[Devel] [PATCH RHEL10 COMMIT] sched/cpuacct: guard ve_root_tg() with CONFIG_CFS_CPULIMIT

[Konstantin Khorenko <khorenko@virtuozzo.com>]

The commit is pushed to "branch-rh10-6.12.0-211.39.1.16.x.vz10-ovz" and will appear at git at bitbucket.org:openvz/vzkernel.git
after rh10-6.12.0-211.39.1.16.6.vz10
------>
commit bd117ee4adf3296f8cb3910e212a42ce66a61268
Author: Konstantin Khorenko <khorenko@virtuozzo.com>
Date:   Thu Aug 20 18:43:29 2026 +0200

    sched/cpuacct: guard ve_root_tg() with CONFIG_CFS_CPULIMIT
    
    ve_root_tg() has exactly two callers, tg_cpu_rate() and tg_nr_cpus(),
    and both reference it only from inside #ifdef CONFIG_CFS_CPULIMIT: the
    task_group fields they read, ::cpu_rate and ::nr_cpus, do not exist
    without that option.  So with CONFIG_CFS_CPULIMIT=n the helper is not
    used at all, and since our configs set CONFIG_WERROR=y the build fails:
    
      kernel/sched/cpuacct.c:373:27: error: 've_root_tg' defined but not
                                     used [-Werror=unused-function]
    
    x86_64 defconfig hits this: CONFIG_VE defaults to y, while
    CONFIG_CFS_BANDWIDTH - the only thing that selects CONFIG_CFS_CPULIMIT -
    is off.
    
    Compile ve_root_tg() under the same condition as its call sites.
    
    Fixes: 095994c57b84 ("ve/sched/stat: Introduce functions to calculate vcpustat data")
    Feature: sched: emulate virtual cpus for Containers
    https://virtuozzo.atlassian.net/browse/VSTOR-134732
    Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
---
 kernel/sched/cpuacct.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index 01a2b2c3c5b7..6b0ed967316e 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -370,6 +370,7 @@ struct cgroup_subsys cpuacct_cgrp_subsys = {
 	.threaded       = true,
 };
 
+#ifdef CONFIG_CFS_CPULIMIT
 static struct task_group *ve_root_tg(struct task_group *tg) {
 	struct cgroup_subsys_state *css;
 
@@ -379,6 +380,7 @@ static struct task_group *ve_root_tg(struct task_group *tg) {
 	css = css_ve_root1(&tg->css);
 	return css ? css_tg(css) : NULL;
 }
+#endif
 
 static unsigned int tg_cpu_rate(struct task_group *tg)
 {