linux-kernel - Re: Qemu crashes in -next due to 'of: remove *phandle properties from expanded device tree'

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Date:   Thu, 15 Jun 2017 00:58:20 -0700
From:   Frank Rowand <frowand.list@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Frank Rowand <frank.rowand@...y.com>, linux-kernel@...r.kernel.org,
        Rob Herring <robh@...nel.org>
Subject: Re: Qemu crashes in -next due to 'of: remove *phandle properties from
 expanded device tree'

On 06/14/17 21:12, Guenter Roeck wrote:

< snip >

> Good (v4.12-rc4):
> 

< snip >

> OF: Checking node /soc@...00000/pic@...00
> OF:     type match
> OF:   node '/soc@...00000/pic@...00' compatible '' type 'open-pic' name '' score 2
> OF:   node '/soc@...00000/pic@...00' compatible 'open-pic' type '' name '' score 0

< snip >

> 
> bad:

< snip >

> OF: Checking node /soc@...00000/pic@...00
> OF:   node '/soc@...00000/pic@...00' compatible '' type 'open-pic' name '' score 0
> OF:   node '/soc@...00000/pic@...00' compatible 'open-pic' type '' name '' score 0

< snip >

> No matching open-pic node
> ------------[ cut here ]------------
> kernel BUG at arch/powerpc/platforms/85xx/corenet_generic.c:50!
> 
> So, in __of_device_is_compatible(), the difference is in
> __of_device_is_compatible() after
> 
>         /* Matching type is better than matching name */
> 
> Further debugging shows that device->type is NULL in the bad case.
> 
> OF: Checking node /soc@...00000/pic@...00
> OF:     trying type match open-pic - <NULL>
> OF:   node '/soc@...00000/pic@...00' compatible '' type 'open-pic' name '' score 0
> OF:   node '/soc@...00000/pic@...00' compatible 'open-pic' type '' name '' score 0
> 
> Do you need more information ?

I think I know what part of my patch is causing the problem.

Can you try the following patch to see if if fixes the failure in
__of_device_is_compatible()?

If this fixes the failure, then I know what is going on.  If it works
then I will have to rework my original patch in a different way than
this quick hack.

-Frank



---
 drivers/of/dynamic.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

Index: b/drivers/of/dynamic.c
===================================================================
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -218,6 +218,20 @@ int of_property_notify(int action, struc
 
 static void __of_attach_node(struct device_node *np)
 {
+	const __be32 *phandle;
+	int sz;
+
+	/* use "<NULL>" to be consistent with populate_node() */
+	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;