From: "Jarkko Sakkinen" <jarkko@kernel.org>
To: "Haitao Huang" <haitao.huang@linux.intel.com>,
<dave.hansen@linux.intel.com>, <tj@kernel.org>,
<linux-kernel@vger.kernel.org>, <linux-sgx@vger.kernel.org>,
<x86@kernel.org>, <cgroups@vger.kernel.org>, <tglx@linutronix.de>,
<mingo@redhat.com>, <bp@alien8.de>, <hpa@zytor.com>,
<sohil.mehta@intel.com>
Cc: <zhiquan1.li@intel.com>, <kristen@linux.intel.com>,
<seanjc@google.com>, <zhanb@microsoft.com>,
<anakrish@microsoft.com>, <mikko.ylinen@linux.intel.com>,
<yangjie@microsoft.com>
Subject: Re: [PATCH v5 01/18] cgroup/misc: Add per resource callbacks for CSS events
Date: Tue, 03 Oct 2023 01:47:34 +0300 [thread overview]
Message-ID: <CVYBI76N4PTF.38BQ9KIBIOGEH@seitikki> (raw)
In-Reply-To: <op.2bwqct0rwjvjmi@hhuan26-mobl.amr.corp.intel.com>
On Wed Sep 27, 2023 at 4:56 AM EEST, Haitao Huang wrote:
> On Tue, 26 Sep 2023 08:13:18 -0500, Jarkko Sakkinen <jarkko@kernel.org>
> wrote:
>
> ...
> >> > >> /**
> >> > >> @@ -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 = css_misc(css);
> >> > >> + enum misc_res_type i;
> >> > >> +
> >> > >> + for (i = 0; i < MISC_CG_RES_TYPES; i++)
> >> > >> + if (cg->res[i].free)
> >> > >> + cg->res[i].free(cg);
> >> > >> +
> >> > >> + kfree(cg);
> >> > >> }
> >> > >>
> >> > >> /* Cgroup controller callbacks */
> >> > >> --
> >> > >> 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).
> >> > >
> >> >
> >> > These callbacks are chained from cgroup_subsys, and they are defined
> >> > separately so it'd be better follow the same pattern. Or change
> >> together
> >> > with cgroup_subsys if we want to do that. Reasonable?
> >>
> >> I noticed this one later:
> >>
> >> It would better to create a separate ops struct and declare the instance
> >> as const at minimum.
> >>
> >> Then there is no need for dynamic assigment of ops and all that is in
> >> rodata. This is improves both security and also allows static analysis
> >> bit better.
> >>
> >> Now you have to dynamically trace the struct instance, e.g. in case of
> >> a bug. If this one done, it would be already in the vmlinux.
> >I.e. then in the driver you can have static const struct declaration
> > with *all* pointers pre-assigned.
> >
> > Not sure if cgroups follows this or not but it is *objectively*
> > better. Previous work is not always best possible work...
> >
>
> IIUC, like vm_ops field in vma structs. Although function pointers in
> vm_ops are assigned statically, but you still need dynamically assign
> vm_ops for each instance of vma.
>
> So the code will look like this:
>
> if (parent_cg->res[i].misc_ops && parent_cg->res[i].misc_ops->alloc)
> {
> ...
> }
>
> I don't see this is the pattern used in cgroups and no strong opinion
> either way.
>
> TJ, do you have preference on this?
I do have strong opinion on this. In the client side we want as much
things declared statically as we can because it gives more tools for
statical analysis.
I don't want to see dynamic assignments in the SGX driver, when they
are not actually needed, no matter things are done in cgroups.
> Thanks
> Haitao
BR, Jarkko
next prev parent reply other threads:[~2023-10-02 22:47 UTC|newest]
Thread overview: 119+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-23 3:06 [PATCH v5 00/18] Add Cgroup support for SGX EPC memory Haitao Huang
2023-09-23 3:06 ` [PATCH v5 01/18] cgroup/misc: Add per resource callbacks for CSS events Haitao Huang
2023-09-25 17:09 ` Jarkko Sakkinen
2023-09-26 3:04 ` Haitao Huang
2023-09-26 13:10 ` Jarkko Sakkinen
2023-09-26 13:13 ` Jarkko Sakkinen
2023-09-27 1:56 ` Haitao Huang
2023-10-02 22:47 ` Jarkko Sakkinen [this message]
2023-10-02 22:55 ` Jarkko Sakkinen
2023-10-04 15:45 ` Haitao Huang
2023-10-04 17:18 ` Tejun Heo
2023-09-27 9:20 ` Huang, Kai
2023-10-03 14:29 ` Haitao Huang
2023-10-17 18:55 ` Michal Koutný
2023-09-23 3:06 ` [PATCH v5 02/18] cgroup/misc: Add SGX EPC resource type and export APIs for SGX driver Haitao Huang
2023-09-25 18:50 ` Tejun Heo
2023-09-28 3:59 ` Huang, Kai
2023-10-03 7:00 ` Haitao Huang
2023-10-03 19:33 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 03/18] x86/sgx: Add sgx_epc_lru_lists to encapsulate LRU lists Haitao Huang
2023-09-23 3:06 ` [PATCH v5 04/18] x86/sgx: Use sgx_epc_lru_lists for existing active page list Haitao Huang
2023-09-23 3:06 ` [PATCH v5 05/18] x86/sgx: Store reclaimable EPC pages in sgx_epc_lru_lists Haitao Huang
2023-09-27 10:14 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 06/18] x86/sgx: Introduce EPC page states Haitao Huang
2023-09-25 17:11 ` Jarkko Sakkinen
2023-09-27 10:28 ` Huang, Kai
2023-10-03 4:49 ` Haitao Huang
2023-10-03 20:03 ` Huang, Kai
2023-10-04 15:24 ` Haitao Huang
2023-10-04 21:05 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 07/18] x86/sgx: Introduce RECLAIM_IN_PROGRESS state Haitao Huang
2023-09-25 17:13 ` Jarkko Sakkinen
2023-09-27 10:42 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 08/18] x86/sgx: Use a list to track to-be-reclaimed pages Haitao Huang
2023-09-28 9:28 ` Huang, Kai
2023-10-03 5:09 ` Haitao Huang
2023-09-23 3:06 ` [PATCH v5 09/18] x86/sgx: Store struct sgx_encl when allocating new VA pages Haitao Huang
2023-09-27 11:14 ` Huang, Kai
2023-09-27 15:35 ` Haitao Huang
2023-09-27 21:21 ` Huang, Kai
2023-09-29 15:06 ` Haitao Huang
2023-10-02 11:05 ` Huang, Kai
2023-09-27 11:35 ` Huang, Kai
2023-10-03 6:45 ` Haitao Huang
2023-10-03 20:07 ` Huang, Kai
2023-10-04 15:03 ` Haitao Huang
2023-10-04 21:13 ` Huang, Kai
2023-10-05 4:22 ` Haitao Huang
2023-10-05 6:49 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 10/18] x86/sgx: Add EPC page flags to identify owner types Haitao Huang
2023-09-23 3:06 ` [PATCH v5 11/18] x86/sgx: store unreclaimable pages in LRU lists Haitao Huang
2023-09-27 11:57 ` Huang, Kai
2023-10-03 5:42 ` Haitao Huang
2023-09-28 9:41 ` Huang, Kai
2023-10-03 5:15 ` Haitao Huang
2023-10-03 20:12 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 12/18] x86/sgx: Add EPC OOM path to forcefully reclaim EPC Haitao Huang
2023-10-09 23:45 ` Huang, Kai
2023-10-10 0:23 ` Sean Christopherson
2023-10-10 0:50 ` Huang, Kai
2023-10-10 1:34 ` Huang, Kai
2023-10-10 16:49 ` Haitao Huang
2023-10-11 0:51 ` Huang, Kai
2023-10-12 13:27 ` Haitao Huang
2023-10-16 10:57 ` Huang, Kai
2023-10-16 19:52 ` Haitao Huang
2023-10-16 21:09 ` Huang, Kai
2023-10-17 0:10 ` Haitao Huang
2023-10-17 1:34 ` Huang, Kai
2023-10-17 12:58 ` Haitao Huang
2023-10-17 18:54 ` Michal Koutný
2023-10-17 19:13 ` Michal Koutný
2023-10-18 4:39 ` Haitao Huang
2023-10-18 4:37 ` Haitao Huang
2023-10-18 13:55 ` Dave Hansen
2023-10-18 15:26 ` Haitao Huang
2023-10-18 15:37 ` Dave Hansen
2023-10-18 15:52 ` Michal Koutný
2023-10-18 16:25 ` Haitao Huang
2023-10-16 21:32 ` Sean Christopherson
2023-10-17 0:09 ` Haitao Huang
2023-10-17 15:43 ` Sean Christopherson
2023-10-17 11:49 ` Mikko Ylinen
2023-10-11 1:14 ` Huang, Kai
2023-10-16 11:02 ` Huang, Kai
2023-10-10 1:42 ` Haitao Huang
2023-10-10 2:23 ` Huang, Kai
2023-10-10 13:26 ` Haitao Huang
2023-10-11 0:01 ` Sean Christopherson
2023-10-11 15:02 ` Haitao Huang
2023-10-10 1:04 ` Haitao Huang
2023-10-10 1:18 ` Huang, Kai
2023-10-10 1:38 ` Haitao Huang
2023-10-10 2:12 ` Huang, Kai
2023-10-10 17:05 ` Haitao Huang
2023-10-11 0:31 ` Huang, Kai
2023-10-11 16:04 ` Haitao Huang
2023-09-23 3:06 ` [PATCH v5 13/18] x86/sgx: Expose sgx_reclaim_pages() for use by EPC cgroup Haitao Huang
2023-10-05 12:24 ` Huang, Kai
2023-10-05 19:23 ` Haitao Huang
2023-10-05 20:25 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 14/18] x86/sgx: Add helper to grab pages from an arbitrary EPC LRU Haitao Huang
2023-09-23 3:06 ` [PATCH v5 15/18] x86/sgx: Prepare for multiple LRUs Haitao Huang
2023-10-05 12:30 ` Huang, Kai
2023-10-05 19:33 ` Haitao Huang
2023-10-05 20:38 ` Huang, Kai
2023-09-23 3:06 ` [PATCH v5 16/18] x86/sgx: Limit process EPC usage with misc cgroup controller Haitao Huang
2023-09-25 17:15 ` Jarkko Sakkinen
2023-10-05 21:01 ` Huang, Kai
2023-10-10 0:12 ` Huang, Kai
2023-10-10 0:16 ` Huang, Kai
2023-10-10 0:26 ` Huang, Kai
2023-10-22 18:26 ` Haitao Huang
2023-10-10 9:19 ` Huang, Kai
2023-10-10 9:32 ` Huang, Kai
2023-10-17 18:54 ` Michal Koutný
2023-10-19 16:05 ` Haitao Huang
2023-09-23 3:06 ` [PATCH v5 17/18] Docs/x86/sgx: Add description for cgroup support Haitao Huang
2023-09-23 3:06 ` [PATCH v5 18/18] selftests/sgx: Add scripts for EPC cgroup testing Haitao Huang
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