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'.
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()
?
Dave, perhaps you know this?
[*] register_node_type() and kobject_event_init() are postcore init
calls, so this would be non-racy.
> thanks,
>
> greg k-h
/Jarkko
