From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
reinette.chatre@intel.com, tony.luck@intel.com,
linux-kernel@vger.kernel.org, linux-sgx@vger.kernel.org
Subject: Re: [PATCH v8 2/2] x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node
Date: Mon, 25 Oct 2021 07:15:46 +0200 [thread overview]
Message-ID: <YXY9gsIn+VhmPhHU@kroah.com> (raw)
In-Reply-To: <2b30027eb017216986e88008fdc925d0e6c61ce0.camel@kernel.org>
On Sun, Oct 24, 2021 at 05:24:43PM +0300, Jarkko Sakkinen wrote:
> On Sat, 2021-10-23 at 08:33 +0200, Greg Kroah-Hartman wrote:
> > On Sat, Oct 23, 2021 at 04:02:48AM +0300, Jarkko Sakkinen wrote:
> > > On Mon, 2021-10-18 at 16:35 +0200, Greg Kroah-Hartman wrote:
> > > > > + ret = sysfs_create_group(&dev->kobj, &sgx_node_attr_group);
> > > >
> > > > A huge hint, if a driver has to call a sysfs_* call, something is wrong.
> > > >
> > > > Something is wrong here.
> > > >
> > > > Why are you messing around with a kobject? This is a device, that you
> > > > control, you can just set the default attribute group for it and then
> > > > the driver core will add and remove the sysfs group at the proper time,
> > > > in the proper way. Right now you are racing userspace and loosing.
> > > >
> > > > Use the default group list, that is what it is there for.
> > >
> > > I used sysfs_create_group() because node_devices is not owned by SGX
> > > code. It is managed in drivers/base/node.c, and also initialized before
> > > SGX.
> >
> > Then that is broken, please do not use that device as your code does not
> > "own" it. Or fix the logic to be initialized earlier.
>
> To get a synchronous initialization, I'd need to add the attributes as
> part of this declaration:
>
> static struct attribute *node_dev_attrs[] = {
> &dev_attr_cpumap.attr,
> &dev_attr_cpulist.attr,
> &dev_attr_meminfo.attr,
> &dev_attr_numastat.attr,
> &dev_attr_distance.attr,
> &dev_attr_vmstat.attr,
> NULL
> };
> ATTRIBUTE_GROUPS(node_dev);
>
> That guarantees that the attribute exists at the time when the
> node is created, e.g. in that sense this will fix the race with
> uevent code.
>
> However, up until sgx_init() has been completed, the attribute
> will emit '0'.
Is that a problem? Who would be wanting to use sgx until that happens?
You have this issue today anyway, right?
> If I change sgx_init() from device_initcall() to
> core_initcall() (i.e. one before postcore_initcall(), can I
> expect these to work:
>
> * node_isset()
> * node_set()
> * num_possibles_nodes()
> * numa_node_id()
> * next_node_in()
>
> ?
You should be able to test this out yourself :)
thanks,
greg k-h
next prev parent reply other threads:[~2021-10-25 5:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-18 13:57 [PATCH v8 1/2] x86/sgx: Rename fallback labels in sgx_init() Jarkko Sakkinen
2021-10-18 13:57 ` [PATCH v8 2/2] x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node Jarkko Sakkinen
2021-10-18 14:35 ` Greg Kroah-Hartman
2021-10-23 1:02 ` Jarkko Sakkinen
2021-10-23 6:33 ` Greg Kroah-Hartman
2021-10-24 14:24 ` Jarkko Sakkinen
2021-10-25 5:15 ` Greg Kroah-Hartman [this message]
2021-10-25 23:46 ` Jarkko Sakkinen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YXY9gsIn+VhmPhHU@kroah.com \
--to=gregkh@linuxfoundation.org \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=jarkko@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-sgx@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=reinette.chatre@intel.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).