Re: [PATCH 1/4] of: remove *phandle properties from expanded device tree

[Frank Rowand <frowand.list@gmail.com>]

Adding Stephen.

On 04/14/17 20:55, frowand.list@gmail.com wrote:
> From: Frank Rowand <frank.rowand@sony.com>
> 
> Remove "phandle" and "linux,phandle" properties from the internal
> device tree.  The phandle will still be in the struct device_node
> phandle field.
> 
> This is to resolve the issue found by Stephen Boyd [1] when he changed
> the type of struct property.value from void * to const void *.  As
> a result of the type change, the overlay code had compile errors
> where the resolver updates phandle values.
> 
>   [1] http://lkml.iu.edu/hypermail/linux/kernel/1702.1/04160.html
> 
> - Add sysfs infrastructure to report np->phandle, as if it was a property.
> - Do not create "phandle" "ibm,phandle", and "linux,phandle" properties
>   in the expanded device tree.
> - Remove no longer needed checks to exclude "phandle" and "linux,phandle"
>   properties in several locations.
> - A side effect of these changes is that the obsolete "linux,phandle"
>   properties will no longer appear in /proc/device-tree
> 
> Signed-off-by: Frank Rowand <frank.rowand@sony.com>
> ---
>  drivers/of/base.c     | 51 ++++++++++++++++++++++++++++++++++++++++++++++++---
>  drivers/of/dynamic.c  | 29 ++++++++++++++++-------------
>  drivers/of/fdt.c      | 40 ++++++++++++++++++++++++----------------
>  drivers/of/overlay.c  |  4 +---
>  drivers/of/resolver.c | 23 +----------------------
>  include/linux/of.h    |  1 +
>  6 files changed, 91 insertions(+), 57 deletions(-)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index d7c4629a3a2d..197946615503 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -116,6 +116,19 @@ static ssize_t of_node_property_read(struct file *filp, struct kobject *kobj,
>  	return memory_read_from_buffer(buf, count, &offset, pp->value, pp->length);
>  }
>  
> +static ssize_t of_node_phandle_read(struct file *filp, struct kobject *kobj,
> +				struct bin_attribute *bin_attr, char *buf,
> +				loff_t offset, size_t count)
> +{
> +	phandle phandle;
> +	struct device_node *np;
> +
> +	np = container_of(bin_attr, struct device_node, attr_phandle);
> +	phandle = cpu_to_be32(np->phandle);
> +	return memory_read_from_buffer(buf, count, &offset, &phandle,
> +				       sizeof(phandle));
> +}
> +
>  /* always return newly allocated name, caller must free after use */
>  static const char *safe_name(struct kobject *kobj, const char *orig_name)
>  {
> @@ -164,6 +177,38 @@ int __of_add_property_sysfs(struct device_node *np, struct property *pp)
>  	return rc;
>  }
>  
> +/*
> + * In the imported device tree (fdt), phandle is a property.  In the
> + * internal data structure it is instead stored in the struct device_node.
> + * Make phandle visible in sysfs as if it was a property.
> + */
> +static int __of_add_phandle_sysfs(struct device_node *np)
> +{
> +	int rc;
> +
> +	if (IS_ENABLED(CONFIG_PPC_PSERIES))
> +		return 0;
> +
> +	if (!IS_ENABLED(CONFIG_SYSFS))
> +		return 0;
> +
> +	if (!of_kset || !of_node_is_attached(np))
> +		return 0;
> +
> +	if (!np->phandle || np->phandle == 0xffffffff)
> +		return 0;
> +
> +	sysfs_bin_attr_init(&pp->attr);
> +	np->attr_phandle.attr.name = "phandle";
> +	np->attr_phandle.attr.mode = 0444;
> +	np->attr_phandle.size = sizeof(np->phandle);
> +	np->attr_phandle.read = of_node_phandle_read;
> +
> +	rc = sysfs_create_bin_file(&np->kobj, &np->attr_phandle);
> +	WARN(rc, "error adding attribute phandle to node %s\n", np->full_name);
> +	return rc;
> +}
> +
>  int __of_attach_node_sysfs(struct device_node *np)
>  {
>  	const char *name;
> @@ -193,6 +238,8 @@ int __of_attach_node_sysfs(struct device_node *np)
>  	if (rc)
>  		return rc;
>  
> +	__of_add_phandle_sysfs(np);
> +
>  	for_each_property_of_node(np, pp)
>  		__of_add_property_sysfs(np, pp);
>  
> @@ -2097,9 +2144,7 @@ void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
>  		int id, len;
>  
>  		/* Skip those we do not want to proceed */
> -		if (!strcmp(pp->name, "name") ||
> -		    !strcmp(pp->name, "phandle") ||
> -		    !strcmp(pp->name, "linux,phandle"))
> +		if (!strcmp(pp->name, "name"))
>  			continue;
>  
>  		np = of_find_node_by_path(pp->value);
> diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> index 888fdbc09992..c6fd3f32bfcb 100644
> --- a/drivers/of/dynamic.c
> +++ b/drivers/of/dynamic.c
> @@ -218,19 +218,6 @@ int of_property_notify(int action, struct device_node *np,
>  
>  void __of_attach_node(struct device_node *np)
>  {
> -	const __be32 *phandle;
> -	int sz;
> -
> -	np->name = __of_get_property(np, "name", NULL) ? : "<NULL>";
> -	np->type = __of_get_property(np, "device_type", NULL) ? : "<NULL>";
> -
> -	phandle = __of_get_property(np, "phandle", &sz);
> -	if (!phandle)
> -		phandle = __of_get_property(np, "linux,phandle", &sz);
> -	if (IS_ENABLED(CONFIG_PPC_PSERIES) && !phandle)
> -		phandle = __of_get_property(np, "ibm,phandle", &sz);
> -	np->phandle = (phandle && (sz >= 4)) ? be32_to_cpup(phandle) : 0;
> -
>  	np->child = NULL;
>  	np->sibling = np->parent->child;
>  	np->parent->child = np;
> @@ -244,10 +231,22 @@ int of_attach_node(struct device_node *np)
>  {
>  	struct of_reconfig_data rd;
>  	unsigned long flags;
> +	const __be32 *phandle;
> +	int sz;
>  
>  	memset(&rd, 0, sizeof(rd));
>  	rd.dn = np;
>  
> +	np->name = __of_get_property(np, "name", NULL) ? : "<NULL>";
> +	np->type = __of_get_property(np, "device_type", NULL) ? : "<NULL>";
> +
> +	phandle = __of_get_property(np, "phandle", &sz);
> +	if (!phandle)
> +		phandle = __of_get_property(np, "linux,phandle", &sz);
> +	if (IS_ENABLED(CONFIG_PPC_PSERIES) && !phandle)
> +		phandle = __of_get_property(np, "ibm,phandle", &sz);
> +	np->phandle = (phandle && (sz >= 4)) ? be32_to_cpup(phandle) : 0;
> +
>  	mutex_lock(&of_mutex);
>  	raw_spin_lock_irqsave(&devtree_lock, flags);
>  	__of_attach_node(np);
> @@ -441,6 +440,10 @@ struct device_node *__of_node_dup(const struct device_node *np, const char *fmt,
>  			}
>  		}
>  	}
> +
> +	node->name = __of_get_property(node, "name", NULL) ? : "<NULL>";
> +	node->type = __of_get_property(node, "device_type", NULL) ? : "<NULL>";
> +
>  	return node;
>  
>   err_prop:
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index e5ce4b59e162..270f31b0c259 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -181,6 +181,8 @@ static void populate_properties(const void *blob,
>  		const __be32 *val;
>  		const char *pname;
>  		u32 sz;
> +		int prop_is_phandle = 0;
> +		int prop_is_ibm_phandle = 0;
>  
>  		val = fdt_getprop_by_offset(blob, cur, &pname, &sz);
>  		if (!val) {
> @@ -196,11 +198,6 @@ static void populate_properties(const void *blob,
>  		if (!strcmp(pname, "name"))
>  			has_name = true;
>  
> -		pp = unflatten_dt_alloc(mem, sizeof(struct property),
> -					__alignof__(struct property));
> -		if (dryrun)
> -			continue;
> -
>  		/* We accept flattened tree phandles either in
>  		 * ePAPR-style "phandle" properties, or the
>  		 * legacy "linux,phandle" properties.  If both
> @@ -208,23 +205,34 @@ static void populate_properties(const void *blob,
>  		 * will get weird. Don't do that.
>  		 */
>  		if (!strcmp(pname, "phandle") ||
> -		    !strcmp(pname, "linux,phandle")) {
> -			if (!np->phandle)
> -				np->phandle = be32_to_cpup(val);
> -		}
> +		    !strcmp(pname, "linux,phandle"))
> +			prop_is_phandle = 1;
>  
>  		/* And we process the "ibm,phandle" property
>  		 * used in pSeries dynamic device tree
>  		 * stuff
>  		 */
> -		if (!strcmp(pname, "ibm,phandle"))
> -			np->phandle = be32_to_cpup(val);
> +		if (!strcmp(pname, "ibm,phandle")) {
> +			prop_is_phandle = 1;
> +			prop_is_ibm_phandle = 1;
> +		}
> +
> +		if (!prop_is_phandle)
> +			pp = unflatten_dt_alloc(mem, sizeof(struct property),
> +						__alignof__(struct property));
>  
> -		pp->name   = (char *)pname;
> -		pp->length = sz;
> -		pp->value  = (__be32 *)val;
> -		*pprev     = pp;
> -		pprev      = &pp->next;
> +		if (dryrun)
> +			continue;
> +
> +		if (!prop_is_phandle) {
> +			pp->name   = (char *)pname;
> +			pp->length = sz;
> +			pp->value  = (__be32 *)val;
> +			*pprev     = pp;
> +			pprev      = &pp->next;
> +		} else if (prop_is_ibm_phandle || !np->phandle) {
> +			np->phandle = be32_to_cpup(val);
> +		}
>  	}
>  
>  	/* With version 0x10 we may not have the name property,
> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> index 7827786718d8..ca0b85f5deb1 100644
> --- a/drivers/of/overlay.c
> +++ b/drivers/of/overlay.c
> @@ -101,9 +101,7 @@ static int of_overlay_apply_single_property(struct of_overlay *ov,
>  	tprop = of_find_property(target, prop->name, NULL);
>  
>  	/* special properties are not meant to be updated (silent NOP) */
> -	if (of_prop_cmp(prop->name, "name") == 0 ||
> -	    of_prop_cmp(prop->name, "phandle") == 0 ||
> -	    of_prop_cmp(prop->name, "linux,phandle") == 0)
> +	if (!of_prop_cmp(prop->name, "name"))
>  		return 0;
>  
>  	propn = __of_prop_dup(prop, GFP_KERNEL);
> diff --git a/drivers/of/resolver.c b/drivers/of/resolver.c
> index 7ae9863cb0a4..624cbaeae0a4 100644
> --- a/drivers/of/resolver.c
> +++ b/drivers/of/resolver.c
> @@ -71,30 +71,11 @@ static void adjust_overlay_phandles(struct device_node *overlay,
>  		int phandle_delta)
>  {
>  	struct device_node *child;
> -	struct property *prop;
> -	phandle phandle;
>  
>  	/* adjust node's phandle in node */
>  	if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
>  		overlay->phandle += phandle_delta;
>  
> -	/* copy adjusted phandle into *phandle properties */
> -	for_each_property_of_node(overlay, prop) {
> -
> -		if (of_prop_cmp(prop->name, "phandle") &&
> -		    of_prop_cmp(prop->name, "linux,phandle"))
> -			continue;
> -
> -		if (prop->length < 4)
> -			continue;
> -
> -		phandle = be32_to_cpup(prop->value);
> -		if (phandle == OF_PHANDLE_ILLEGAL)
> -			continue;
> -
> -		*(uint32_t *)prop->value = cpu_to_be32(overlay->phandle);
> -	}
> -
>  	for_each_child_of_node(overlay, child)
>  		adjust_overlay_phandles(child, phandle_delta);
>  }
> @@ -197,9 +178,7 @@ static int adjust_local_phandle_references(struct device_node *local_fixups,
>  	for_each_property_of_node(local_fixups, prop_fix) {
>  
>  		/* skip properties added automatically */
> -		if (!of_prop_cmp(prop_fix->name, "name") ||
> -		    !of_prop_cmp(prop_fix->name, "phandle") ||
> -		    !of_prop_cmp(prop_fix->name, "linux,phandle"))
> +		if (!of_prop_cmp(prop_fix->name, "name"))
>  			continue;
>  
>  		if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 21e6323de0f3..4e86e05853f3 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -61,6 +61,7 @@ struct device_node {
>  	struct	kobject kobj;
>  	unsigned long _flags;
>  	void	*data;
> +	struct bin_attribute attr_phandle;
>  #if defined(CONFIG_SPARC)
>  	const char *path_component_name;
>  	unsigned int unique_id;
>