sami Tolvanen , Aaron Tomlin , Mike Leach , Leo Yan , Thierry Reding , Jonathan Hunter , Rahul Bukte , linux-kernel@vger.kernel.org, coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, driver-core@lists.linux.dev, rust-for-linux@vger.kernel.org, linux-doc@vger.kernel.org, Daniel Palmer , Tim Bird , linux-modules@vger.kernel.org, linux-tegra@vger.kernel.org, Sumit Gupta Subject: Re: [PATCH v5 2/4] kernel: param: initialize module_kset in a pure_initcall Message-ID: References: <20260518-acpi_mod_name-v5-0-705ccc430885@sony.com> <20260518-acpi_mod_name-v5-2-705ccc430885@sony.com> Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hi Petr, Thanks for the feedback! On Fri, May 22, 2026 at 03:06:04PM +0200, Petr Pavlu wrote: > On 5/18/26 12:19 PM, Shashank Balaji wrote: > > Commit "driver core: platform: set mod_name in driver registration" will set > > struct device_driver's mod_name member for platform driver registration. For a > > driver to be registered with its mod_name set, module_kset needs to be > > initialized, which currently happens in a subsys_initcall in param_sysfs_init(). > > The tegra cbb drivers register themselves before module_kset init, in a > > core_initcall. This works currently because lookup_or_create_module_kobject(), > > which dereferences module_kset via kset_find_obj(), is not called if mod_name > > is not set, which is the case now. > > > > So in preparation for the commit "driver core: platform: set mod_name in driver registration", > > move module_kset init to pure_initcall level, ensuring it happens before tegra > > cbb driver registration. > > > > Suggested-by: Gary Guo > > Co-developed-by: Rahul Bukte > > Signed-off-by: Rahul Bukte > > Signed-off-by: Shashank Balaji > > --- > > Patch 4 depends on this patch > > --- > > kernel/params.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/kernel/params.c b/kernel/params.c > > index 74d620bc2521..ac088d4b09a9 100644 > > --- a/kernel/params.c > > +++ b/kernel/params.c > > @@ -957,7 +957,7 @@ static int __init param_sysfs_init(void) > > > > return 0; > > } > > -subsys_initcall(param_sysfs_init); > > +pure_initcall(param_sysfs_init); > > > > /* > > * param_sysfs_builtin_init - add sysfs version and parameter > > > > The change looks ok to me functionality-wise. Sysfs is initialized > earlier in do_basic_setup() and other code, such as classes_init(), > calls kset_create_and_add() similarly early. > > One minor issue is that pure_initcall() was originally intended for > static variable initialization. The file include/linux/init.h says: > > | /* > | * A "pure" initcall has no dependencies on anything else, and purely > | * initializes variables that couldn't be statically initialized. > | * > | * This only exists for built-in code, not for modules. > | * Keep main.c:initcall_level_names[] in sync. > | */ > | #define pure_initcall(fn) __define_initcall(fn, 0) > > The patch stretches the intended use of pure_initcall() somewhat in this > regard. However, other code already appears to do the same, so I guess > this is ok. Ah yeah, I thought of this too, but it seems like everyone else is doing it. Linus introduced pure_initcall in b3438f8266cb ("Add "pure_initcall" for static variable initialization") with the comment, and he introduced another user of it in 140d0b2108fa ("Do 'shm_init_ns()' in an early pure_initcall") which already stretches the intended use as per the comment. Given that it's just being used for "run me before core_initcall; early_initcall is too early for me" without any "pureness" requirements, I suppose the comment is due for a revision? > Additionally, I think it would be good to update the comment preceding > param_sysfs_init(). It currently says: > > | /* > | * param_sysfs_init - create "module" kset > | * > | * This must be done before the initramfs is unpacked and > | * request_module() thus becomes possible, because otherwise the > | * module load would fail in mod_sysfs_init. > | */ > > I suggest changing it to something like follows: > > This must be done before any driver registration so that when a driver comes > from a built-in module, the driver core can add the module under /sys/module > and create the associated driver symlinks. Thanks for catching this! I'll add it in the next revision. Thanks, Shashank