Re: [RFC PATCH] software node: Skip duplicated software_node sysfs

[Qian Cai <quic_qiancai@xxxxxxxxxxx>]

On 11/5/21 3:39 PM, Andy Shevchenko wrote:
>> Andy, thanks for the pointers so far. I was able to trace
>> set_primary_fwnode() and set_secondary_fwnode().
> 
> Can you share the trace you have got?


I used a simple debugging patch below:

diff --git a/drivers/base/core.c b/drivers/base/core.c

index fd034d742447..d8ae96289acf 100644

--- a/drivers/base/core.c

+++ b/drivers/base/core.c

@@ -4742,6 +4742,11 @@ void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)

 	struct device *parent = dev->parent;

 	struct fwnode_handle *fn = dev->fwnode;

 

+	printk("KK set_primary_fwnode dev name = %s, fwnode = %px\n", dev_name(dev), fwnode);

+	if (parent)

+		printk("KK parent = %s\n", dev_name(dev->parent));

+	if (fwnode && fwnode->dev)

+		printk("KK fwnode->dev = %s\n", dev_name(fwnode->dev));

 	if (fwnode) {

 		if (fwnode_is_primary(fn))

 			fn = fn->secondary;

@@ -4761,6 +4766,8 @@ void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)

 			dev->fwnode = NULL;

 		}

 	}

+	if (fwnode)

+		printk("KK secondary = %px\n", dev->fwnode->secondary);

 }

 EXPORT_SYMBOL_GPL(set_primary_fwnode);

 

@@ -4775,13 +4782,20 @@ EXPORT_SYMBOL_GPL(set_primary_fwnode);

  */

 void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode)

 {

+	printk("KK set_secondary_fwnode dev name = %s, fwnode = %px\n", dev_name(dev), fwnode);

+	if (dev->parent)

+		printk("KK parent = %s\n", dev_name(dev->parent));

+	if (fwnode && fwnode->dev)

+		printk("KK fwnode->dev = %s\n", dev_name(fwnode->dev));

 	if (fwnode)

 		fwnode->secondary = ERR_PTR(-ENODEV);

 

-	if (fwnode_is_primary(dev->fwnode))

+	if (fwnode_is_primary(dev->fwnode)) {

 		dev->fwnode->secondary = fwnode;

-	else

+		printk("KK primary = %px\n", dev->fwnode);

+	} else {

 		dev->fwnode = fwnode;

+	}

 }

 EXPORT_SYMBOL_GPL(set_secondary_fwnode);

 
Then, here are the relevant outputs indicating that
"808622B7:01" and  "xhci-hcd.3.auto" have the same
primary but different secondaries.

[   11.233280] KK set_secondary_fwnode dev name = 808622B7:01, fwnode = ffff000838618840

[   11.241846] KK parent = platform

[   11.245790] KK primary = ffff0008064b9010

[   11.259838] KK set_primary_fwnode dev name = (null), fwnode = ffff0008064b9010

[   11.267795] KK parent = 808622B7:01

[   11.272000] KK fwnode->dev = 808622B7:01

[   11.276636] KK secondary = ffff000838618840

[   11.680489] KK set_secondary_fwnode dev name = xhci-hcd.3.auto, fwnode = ffff000838325040

[   11.689406] KK parent = 808622B7:01

[   11.693916] KK primary = ffff0008064b9010
[   11.698763] sysfs: cannot create duplicate filename '/devices/platform/808622B7:01/xhci-hcd.3.auto/software_node'