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 EFFDA223DC3; Fri, 25 Apr 2025 12:46:19 +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=1745585180; cv=none; b=MlcUmbMx4JzWj/g+P7YHhQS3SP29/3QfazafnSdPAlx6TOkzMYFLfbEnLAvi7YRXB0LmOwEBOlKydCaqdJq9SeSU2hX16U12si2uCYty3lhcwCx2wbKMd3yOzrVQlsLD1gfFzdT6IH/KCCClW5xeLsQMzKeh9cRfnyHKQM5OYbc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745585180; c=relaxed/simple; bh=RyZzOhYNGchRN3ugr7fK0F/2/XaoG4Vzk96bQ8xPeeQ=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=Bfyah54Kkic3dM6D4bGM9xGxWMs4KxUQ+lkt+a0pobhpSOTK5OdZ1lkA0qJ/X9f+g7Y2vvkb5zxioK0HKnKl6sAVkf+VXJ3ZbR66gPUCZTRIgL1cRI1QPNQ645UB0Hk49j7WEK3ecpGnITlbl8YIiYLtYwwBU9BdaE7/45ECni4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XS0UMCWQ; 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="XS0UMCWQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 630AFC4CEE4; Fri, 25 Apr 2025 12:46:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745585179; bh=RyZzOhYNGchRN3ugr7fK0F/2/XaoG4Vzk96bQ8xPeeQ=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=XS0UMCWQK0QkQK/d+i+sHrdlSBU7I6hgxvFgwNoS8kaW7X2e2BNLJFa7GatiXDGBE R9IdtiTtmaNEc8q5CgW5rr5gRlslJoRfAIeiFIfMV7lEceBb/i3zpfIHOd8LDsAN8S KJVx6fHKeZonYP6BIhFboAeyb0bIthXz6heLKJMH+4TMidyxJkHR+/C3FIBSkvbzrX 3ka09NeZ+3LiublSun31yxW0QVfJ79i9iQszXcbKG74PfcAwo1DyVzQmyqg81BM4wi K/853y6FradARZ3rqKy/YjHvI001N0Ygtv3Ko/jodgNbeh1th/RHKJCWaVGBn00qxX XPK0+z/YxjjbA== Message-ID: Subject: Re: [PATCH v4 7/7] net: register debugfs file for net_device refcnt tracker From: Jeff Layton To: Jakub Kicinski , Andrew Lunn Cc: Andrew Morton , "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Kuniyuki Iwashima , Qasim Ijaz , Nathan Chancellor , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Date: Fri, 25 Apr 2025 08:46:17 -0400 In-Reply-To: <20250424155238.7d0d2a29@kernel.org> References: <20250418-reftrack-dbgfs-v4-0-5ca5c7899544@kernel.org> <20250418-reftrack-dbgfs-v4-7-5ca5c7899544@kernel.org> <20250423165323.270642e3@kernel.org> <20250423173231.5c61af5b@kernel.org> <4118dbd6-2b4b-42c3-9d1e-2b533fc92a66@lunn.ch> <20250424155238.7d0d2a29@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 cDEsvv5IMmeMe1/qLZ6NaVkNuL3WOXvxaVT9USW1+/SGipO2IpKJjeDZfehlB/kpfF24+RrK+seQf CBYyUE8QJpvTZyfUHNYldXlrjO6n5MdOempLqWpfOmcGkwnyNRBR46g/jf8KnPRwXs509yAqDB6sE LZH+yWr9LQZEwARAQABtCVKZWZmIExheXRvbiA8amxheXRvbkBwb29jaGllcmVkcy5uZXQ+iQI7BB MBAgAlAhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAUCTpXWPAIZAQAKCRAADmhBGVaCFc65D/4 gBLNMHopQYgG/9RIM3kgFCCQV0pLv0hcg1cjr+bPI5f1PzJoOVi9s0wBDHwp8+vtHgYhM54yt43uI 7Htij0RHFL5eFqoVT4TSfAg2qlvNemJEOY0e4daljjmZM7UtmpGs9NN0r9r50W82eb5Kw5bc/r0km R/arUS2st+ecRsCnwAOj6HiURwIgfDMHGPtSkoPpu3DDp/cjcYUg3HaOJuTjtGHFH963B+f+hyQ2B rQZBBE76ErgTDJ2Db9Ey0kw7VEZ4I2nnVUY9B5dE2pJFVO5HJBMp30fUGKvwaKqYCU2iAKxdmJXRI ONb7dSde8LqZahuunPDMZyMA5+mkQl7kpIpR6kVDIiqmxzRuPeiMP7O2FCUlS2DnJnRVrHmCljLkZ Wf7ZUA22wJpepBligemtSRSbqCyZ3B48zJ8g5B8xLEntPo/NknSJaYRvfEQqGxgk5kkNWMIMDkfQO lDSXZvoxqU9wFH/9jTv1/6p8dHeGM0BsbBLMqQaqnWiVt5mG92E1zkOW69LnoozE6Le+12DsNW7Rj iR5K+27MObjXEYIW7FIvNN/TQ6U1EOsdxwB8o//Yfc3p2QqPr5uS93SDDan5ehH59BnHpguTc27Xi QQZ9EGiieCUx6Zh2ze3X2UW9YNzE15uKwkkuEIj60NvQRmEDfweYfOfPVOueC+iFifbQgSmVmZiBM YXl0b24gPGpsYXl0b25AcmVkaGF0LmNvbT6JAjgEEwECACIFAk6V0q0CGwMGCwkIBwMCBhUIAgkKC wQWAgMBAh4BAheAAAoJEAAOaEEZVoIViKUQALpvsacTMWWOd7SlPFzIYy2/fjvKlfB/Xs4YdNcf9q LqF+lk2RBUHdR/dGwZpvw/OLmnZ8TryDo2zXVJNWEEUFNc7wQpl3i78r6UU/GUY/RQmOgPhs3epQC 3PMJj4xFx+VuVcf/MXgDDdBUHaCTT793hyBeDbQuciARDJAW24Q1RCmjcwWIV/pgrlFa4lAXsmhoa c8UPc82Ijrs6ivlTweFf16VBc4nSLX5FB3ls7S5noRhm5/Zsd4PGPgIHgCZcPgkAnU1S/A/rSqf3F LpU+CbVBDvlVAnOq9gfNF+QiTlOHdZVIe4gEYAU3CUjbleywQqV02BKxPVM0C5/oVjMVx3bri75n1 TkBYGmqAXy9usCkHIsG5CBHmphv9MHmqMZQVsxvCzfnI5IO1+7MoloeeW/lxuyd0pU88dZsV/riHw 87i2GJUJtVlMl5IGBNFpqoNUoqmvRfEMeXhy/kUX4Xc03I1coZIgmwLmCSXwx9MaCPFzV/dOOrju2 xjO+2sYyB5BNtxRqUEyXglpujFZqJxxau7E0eXoYgoY9gtFGsspzFkVNntamVXEWVVgzJJr/EWW0y +jNd54MfPRqH+eCGuqlnNLktSAVz1MvVRY1dxUltSlDZT7P2bUoMorIPu8p7ZCg9dyX1+9T6Muc5d Hxf/BBP/ir+3e8JTFQBFOiLNdFtB9KZWZmIExheXRvbiA8amxheXRvbkBzYW1iYS5vcmc+iQI4BBM BAgAiBQJOldK9AhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRAADmhBGVaCFWgWD/0ZRi4h N9FK2BdQs9RwNnFZUr7JidAWfCrs37XrA/56olQl3ojn0fQtrP4DbTmCuh0SfMijB24psy1GnkPep naQ6VRf7Dxg/Y8muZELSOtsv2CKt3/02J1BBitrkkqmHyni5fLLYYg6fub0T/8Kwo1qGPdu1hx2BQ RERYtQ/S5d/T0cACdlzi6w8rs5f09hU9Tu4qV1JLKmBTgUWKN969HPRkxiojLQziHVyM/weR5Reu6 FZVNuVBGqBD+sfk/c98VJHjsQhYJijcsmgMb1NohAzwrBKcSGKOWJToGEO/1RkIN8tqGnYNp2G+aR 685D0chgTl1WzPRM6mFG1+n2b2RR95DxumKVpwBwdLPoCkI24JkeDJ7lXSe3uFWISstFGt0HL8Eew P8RuGC8s5h7Ct91HMNQTbjgA+Vi1foWUVXpEintAKgoywaIDlJfTZIl6Ew8ETN/7DLy8bXYgq0Xzh aKg3CnOUuGQV5/nl4OAX/3jocT5Cz/OtAiNYj5mLPeL5z2ZszjoCAH6caqsF2oLyAnLqRgDgR+wTQ T6gMhr2IRsl+cp8gPHBwQ4uZMb+X00c/Amm9VfviT+BI7B66cnC7Zv6Gvmtu2rEjWDGWPqUgccB7h dMKnKDthkA227/82tYoFiFMb/NwtgGrn5n2vwJyKN6SEoygGrNt0SI84y6hEVbQlSmVmZiBMYXl0b 24gPGpsYXl0b25AcHJpbWFyeWRhdGEuY29tPokCOQQTAQIAIwUCU4xmKQIbAwcLCQgHAwIBBhUIAg kKCwQWAgMBAh4BAheAAAoJEAAOaEEZVoIV1H0P/j4OUTwFd7BBbpoSp695qb6HqCzWMuExsp8nZjr uymMaeZbGr3OWMNEXRI1FWNHMtcMHWLP/RaDqCJil28proO+PQ/yPhsr2QqJcW4nr91tBrv/MqItu AXLYlsgXqp4BxLP67bzRJ1Bd2x0bWXurpEXY//VBOLnODqThGEcL7jouwjmnRh9FTKZfBDpFRaEfD FOXIfAkMKBa/c9TQwRpx2DPsl3eFWVCNuNGKeGsirLqCxUg5kWTxEorROppz9oU4HPicL6rRH22Ce 6nOAON2vHvhkUuO3GbffhrcsPD4DaYup4ic+DxWm+DaSSRJ+e1yJvwi6NmQ9P9UAuLG93S2MdNNbo sZ9P8k2mTOVKMc+GooI9Ve/vH8unwitwo7ORMVXhJeU6Q0X7zf3SjwDq2lBhn1DSuTsn2DbsNTiDv qrAaCvbsTsw+SZRwF85eG67eAwouYk+dnKmp1q57LDKMyzysij2oDKbcBlwB/TeX16p8+LxECv51a sjS9TInnipssssUDrHIvoTTXWcz7Y5wIngxDFwT8rPY3EggzLGfK5Zx2Q5S/N0FfmADmKknG/D8qG IcJE574D956tiUDKN4I+/g125ORR1v7bP+OIaayAvq17RP+qcAqkxc0x8iCYVCYDouDyNvWPGRhbL UO7mlBpjW9jK9e2fvZY9iw3QzIPGKtClKZWZmIExheXRvbiA8amVmZi5sYXl0b25AcHJpbWFyeWRh dGEuY29tPokCOQQTAQIAIwUCU4xmUAIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEAAOa EEZVoIVzJoQALFCS6n/FHQS+hIzHIb56JbokhK0AFqoLVzLKzrnaeXhE5isWcVg0eoV2oTScIwUSU apy94if69tnUo4Q7YNt8/6yFM6hwZAxFjOXR0ciGE3Q+Z1zi49Ox51yjGMQGxlakV9ep4sV/d5a50 M+LFTmYSAFp6HY23JN9PkjVJC4PUv5DYRbOZ6Y1+TfXKBAewMVqtwT1Y+LPlfmI8dbbbuUX/kKZ5d dhV2736fgyfpslvJKYl0YifUOVy4D1G/oSycyHkJG78OvX4JKcf2kKzVvg7/Rnv+AueCfFQ6nGwPn 0P91I7TEOC4XfZ6a1K3uTp4fPPs1Wn75X7K8lzJP/p8lme40uqwAyBjk+IA5VGd+CVRiyJTpGZwA0 jwSYLyXboX+Dqm9pSYzmC9+/AE7lIgpWj+3iNisp1SWtHc4pdtQ5EU2SEz8yKvDbD0lNDbv4ljI7e flPsvN6vOrxz24mCliEco5DwhpaaSnzWnbAPXhQDWb/lUgs/JNk8dtwmvWnqCwRqElMLVisAbJmC0 BhZ/Ab4sph3EaiZfdXKhiQqSGdK4La3OTJOJYZphPdGgnkvDV9Pl1QZ0ijXQrVIy3zd6VCNaKYq7B AKidn5g/2Q8oio9Tf4XfdZ9dtwcB+bwDJFgvvDYaZ5bI3ln4V3EyW5i2NfXazz/GA/I/ZtbsigCFc 8ftCBKZWZmIExheXRvbiA8amxheXRvbkBrZXJuZWwub3JnPokCOAQTAQIAIgUCWe8u6AIbAwYLCQg HAwIGFQgCCQoLBBYCAwECHgECF4AACgkQAA5oQRlWghUuCg/+Lb/xGxZD2Q1oJVAE37uW308UpVSD 2tAMJUvFTdDbfe3zKlPDTuVsyNsALBGclPLagJ5ZTP+Vp2irAN9uwBuacBOTtmOdz4ZN2tdvNgozz uxp4CHBDVzAslUi2idy+xpsp47DWPxYFIRP3M8QG/aNW052LaPc0cedYxp8+9eiVUNpxF4SiU4i9J DfX/sn9XcfoVZIxMpCRE750zvJvcCUz9HojsrMQ1NFc7MFT1z3MOW2/RlzPcog7xvR5ENPH19ojRD 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: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Thu, 2025-04-24 at 15:52 -0700, Jakub Kicinski wrote: > On Thu, 24 Apr 2025 14:10:03 +0200 Andrew Lunn wrote: > > > > > > How much naming the objects in a "user readable" fashion actual= ly > > > > > > matter? It'd be less churn to create some kind of "object class= " > > > > > > with a directory level named after what's already passed to > > > > > > ref_tracker_dir_init() and then id the objects by the pointer v= alue=20 > > > > > > as sub-dirs of that? =20 > > > > >=20 > > > > > That sounds closer to what I had done originally. Andrew L. sugge= sted > > > > > the flat directory that this version represents. I'm fine with wh= atever > > > > > hierarchy, but let's decide that before I respin again. =20 > > > >=20 > > > > Sorry about that :( > > > > =20 > > >=20 > > > No worries...but we do need to decide what this directory hierarchy > > > should look like. > > >=20 > > > Andrew's point earlier was that this is just debugfs, so a flat > > > "ref_tracker" directory full of files is fine. I tend to agree with > > > him; NAME_MAX is 255, so we have plenty of room to make uniquely-name= d > > > files. > > >=20 > > > We could build a dir hierarchy though. Something like: > > >=20 > > > - ref_tracker > > > + netdev > > > + netns =20 > >=20 > > How do you make that generic? How due the GPU users of reftracker fit > > in? And whatever the next users are? A flat directory keeps it > > simple. Anybody capable of actually using this has to have a level of > > intelligence sufficient for glob(3). > >=20 > > However, a varargs format function does make sense, since looking at > > the current users, many of them will need it. >=20 > No preference on my side about the hierarchy TBH. I just defaulted to > thinking about it in terms of a hierarchy class/id rather than class-id > but shouldn't matter. >=20 > The main point I was trying to make was about using a synthetic ID - > like the pointer value. For the netdevs this patchset waits until=20 > the very end of the registration process to add the debugfs dir > because (I'm guessing) the name isn't assigned when we alloc=20 > the device (and therefore when we call ref_tracker_dir_init()). >=20 > Using synthetic ID lets us register the debugfs from > ref_tracker_dir_init(). >=20 Yes, exactly. dev->name doesn't get populated until later, so we have to delay creating the debugfs file if we want the name to be meaningful. Ditto for the netns and its inode number. We certainly could move to "classname@%px" format. If we go that route, I'd suggest that we convert the ref_tracker_dir.name field to a const char * pointer, and have the ref_tracker_dir_init() callers pass in a pointer to a static classname string. No need to keep copies in that case. The i915 ref_trackers would need to be changed, but hopefully that's not a problem. With that change we could register the debugfs files in ref_tracker_dir_init() instead of having an extra call. The caveat there is that some of these objects get created very early (e.g. init_net), before debugfs comes online, so we'll miss creating debugfs files for those objects. Maybe that's no big deal. > In fact using "registered name" can be misleading. In modern setups > where devices are renamed based on the system topology, after > registration. >=20 > The Ethernet interface on my laptop is called enp0s13f0u1u1, > not eth0. It is renamed by systemd right _after_ registration. >=20 > [45224.911324] r8152 2-1.1:1.0 eth0: v1.12.13 > [45225.220032] r8152 2-1.1:1.0 enp0s13f0u1u1: renamed from eth0 >=20 > so in (most?) modern systems the name we carefully printed > into the debugfs name will in fact not match the current device name. > What more we don't try to keep the IDs monotonically increasing.=20 > If I plug in another Ethernet card it will also be called eth0 when > it's registered, again. You can experiment by adding dummy devices: >=20 > # ip link add type dummy > # ip link > ... > 2: dummy0: mtu 1500 qdisc noop state DOWN mode DEFAULT = group default qlen 1000 > link/ether b2:51:ee:5b:4b:83 brd ff:ff:ff:ff:ff:ff >=20 > # ip link set dev dummy0 name other-name > [ 206.747381][ T670] other-name: renamed from dummy0 > # ip link > ... > 2: other-name: mtu 1500 qdisc noop state DOWN mode DEFA= ULT group default qlen 1000 > link/ether b2:51:ee:5b:4b:83 brd ff:ff:ff:ff:ff:ff >=20 > # ip link add type dummy > # ip link > ... > 2: other-name: mtu 1500 qdisc noop state DOWN mode DEFA= ULT group default qlen 1000 > link/ether b2:51:ee:5b:4b:83 brd ff:ff:ff:ff:ff:ff > 3: dummy0: mtu 1500 qdisc noop state DOWN mode DEFAULT = group default qlen 1000 > link/ether b2:51:ee:5b:4b:83 brd ff:ff:ff:ff:ff:ff >=20 >=20 > The second device is called dummy0, again, because that name was > "free". So with the current code we delay the registration of debugfs > just to provide a name which is in fact misleading :S >=20 Lovely. > But with all that said, I guess you still want the "meaningful" ID for > the netns, and that one is in fact stable :S I would prefer that, but if that's not feasible then I can live without meaningful names. We'd just have to determine some way to get the address of a particular netns or netdev, which is an extra step when debugging, but one we can do (e.g., with drgn). --=20 Jeff Layton