[PATCHv2 1/2] of: add __of_add_property() without lock operations

[PATCHv2 1/2] of: add __of_add_property() without lock operations

[Xiubo Li]

There two places will use the same code for adding one new property to
the DT node. Adding __of_add_property() and prepare for fixing
of_update_property()'s bug.

Signed-off-by: Xiubo Li <Li.Xiubo-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
---
 drivers/of/base.c | 38 ++++++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 14 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index f807d0e..b86b77a 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1469,11 +1469,31 @@ static int of_property_notify(int action, struct device_node *np,
 #endif
 
 /**
+ * __of_add_property - Add a property to a node without lock operations
+ */
+static int __of_add_property(struct device_node *np, struct property *prop)
+{
+	struct property **next;
+
+	prop->next = NULL;
+	next = &np->properties;
+	while (*next) {
+		if (strcmp(prop->name, (*next)->name) == 0)
+			/* duplicate ! don't insert it */
+			return -EEXIST;
+
+		next = &(*next)->next;
+	}
+	*next = prop;
+
+	return 0;
+}
+
+/**
  * of_add_property - Add a property to a node
  */
 int of_add_property(struct device_node *np, struct property *prop)
 {
-	struct property **next;
 	unsigned long flags;
 	int rc;
 
@@ -1481,27 +1501,17 @@ int of_add_property(struct device_node *np, struct property *prop)
 	if (rc)
 		return rc;
 
-	prop->next = NULL;
 	raw_spin_lock_irqsave(&devtree_lock, flags);
-	next = &np->properties;
-	while (*next) {
-		if (strcmp(prop->name, (*next)->name) == 0) {
-			/* duplicate ! don't insert it */
-			raw_spin_unlock_irqrestore(&devtree_lock, flags);
-			return -1;
-		}
-		next = &(*next)->next;
-	}
-	*next = prop;
+	rc = __of_add_property(np, prop);
 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 
 #ifdef CONFIG_PROC_DEVICETREE
 	/* try to add to proc as well if it was initialized */
-	if (np->pde)
+	if (!rc && np->pde)
 		proc_device_tree_add_prop(np->pde, prop);
 #endif /* CONFIG_PROC_DEVICETREE */
 
-	return 0;
+	return rc;
 }
 
 /**
-- 
1.8.4


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[PATCHv2 2/2] of: fix of_update_property()

[Xiubo Li]

The of_update_property() is intented to update a property in a node
and if the property does not exist, will add it.

The second search of the property is possibly won't be found, that
maybe removed by other thread just before the second search begain.

Using the __of_find_property() and __of_add_property() instead and
move them into lock operations.

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
---
 drivers/of/base.c | 36 ++++++++++++++----------------------
 1 file changed, 14 insertions(+), 22 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index b86b77a..458072d 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1573,7 +1573,7 @@ int of_update_property(struct device_node *np, struct property *newprop)
 {
 	struct property **next, *oldprop;
 	unsigned long flags;
-	int rc, found = 0;
+	int rc = 0;
 
 	rc = of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop);
 	if (rc)
@@ -1582,36 +1582,28 @@ int of_update_property(struct device_node *np, struct property *newprop)
 	if (!newprop->name)
 		return -EINVAL;
 
-	oldprop = of_find_property(np, newprop->name, NULL);
-	if (!oldprop)
-		return of_add_property(np, newprop);
-
 	raw_spin_lock_irqsave(&devtree_lock, flags);
-	next = &np->properties;
-	while (*next) {
-		if (*next == oldprop) {
-			/* found the node */
-			newprop->next = oldprop->next;
-			*next = newprop;
-			oldprop->next = np->deadprops;
-			np->deadprops = oldprop;
-			found = 1;
-			break;
-		}
-		next = &(*next)->next;
+	oldprop = __of_find_property(np, newprop->name, NULL);
+	if (!oldprop) {
+		/* add the node */
+		rc = __of_add_property(np, newprop);
+	} else {
+		/* replace the node */
+		next = &oldprop;
+		newprop->next = oldprop->next;
+		*next = newprop;
+		oldprop->next = np->deadprops;
+		np->deadprops = oldprop;
 	}
 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 
-	if (!found)
-		return -ENODEV;
-
 #ifdef CONFIG_PROC_DEVICETREE
 	/* try to add to proc as well if it was initialized */
-	if (np->pde)
+	if (!rc && np->pde)
 		proc_device_tree_update_prop(np->pde, newprop, oldprop);
 #endif /* CONFIG_PROC_DEVICETREE */
 
-	return 0;
+	return rc;
 }
 
 #if defined(CONFIG_OF_DYNAMIC)
-- 
1.8.4

Re: [PATCHv2 1/2] of: add __of_add_property() without lock operations

[Grant Likely]

On Wed, 22 Jan 2014 13:57:39 +0800, Xiubo Li <Li.Xiubo@freescale.com> wrote:
> There two places will use the same code for adding one new property to
> the DT node. Adding __of_add_property() and prepare for fixing
> of_update_property()'s bug.
> 
> Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>

Applied, thanks.

g.

> ---
>  drivers/of/base.c | 38 ++++++++++++++++++++++++--------------
>  1 file changed, 24 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index f807d0e..b86b77a 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -1469,11 +1469,31 @@ static int of_property_notify(int action, struct device_node *np,
>  #endif
>  
>  /**
> + * __of_add_property - Add a property to a node without lock operations
> + */
> +static int __of_add_property(struct device_node *np, struct property *prop)
> +{
> +	struct property **next;
> +
> +	prop->next = NULL;
> +	next = &np->properties;
> +	while (*next) {
> +		if (strcmp(prop->name, (*next)->name) == 0)
> +			/* duplicate ! don't insert it */
> +			return -EEXIST;
> +
> +		next = &(*next)->next;
> +	}
> +	*next = prop;
> +
> +	return 0;
> +}
> +
> +/**
>   * of_add_property - Add a property to a node
>   */
>  int of_add_property(struct device_node *np, struct property *prop)
>  {
> -	struct property **next;
>  	unsigned long flags;
>  	int rc;
>  
> @@ -1481,27 +1501,17 @@ int of_add_property(struct device_node *np, struct property *prop)
>  	if (rc)
>  		return rc;
>  
> -	prop->next = NULL;
>  	raw_spin_lock_irqsave(&devtree_lock, flags);
> -	next = &np->properties;
> -	while (*next) {
> -		if (strcmp(prop->name, (*next)->name) == 0) {
> -			/* duplicate ! don't insert it */
> -			raw_spin_unlock_irqrestore(&devtree_lock, flags);
> -			return -1;
> -		}
> -		next = &(*next)->next;
> -	}
> -	*next = prop;
> +	rc = __of_add_property(np, prop);
>  	raw_spin_unlock_irqrestore(&devtree_lock, flags);
>  
>  #ifdef CONFIG_PROC_DEVICETREE
>  	/* try to add to proc as well if it was initialized */
> -	if (np->pde)
> +	if (!rc && np->pde)
>  		proc_device_tree_add_prop(np->pde, prop);
>  #endif /* CONFIG_PROC_DEVICETREE */
>  
> -	return 0;
> +	return rc;
>  }
>  
>  /**
> -- 
> 1.8.4
> 
> 

Re: [PATCHv2 2/2] of: fix of_update_property()

[Grant Likely]

On Wed, 22 Jan 2014 13:57:40 +0800, Xiubo Li <Li.Xiubo-KZfg59tc24xl57MIdRCFDg@public.gmane.org> wrote:
> The of_update_property() is intented to update a property in a node
> and if the property does not exist, will add it.
> 
> The second search of the property is possibly won't be found, that
> maybe removed by other thread just before the second search begain.
> 
> Using the __of_find_property() and __of_add_property() instead and
> move them into lock operations.
> 
> Signed-off-by: Xiubo Li <Li.Xiubo-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> Cc: Pantelis Antoniou <panto-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>

Applied, thanks

g.

> ---
>  drivers/of/base.c | 36 ++++++++++++++----------------------
>  1 file changed, 14 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index b86b77a..458072d 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -1573,7 +1573,7 @@ int of_update_property(struct device_node *np, struct property *newprop)
>  {
>  	struct property **next, *oldprop;
>  	unsigned long flags;
> -	int rc, found = 0;
> +	int rc = 0;
>  
>  	rc = of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop);
>  	if (rc)
> @@ -1582,36 +1582,28 @@ int of_update_property(struct device_node *np, struct property *newprop)
>  	if (!newprop->name)
>  		return -EINVAL;
>  
> -	oldprop = of_find_property(np, newprop->name, NULL);
> -	if (!oldprop)
> -		return of_add_property(np, newprop);
> -
>  	raw_spin_lock_irqsave(&devtree_lock, flags);
> -	next = &np->properties;
> -	while (*next) {
> -		if (*next == oldprop) {
> -			/* found the node */
> -			newprop->next = oldprop->next;
> -			*next = newprop;
> -			oldprop->next = np->deadprops;
> -			np->deadprops = oldprop;
> -			found = 1;
> -			break;
> -		}
> -		next = &(*next)->next;
> +	oldprop = __of_find_property(np, newprop->name, NULL);
> +	if (!oldprop) {
> +		/* add the node */
> +		rc = __of_add_property(np, newprop);
> +	} else {
> +		/* replace the node */
> +		next = &oldprop;
> +		newprop->next = oldprop->next;
> +		*next = newprop;
> +		oldprop->next = np->deadprops;
> +		np->deadprops = oldprop;
>  	}
>  	raw_spin_unlock_irqrestore(&devtree_lock, flags);
>  
> -	if (!found)
> -		return -ENODEV;
> -
>  #ifdef CONFIG_PROC_DEVICETREE
>  	/* try to add to proc as well if it was initialized */
> -	if (np->pde)
> +	if (!rc && np->pde)
>  		proc_device_tree_update_prop(np->pde, newprop, oldprop);
>  #endif /* CONFIG_PROC_DEVICETREE */
>  
> -	return 0;
> +	return rc;
>  }
>  
>  #if defined(CONFIG_OF_DYNAMIC)
> -- 
> 1.8.4
> 
> 

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Re: [PATCHv2 2/2] of: fix of_update_property()

[Grant Likely]

On Wed, 22 Jan 2014 13:57:40 +0800, Xiubo Li <Li.Xiubo-KZfg59tc24xl57MIdRCFDg@public.gmane.org> wrote:
> The of_update_property() is intented to update a property in a node
> and if the property does not exist, will add it.
> 
> The second search of the property is possibly won't be found, that
> maybe removed by other thread just before the second search begain.
> 
> Using the __of_find_property() and __of_add_property() instead and
> move them into lock operations.
> 
> Signed-off-by: Xiubo Li <Li.Xiubo-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> Cc: Pantelis Antoniou <panto-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>

I've had to revert this patch. See below...

> ---
>  drivers/of/base.c | 36 ++++++++++++++----------------------
>  1 file changed, 14 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index b86b77a..458072d 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -1573,7 +1573,7 @@ int of_update_property(struct device_node *np, struct property *newprop)
>  {
>  	struct property **next, *oldprop;
>  	unsigned long flags;
> -	int rc, found = 0;
> +	int rc = 0;
>  
>  	rc = of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop);
>  	if (rc)
> @@ -1582,36 +1582,28 @@ int of_update_property(struct device_node *np, struct property *newprop)
>  	if (!newprop->name)
>  		return -EINVAL;
>  
> -	oldprop = of_find_property(np, newprop->name, NULL);
> -	if (!oldprop)
> -		return of_add_property(np, newprop);
> -
>  	raw_spin_lock_irqsave(&devtree_lock, flags);
> -	next = &np->properties;
> -	while (*next) {
> -		if (*next == oldprop) {
> -			/* found the node */
> -			newprop->next = oldprop->next;
> -			*next = newprop;
> -			oldprop->next = np->deadprops;
> -			np->deadprops = oldprop;
> -			found = 1;
> -			break;
> -		}
> -		next = &(*next)->next;
> +	oldprop = __of_find_property(np, newprop->name, NULL);
> +	if (!oldprop) {
> +		/* add the node */
> +		rc = __of_add_property(np, newprop);
> +	} else {
> +		/* replace the node */
> +		next = &oldprop;

Ugh. I just looked closer and the above line is completely broken.
&oldprop is the address of 'oldprop' on the stack, *not* the address of
the previous item in the list. The while loop is still required to find it.

g.

> +		newprop->next = oldprop->next;
> +		*next = newprop;
> +		oldprop->next = np->deadprops;
> +		np->deadprops = oldprop;
>  	}
>  	raw_spin_unlock_irqrestore(&devtree_lock, flags);
>  
> -	if (!found)
> -		return -ENODEV;
> -
>  #ifdef CONFIG_PROC_DEVICETREE
>  	/* try to add to proc as well if it was initialized */
> -	if (np->pde)
> +	if (!rc && np->pde)
>  		proc_device_tree_update_prop(np->pde, newprop, oldprop);
>  #endif /* CONFIG_PROC_DEVICETREE */
>  
> -	return 0;
> +	return rc;
>  }
>  
>  #if defined(CONFIG_OF_DYNAMIC)
> -- 
> 1.8.4
> 
> 

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RE: [PATCHv2 2/2] of: fix of_update_property()

[Li.Xiubo]

> Subject: Re: [PATCHv2 2/2] of: fix of_update_property()
> 
> On Wed, 22 Jan 2014 13:57:40 +0800, Xiubo Li <Li.Xiubo@freescale.com> wrote:
> > The of_update_property() is intented to update a property in a node
> > and if the property does not exist, will add it.
> >
> > The second search of the property is possibly won't be found, that
> > maybe removed by other thread just before the second search begain.
> >
> > Using the __of_find_property() and __of_add_property() instead and
> > move them into lock operations.
> >
> > Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
> > Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
> 
> I've had to revert this patch. See below...
> 
> > ---
> >  drivers/of/base.c | 36 ++++++++++++++----------------------
> >  1 file changed, 14 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/of/base.c b/drivers/of/base.c
> > index b86b77a..458072d 100644
> > --- a/drivers/of/base.c
> > +++ b/drivers/of/base.c
> > @@ -1573,7 +1573,7 @@ int of_update_property(struct device_node *np, struct
> property *newprop)
> >  {
> >  	struct property **next, *oldprop;
> >  	unsigned long flags;
> > -	int rc, found = 0;
> > +	int rc = 0;
> >
> >  	rc = of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop);
> >  	if (rc)
> > @@ -1582,36 +1582,28 @@ int of_update_property(struct device_node *np,
> struct property *newprop)
> >  	if (!newprop->name)
> >  		return -EINVAL;
> >
> > -	oldprop = of_find_property(np, newprop->name, NULL);
> > -	if (!oldprop)
> > -		return of_add_property(np, newprop);
> > -
> >  	raw_spin_lock_irqsave(&devtree_lock, flags);
> > -	next = &np->properties;
> > -	while (*next) {
> > -		if (*next == oldprop) {
> > -			/* found the node */
> > -			newprop->next = oldprop->next;
> > -			*next = newprop;
> > -			oldprop->next = np->deadprops;
> > -			np->deadprops = oldprop;
> > -			found = 1;
> > -			break;
> > -		}
> > -		next = &(*next)->next;
> > +	oldprop = __of_find_property(np, newprop->name, NULL);
> > +	if (!oldprop) {
> > +		/* add the node */
> > +		rc = __of_add_property(np, newprop);
> > +	} else {
> > +		/* replace the node */
> > +		next = &oldprop;
> 
> Ugh. I just looked closer and the above line is completely broken.
> &oldprop is the address of 'oldprop' on the stack, *not* the address of
> the previous item in the list. The while loop is still required to find it.
> 

Yes, I'll fix this.

Thanks very much.

BRs
Xiubo


> g.
> 
> > +		newprop->next = oldprop->next;
> > +		*next = newprop;
> > +		oldprop->next = np->deadprops;
> > +		np->deadprops = oldprop;
> >  	}
> >  	raw_spin_unlock_irqrestore(&devtree_lock, flags);
> >
> > -	if (!found)
> > -		return -ENODEV;
> > -
> >  #ifdef CONFIG_PROC_DEVICETREE
> >  	/* try to add to proc as well if it was initialized */
> > -	if (np->pde)
> > +	if (!rc && np->pde)
> >  		proc_device_tree_update_prop(np->pde, newprop, oldprop);
> >  #endif /* CONFIG_PROC_DEVICETREE */
> >
> > -	return 0;
> > +	return rc;
> >  }
> >
> >  #if defined(CONFIG_OF_DYNAMIC)
> > --
> > 1.8.4
> >
> >
> 
>