Re: [PATCH V1 1/2] mm/damon/sysfs: avoid call damon_target_has_pid() repeatedly

SeongJae Park
2022-09-16T08:43:01Z

On Thu, 15 Sep 2022 22:22:36 +0800 Xin Hao <xhao@linux.alibaba.com> wrote:

> In damon_sysfs_destroy_targets(), we call damon_target_has_pid() to
> check whether the 'ctx' include a valid pid, but there no need to call
> damon_target_has_pid() to check repeatedly, just need call it once.

Good eyes, nice finding!

>
> Signed-off-by: Xin Hao <xhao@linux.alibaba.com>
> ---
> mm/damon/sysfs.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
> index 1fa0023f136e..966ea7892ccf 100644
> --- a/mm/damon/sysfs.c
> +++ b/mm/damon/sysfs.c
> @@ -2143,9 +2143,13 @@ static int damon_sysfs_set_attrs(struct damon_ctx *ctx,
> static void damon_sysfs_destroy_targets(struct damon_ctx *ctx)
> {
> struct damon_target *t, *next;
> + bool has_pid = false;
> +
> + if (damon_target_has_pid(ctx))
> + has_pid = true;

How about doing more simple and short like below?

bool has_pid = damon_target_has_pid(ctx)

Other than this,

Reviewed-by: SeongJae Park <sj@kernel.org>

Thanks,
SJ

>
> damon_for_each_target_safe(t, next, ctx) {
> - if (damon_target_has_pid(ctx))
> + if (has_pid)
> put_pid(t->pid);
> damon_destroy_target(t);
> }
> --
> 2.31.0