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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 720B7CE7AA5 for ; Mon, 25 Sep 2023 17:09:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232303AbjIYRJg (ORCPT ); Mon, 25 Sep 2023 13:09:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42954 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229437AbjIYRJe (ORCPT ); Mon, 25 Sep 2023 13:09:34 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2688ABC; Mon, 25 Sep 2023 10:09:28 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1E4DC433C7; Mon, 25 Sep 2023 17:09:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1695661767; bh=p6AzNXPdHriEeTlj5yWJ1nJYbwWDrFUzUL7AtEgJGzM=; h=Date:Cc:Subject:From:To:References:In-Reply-To:From; b=Rb57uamRYmdcgr+E9zoGsXBzpmzv/veQrH19wWJksDsp7SCwfr8QNfo91IbyIwlAi vUvSWHrqtcbHFH3jKgQEb1Sp1WvEEiKBpnLKgwLeB0DIYOt8WjigfyOuYKS1U5w2sa lNiYTHsjCWxtY3T36p26/qrL7CtC7ESUnjgQttsgFpImVpu044JCrt0An0XNXtT2er r/fqJa9NCk4bn5FviDfTYHqYod3kAR3CJR7OGn1qUcpEIHMDqefAg6fBdETBDvq2rr cyrZVyS3K9sWaWv3zjHvMCeeAJ3mri9QhCnHwKCd/pphO5WL5+Ts6ZZieqdEndkTwr ANLbSJkRngJwQ== Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 25 Sep 2023 20:09:21 +0300 Message-Id: Cc: , , , , , , Subject: Re: [PATCH v5 01/18] cgroup/misc: Add per resource callbacks for CSS events From: "Jarkko Sakkinen" To: "Haitao Huang" , , , , , , , , , , , X-Mailer: aerc 0.14.0 References: <20230923030657.16148-1-haitao.huang@linux.intel.com> <20230923030657.16148-2-haitao.huang@linux.intel.com> In-Reply-To: <20230923030657.16148-2-haitao.huang@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat Sep 23, 2023 at 6:06 AM EEST, Haitao Huang wrote: > From: Kristen Carlson Accardi > > The misc cgroup controller (subsystem) currently does not perform > resource type specific action for Cgroups Subsystem State (CSS) events: > the 'css_alloc' event when a cgroup is created and the 'css_free' event > when a cgroup is destroyed, or in event of user writing the max value to > the misc.max file to set the usage limit of a specific resource > [admin-guide/cgroup-v2.rst, 5-9. Misc]. > > Define callbacks for those events and allow resource providers to > register the callbacks per resource type as needed. This will be > utilized later by the EPC misc cgroup support implemented in the SGX > driver: > - On css_alloc, allocate and initialize necessary structures for EPC > reclaiming, e.g., LRU list, work queue, etc. > - On css_free, cleanup and free those structures created in alloc. > - On max_write, trigger EPC reclaiming if the new limit is at or below > current usage. > > Signed-off-by: Kristen Carlson Accardi > Signed-off-by: Haitao Huang > --- > V5: > - Remove prefixes from the callback names (tj) > - Update commit message (Jarkko) > > V4: > - Moved this to the front of the series. > - Applies on cgroup/for-6.6 with the overflow fix for misc. > > V3: > - Removed the released() callback > --- > include/linux/misc_cgroup.h | 5 +++++ > kernel/cgroup/misc.c | 32 +++++++++++++++++++++++++++++--- > 2 files changed, 34 insertions(+), 3 deletions(-) > > diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h > index e799b1f8d05b..96a88822815a 100644 > --- a/include/linux/misc_cgroup.h > +++ b/include/linux/misc_cgroup.h > @@ -37,6 +37,11 @@ struct misc_res { > u64 max; > atomic64_t usage; > atomic64_t events; > + > + /* per resource callback ops */ > + int (*alloc)(struct misc_cg *cg); > + void (*free)(struct misc_cg *cg); > + void (*max_write)(struct misc_cg *cg); > }; > =20 > /** > diff --git a/kernel/cgroup/misc.c b/kernel/cgroup/misc.c > index 79a3717a5803..62c9198dee21 100644 > --- a/kernel/cgroup/misc.c > +++ b/kernel/cgroup/misc.c > @@ -276,10 +276,13 @@ static ssize_t misc_cg_max_write(struct kernfs_open= _file *of, char *buf, > =20 > cg =3D css_misc(of_css(of)); > =20 > - if (READ_ONCE(misc_res_capacity[type])) > + if (READ_ONCE(misc_res_capacity[type])) { > WRITE_ONCE(cg->res[type].max, max); > - else > + if (cg->res[type].max_write) > + cg->res[type].max_write(cg); > + } else { > ret =3D -EINVAL; > + } > =20 > return ret ? ret : nbytes; > } > @@ -383,23 +386,39 @@ static struct cftype misc_cg_files[] =3D { > static struct cgroup_subsys_state * > misc_cg_alloc(struct cgroup_subsys_state *parent_css) > { > + struct misc_cg *parent_cg; > enum misc_res_type i; > struct misc_cg *cg; > + int ret; > =20 > if (!parent_css) { > cg =3D &root_cg; > + parent_cg =3D &root_cg; > } else { > cg =3D kzalloc(sizeof(*cg), GFP_KERNEL); > if (!cg) > return ERR_PTR(-ENOMEM); > + parent_cg =3D css_misc(parent_css); > } > =20 > for (i =3D 0; i < MISC_CG_RES_TYPES; i++) { > WRITE_ONCE(cg->res[i].max, MAX_NUM); > atomic64_set(&cg->res[i].usage, 0); > + if (parent_cg->res[i].alloc) { > + ret =3D parent_cg->res[i].alloc(cg); > + if (ret) > + goto alloc_err; > + } > } > =20 > return &cg->css; > + > +alloc_err: > + for (i =3D 0; i < MISC_CG_RES_TYPES; i++) > + if (parent_cg->res[i].free) > + cg->res[i].free(cg); > + kfree(cg); > + return ERR_PTR(ret); > } > =20 > /** > @@ -410,7 +429,14 @@ misc_cg_alloc(struct cgroup_subsys_state *parent_css= ) > */ > static void misc_cg_free(struct cgroup_subsys_state *css) > { > - kfree(css_misc(css)); > + struct misc_cg *cg =3D css_misc(css); > + enum misc_res_type i; > + > + for (i =3D 0; i < MISC_CG_RES_TYPES; i++) > + if (cg->res[i].free) > + cg->res[i].free(cg); > + > + kfree(cg); > } > =20 > /* Cgroup controller callbacks */ > --=20 > 2.25.1 Since the only existing client feature requires all callbacks, should this not have that as an invariant? I.e. it might be better to fail unless *all* ops are non-nil (e.g. to catch issues in the kernel code). BR, Jarkko