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

Baoquan He
2023-06-01T10:50:43Z

On 06/01/23 at 06:40pm, Baoquan He wrote:
> 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>

Just noticed Andrew has picked this one, please ignore this.

>
> >
> > 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;
> >
>