[PATCH] of: base: remove unnecessary for loop

[PATCH] of: base: remove unnecessary for loop

[권오훈]

In __of_get_next_child function, loop iteration for getting next node is
unnecessary.

for loop is already checking if next is NULL or not, and
of_node_get(next) always returns next itself.

Therefore checking return value in the if clause always evaluates to
true, and thus it always breaks out from for loop in the first iteration.

Remove the unnecessary for loop for readability.

I tested the code as below, and it showed that BUG was never called.

-       for (; next; next = next->sibling)
+       for (; next; next = next->sibling) {
                if (of_node_get(next))
                        break;
+               BUG();
+       }

Signed-off-by: Ohhoon Kwon <ohoono.kwon@samsung.com>
---
 drivers/of/base.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 48e941f99558..ca60988ef428 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -708,9 +708,7 @@ static struct device_node *__of_get_next_child(const struct device_node *node,
 		return NULL;
 
 	next = prev ? prev->sibling : node->child;
-	for (; next; next = next->sibling)
-		if (of_node_get(next))
-			break;
+	of_node_get(next);
 	of_node_put(prev);
 	return next;
 }
-- 
2.17.1

[PATCH] of: of_reserved_mem: match memblock_free with memblock_reserve

[권오훈]

When __reserved_mem_init_node called from fdt_init_reserved_mem fails,
we try to undo __reserved_mem_alloc_size to prevent memory leak.
'commit d0b8ed47e83a ("of: reserved_mem: fix reserve memory leak")'

Meanwhile, __reserved_mem_alloc_size calls
early_init_dt_alloc_reserved_memory_arch to allocate memory,
which calls
1) memblock_remove when rmem is declared nomap,
2) memblock_reserve, otherwise.

static int __init early_init_dt_alloc_reserved_memory_arch(
...
	if (nomap)
		return memblock_remove(base, size);

	return memblock_reserve(base, size);
}

Therefore the proper undo-logic should be as follows:
1) memblock_add when rmem is declared nomap,
2) memblock_free, otherwise.

Match the undo functions for readability.

Signed-off-by: Ohhoon Kwon <ohoono.kwon@samsung.com>
---
 drivers/of/of_reserved_mem.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 15e2417974d6..2279e1b55d1d 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -273,9 +273,10 @@ void __init fdt_init_reserved_mem(void)
 			if (err != 0 && err != -ENOENT) {
 				pr_info("node %s compatible matching fail\n",
 					rmem->name);
-				memblock_free(rmem->base, rmem->size);
 				if (nomap)
 					memblock_add(rmem->base, rmem->size);
+				else
+					memblock_free(rmem->base, rmem->size);
 			}
 		}
 	}
-- 
2.17.1

Re: [PATCH] of: base: remove unnecessary for loop

[Rob Herring]

On Thu, 01 Jul 2021 23:03:28 +0900, 권오훈 wrote:
> In __of_get_next_child function, loop iteration for getting next node is
> unnecessary.
> 
> for loop is already checking if next is NULL or not, and
> of_node_get(next) always returns next itself.
> 
> Therefore checking return value in the if clause always evaluates to
> true, and thus it always breaks out from for loop in the first iteration.
> 
> Remove the unnecessary for loop for readability.
> 
> I tested the code as below, and it showed that BUG was never called.
> 
> -       for (; next; next = next->sibling)
> +       for (; next; next = next->sibling) {
>                 if (of_node_get(next))
>                         break;
> +               BUG();
> +       }
> 
> Signed-off-by: Ohhoon Kwon <ohoono.kwon@samsung.com>
> ---
>  drivers/of/base.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 

Applied, thanks!