Re: [PATCH] kexec: Avoid calculating array size twice

Baoquan He
2023-06-01T10:41:15Z

On 05/25/23 at 04:26pm, Simon Horman wrote:
> Avoid calculating array size twice in kexec_purgatory_setup_sechdrs().
> Once using array_size(), and once open-coded.
>
> Flagged by Coccinelle:
>
> .../kexec_file.c:881:8-25: WARNING: array_size is already used (line 877) to compute the same size

Amazingly smart. Thanks.

Acked-by: Baoquan He <bhe@redhat.com>

>
> No functional change intended.
> Compile tested only.
>
> Signed-off-by: Simon Horman <horms@kernel.org>
> ---
> kernel/kexec_file.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index f989f5f1933b..3f5677679744 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -867,6 +867,7 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
> {
> unsigned long bss_addr;
> unsigned long offset;
> + size_t sechdrs_size;
> Elf_Shdr *sechdrs;
> int i;
>
> @@ -874,11 +875,11 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
> * The section headers in kexec_purgatory are read-only. In order to
> * have them modifiable make a temporary copy.
> */
> - sechdrs = vzalloc(array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum));
> + sechdrs_size = array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum);
> + sechdrs = vzalloc(sechdrs_size);
> if (!sechdrs)
> return -ENOMEM;
> - memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff,
> - pi->ehdr->e_shnum * sizeof(Elf_Shdr));
> + memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff, sechdrs_size);
> pi->sechdrs = sechdrs;
>
> offset = 0;
>