linux-kernel - [PATCH] debug cgroup: use task_css_set instead of rcu

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Message-Id: <1511125717-12126-1-git-send-email-wanglong19@meituan.com>
Date:   Sun, 19 Nov 2017 16:08:37 -0500
From:   Wang Long <wanglong19@...tuan.com>
To:     tj@...nel.org
Cc:     longman@...hat.com, kstewart@...uxfoundation.org,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org
Subject: [PATCH] debug cgroup: use task_css_set instead of rcu_dereference

This macro `task_css_set` verifies that the caller is
inside proper critical section if the kernel set CONFIG_PROVE_RCU=y.

Signed-off-by: Wang Long <wanglong19@...tuan.com>
---
 kernel/cgroup/debug.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup/debug.c b/kernel/cgroup/debug.c
index 5f780d8..9caeda6 100644
--- a/kernel/cgroup/debug.c
+++ b/kernel/cgroup/debug.c
@@ -50,7 +50,7 @@ static int current_css_set_read(struct seq_file *seq, void *v)
 
 	spin_lock_irq(&css_set_lock);
 	rcu_read_lock();
-	cset = rcu_dereference(current->cgroups);
+	cset = task_css_set(current);
 	refcnt = refcount_read(&cset->refcount);
 	seq_printf(seq, "css_set %pK %d", cset, refcnt);
 	if (refcnt > cset->nr_tasks)
@@ -96,7 +96,7 @@ static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
 
 	spin_lock_irq(&css_set_lock);
 	rcu_read_lock();
-	cset = rcu_dereference(current->cgroups);
+	cset = task_css_set(current);
 	list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
 		struct cgroup *c = link->cgrp;
 
-- 
1.8.3.1