Re: [PATCH v4 1/4] of: remove *phandle properties from expanded device tree

From: Frank Rowand
Date: Sat Jun 10 2017 - 00:39:48 EST

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In reply to: Frank Rowand: "Re: [PATCH v4 1/4] of: remove *phandle properties from expanded device tree"
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On 06/09/17 19:35, Frank Rowand wrote:
> On 05/15/17 15:23, Rob Herring wrote:
>> On Mon, May 1, 2017 at 9:46 PM, <frowand.list@xxxxxxxxx> wrote:
>>> From: Frank Rowand <frank.rowand@xxxxxxxx>
>>>
>>> Remove "phandle", "linux,phandle", and "ibm,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 phandle properties in of_attach_node(), for nodes dynamically
>>> attached to the live tree. Add the phandle sysfs entry for these nodes.
>>> - When creating an overlay changeset, duplicate the node phandle in
>>> __of_node_dup().
>>> - 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" and
>>> "ibm,phandle" properties will no longer appear in /proc/device-tree (they
>>> will appear as "phandle").
>>>
>>> Signed-off-by: Frank Rowand <frank.rowand@xxxxxxxx>
>>> ---
>>> drivers/of/base.c | 48 ++++++++++++++++++++++++++++++++++++++++---
>>> drivers/of/dynamic.c | 54 +++++++++++++++++++++++++++++++++++++------------
>>> drivers/of/fdt.c | 40 +++++++++++++++++++++---------------
>>> drivers/of/of_private.h | 1 +
>>> drivers/of/overlay.c | 4 +---
>>> drivers/of/resolver.c | 23 +--------------------
>>> include/linux/of.h | 1 +
>>> 7 files changed, 114 insertions(+), 57 deletions(-)
>>>
>>> diff --git a/drivers/of/base.c b/drivers/of/base.c
>>> index d7c4629a3a2d..8a0cf9003cf8 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 +177,35 @@ 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.
>>> + */
>>> +int __of_add_phandle_sysfs(struct device_node *np)
>>> +{
>>> + int rc;
>>> +
>>> + 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(&np->attr_phandle);
>>> + 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 +235,8 @@ 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 +2141,7 @@ 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..59545b8fbf46 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;
>>> @@ -243,11 +230,47 @@ void __of_attach_node(struct device_node *np)
>>> int of_attach_node(struct device_node *np)
>>> {
>>> struct of_reconfig_data rd;
>>> + struct property *prev;
>>> + struct property *prop;
>>> + struct property *save_next;
>>> 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>";
>>
>> Why can't we just store NULL here? I know you're just moving this
>> existing code, but now we have it twice. I assume there was some
>> reason, so at least a comment why would be good. (I'm guessing it's
>> because strcmp won't take a NULL).
>
> Comment added.
>
> (Yes, the users of the string pointer are not expecting 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;
>>> +
>>> + /* remove phandle properties from node */
>>> + prev = NULL;
>>> + for (prop = np->properties; prop != NULL; ) {
>>> + save_next = prop->next;
>>> + if (!strcmp(prop->name, "phandle") ||
>>> + !strcmp(prop->name, "ibm,phandle") ||
>>> + !strcmp(prop->name, "linux,phandle")) {
>>> + if (prev)
>>> + prev->next = prop->next;
>>> + else
>>> + np->properties = prop->next;
>>> + prop->next = np->deadprops;
>>> + np->deadprops = prop;
>>> + } else {
>>> + prev = prop;
>>> + }
>>> + prop = save_next;
>>> + }
>>> +
>>> + __of_add_phandle_sysfs(np);
>>> +
>>> mutex_lock(&of_mutex);
>>> raw_spin_lock_irqsave(&devtree_lock, flags);
>>> __of_attach_node(np);
>>> @@ -429,6 +452,7 @@ struct device_node *__of_node_dup(const struct device_node *np, const char *fmt,
>>> /* Iterate over and duplicate all properties */
>>> if (np) {
>>> struct property *pp, *new_pp;
>>> + node->phandle = np->phandle;
>>> for_each_property_of_node(np, pp) {
>>> new_pp = __of_prop_dup(pp, GFP_KERNEL);
>>> if (!new_pp)
>>> @@ -441,6 +465,10 @@ 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;
>>
>> Can be bool.
>
> These two variables eliminated while addressing the next comment.

That change resulted in a warning for "make W=2", so
prop_is_phandle added back, changed to bool.

>>>
>>> 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) {
>>
>> This logic is a bit strange. I think it would be a bit better if we
>> can keep all the phandle code together and end with a continue, then
>> have the property handling code at the end of the loop.
>
> I will do this. One side effect will be that the value of property
> "ibm,phandle" will no longer override the value of properties "phandle"
> and "linux,phandle".
>
>
>>> + np->phandle = be32_to_cpup(val);
>>> + }
>>> }
>>>
>>> /* With version 0x10 we may not have the name property,
>>> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
>>> index 18bbb4517e25..33f11a5384f3 100644
>>> --- a/drivers/of/of_private.h
>>> +++ b/drivers/of/of_private.h
>>> @@ -47,6 +47,7 @@ extern int of_property_notify(int action, struct device_node *np,
>>> extern void of_node_release(struct kobject *kobj);
>>> extern int __of_changeset_apply(struct of_changeset *ocs);
>>> extern int __of_changeset_revert(struct of_changeset *ocs);
>>> +extern int __of_add_phandle_sysfs(struct device_node *np);
>>> #else /* CONFIG_OF_DYNAMIC */
>>> static inline int of_property_notify(int action, struct device_node *np,
>>> struct property *prop, struct property *old_prop)
>>> 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;
>>> --
>>> Frank Rowand <frank.rowand@xxxxxxxx>
>
>

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In reply to: Frank Rowand: "Re: [PATCH v4 1/4] of: remove *phandle properties from expanded device tree"
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