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Subject: Re: [PATCH 05.1/16] of:overlay: missing name, phandle, linux,phandle
 in new nodes
From:   Frank Rowand <frowand.list@gmail.com>
To:     Rob Herring <robh+dt@kernel.org>,
        Pantelis Antoniou <pantelis.antoniou@konsulko.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Alan Tull <atull@kernel.org>, Moritz Fischer <mdf@kernel.org>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        devicetree@vger.kernel.org, linux-fpga@vger.kernel.org
References: <CANk1AXQScT_b1_UOiVuWNcB=LiA3gvvZrw53H1XVSCNqsGPqtA@mail.gmail.com>
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Message-ID: <f20d06c3-5db7-3547-7b8b-d43d474683f1@gmail.com>
Date:   Tue, 9 Oct 2018 23:49:20 -0700
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On 10/09/18 23:04, frowand.list@gmail.com wrote:
> From: Frank Rowand <frank.rowand@sony.com>
> 
> 
> "of: overlay: use prop add changeset entry for property in new nodes"
> fixed a problem where an 'update property' changeset entry was
> created for properties contained in nodes added by a changeset.
> The fix was to use an 'add property' changeset entry.
> 
> This exposed more bugs in the apply overlay code.  The properties
> 'name', 'phandle', and 'linux,phandle' were filtered out by
> add_changeset_property() as special properties.  Change the filter
> to be only for existing nodes, not newly added nodes.
> 
> The second bug is that the 'name' property does not exist in the
> newest FDT version, and has to be constructed from the node's
> full_name.  Construct an 'add property' changeset entry for
> newly added nodes.
> 
> Signed-off-by: Frank Rowand <frank.rowand@sony.com>
> ---
> 
> 
> Hi Alan,
> 
> Thanks for reporting the problem with missing node names.
> 
> I was able to replicate the problem, and have created this preliminary
> version of a patch to fix the problem.
> 
> I have not extensively reviewed the patch yet, but would appreciate
> if you can confirm this fixes your problem.
> 
> I created this patch as patch 17 of the series, but have also
> applied it as patch 05.1, immediately after patch 05/16, and
> built the kernel, booted, and verified name and phandle for
> one of the nodes in a unittest overlay for both cases.  So
> minimal testing so far on my part.
> 
> I have not verified whether the series builds and boots after
> each of patches 06..16 if this patch is applied as patch 05.1.
> 
> There is definitely more work needed for me to complete this
> patch because it allocates some more memory, but does not yet
> free it when the overlay is released.
> 
> -Frank
> 
> 
>  drivers/of/overlay.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 67 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> index 0b0904f44bc7..9746cea2aa91 100644
> --- a/drivers/of/overlay.c
> +++ b/drivers/of/overlay.c
> @@ -301,10 +301,11 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
>  	struct property *new_prop = NULL, *prop;
>  	int ret = 0;
>  
> -	if (!of_prop_cmp(overlay_prop->name, "name") ||
> -	    !of_prop_cmp(overlay_prop->name, "phandle") ||
> -	    !of_prop_cmp(overlay_prop->name, "linux,phandle"))
> -		return 0;
> +	if (target->in_livetree)
> +		if (!of_prop_cmp(overlay_prop->name, "name") ||
> +		    !of_prop_cmp(overlay_prop->name, "phandle") ||
> +		    !of_prop_cmp(overlay_prop->name, "linux,phandle"))
> +			return 0;

This is a big hammer patch.

Nobody should waste time reviewing this patch.

The following part should not be needed (though the above section might have
to become _slightly_ more complex).

-Frank
>  
>  	if (target->in_livetree)
>  		prop = of_find_property(target->np, overlay_prop->name, NULL);
> @@ -443,10 +444,13 @@ static int build_changeset_next_level(struct overlay_changeset *ovcs,
>  		struct target *target, const struct device_node *overlay_node)
>  {
>  	struct device_node *child;
> -	struct property *prop;
> +	struct property *prop, *name_prop;
> +	bool has_name = false;
>  	int ret;
>  
>  	for_each_property_of_node(overlay_node, prop) {
> +		if (!strcmp(prop->name, "name"))
> +			has_name = true;
>  		ret = add_changeset_property(ovcs, target, prop, 0);
>  		if (ret) {
>  			pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
> @@ -455,6 +459,57 @@ static int build_changeset_next_level(struct overlay_changeset *ovcs,
>  		}
>  	}
>  
> +	/*
> +	 * With FDT version 0x10 we may not have the name property,
> +	 * recreate it here from the unit name if absent
> +	 */
> +
> +	if (!has_name) {
> +		const char *p = target->np->full_name, *ps = p, *pa = NULL;
> +		int len;
> +
> +		/*
> +		 * zzz
> +		 * TODO: stash name_prop on a list in ovcs, to be freed
> +		 * after overlay removed
> +		 */
> +
> +		while (*p) {
> +			if ((*p) == '@')
> +				pa = p;
> +			else if ((*p) == '/')
> +				ps = p + 1;
> +			p++;
> +		}
> +
> +		if (pa < ps)
> +			pa = p;
> +		len = (pa - ps) + 1;
> +
> +		name_prop = kmalloc(sizeof(*name_prop), GFP_KERNEL);
> +		if (!name_prop)
> +			return -ENOMEM;
> +
> +		name_prop->name = kstrdup("name", GFP_KERNEL);
> +		name_prop->value = kmalloc(len, GFP_KERNEL);
> +		if (!name_prop->name || !name_prop->value) {
> +			ret = -ENOMEM;
> +			goto err_free_name_prop;
> +		}
> +
> +		memcpy(name_prop->value, ps, len - 1);
> +		((char *)name_prop->value)[len - 1] = 0;
> +
> +		name_prop->length = strlen(name_prop->value) + 1;
> +
> +		ret = add_changeset_property(ovcs, target, name_prop, 0);
> +		if (ret) {
> +			pr_debug("Failed to apply name_prop @%pOF/%s, err=%d\n",
> +				 target->np, name_prop->name, ret);
> +			goto err_free_name_prop;
> +		}
> +	}
> +
>  	for_each_child_of_node(overlay_node, child) {
>  		ret = add_changeset_node(ovcs, target, child);
>  		if (ret) {
> @@ -466,6 +521,13 @@ static int build_changeset_next_level(struct overlay_changeset *ovcs,
>  	}
>  
>  	return 0;
> +
> +err_free_name_prop:
> +	kfree(name_prop->name);
> +	kfree(name_prop->value);
> +	kfree(name_prop);
> +	return ret;
> +
>  }
>  
>  /*
>