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Date: Mon, 15 May 2017 17:23:09 -0500
From: Rob Herring <robh+dt@...nel.org>
To: Frank Rowand <frowand.list@...il.com>
Cc: Stephen Boyd <stephen.boyd@...aro.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/4] of: remove *phandle properties from expanded
device tree
On Mon, May 1, 2017 at 9:46 PM, <frowand.list@...il.com> wrote:
> From: Frank Rowand <frank.rowand@...y.com>
>
> 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@...y.com>
> ---
> 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).
> +
> + 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.
>
> 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.
> + 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@...y.com>
>
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