2021-10-14 07:58:32

by Jiabing Wan

Subject: [PATCH] powerpc/pseries/iommu: Add of_node_put() before break

Fix following coccicheck warning:

./arch/powerpc/platforms/pseries/iommu.c:924:1-28: WARNING: Function
for_each_node_with_property should have of_node_put() before break

Early exits from for_each_node_with_property should decrement the
node reference counter.

Signed-off-by: Wan Jiabing <[email protected]>
---
arch/powerpc/platforms/pseries/iommu.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 269f61d519c2..c140aa683f66 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -929,8 +929,10 @@ static void find_existing_ddw_windows_named(const char *name)
}

window = ddw_list_new_entry(pdn, dma64);
- if (!window)
+ if (!window) {
+ of_node_put(pdn);
break;
+ }

spin_lock(&dma_win_list_lock);
list_add(&window->list, &dma_win_list);
--
2.20.1

2021-10-14 19:08:08

by Leonardo Brás

Subject: Re: [PATCH] powerpc/pseries/iommu: Add of_node_put() before break

Hello Wan, thank you for this patch.


On Thu, 2021-10-14 at 03:56 -0400, Wan Jiabing wrote:
> Fix following coccicheck warning:
>
> ./arch/powerpc/platforms/pseries/iommu.c:924:1-28: WARNING: Function
> for_each_node_with_property should have of_node_put() before break
>
> Early exits from for_each_node_with_property should decrement the
> node reference counter.

Yeah, it makes sense to me.

for_each_node_with_property calls of_find_node_with_property() at each
step, which ends up calling of_node_put() after using each node.

Introducing this break caused this of_node_put not to happen to the
last node, so IIUC this patch fixes a possible issue if kzalloc() fails
in ddw_list_new_entry().

Another option would be s/break/continue here, but it does not make
sense to keep trying next nodes if there is no memory to allocate for a
struct dma_win (4 pointers).

On the other hard, failing on allocating such small space should not
happen often (if it will ever happen), so a 'continue' here makes code
simpler.

Anyway, FWIW:
Reviewed-by: Leonardo Bras <[email protected]>


Best regards,
Leo

>
> Signed-off-by: Wan Jiabing <[email protected]>
> ---
>  arch/powerpc/platforms/pseries/iommu.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/platforms/pseries/iommu.c
> b/arch/powerpc/platforms/pseries/iommu.c
> index 269f61d519c2..c140aa683f66 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -929,8 +929,10 @@ static void find_existing_ddw_windows_named(const
> char *name)
>                 }
>  
>                 window = ddw_list_new_entry(pdn, dma64);
> -               if (!window)
> +               if (!window) {
> +                       of_node_put(pdn);
>                         break;
> +               }
>  
>                 spin_lock(&dma_win_list_lock);
>                 list_add(&window->list, &dma_win_list);

2021-11-02 11:42:02

by Michael Ellerman

Subject: Re: [PATCH] powerpc/pseries/iommu: Add of_node_put() before break

On Thu, 14 Oct 2021 03:56:04 -0400, Wan Jiabing wrote:
> Fix following coccicheck warning:
>
> ./arch/powerpc/platforms/pseries/iommu.c:924:1-28: WARNING: Function
> for_each_node_with_property should have of_node_put() before break
>
> Early exits from for_each_node_with_property should decrement the
> node reference counter.
>
> [...]

Applied to powerpc/next.

[1/1] powerpc/pseries/iommu: Add of_node_put() before break
https://git.kernel.org/powerpc/c/915b368f6968122fcab31fd6441ed4ba7cc7574c

cheers