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[PATCH cgroup/for-6.6-fixes] cgroup: Put cgroup_local_stat_show() inside CONFIG_CGROUP_SCHED

Tejun Heo posted 1 patch 2 years, 3 months ago 
kernel/cgroup/cgroup.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
[PATCH cgroup/for-6.6-fixes] cgroup: Put cgroup_local_stat_show() inside CONFIG_CGROUP_SCHED
Posted by Tejun Heo 2 years, 3 months ago 
From d8416c5d2a38e36651f022be01bb234a404b8f01 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Sat, 2 Sep 2023 05:28:06 -1000

677ea015f231 ("sched: add throttled time stat for throttled children") which
was merged through the sched branch added cgroup_local_stat_show() which is
marked with __maybe_unused and used iff CONFIG_CGROUP_SCHED is set. This was
following the existing pattern of cgroup_extra_stat_show().

However, in the cgroup tree, 1299eb2b0ad5 ("cgroup: minor cleanup for
cgroup_extra_stat_show()") moved cgroup_extra_stat_show() inside
CONFIG_CGROUP_SCHED and dropped __maybe_unused and subsequently d1d4ff5d11a5
("cgroup: put cgroup_tryget_css() inside CONFIG_CGROUP_SCHED") moved
cgroup_tryget_css() inside the config option too as cgroup_extra_stat_show()
was the only user.

When the tree commits met in mainline, this led to a build breakage when
!CONFIG_CGROUP_SCHED as cgroup_tryget_css() was no longer available for the
__maybe_unused cgroup_local_stat_show().

Fix it by moving cgroup_local_stat_show() inside CONFIG_CGROUP_SCHED and
also drop __maybe_unused.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: "Sudip Mukherjee (Codethink)" <sudipm.mukherjee@gmail.com>
Link: http://lkml.kernel.org/r/ZPMdTJ7zwrCkdMTu@debian
Fixes: 677ea015f231 ("sched: add throttled time stat for throttled children")
Cc: Josh Don <joshdon@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
---
Sorry about that. This should fix it. Guess nobody is building linux-next w/
!CONFIG_CGROUP_SCHED. I'll send the pull request to Linus soon.

Thanks.

 kernel/cgroup/cgroup.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index babb34a643ea..156eb96d7cc5 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -3686,8 +3686,9 @@ static int cpu_stat_show(struct seq_file *seq, void *v)
 	return ret;
 }
 
-static int __maybe_unused cgroup_local_stat_show(struct seq_file *seq,
-						 struct cgroup *cgrp, int ssid)
+#ifdef CONFIG_CGROUP_SCHED
+static int cgroup_local_stat_show(struct seq_file *seq, struct cgroup *cgrp,
+				  int ssid)
 {
 	struct cgroup_subsys *ss = cgroup_subsys[ssid];
 	struct cgroup_subsys_state *css;
@@ -3704,6 +3705,7 @@ static int __maybe_unused cgroup_local_stat_show(struct seq_file *seq,
 	css_put(css);
 	return ret;
 }
+#endif
 
 static int cpu_local_stat_show(struct seq_file *seq, void *v)
 {
-- 
2.42.0
Re: [PATCH cgroup/for-6.6-fixes] cgroup: Put cgroup_local_stat_show() inside CONFIG_CGROUP_SCHED
Posted by kernel test robot 2 years, 3 months ago 
Hi Tejun,

kernel test robot noticed the following build warnings:

[auto build test WARNING on next-20230831]
[cannot apply to linus/master v6.5 v6.5-rc7 v6.5-rc6 v6.5]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Tejun-Heo/cgroup-Put-cgroup_local_stat_show-inside-CONFIG_CGROUP_SCHED/20230902-234358
base:   next-20230831
patch link:    https://lore.kernel.org/r/ZPNX-jZAZbebizXA%40slm.duckdns.org
patch subject: [PATCH cgroup/for-6.6-fixes] cgroup: Put cgroup_local_stat_show() inside CONFIG_CGROUP_SCHED
config: arm-defconfig (https://download.01.org/0day-ci/archive/20230903/202309030303.qSTfRgZC-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230903/202309030303.qSTfRgZC-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309030303.qSTfRgZC-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/cgroup/cgroup.c:503:36: warning: 'cgroup_tryget_css' defined but not used [-Wunused-function]
     503 | static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,
         |                                    ^~~~~~~~~~~~~~~~~


vim +/cgroup_tryget_css +503 kernel/cgroup/cgroup.c

42809dd4225b2f kernel/cgroup.c        Tejun Heo 2012-11-19  494  
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  495  /**
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  496   * cgroup_tryget_css - try to get a cgroup's css for the specified subsystem
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  497   * @cgrp: the cgroup of interest
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  498   * @ss: the subsystem of interest
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  499   *
08b2b6fdf6b260 kernel/cgroup/cgroup.c Zhen Lei  2021-05-24  500   * Find and get @cgrp's css associated with @ss.  If the css doesn't exist
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  501   * or is offline, %NULL is returned.
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  502   */
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23 @503  static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp,
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  504  						     struct cgroup_subsys *ss)
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  505  {
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  506  	struct cgroup_subsys_state *css;
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  507  
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  508  	rcu_read_lock();
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  509  	css = cgroup_css(cgrp, ss);
a581563f1bef03 kernel/cgroup/cgroup.c Peng Wang 2019-07-03  510  	if (css && !css_tryget_online(css))
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  511  		css = NULL;
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  512  	rcu_read_unlock();
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  513  
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  514  	return css;
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  515  }
d41bf8c9deaed1 kernel/cgroup/cgroup.c Tejun Heo 2017-10-23  516  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
Re: [PATCH cgroup/for-6.6-fixes] cgroup: Put cgroup_local_stat_show() inside CONFIG_CGROUP_SCHED
Posted by Linus Torvalds 2 years, 3 months ago 
On Sat, 2 Sept 2023 at 08:42, Tejun Heo <tj@kernel.org> wrote:
>
> Sorry about that. This should fix it. Guess nobody is building linux-next w/
> !CONFIG_CGROUP_SCHED. I'll send the pull request to Linus soon.

I solved it slightly differently by moving the whole function around
rather than adding yet another #ifdef.

See 76be05d4fd6c ("cgroup: fix build when CGROUP_SCHED is not enabled")

                Linus

Patchew 2.1-devel-b67e4c2

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