Re: [PATCH v3 2/2] staging: android: Remove BUG from ion_system_heap.c

[Dan Carpenter]

On Wed, Aug 19, 2020 at 10:39:34PM +0300, Tomer Samara wrote:
> Remove BUG()  at ion_sytem_heap.c and error handling to:
>  - free_buffer_page
>  - alloc_buffer_page
> this fix the following checkpatch issue:
> Avoid crashing the kernel - try using WARN_ON &
> recovery code ratherthan BUG() or BUG_ON().
> 
> Signed-off-by: Tomer Samara 
> ---
>  drivers/staging/android/ion/ion_system_heap.c | 15 ---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/android/ion/ion_system_heap.c 
> b/drivers/staging/android/ion/ion_system_heap.c
> index eac0632ab4e8..56d53268b82c 100644
> --- a/drivers/staging/android/ion/ion_system_heap.c
> +++ b/drivers/staging/android/ion/ion_system_heap.c
> @@ -30,7 +30,7 @@ static int order_to_index(unsigned int order)
>   for (i = 0; i < NUM_ORDERS; i++)
>   if (order == orders[i])
>   return i;
> - BUG();
> +
>   return -1;
>  }

Just delete the BUG() and put a comment that /* This is impossible. */
so that reviewers know that we never return -1.

I suspect that there are some static analysis tools which might complain
about this -1 return.  But those tools are pretty crap.  Never change
code just to make the tools happy.

regards,
dan carpenter

[PATCH v3 2/2] staging: android: Remove BUG from ion_system_heap.c

[Tomer Samara]

Remove BUG()  at ion_sytem_heap.c and error handling to:
 - free_buffer_page
 - alloc_buffer_page
this fix the following checkpatch issue:
Avoid crashing the kernel - try using WARN_ON &
recovery code ratherthan BUG() or BUG_ON().

Signed-off-by: Tomer Samara 
---
 drivers/staging/android/ion/ion_system_heap.c | 15 ---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/android/ion/ion_system_heap.c 
b/drivers/staging/android/ion/ion_system_heap.c
index eac0632ab4e8..56d53268b82c 100644
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -30,7 +30,7 @@ static int order_to_index(unsigned int order)
for (i = 0; i < NUM_ORDERS; i++)
if (order == orders[i])
return i;
-   BUG();
+
return -1;
 }
 
@@ -48,8 +48,13 @@ static struct page *alloc_buffer_page(struct ion_system_heap 
*heap,
  struct ion_buffer *buffer,
  unsigned long order)
 {
-   struct ion_page_pool *pool = heap->pools[order_to_index(order)];
+   struct ion_page_pool *pool;
+   int index = order_to_index(order);
 
+   if (index < 0)
+   return NULL;
+
+   pool = heap->pools[index];
return ion_page_pool_alloc(pool);
 }
 
@@ -58,6 +63,7 @@ static void free_buffer_page(struct ion_system_heap *heap,
 {
struct ion_page_pool *pool;
unsigned int order = compound_order(page);
+   int index;
 
/* go to system */
if (buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE) {
@@ -65,8 +71,11 @@ static void free_buffer_page(struct ion_system_heap *heap,
return;
}
 
-   pool = heap->pools[order_to_index(order)];
+   index = order_to_index(order);
+   if (index < 0)
+   return;
 
+   pool = heap->pools[index];
ion_page_pool_free(pool, page);
 }
 
-- 
2.25.1