Re: [PATCH v7 3/3] edac: Add support for Amazon's Annapurna Labs L2 EDAC

[Hawa, Hanna]

On 1/15/2020 8:50 PM, James Morse wrote:
> Hi Hanna,
>
> On 15/10/2019 13:09, Hanna Hawa wrote:
> > Adds support for Amazon's Annapurna Labs L2 EDAC driver to detect and
> > report L2 errors.
>
>
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 7887a62dc843..0eabcfcf91a9 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -748,6 +748,11 @@ M:	Hanna Hawa <hhhawa@xxxxxxxxxx>
> >   S:	Maintained
> >   F:	drivers/edac/al_l1_edac.c
> >   
> > +AMAZON ANNAPURNA LABS L2 EDAC
> > +M:	Hanna Hawa <hhhawa@xxxxxxxxxx>
> > +S:	Maintained
> > +F:	drivers/edac/al_l2_edac.c
>
> (Why not add the file to the previous section? All this does is come up with an email
> address based on the file)

Added new section as this separated driver.

> > diff --git a/drivers/edac/al_l2_edac.c b/drivers/edac/al_l2_edac.c
> > new file mode 100644
> > index 000000000000..156610c85591
> > --- /dev/null
> > +++ b/drivers/edac/al_l2_edac.c
> > @@ -0,0 +1,251 @@
> > +static int al_l2_edac_probe(struct platform_device *pdev)
> > +{
>
> > +	for_each_possible_cpu(i) {
> > +		struct device_node *cpu;
> > +		struct device_node *cpu_cache;
> > +		struct al_l2_cache *l2_cache;
> > +		bool found = false;
> > +
> > +		cpu = of_get_cpu_node(i, NULL);
> > +		if (!cpu)
> > +			continue;
> > +
> > +		cpu_cache = of_find_next_cache_node(cpu);
> > +		list_for_each_entry(l2_cache, &al_l2->l2_caches, list_node) {
> > +			if (l2_cache->of_node == cpu_cache) {
> > +				found = true;
> > +				break;
> > +			}
> > +		}
> > +
> > +		if (found) {
> > +			cpumask_set_cpu(i, &l2_cache->cluster_cpus);
>
> 			of_node_put(cpu_cache); ?
>
> (I can see why you might keep the reference in the else block)

Will be added in next PS.

> > +		} else {
> > +			l2_cache = devm_kzalloc(dev, sizeof(*l2_cache),
> > +						GFP_KERNEL);
> > +			l2_cache->of_node = cpu_cache;
> > +			list_add(&l2_cache->list_node, &al_l2->l2_caches);
> > +			cpumask_set_cpu(i, &l2_cache->cluster_cpus);
> > +		}
> > +
> > +		of_node_put(cpu);
> > +	}
> > +
> > +	if (list_empty(&al_l2->l2_caches)) {
> > +		dev_err(dev, "L2 Cache list is empty for EDAC device\n");
> > +		ret = -EINVAL;
> > +		goto err;
> > +	}
>
> You are doing this at probe time to create a static list of which CPUs map onto the L2
> caches. cacheinfo does something very similar, but it looks like you can't use it as its
> only populated for online CPUs, and you'd need to walk multiple CPUs cacheinfo leaves to
> find the same information. The alternative is more complicated.

> > +	ret = edac_device_add_device(edac_dev);
> > +	if (ret)
>
> Any references held in the al_l2->l2_caches list leak here.
>
>
> > +		goto err;
> > +
> > +	return 0;
> > +
> > +err:
> > +	dev_err(dev, "Failed to add L2 edac device (%d)\n", ret);
> > +	edac_device_free_ctl_info(edac_dev);
> > +
> > +	return ret;
> > +}
>
>
> > +static int al_l2_edac_remove(struct platform_device *pdev)
> > +{
> > +	struct edac_device_ctl_info *edac_dev = platform_get_drvdata(pdev);
>
> Do you need to roll over the al_l2->l2_caches list to of_node_put() the l2_cache's ?

will add loop after for_each_possible_cpu() to call of_node_put() on 
each l2_cache.

> > +	edac_device_del_device(edac_dev->dev);
> > +	edac_device_free_ctl_info(edac_dev);
> > +
> > +	return 0;
> > +}
>
> [..]
>
> > +static const struct of_device_id al_l2_edac_of_match[] = {
> > +	{ .compatible = "al,alpine-v2" },
> > +	{ .compatible = "amazon,alpine-v3" },
> > +	{}
> > +};
>
> Same comment on these being machine compatibles and what property that applies to.

Fix comments from your review from L1 driver.

> The code to match the platform and create the platform_device is identical, is there any
> way it can be shared?
>
> I'm guessing the two-files is because these can be built as independent modules. Would
> anyone ever have one, but not the other? The L1 support is optional, but you've listed the
> same set of platforms in both cases here, so do we need to support one but not the other
> today?

It's not related to that platform will have one, but not the other. The 
two drivers are not related to each other, I agree with you that there 
is identical code in matching platform. But this is not good reason to 
combine the two drivers.

Thanks,
Hanna

> Thanks,
>
> James