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 D7E001A2632; Tue, 15 Apr 2025 10:23:13 +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=1744712593; cv=none; b=nGQsn1hlrJg0frlGlsrTpOL0P9SQFeJZIMQvs9EGZxQDPbCCUHTrwgFVrfMaTkm/KjPMF2d54ZwEmf7psqxT8o3lXpIFBmlh4rvddQqjcat6aPvgbAWGeEn/FoQdGMq3Ua40Lz3ul+UOcOBQ+w8rLeDq3OQdtB7UawkMIUx6pIQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744712593; c=relaxed/simple; bh=klDN7uanomzpPG7T/DWheax52c37vyO3EtaOg7Qv0N0=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=DT/LfiZ8uR15jjxbiNWm4IyN4eYTUvRo6XeDwXsit9JWX0/AVAp7ALy35UzZAf7Q90VWIk3qKHW162Qm+VV7KKUhhavICE+zcOAp4j+dmckLHDIDHDDHe+h3+KaSnki9DtFv2MD/BUS9y9gXiebY++s25SbeaEEeGnRs6cgFyMk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=i8MwxKKl; 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="i8MwxKKl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4CDDEC4CEDD; Tue, 15 Apr 2025 10:23:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744712593; bh=klDN7uanomzpPG7T/DWheax52c37vyO3EtaOg7Qv0N0=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=i8MwxKKlcjgP4yY11TzYkm8R/gD9M/auuZxoyjOlm5O8kUldnm7SSTJxG3xog/eHj Ffc5PJ4T+0Y4cKNjqfmrtBXzrVO5by82wXa7e4Dqivi3wz5UcnQIQGOATnajifactX hbOv98T3mshh7BiRw7/qNLdzrrxACqOe4nDIipYkyVBYb6kFjOAX0jWpb3FS7MdNoV CBPDklubxlMX/aYo1SHi83WdUGNYy/AhFpwzFm288kIrbgs4yqf42XNT9PZy5bf+LH rDNmot0zZiNPeVe9a2X6YDd0dV8N8twm5g69pv7DBiBAgvGyxw24TYF+jIttchFHk8 Egc1gHUUuwR1g== Message-ID: Subject: Re: [PATCH 2/4] ref_tracker: add ability to register a file in debugfs for a ref_tracker_dir From: Jeff Layton To: Andrew Lunn Cc: Andrew Morton , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Qasim Ijaz , Nathan Chancellor , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Date: Tue, 15 Apr 2025 06:23:10 -0400 In-Reply-To: References: <20250414-reftrack-dbgfs-v1-0-f03585832203@kernel.org> <20250414-reftrack-dbgfs-v1-2-f03585832203@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV YrOOI5VGLHge0awt7bhMCTM9KAfPc+xL/ZxAMVWd3NCk5SamL2cE99UWgtvNOIYU8m6EjTLhsj8sn VluJH0/RcxEeFbnSaswVChNSGa7mXJrTR22lRL6ZPjdMgS2Km90haWPRc8Wolcz07Y2se0xpGVLEQ 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CHqumUHRry+RF0lH00clzX/W8OrQJZtoBPXv9ahka/Vp7kEulcBJr1cH5Wz/WprhsIM7U9pse1f1g Yy9YbXtWctUz8uvDR7shsQxAhX3qO7DilMtuGo1v97I/Kx4gXQ52syh/w6EBny71CZrOgD6kJwPVV AaM1LRC28muq91WCFhs/nzHozpbzcheyGtMUI2Ao4K6mnY+3zIuXPygZMFr9KXE6fF7HzKxKuZMJO aEZCiDOq0anx6FmOzs5E6Jqdpo/mtI8beK+BE7Va6ni7YrQlnT0i3vaTVMTiCThbqsB20VrbMjlhp f8lfK1XVNbRq/R7GZ9zHESlsa35ha60yd/j3pu5hT2xyy8krV8vGhHvnJ1XRMJBAB/UYb6FyC7S+m QZIQXVeAA+smfTT0tDrisj1U5x6ZB9b3nBg65kc= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.3 (3.54.3-1.fc41) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2025-04-15 at 01:08 +0200, Andrew Lunn wrote: > On Mon, Apr 14, 2025 at 10:45:47AM -0400, Jeff Layton wrote: > > Currently, there is no convenient way to see the info that the > > ref_tracking infrastructure collects. Add a new function that other > > subsystems can optionally call to update the name field in the > > ref_tracker_dir and register a corresponding seq_file for it in the > > top-level ref_tracker directory. > >=20 > > Also, alter the pr_ostream infrastructure to allow the caller to specif= y > > a seq_file to which the output should go instead of printing to an > > arbitrary buffer or the kernel's ring buffer. >=20 > When i see an Also, or And, or a list in a commit message, i always > think, should this be multiple patches? >=20 Sure. I actually had this part in a separate patch earlier, but I don't usually like adding functions with no callers and this patch was pretty small. I can break it up though. > > struct ostream { > > char *buf; > > + struct seq_file *seq; > > int size, used; > > }; > > =20 > > @@ -73,7 +83,9 @@ struct ostream { > > ({ \ > > struct ostream *_s =3D (stream); \ > > \ > > - if (!_s->buf) { \ > > + if (_s->seq) { \ > > + seq_printf(_s->seq, fmt, ##args); \ > > + } else if (!_s->buf) { \ > > pr_err(fmt, ##args); \ > > } else { \ > > int ret, len =3D _s->size - _s->used; \ >=20 > The pr_ostream() macro is getting pretty convoluted. It currently > supports two user cases: >=20 > struct ostream os =3D {}; which means just use pr_err(). >=20 > And os.buf points to an allocated buffer and the output should be > dumped there. >=20 > You are about to add a third. >=20 > Is it about time this got split up into three helper functions, and > you pass one to __ref_tracker_dir_pr_ostream()? Your choice. >=20 Maybe? It doesn't seem worth it for this, but I'll take a look. > > +/** > > + * ref_tracker_dir_debugfs - create debugfs file for ref_tracker_dir > > + * @dir: ref_tracker_dir to finalize > > + * @name: updated name of the ref_tracker_dir > > + * > > + * In some cases, the name given to a ref_tracker_dir is based on inco= mplete information, > > + * and may not be unique. Call this to finalize the name of @dir, and = create a debugfs > > + * file for it. >=20 > Maybe extend the documentation with a comment that is name is not > unique within debugfs directory, a warning will be emitted but it is > not fatal to the tracker. >=20 Ok. > > + */ > > +void ref_tracker_dir_debugfs(struct ref_tracker_dir *dir, const char *= name) > > +{ > > + strscpy(dir->name, name, sizeof(dir->name)); >=20 > I don't know about this. Should we really overwrite the name passed > earlier? Would it be better to treat the name here only as the debugfs > filename? >=20 I think it's safe. The only thing that currently uses ->name is pr_ostream(), AFAICT. > > + if (ref_tracker_debug_dir) { >=20 > Not needed >=20 If we call debugfs_create_file() and pass in NULL as the parent, it will try to create the entry at the root of debugfs. We can get rid of this though if we initialize ref_tracker_debug_dir to an ERR_PTR value. I'll see about doing that. > > + dir->dentry =3D debugfs_create_file(dir->name, S_IFREG | 0400, > > + ref_tracker_debug_dir, dir, > > + &ref_tracker_debugfs_fops); > > + if (IS_ERR(dir->dentry)) { > > + pr_warn("ref_tracker: unable to create debugfs file for %s: %pe\n", > > + dir->name, dir->dentry); > > + dir->dentry =3D NULL; >=20 > this last statement should also be unneeded. >=20 Only if ref_tracker_debug_dir is initialized to an ERR_PTR. --=20 Jeff Layton