[Devel] [PATCH RHEL8 COMMIT] cgroup: Export put_css_set and get_css_set to cgroup.h

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-240.1.1.vz8.5.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-240.1.1.vz8.5.5
------>
commit fb3ea62c3743fe48060be69a68e36c415f1b1cae
Author: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>
Date:   Wed Mar 3 20:21:11 2021 +0300

    cgroup: Export put_css_set and get_css_set to cgroup.h
    
    Cherry-picked from vz7 commit
    8222bbe47ed1 ("cgroup: exported __put_css_set and wrappers to cgroup.h")
    
    Signed-off-by: Valeriy.Vdovin <valeriy.vdovin at virtuozzo.com>
    Reviewed-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    
    =====================
    Patchset description:
    
    ve/cgroup: Port release_agent virtualization from vz7
    
    This patchset ports virtualization of cgroup release_agent
    virtualization from vz7.
    
    Major challanges of porting are differences between vz7 and vz8 cgroup
    implementations:
    - transition of cgroups to kernfs
    - slightly changed locking scheme, which relies on css_set_lock in
      places, previously relied on cgroup_mutex.
    
    There is a small number of patches that have been ported without
    modifications, but most of the patches had suffered a lot of
    modification due to the factors described above.
    
    v1:
      - original patchset
    v2:
      - removed port of CGRP_REMOVED due to the use of CSS_ONLINE in VZ8 for
        same reason
      - changed ve_set(get)_release_agent_path signature for more optimal
      - added ve->is_running check before calling userspace executable
    v3:
      - use goto after check for ve->is_running in last patch
---
 include/linux/cgroup.h          | 28 ++++++++++++++++++++++++++++
 kernel/cgroup/cgroup-internal.h | 27 ---------------------------
 kernel/cgroup/cgroup.c          |  1 +
 3 files changed, 29 insertions(+), 27 deletions(-)

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 808b31605d07..391702cf43bd 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -512,6 +512,34 @@ task_get_css(struct task_struct *task, int subsys_id)
 	return css;
 }
 
+void put_css_set_locked(struct css_set *cset);
+
+static inline void put_css_set(struct css_set *cset)
+{
+	unsigned long flags;
+
+	/*
+	 * Ensure that the refcount doesn't hit zero while any readers
+	 * can see it. Similar to atomic_dec_and_lock(), but for an
+	 * rwlock
+	 */
+	if (refcount_dec_not_one(&cset->refcount))
+		return;
+
+	spin_lock_irqsave(&css_set_lock, flags);
+	put_css_set_locked(cset);
+	spin_unlock_irqrestore(&css_set_lock, flags);
+}
+
+/*
+ * refcounted get/put for css_set objects
+ */
+static inline void get_css_set(struct css_set *cset)
+{
+	refcount_inc(&cset->refcount);
+}
+
+
 /**
  * task_css_is_root - test whether a task belongs to the root css
  * @task: the target task
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index ce1c1553c696..829997989c41 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -159,33 +159,6 @@ static inline bool notify_on_release(const struct cgroup *cgrp)
 	return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
 }
 
-void put_css_set_locked(struct css_set *cset);
-
-static inline void put_css_set(struct css_set *cset)
-{
-	unsigned long flags;
-
-	/*
-	 * Ensure that the refcount doesn't hit zero while any readers
-	 * can see it. Similar to atomic_dec_and_lock(), but for an
-	 * rwlock
-	 */
-	if (refcount_dec_not_one(&cset->refcount))
-		return;
-
-	spin_lock_irqsave(&css_set_lock, flags);
-	put_css_set_locked(cset);
-	spin_unlock_irqrestore(&css_set_lock, flags);
-}
-
-/*
- * refcounted get/put for css_set objects
- */
-static inline void get_css_set(struct css_set *cset)
-{
-	refcount_inc(&cset->refcount);
-}
-
 bool cgroup_ssid_enabled(int ssid);
 bool cgroup_on_dfl(const struct cgroup *cgrp);
 bool cgroup_is_thread_root(struct cgroup *cgrp);
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 946031fcb393..de105e651607 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -58,6 +58,7 @@
 #include <linux/psi.h>
 #include <net/sock.h>
 #include <linux/ve.h>
+#include <linux/cgroup.h>
 
 #include <linux/rh_features.h>