linux-kernel - [PATCH v2 -next] cgroup/pids: Remove unreachable paths of pids_{can,cancel}

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Message-Id: <20240805004304.57314-1-xiujianfeng@huaweicloud.com>
Date: Mon,  5 Aug 2024 00:43:04 +0000
From: Xiu Jianfeng <xiujianfeng@...weicloud.com>
To: tj@...nel.org,
	lizefan.x@...edance.com,
	hannes@...xchg.org,
	mkoutny@...e.com
Cc: cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	xiujianfeng@...wei.com
Subject: [PATCH v2 -next] cgroup/pids: Remove unreachable paths of pids_{can,cancel}_fork

From: Xiu Jianfeng <xiujianfeng@...wei.com>

According to the implementation of cgroup_css_set_fork(), it will fail
if cset cannot be found and the can_fork/cancel_fork methods will not
be called in this case, which means that the argument 'cset' for these
methods must not be NULL, so remove the unrechable paths in them.

Signed-off-by: Xiu Jianfeng <xiujianfeng@...wei.com>
---
v2: reword the commit message
---
 kernel/cgroup/pids.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/kernel/cgroup/pids.c b/kernel/cgroup/pids.c
index 34aa63d7c9c6..8f61114c36dd 100644
--- a/kernel/cgroup/pids.c
+++ b/kernel/cgroup/pids.c
@@ -272,15 +272,10 @@ static void pids_event(struct pids_cgroup *pids_forking,
  */
 static int pids_can_fork(struct task_struct *task, struct css_set *cset)
 {
-	struct cgroup_subsys_state *css;
 	struct pids_cgroup *pids, *pids_over_limit;
 	int err;
 
-	if (cset)
-		css = cset->subsys[pids_cgrp_id];
-	else
-		css = task_css_check(current, pids_cgrp_id, true);
-	pids = css_pids(css);
+	pids = css_pids(cset->subsys[pids_cgrp_id]);
 	err = pids_try_charge(pids, 1, &pids_over_limit);
 	if (err)
 		pids_event(pids, pids_over_limit);
@@ -290,14 +285,9 @@ static int pids_can_fork(struct task_struct *task, struct css_set *cset)
 
 static void pids_cancel_fork(struct task_struct *task, struct css_set *cset)
 {
-	struct cgroup_subsys_state *css;
 	struct pids_cgroup *pids;
 
-	if (cset)
-		css = cset->subsys[pids_cgrp_id];
-	else
-		css = task_css_check(current, pids_cgrp_id, true);
-	pids = css_pids(css);
+	pids = css_pids(cset->subsys[pids_cgrp_id]);
 	pids_uncharge(pids, 1);
 }
 
-- 
2.34.1