From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 0D1561A28D; Mon, 14 Apr 2025 12:48:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744634909; cv=none; b=ZoitksxqSXHCAW+XGAmMgZl6tRoRx3nUjff6mtfsTbx8F+fz9Gw4gz6iU6rLwcv3BdtLRbgPbwe2Be/tHebdXMkQAIvrHtSoGdghM9i04f6Qc6nEcNE6R720psgpdxY9wueJtTt5sMqpg+VHSOiZBbp76JqhxowcBiZE0ZnvKjw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744634909; c=relaxed/simple; bh=5RzIFJOiTbN0vX462+6AoJyYWW3P/YzuGGmYLNmznIs=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=U/12Fd4K/hdQS7k1e2TwRC6tNtix+RG24Fr+/JLgvoztjwoz2CM1P87jwulMkeRGATP50CPzGVOdgZV3fAuV5dwJqdbhDauhcV+4xOtrchWHBi/vsMuVEpI7N9YtXzylxeyr04VoH9U6NdLv6gvalH3GT/YRO2EGiYew2eBDXdk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=afVN0bFU; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="afVN0bFU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B1603C4CEE2; Mon, 14 Apr 2025 12:48:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744634908; bh=5RzIFJOiTbN0vX462+6AoJyYWW3P/YzuGGmYLNmznIs=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=afVN0bFU9Zb+3grQfOLGhD9Ol+1maQWMmnpbyABr8RjS1k1Pyl85OFI9js7C1BJwg UJv+v4+OwLj2+dJgsSwSe6NLJgsg2TmFng8yp3ZUqDfUhv7MUtH3mKWSTiQJ6yyZYq T1jyMWwfw15AWLTUaeWrb7Bnhg3qTzrX+ESvLXZCvUa/r8HuvpLXemBqKmO8FqsMox 8SyAiLZeMabyBD1iqVtCSLxH0WYrvHNynk1fA59EYYmvr+Hf2P654M3Qd5yoWks3ny LfrYx4GrBphwDLpzbkGtjn3xmMG183v8o8sT1Evyb6HFrMFwXYWJjSvnMG9BEyqQg/ /B18nvyGa4WNA== Message-ID: Subject: Re: [PATCH v2 2/2] net: add debugfs files for showing netns refcount tracking info From: Jeff Layton To: Andrew Lunn Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Andrew Morton , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 14 Apr 2025 08:48:26 -0400 In-Reply-To: <1bc3164b-0e41-49e1-9ed2-cf37997ab53e@lunn.ch> References: <20250408-netns-debugfs-v2-0-ca267f51461e@kernel.org> <20250408-netns-debugfs-v2-2-ca267f51461e@kernel.org> <1e717326-8551-419e-b185-5cfb20573b4f@lunn.ch> <91d6d3c60ef5d4ed90418f8a06228767be8a5b1b.camel@kernel.org> <23f93f84e000ebee28614bf85a4013648fa66a00.camel@kernel.org> <71adf369-a803-4d06-906c-97b5bf48bcf8@lunn.ch> <1bc3164b-0e41-49e1-9ed2-cf37997ab53e@lunn.ch> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 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input from the i915 folks then. > > >=20 > > > That is why i think it would be better to add a warning, give the i91= 5 > > > folks a heads up, and leave them to fix it how they want. We want the > > > warning anyway to cover new refcount instances being added. > > >=20 > >=20 > > There will definitely be a pr_warn() if creation fails. I was hoping to > > send a suggested change alongside the patchset, but I may have to just > > leave it up to them. > >=20 > > I threw together a draft patchset that auto-registers a debugfs file > > for every call to ref_tracker_dir_init(). The problem I've hit now > > though is that at least in the networking cases, the kernel calls > > ref_tracker_dir_init() very early in the process of creating a new > > objects, so we're not getting good names here: > >=20 > > The "name" in alloc_netdev_mqs is actually a format string, so we end > > up with a name like "eth%d" here: > >=20 > > net/core/dev.c: ref_tracker_dir_init(&dev->refcnt_tracker, 128, name); > =C2=A0 >=20 >=20 >=20 > Oh, yes, never thought about that... >=20 > It also seems like it might be a common problem, the subsystem defined > name has not been given yet, although the core dev_name(dev) should > work. But in netdev drivers, alloc_netdev_mqs() does not have access > to that. >=20 > > At the point that we call these (preinit), net->ns.inum hasn't been > > assigned yet, so we can't incorporate it properly into the dentry name: > >=20 > > net/core/net_namespace.c: ref_tracker_dir_init(&net->refcnt_track= er, 128, "net refcnt"); > > net/core/net_namespace.c: ref_tracker_dir_init(&net->notrefcnt_tr= acker, 128, "net notrefcnt"); > >=20 > > We could do the ref_tracker_dir_init() calls later, but we may end up > > missing some references that way (or end up crashing because the "dir" > > isn't initialized. > >=20 > > My current thinking is to add a new ref_tracker_dir_finalize() function > > that we could use to=C2=A0finalize the name and register the debugfs fi= les > > after we have the requisite info. It's an extra manual step, but I like > > that better than moving around the ref_tracker_dir_init() calls. >=20 > Agree. Although, bike shedding, i don't really like the _finalize in > ref_tracker_dir_finalize(). Ideally this should be optional and > populate debugfs. _finalize does not sound particularly optional. So > maybe ref_tracker_dir_debugfs()? >=20 I'm terrible at naming, so we can go with that. That last step will definitely be optional. > This also has the advantage of we need to worry less about GPU > drivers. They see no change in behaviour, but we can give them a heads > up the new call exists if they want to use it to populate debugfs. >=20 +1 --=20 Jeff Layton