[PATCH] percpu: convert flexible array initializers to use struct_size()

[PATCH] percpu: convert flexible array initializers to use struct_size()

[Dennis Zhou]

Use the safer macro as sparked by the long discussion in [1].

[1] https://lore.kernel.org/lkml/20200917204514.GA2880159@google.com/

Signed-off-by: Dennis Zhou <dennis@kernel.org>
---
I'll apply it to for-5.10-fixes.

 mm/percpu.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index 66a93f096394..ad7a37ee74ef 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1315,8 +1315,8 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
 	region_size = ALIGN(start_offset + map_size, lcm_align);
 
 	/* allocate chunk */
-	alloc_size = sizeof(struct pcpu_chunk) +
-		BITS_TO_LONGS(region_size >> PAGE_SHIFT) * sizeof(unsigned long);
+	alloc_size = struct_size(chunk, populated,
+				 BITS_TO_LONGS(region_size >> PAGE_SHIFT));
 	chunk = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
 	if (!chunk)
 		panic("%s: Failed to allocate %zu bytes\n", __func__,
@@ -2521,8 +2521,8 @@ void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
 	pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
 	pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
 	pcpu_atom_size = ai->atom_size;
-	pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
-		BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
+	pcpu_chunk_struct_size = struct_size(chunk, populated,
+					     BITS_TO_LONGS(pcpu_unit_pages));
 
 	pcpu_stats_save_ai(ai);
 
-- 
2.29.1.341.ge80a0c044ae-goog

Re: [PATCH] percpu: convert flexible array initializers to use struct_size()

[Gustavo A. R. Silva]

On 10/30/20 15:58, Dennis Zhou wrote:
> Use the safer macro as sparked by the long discussion in [1].
> 
> [1] https://lore.kernel.org/lkml/20200917204514.GA2880159@google.com/
> 
> Signed-off-by: Dennis Zhou <dennis@kernel.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
--
Gustavo

> ---
> I'll apply it to for-5.10-fixes.
> 
>  mm/percpu.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/percpu.c b/mm/percpu.c
> index 66a93f096394..ad7a37ee74ef 100644
> --- a/mm/percpu.c
> +++ b/mm/percpu.c
> @@ -1315,8 +1315,8 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
>  	region_size = ALIGN(start_offset + map_size, lcm_align);
>  
>  	/* allocate chunk */
> -	alloc_size = sizeof(struct pcpu_chunk) +
> -		BITS_TO_LONGS(region_size >> PAGE_SHIFT) * sizeof(unsigned long);
> +	alloc_size = struct_size(chunk, populated,
> +				 BITS_TO_LONGS(region_size >> PAGE_SHIFT));
>  	chunk = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
>  	if (!chunk)
>  		panic("%s: Failed to allocate %zu bytes\n", __func__,
> @@ -2521,8 +2521,8 @@ void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
>  	pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
>  	pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
>  	pcpu_atom_size = ai->atom_size;
> -	pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
> -		BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
> +	pcpu_chunk_struct_size = struct_size(chunk, populated,
> +					     BITS_TO_LONGS(pcpu_unit_pages));
>  
>  	pcpu_stats_save_ai(ai);
>  
>