2023-05-25 14:55:50

by Simon Horman

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

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

No functional change intended.
Compile tested only.

Signed-off-by: Simon Horman <[email protected]>
---
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;

2023-06-01 10:59:28

by Baoquan He

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

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 <[email protected]>

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

>
> >
> > No functional change intended.
> > Compile tested only.
> >
> > Signed-off-by: Simon Horman <[email protected]>
> > ---
> > 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;
> >
>

2023-06-01 11:00:32

by Baoquan He

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

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 <[email protected]>

>
> No functional change intended.
> Compile tested only.
>
> Signed-off-by: Simon Horman <[email protected]>
> ---
> 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;
>