[PATCH] nvmem: core: add a missing of_node_put

[PATCH] nvmem: core: add a missing of_node_put

[Christophe JAILLET]

'for_each_child_of_node' performs an of_node_get on each iteration, so a
return from the middle of the loop requires an of_node_put.

Fixes: e888d445ac33 ("nvmem: resolve cells from DT at registration time")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/nvmem/core.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index bca671ff4e54..4375e52ba6c2 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -686,12 +686,15 @@ static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
 			continue;
 		if (len < 2 * sizeof(u32)) {
 			dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
+			of_node_put(child);
 			return -EINVAL;
 		}
 
 		cell = kzalloc(sizeof(*cell), GFP_KERNEL);
-		if (!cell)
+		if (!cell) {
+			of_node_put(child);
 			return -ENOMEM;
+		}
 
 		cell->nvmem = nvmem;
 		cell->np = of_node_get(child);
@@ -717,6 +720,7 @@ static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
 			kfree_const(cell->name);
 			of_node_put(cell->np);
 			kfree(cell);
+			of_node_put(child);
 			return -EINVAL;
 		}
 
-- 
2.27.0

Re: [PATCH] nvmem: core: add a missing of_node_put

[Srinivas Kandagatla]

On 20/04/2021 21:12, Christophe JAILLET wrote:
> 'for_each_child_of_node' performs an of_node_get on each iteration, so a
> return from the middle of the loop requires an of_node_put.
> 
> Fixes: e888d445ac33 ("nvmem: resolve cells from DT at registration time")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
>   drivers/nvmem/core.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index bca671ff4e54..4375e52ba6c2 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -686,12 +686,15 @@ static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
>   			continue;
>   		if (len < 2 * sizeof(u32)) {
>   			dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
> +			of_node_put(child);
>   			return -EINVAL;
>   		}
>   
>   		cell = kzalloc(sizeof(*cell), GFP_KERNEL);
> -		if (!cell)
> +		if (!cell) {
> +			of_node_put(child);
>   			return -ENOMEM;
> +		}
>   
>   		cell->nvmem = nvmem;
>   		cell->np = of_node_get(child);
> @@ -717,6 +720,7 @@ static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
>   			kfree_const(cell->name);
>   			of_node_put(cell->np);
>   			kfree(cell);
> +			of_node_put(child);

two of_node_put looks bit confusing to the reader, can you move the

cell->np = of_node_get(child); just before nvmem_cell_add(cell);
so that we can remove extra put.

Was this reported by some kind of static analysis tool?

--srini



>   			return -EINVAL;
>   		}
>   
> 

Re: [PATCH] nvmem: core: add a missing of_node_put

[Christophe JAILLET]

Le 23/04/2021 à 11:30, Srinivas Kandagatla a écrit :
> 
> 
> On 20/04/2021 21:12, Christophe JAILLET wrote:
>> 'for_each_child_of_node' performs an of_node_get on each iteration, so a
>> return from the middle of the loop requires an of_node_put.
>>
>> Fixes: e888d445ac33 ("nvmem: resolve cells from DT at registration time")
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
>> ---
>>   drivers/nvmem/core.c | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
>> index bca671ff4e54..4375e52ba6c2 100644
>> --- a/drivers/nvmem/core.c
>> +++ b/drivers/nvmem/core.c
>> @@ -686,12 +686,15 @@ static int nvmem_add_cells_from_of(struct 
>> nvmem_device *nvmem)
>>               continue;
>>           if (len < 2 * sizeof(u32)) {
>>               dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
>> +            of_node_put(child);
>>               return -EINVAL;
>>           }
>>           cell = kzalloc(sizeof(*cell), GFP_KERNEL);
>> -        if (!cell)
>> +        if (!cell) {
>> +            of_node_put(child);
>>               return -ENOMEM;
>> +        }
>>           cell->nvmem = nvmem;
>>           cell->np = of_node_get(child);
>> @@ -717,6 +720,7 @@ static int nvmem_add_cells_from_of(struct 
>> nvmem_device *nvmem)
>>               kfree_const(cell->name);
>>               of_node_put(cell->np);
>>               kfree(cell);
>> +            of_node_put(child);
> 
> two of_node_put looks bit confusing to the reader, can you move the
> 
> cell->np = of_node_get(child); just before nvmem_cell_add(cell);
> so that we can remove extra put.
> 

Sure.
I didn't pay attention that cell->np and child were the same and that 
the code looked odd now.

Thx for the review and the comment.


> Was this reported by some kind of static analysis tool?
 >

Yes, this was found by coccinelle.
The script used was an old one posted by Julia Lawall a few years ago:

// <smpl>
@r@
local idexpression n;
expression e1,e2;
iterator name for_each_node_by_name, for_each_node_by_type,
for_each_compatible_node, for_each_matching_node,
for_each_matching_node_and_match, for_each_child_of_node,
for_each_available_child_of_node, for_each_node_with_property;
iterator i;
statement S;
expression list [n1] es;
@@

(
(
for_each_node_by_name(n,e1) S
|
for_each_node_by_type(n,e1) S
|
for_each_compatible_node(n,e1,e2) S
|
for_each_matching_node(n,e1) S
|
for_each_matching_node_and_match(n,e1,e2) S
|
for_each_child_of_node(e1,n) S
|
for_each_available_child_of_node(e1,n) S
|
for_each_node_with_property(n,e1) S
)
&
i(es,n,...) S
)

@@
local idexpression r.n;
iterator r.i;
expression e;
expression list [r.n1] es;
@@

  i(es,n,...) {
    ...
(
    of_node_put(n);
|
    e = n
|
    return n;
|
+  of_node_put(n);
?  return ...;
)
    ...
  }

@@
local idexpression r.n;
iterator r.i;
expression e;
expression list [r.n1] es;
@@

  i(es,n,...) {
    ...
(
    of_node_put(n);
|
    e = n
|
+  of_node_put(n);
?  break;
)
    ...
  }
... when != n

@@
local idexpression r.n;
iterator r.i;
expression e;
identifier l;
expression list [r.n1] es;
@@

  i(es,n,...) {
    ...
(
    of_node_put(n);
|
    e = n
|
+  of_node_put(n);
?  goto l;
)
    ...
  }
...
l: ... when != n
// </smpl>


> 
> --srini
> 
> 
> 
>>               return -EINVAL;
>>           }
>>
>