Re: [PATCH 1/2] mm/damon: simplify the parameter passing for 'check_accesses'

SeongJae Park
2022-08-26T17:08:27Z

Hi Kaixu,

On Fri, 26 Aug 2022 16:31:17 +0800 xiakaixu1987@gmail.com wrote:

> From: Kaixu Xia <kaixuxia@tencent.com>
>
> The parameter 'struct damon_ctx *ctx' is unnecessary in damon
> 'check_accesses' callback operation, so we can remove it.

Thank you for the finding, but this wording is not 100% perfect, strictly
speaking. The callback operations indeed use the parameter, but the internal
functions called by the callbacks (__damon_{p,v}a_check_access()) aren't.

Could you please update the message?

>
> Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
> ---
> mm/damon/paddr.c | 5 ++---
> mm/damon/vaddr.c | 5 ++---
> 2 files changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
> index dc131c6a5403..6b0d9e6aa677 100644
> --- a/mm/damon/paddr.c
> +++ b/mm/damon/paddr.c
> @@ -166,8 +166,7 @@ static bool damon_pa_young(unsigned long paddr, unsigned long *page_sz)
> return result.accessed;
> }
>
> -static void __damon_pa_check_access(struct damon_ctx *ctx,
> - struct damon_region *r)
> +static void __damon_pa_check_access(struct damon_region *r)
> {
> static unsigned long last_addr;
> static unsigned long last_page_sz = PAGE_SIZE;
> @@ -196,7 +195,7 @@ static unsigned int damon_pa_check_accesses(struct damon_ctx *ctx)
>
> damon_for_each_target(t, ctx) {
> damon_for_each_region(r, t) {
> - __damon_pa_check_access(ctx, r);
> + __damon_pa_check_access(r);
> max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
> }
> }
> diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
> index 3c7b9d6dca95..c8c2f306bb6d 100644
> --- a/mm/damon/vaddr.c
> +++ b/mm/damon/vaddr.c
> @@ -532,8 +532,7 @@ static bool damon_va_young(struct mm_struct *mm, unsigned long addr,
> * mm 'mm_struct' for the given virtual address space
> * r the region to be checked
> */
> -static void __damon_va_check_access(struct damon_ctx *ctx,
> - struct mm_struct *mm, struct damon_region *r)
> +static void __damon_va_check_access(struct mm_struct *mm, struct damon_region *r)

I still prefer 80 columns rule[1]. Could you please break this line?

[1] https://docs.kernel.org/process/coding-style.html#breaking-long-lines-and-strings

> {
> static struct mm_struct *last_mm;
> static unsigned long last_addr;
> @@ -568,7 +567,7 @@ static unsigned int damon_va_check_accesses(struct damon_ctx *ctx)
> if (!mm)
> continue;
> damon_for_each_region(r, t) {
> - __damon_va_check_access(ctx, mm, r);
> + __damon_va_check_access(mm, r);
> max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
> }
> mmput(mm);
> --
> 2.27.0

Thanks,
SJ