2024-05-24 09:26:28

by Xiu Jianfeng

Subject: [PATCH -next] cgroup/pids: replace can_attach and cancel_attach with attach hook

Currently pids_can_attach() always returns 0 and never fails, so the
can_attach() and cancel_attach() hooks can be replaced by attach(),
since attach() is guaranteed to succeed and don't need to fallback.

Signed-off-by: Xiu Jianfeng <[email protected]>
---
kernel/cgroup/pids.c | 25 ++-----------------------
1 file changed, 2 insertions(+), 23 deletions(-)

diff --git a/kernel/cgroup/pids.c b/kernel/cgroup/pids.c
index 0e5ec7d59b4d..86d06f709957 100644
--- a/kernel/cgroup/pids.c
+++ b/kernel/cgroup/pids.c
@@ -186,7 +186,7 @@ static int pids_try_charge(struct pids_cgroup *pids, int num)
return -EAGAIN;
}

-static int pids_can_attach(struct cgroup_taskset *tset)
+static void pids_attach(struct cgroup_taskset *tset)
{
struct task_struct *task;
struct cgroup_subsys_state *dst_css;
@@ -207,26 +207,6 @@ static int pids_can_attach(struct cgroup_taskset *tset)
pids_charge(pids, 1);
pids_uncharge(old_pids, 1);
}
-
- return 0;
-}
-
-static void pids_cancel_attach(struct cgroup_taskset *tset)
-{
- struct task_struct *task;
- struct cgroup_subsys_state *dst_css;
-
- cgroup_taskset_for_each(task, dst_css, tset) {
- struct pids_cgroup *pids = css_pids(dst_css);
- struct cgroup_subsys_state *old_css;
- struct pids_cgroup *old_pids;
-
- old_css = task_css(task, pids_cgrp_id);
- old_pids = css_pids(old_css);
-
- pids_charge(old_pids, 1);
- pids_uncharge(pids, 1);
- }
}

/*
@@ -374,8 +354,7 @@ static struct cftype pids_files[] = {
struct cgroup_subsys pids_cgrp_subsys = {
.css_alloc = pids_css_alloc,
.css_free = pids_css_free,
- .can_attach = pids_can_attach,
- .cancel_attach = pids_cancel_attach,
+ .attach = pids_attach,
.can_fork = pids_can_fork,
.cancel_fork = pids_cancel_fork,
.release = pids_release,
--
2.34.1

2024-05-24 09:34:37

by Xiu Jianfeng

Subject: Re: [PATCH -next] cgroup/pids: replace can_attach and cancel_attach with attach hook

Sorry, it's a mistake, please ignore this patch :(

On 2024/5/24 17:18, Xiu Jianfeng wrote:
> Currently pids_can_attach() always returns 0 and never fails, so the
> can_attach() and cancel_attach() hooks can be replaced by attach(),
> since attach() is guaranteed to succeed and don't need to fallback.
>
> Signed-off-by: Xiu Jianfeng <[email protected]>
> ---
> kernel/cgroup/pids.c | 25 ++-----------------------
> 1 file changed, 2 insertions(+), 23 deletions(-)
>
> diff --git a/kernel/cgroup/pids.c b/kernel/cgroup/pids.c
> index 0e5ec7d59b4d..86d06f709957 100644
> --- a/kernel/cgroup/pids.c
> +++ b/kernel/cgroup/pids.c
> @@ -186,7 +186,7 @@ static int pids_try_charge(struct pids_cgroup *pids, int num)
> return -EAGAIN;
> }
>
> -static int pids_can_attach(struct cgroup_taskset *tset)
> +static void pids_attach(struct cgroup_taskset *tset)
> {
> struct task_struct *task;
> struct cgroup_subsys_state *dst_css;
> @@ -207,26 +207,6 @@ static int pids_can_attach(struct cgroup_taskset *tset)
> pids_charge(pids, 1);
> pids_uncharge(old_pids, 1);
> }
> -
> - return 0;
> -}
> -
> -static void pids_cancel_attach(struct cgroup_taskset *tset)
> -{
> - struct task_struct *task;
> - struct cgroup_subsys_state *dst_css;
> -
> - cgroup_taskset_for_each(task, dst_css, tset) {
> - struct pids_cgroup *pids = css_pids(dst_css);
> - struct cgroup_subsys_state *old_css;
> - struct pids_cgroup *old_pids;
> -
> - old_css = task_css(task, pids_cgrp_id);
> - old_pids = css_pids(old_css);
> -
> - pids_charge(old_pids, 1);
> - pids_uncharge(pids, 1);
> - }
> }
>
> /*
> @@ -374,8 +354,7 @@ static struct cftype pids_files[] = {
> struct cgroup_subsys pids_cgrp_subsys = {
> .css_alloc = pids_css_alloc,
> .css_free = pids_css_free,
> - .can_attach = pids_can_attach,
> - .cancel_attach = pids_cancel_attach,
> + .attach = pids_attach,
> .can_fork = pids_can_fork,
> .cancel_fork = pids_cancel_fork,
> .release = pids_release,