Re: [PATCH 1/6 v5] Kernel DLPAR Infrastructure

[Nathan Fontenot]

Benjamin Herrenschmidt wrote:
> On Wed, 2009-10-28 at 15:53 -0500, Nathan Fontenot wrote:
> > This patch provides the kernel DLPAR infrastructure in a new filed named
> > dlpar.c.  The functionality provided is for acquiring and releasing a resource
> > from firmware and the parsing of information returned from the
> > ibm,configure-connector rtas call.  Additionally this exports the pSeries
> > reconfiguration notifier chain so that it can be invoked when device tree 
> > updates are made.
> >
> > Signed-off-by: Nathan Fontenot <nfont at austin.ibm.com> 
> > ---
>
> Hi Nathan !
>
> Finally I get to review this stuff :-)

Thanks!

> > +#define CFG_CONN_WORK_SIZE	4096
> > +static char workarea[CFG_CONN_WORK_SIZE];
> > +static DEFINE_SPINLOCK(workarea_lock);
>
> So I'm not a huge fan of this workarea static. First a static is in
> effect a global name (as far as System.map etc... are concerned) so it
> would warrant a better name. Then, do we really want that 4K of BSS
> taken even on platforms that don't do dlpar ? Any reason why you don't
> just pop a free page with __get_free_page() inside of
> configure_connector() ?

I'm not either, having a static buffer and a lock feels like overkill
for this.  I tried kmalloc, but that didn't work.  I'll try using
__get_free_page.

> > +struct cc_workarea {
> > +	u32	drc_index;
> > +	u32	zero;
> > +	u32	name_offset;
> > +	u32	prop_length;
> > +	u32	prop_offset;
> > +};
> > +
> > +static struct property *parse_cc_property(char *workarea)
> > +{
> > +	struct property *prop;
> > +	struct cc_workarea *ccwa;
> > +	char *name;
> > +	char *value;
> > +
> > +	prop = kzalloc(sizeof(*prop), GFP_KERNEL);
> > +	if (!prop)
> > +		return NULL;
> > +
> > +	ccwa = (struct cc_workarea *)workarea;
> > +	name = workarea + ccwa->name_offset;
> > +	prop->name = kzalloc(strlen(name) + 1, GFP_KERNEL);
> > +	if (!prop->name) {
> > +		kfree(prop);
> > +		return NULL;
> > +	}
> > +
> > +	strcpy(prop->name, name);
> > +
> > +	prop->length = ccwa->prop_length;
> > +	value = workarea + ccwa->prop_offset;
> > +	prop->value = kzalloc(prop->length, GFP_KERNEL);
> > +	if (!prop->value) {
> > +		kfree(prop->name);
> > +		kfree(prop);
> > +		return NULL;
> > +	}
> > +
> > +	memcpy(prop->value, value, prop->length);
> > +	return prop;
> > +}
> > +
> > +static void free_property(struct property *prop)
> > +{
> > +	kfree(prop->name);
> > +	kfree(prop->value);
> > +	kfree(prop);
> > +}
> > +
> > +static struct device_node *parse_cc_node(char *work_area)
> > +{
>
> const char* maybe ?

sure.

> > +	struct device_node *dn;
> > +	struct cc_workarea *ccwa;
> > +	char *name;
> > +
> > +	dn = kzalloc(sizeof(*dn), GFP_KERNEL);
> > +	if (!dn)
> > +		return NULL;
> > +
> > +	ccwa = (struct cc_workarea *)work_area;
> > +	name = work_area + ccwa->name_offset;
>
> I'm wondering whether work_area should be a struct cc_workarea * in the
> first place with a char data[] at the end, but that would mean probably
> tweaking the offsets... no big deal, up to you.

I'll look onto that.  Anything that makes this easier to understand is good.


> > +	dn->full_name = kzalloc(strlen(name) + 1, GFP_KERNEL);
> > +	if (!dn->full_name) {
> > +		kfree(dn);
> > +		return NULL;
> > +	}
> > +
> > +	strcpy(dn->full_name, name);
>
> kstrdup ?

yep, should have used kstrdup.

>  .../...
>
> > +#define NEXT_SIBLING    1
> > +#define NEXT_CHILD      2
> > +#define NEXT_PROPERTY   3
> > +#define PREV_PARENT     4
> > +#define MORE_MEMORY     5
> > +#define CALL_AGAIN	-2
> > +#define ERR_CFG_USE     -9003
> > +
> > +struct device_node *configure_connector(u32 drc_index)
> > +{
>
> It's a global exported function, I'd rather you call it
> dlpar_configure_connector()

ok.

> > +	struct device_node *dn;
> > +	struct device_node *first_dn = NULL;
> > +	struct device_node *last_dn = NULL;
> > +	struct property *property;
> > +	struct property *last_property = NULL;
> > +	struct cc_workarea *ccwa;
> > +	int cc_token;
> > +	int rc;
> > +
> > +	cc_token = rtas_token("ibm,configure-connector");
> > +	if (cc_token == RTAS_UNKNOWN_SERVICE)
> > +		return NULL;
> > +
> > +	spin_lock(&workarea_lock);
> > +
> > +	ccwa = (struct cc_workarea *)&workarea[0];
> > +	ccwa->drc_index = drc_index;
> > +	ccwa->zero = 0;
>
> Popping a free page with gfp (or just kmalloc'ing 4K) would avoid the
> need for the lock too.

yes, see comment at beginning.

> > +	rc = rtas_call(cc_token, 2, 1, NULL, workarea, NULL);
> > +	while (rc) {
> > +		switch (rc) {
> > +		case NEXT_SIBLING:
> > +			dn = parse_cc_node(workarea);
> > +			if (!dn)
> > +				goto cc_error;
> > +
> > +			dn->parent = last_dn->parent;
> > +			last_dn->sibling = dn;
> > +			last_dn = dn;
> > +			break;
> > +
> > +		case NEXT_CHILD:
> > +			dn = parse_cc_node(workarea);
> > +			if (!dn)
> > +				goto cc_error;
> > +
> > +			if (!first_dn)
> > +				first_dn = dn;
> > +			else {
> > +				dn->parent = last_dn;
> > +				if (last_dn)
> > +					last_dn->child = dn;
> > +			}
> > +
> > +			last_dn = dn;
> > +			break;
> > +
> > +		case NEXT_PROPERTY:
> > +			property = parse_cc_property(workarea);
> > +			if (!property)
> > +				goto cc_error;
> > +
> > +			if (!last_dn->properties)
> > +				last_dn->properties = property;
> > +			else
> > +				last_property->next = property;
> > +
> > +			last_property = property;
> > +			break;
> > +
> > +		case PREV_PARENT:
> > +			last_dn = last_dn->parent;
> > +			break;
> > +
> > +		case CALL_AGAIN:
> > +			break;
> > +
> > +		case MORE_MEMORY:
> > +		case ERR_CFG_USE:
> > +		default:
> > +			printk(KERN_ERR "Unexpected Error (%d) "
> > +			       "returned from configure-connector\n", rc);
> > +			goto cc_error;
> > +		}
> > +
> > +		rc = rtas_call(cc_token, 2, 1, NULL, workarea, NULL);
> > +	}
> > +
> > +	spin_unlock(&workarea_lock);
> > +	return first_dn;
> > +
> > +cc_error:
> > +	spin_unlock(&workarea_lock);
> > +
> > +	if (first_dn)
> > +		free_cc_nodes(first_dn);
> > +
> > +	return NULL;
> > +}
> > +
> > +static struct device_node *derive_parent(const char *path)
> > +{
> > +	struct device_node *parent;
> > +	char parent_path[128];
> > +	int parent_path_len;
> > +
> > +	parent_path_len = strrchr(path, '/') - path + 1;
> > +	strlcpy(parent_path, path, parent_path_len);
> > +
> > +	parent = of_find_node_by_path(parent_path);
> > +
> > +	return parent;
> > +}
>
> This ...
>
> > +static int add_one_node(struct device_node *dn)
> > +{
> > +	struct proc_dir_entry *ent;
> > +	int rc;
> > +
> > +	of_node_set_flag(dn, OF_DYNAMIC);
> > +	kref_init(&dn->kref);
> > +	dn->parent = derive_parent(dn->full_name);
> > +
> > +	rc = blocking_notifier_call_chain(&pSeries_reconfig_chain,
> > +					  PSERIES_RECONFIG_ADD, dn);
> > +	if (rc == NOTIFY_BAD) {
> > +		printk(KERN_ERR "Failed to add device node %s\n",
> > +		       dn->full_name);
> > +		return -ENOMEM; /* For now, safe to assume kmalloc failure */
> > +	}
> > +
> > +	of_attach_node(dn);
> > +
> > +#ifdef CONFIG_PROC_DEVICETREE
> > +	ent = proc_mkdir(strrchr(dn->full_name, '/') + 1, dn->parent->pde);
> > +	if (ent)
> > +		proc_device_tree_add_node(dn, ent);
> > +#endif
> > +
> > +	of_node_put(dn->parent);
> > +	return 0;
> > +}
>
>  ... and this ...
>
> > +int add_device_tree_nodes(struct device_node *dn)
> > +{
> > +	struct device_node *child = dn->child;
> > +	struct device_node *sibling = dn->sibling;
> > +	int rc;
> > +
> > +	dn->child = NULL;
> > +	dn->sibling = NULL;
> > +	dn->parent = NULL;
> > +
> > +	rc = add_one_node(dn);
> > +	if (rc)
> > +		return rc;
> > +
> > +	if (child) {
> > +		rc = add_device_tree_nodes(child);
> > +		if (rc)
> > +			return rc;
> > +	}
> > +
> > +	if (sibling)
> > +		rc = add_device_tree_nodes(sibling);
> > +
> > +	return rc;
> > +}
>
>  ... and this ...
>
> > +static int remove_one_node(struct device_node *dn)
> > +{
> > +	struct device_node *parent = dn->parent;
> > +	struct property *prop = dn->properties;
> > +
> > +#ifdef CONFIG_PROC_DEVICETREE
> > +	while (prop) {
> > +		remove_proc_entry(prop->name, dn->pde);
> > +		prop = prop->next;
> > +	}
> > +
> > +	if (dn->pde)
> > +		remove_proc_entry(dn->pde->name, parent->pde);
> > +#endif
> > +
> > +	blocking_notifier_call_chain(&pSeries_reconfig_chain,
> > +			    PSERIES_RECONFIG_REMOVE, dn);
> > +	of_detach_node(dn);
> > +	of_node_put(dn); /* Must decrement the refcount */
> > +
> > +	return 0;
> > +}
>
>  ... and this ...
>
> > +static int _remove_device_tree_nodes(struct device_node *dn)
> > +{
> > +	int rc;
> > +
> > +	if (dn->child) {
> > +		rc = _remove_device_tree_nodes(dn->child);
> > +		if (rc)
> > +			return rc;
> > +	}
> > +
> > +	if (dn->sibling) {
> > +		rc = _remove_device_tree_nodes(dn->sibling);
> > +		if (rc)
> > +			return rc;
> > +	}
> > +
> > +	rc = remove_one_node(dn);
> > +	return rc;
> > +}
>
>  ... repeat myself ...
>
> > +int remove_device_tree_nodes(struct device_node *dn)
> > +{
> > +	int rc;
> > +
> > +	if (dn->child) {
> > +		rc = _remove_device_tree_nodes(dn->child);
> > +		if (rc)
> > +			return rc;
> > +	}
> > +
> > +	rc = remove_one_node(dn);
> > +	return rc;
> > +}
>
>  ... should probably all go to something like drivers/of/dynamic.c or at
> least for now arch/powerpc/kernel/of_dynamic.c along with everything
> related to dynamically adding and removing nodes. I see that potentially
> useful for more than just DLPAR (though DLPAR is the only user right
> now) and should also all be prefixed with of_*

I agree, there should be at least a powerpc generic implementation of these
routines.  The reason I put them here is that I am doing some oddities with
the next, child, and sibling pointers since they point to items not yet in
the device tree.

I saw that Grant Likely is doing updates to all of the of_* stuff right now,
would it be ok to have these routines here, renamed as dlpar_*, and look
to merge them in with Grant's updates when he finishes?
 
> > +#define DR_ENTITY_SENSE		9003
> > +#define DR_ENTITY_PRESENT	1
> > +#define DR_ENTITY_UNUSABLE	2
> > +#define ALLOCATION_STATE	9003
> > +#define ALLOC_UNUSABLE		0
> > +#define ALLOC_USABLE		1
> > +#define ISOLATION_STATE		9001
> > +#define ISOLATE			0
> > +#define UNISOLATE		1
> > +
> > +int acquire_drc(u32 drc_index)
> > +{
> > +	int dr_status, rc;
> > +
> > +	rc = rtas_call(rtas_token("get-sensor-state"), 2, 2, &dr_status,
> > +		       DR_ENTITY_SENSE, drc_index);
> > +	if (rc || dr_status != DR_ENTITY_UNUSABLE)
> > +		return -1;
> > +
> > +	rc = rtas_set_indicator(ALLOCATION_STATE, drc_index, ALLOC_USABLE);
> > +	if (rc)
> > +		return rc;
> > +
> > +	rc = rtas_set_indicator(ISOLATION_STATE, drc_index, UNISOLATE);
> > +	if (rc) {
> > +		rtas_set_indicator(ALLOCATION_STATE, drc_index, ALLOC_UNUSABLE);
> > +		return rc;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +int release_drc(u32 drc_index)
> > +{
> > +	int dr_status, rc;
> > +
> > +	rc = rtas_call(rtas_token("get-sensor-state"), 2, 2, &dr_status,
> > +		       DR_ENTITY_SENSE, drc_index);
> > +	if (rc || dr_status != DR_ENTITY_PRESENT)
> > +		return -1;
> > +
> > +	rc = rtas_set_indicator(ISOLATION_STATE, drc_index, ISOLATE);
> > +	if (rc)
> > +		return rc;
> > +
> > +	rc = rtas_set_indicator(ALLOCATION_STATE, drc_index, ALLOC_UNUSABLE);
> > +	if (rc) {
> > +		rtas_set_indicator(ISOLATION_STATE, drc_index, UNISOLATE);
> > +		return rc;
> > +	}
> > +
> > +	return 0;
> > +}
>
> Both above should have a dlpar_* prefix

will do.

> > +static int pseries_dlpar_init(void)
> > +{
> > +	if (!machine_is(pseries))
> > +		return 0;
> > +
> > +	return 0;
> > +}
> > +device_initcall(pseries_dlpar_init);
>
> What the point ? :-)

Yeah, its a bit odd looking but later patches actually add code to the init routine
to set up memory probe/release and cpu probe/release handlers.

I'll look to add ifdef's around the initcall for cases where no work is to be done.

-Nathan Fontenot

> Cheers
> Ben.
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