From cb154a1d153edf2c399493a4336aebdccdc628f5 Mon Sep 17 00:00:00 2001
Message-Id: <cb154a1d153edf2c399493a4336aebdccdc628f5@dist-git>
From: Pavel Hrdina <phrdina@redhat.com>
Date: Mon, 1 Jul 2019 17:07:27 +0200
Subject: [PATCH] vircgroup: introduce virCgroupV2AddTask
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In cgroups v2 we need to handle threads and processes differently.
If you need to move a process you need to write its pid into
cgrou.procs file and it will move the process with all its threads
as well.  The whole process will be moved if you use tid of any thread.

In order to move only threads at first we need to create threaded group
and after that we can write the relevant thread tids into cgroup.threads
file.  Threads can be moved only into cgroups that are children of
cgroup of its process.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
(cherry picked from commit 48572f8825f2bbd7dabb5afb34efbf7afa2f7302)

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1689297

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Message-Id: <d6fb582c80903fc7725e2dd15165bd167c916f04.1561993100.git.phrdina@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---
 src/util/vircgroupv2.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/util/vircgroupv2.c b/src/util/vircgroupv2.c
index b5fad47ca0..6ffb5ce786 100644
--- a/src/util/vircgroupv2.c
+++ b/src/util/vircgroupv2.c
@@ -432,6 +432,20 @@ virCgroupV2Remove(virCgroupPtr group)
 }
 
 
+static int
+virCgroupV2AddTask(virCgroupPtr group,
+                   pid_t pid,
+                   unsigned int flags)
+{
+    int controller = virCgroupV2GetAnyController(group);
+
+    if (flags & VIR_CGROUP_TASK_THREAD)
+        return virCgroupSetValueI64(group, controller, "cgroup.threads", pid);
+    else
+        return virCgroupSetValueI64(group, controller, "cgroup.procs", pid);
+}
+
+
 virCgroupBackend virCgroupV2Backend = {
     .type = VIR_CGROUP_BACKEND_TYPE_V2,
 
@@ -449,6 +463,7 @@ virCgroupBackend virCgroupV2Backend = {
     .pathOfController = virCgroupV2PathOfController,
     .makeGroup = virCgroupV2MakeGroup,
     .remove = virCgroupV2Remove,
+    .addTask = virCgroupV2AddTask,
 };
 
 
-- 
2.22.0