Re: [PATCH 2/7] acpi, apei, ghes: Introduce more generic mechanism to init/deinit GHES error notifications.

[Tomasz Nowicki <tomasz.nowicki@linaro.org>]

On 13.05.2014 20:13, Borislav Petkov wrote:
> On Wed, Apr 09, 2014 at 05:14:30PM +0200, Tomasz Nowicki wrote:
>> Init/deinit of GHES error notifications are moved to corresponding
>> functions e.g. for SCI ghes_notify_init_sci{sci} and ghes_notify_remove_{sci}
>> which in turn are gathered to ghes_notify_tab table.
>> ghes_probe and ghes_remove check notification support based on
>> function reference pointer in ghes_notify_tab and call it with ghes argument.
>>
>> This approach allows us to change address of a given error notification
>> init/deinit function call in ghes_notify_tab in runtime. In turn,
>> we can avoid #ifdef usage in common code e.g. for NMI which is currently
>> supported by x86.
>>
>> Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
>> ---
>>   drivers/acpi/apei/ghes.c |  242 ++++++++++++++++++++++++++++------------------
>>   1 file changed, 149 insertions(+), 93 deletions(-)
>>
>> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
>> index f7edffc..ca8387e 100644
>> --- a/drivers/acpi/apei/ghes.c
>> +++ b/drivers/acpi/apei/ghes.c
>> @@ -148,6 +148,14 @@ static struct irq_work ghes_proc_irq_work;
>>   struct ghes_estatus_cache *ghes_estatus_caches[GHES_ESTATUS_CACHES_SIZE];
>>   static atomic_t ghes_estatus_cache_alloced;
>>
>> +struct ghes_notify_setup {
>> +	const char *notif_name;
>> +	int 	   (*init_call)(struct ghes *ghes);
>> +	void 	   (*remove_call)(struct ghes *ghes);
>> +};
>
> Please run through checkpatch before submitting:
>
> WARNING: please, no space before tabs
> #44: FILE: drivers/acpi/apei/ghes.c:153:
> +^Iint ^I   (*init_call)(struct ghes *ghes);$
>
> WARNING: please, no space before tabs
> #45: FILE: drivers/acpi/apei/ghes.c:154:
> +^Ivoid ^I   (*remove_call)(struct ghes *ghes);$

My bad, will run it before next submission.

>
>> +
>> +static struct ghes_notify_setup	ghes_notify_tab[];
>> +
>>   static int ghes_ioremap_init(void)
>>   {
>>   	ghes_ioremap_area = __get_vm_area(PAGE_SIZE * GHES_IOREMAP_PAGES,
>> @@ -879,10 +887,6 @@ out:
>>   	return ret;
>>   }
>>
>> -static struct notifier_block ghes_notifier_sci = {
>> -	.notifier_call = ghes_notify_sci,
>> -};
>> -
>>   static unsigned long ghes_esource_prealloc_size(
>>   	const struct acpi_hest_generic *generic)
>>   {
>> @@ -898,33 +902,151 @@ static unsigned long ghes_esource_prealloc_size(
>>   	return prealloc_size;
>>   }
>>
>> +static int ghes_notify_init_nmi(struct ghes *ghes)
>> +{
>> +	unsigned long len;
>> +
>> +	len = ghes_esource_prealloc_size(ghes->generic);
>> +	ghes_estatus_pool_expand(len);
>> +	mutex_lock(&ghes_list_mutex);
>> +	if (list_empty(&ghes_nmi))
>> +		register_nmi_handler(NMI_LOCAL, ghes_notify_nmi, 0, "ghes");
>> +	list_add_rcu(&ghes->list, &ghes_nmi);
>> +	mutex_unlock(&ghes_list_mutex);
>> +
>> +	return 0;
>
> Unconditionally returning 0 seems kinda moot. At least
> register_nmi_handler() retval could be returned...
>
> ...

Yes, it's worth returning register_nmi_handler() retval. Nice catch.

>
>> +static struct ghes_notify_setup
>> +       ghes_notify_tab[ACPI_HEST_NOTIFY_RESERVED] = {
>> +               [ACPI_HEST_NOTIFY_POLLED]   = {"POLLED",
>> +                                              ghes_notify_init_polled,
>> +                                              ghes_notify_remove_polled},
>> +               [ACPI_HEST_NOTIFY_EXTERNAL] = {"EXT_IRQ",
>> +                                              ghes_notify_init_external,
>> +                                              ghes_notify_remove_external},
>> +               [ACPI_HEST_NOTIFY_LOCAL]    = {"LOCAL_IRQ", NULL, NULL},
>> +               [ACPI_HEST_NOTIFY_SCI]      = {"SCI",
>> +                                              ghes_notify_init_sci,
>> +                                              ghes_notify_remove_sci},
>> +               [ACPI_HEST_NOTIFY_NMI]      = {"NMI",
>> +                                              ghes_notify_init_nmi,
>> +                                              ghes_notify_remove_nmi},
>> +               [ACPI_HEST_NOTIFY_CMCI]     = {"CMCI", NULL, NULL},
>> +               [ACPI_HEST_NOTIFY_MCE]      = {"MCE", NULL, NULL},
>> +};
>
> I guess you don't need to save the ->notif_name strings but add
> a function which maps ACPI_HEST_* to strings => smaller struct
> ghes_notify_setup.

Well, we need to keep these strings somewhere :) IMO, this is simpler 
solution. What would be advantage of additional map function?

>
>
>> @@ -944,48 +1066,10 @@ static int ghes_probe(struct platform_device *ghes_dev)
>>   	if (rc < 0)
>>   		goto err;
>>
>> -	switch (generic->notify.type) {
>> -	case ACPI_HEST_NOTIFY_POLLED:
>> -		ghes->timer.function = ghes_poll_func;
>> -		ghes->timer.data = (unsigned long)ghes;
>> -		init_timer_deferrable(&ghes->timer);
>> -		ghes_add_timer(ghes);
>> -		break;
>> -	case ACPI_HEST_NOTIFY_EXTERNAL:
>> -		/* External interrupt vector is GSI */
>> -		rc = acpi_gsi_to_irq(generic->notify.vector, &ghes->irq);
>> -		if (rc) {
>> -			pr_err(GHES_PFX "Failed to map GSI to IRQ for generic hardware error source: %d\n",
>> -			       generic->header.source_id);
>> -			goto err_edac_unreg;
>> -		}
>> -		rc = request_irq(ghes->irq, ghes_irq_func, 0, "GHES IRQ", ghes);
>> -		if (rc) {
>> -			pr_err(GHES_PFX "Failed to register IRQ for generic hardware error source: %d\n",
>> -			       generic->header.source_id);
>> -			goto err_edac_unreg;
>> -		}
>> -		break;
>> -	case ACPI_HEST_NOTIFY_SCI:
>> -		mutex_lock(&ghes_list_mutex);
>> -		if (list_empty(&ghes_sci))
>> -			register_acpi_hed_notifier(&ghes_notifier_sci);
>> -		list_add_rcu(&ghes->list, &ghes_sci);
>> -		mutex_unlock(&ghes_list_mutex);
>> -		break;
>> -	case ACPI_HEST_NOTIFY_NMI:
>> -		len = ghes_esource_prealloc_size(generic);
>> -		ghes_estatus_pool_expand(len);
>> -		mutex_lock(&ghes_list_mutex);
>> -		if (list_empty(&ghes_nmi))
>> -			register_nmi_handler(NMI_LOCAL, ghes_notify_nmi, 0,
>> -						"ghes");
>> -		list_add_rcu(&ghes->list, &ghes_nmi);
>> -		mutex_unlock(&ghes_list_mutex);
>> -		break;
>> -	default:
>> -		BUG();
>
> What happened to those BUG() catch-all stoppers?

I am validating generic->notify.type at the begin of function and return 
error in case of unknown value. I think there is no need to check that 
again.

>
>> -	}
>> +	rc = (*ghes_init_call)(ghes);
>> +	if (rc)
>> +		goto err_edac_unreg;
>> +
>>   	platform_set_drvdata(ghes_dev, ghes);
>>
>>   	return 0;
>> @@ -1003,44 +1087,16 @@ static int ghes_remove(struct platform_device *ghes_dev)
>>   {
>>   	struct ghes *ghes;
>>   	struct acpi_hest_generic *generic;
>> -	unsigned long len;
>> +	void (*ghes_remove_call)(struct ghes *ghes);
>>
>>   	ghes = platform_get_drvdata(ghes_dev);
>> +	ghes->flags |= GHES_EXITING;
>> +
>>   	generic = ghes->generic;
>> +	ghes_remove_call = ghes_notify_tab[generic->notify.type].remove_call;
>>
>> -	ghes->flags |= GHES_EXITING;
>> -	switch (generic->notify.type) {
>> -	case ACPI_HEST_NOTIFY_POLLED:
>> -		del_timer_sync(&ghes->timer);
>> -		break;
>> -	case ACPI_HEST_NOTIFY_EXTERNAL:
>> -		free_irq(ghes->irq, ghes);
>> -		break;
>> -	case ACPI_HEST_NOTIFY_SCI:
>> -		mutex_lock(&ghes_list_mutex);
>> -		list_del_rcu(&ghes->list);
>> -		if (list_empty(&ghes_sci))
>> -			unregister_acpi_hed_notifier(&ghes_notifier_sci);
>> -		mutex_unlock(&ghes_list_mutex);
>> -		break;
>> -	case ACPI_HEST_NOTIFY_NMI:
>> -		mutex_lock(&ghes_list_mutex);
>> -		list_del_rcu(&ghes->list);
>> -		if (list_empty(&ghes_nmi))
>> -			unregister_nmi_handler(NMI_LOCAL, "ghes");
>> -		mutex_unlock(&ghes_list_mutex);
>> -		/*
>> -		 * To synchronize with NMI handler, ghes can only be
>> -		 * freed after NMI handler finishes.
>> -		 */
>> -		synchronize_rcu();
>> -		len = ghes_esource_prealloc_size(generic);
>> -		ghes_estatus_pool_shrink(len);
>> -		break;
>> -	default:
>> -		BUG();
>> -		break;
>
> This one too.
>
For this one I should provide generic->notify.type validation. Will 
rethink and fix it.

Tomasz