Hi all,

On Mon, 20 Sep 2021 18:30:16 +1000 Stephen Rothwell [off-list ref] wrote:

On Mon, 20 Sep 2021 14:55:29 +0800 Yafang Shao [off-list ref] wrote:

quoted

On Mon, Sep 20, 2021 at 9:33 AM Stephen Rothwell [off-list ref] wrote:  

quoted

After merging the tip tree, today's linux-next build (powerpc_ppc64
defconfig) produced this warning:

kernel/sched/debug.c: In function 'print_cfs_group_stats':
kernel/sched/debug.c:460:41: warning: unused variable 'stats' [-Wunused-variable]
  460 |                struct sched_statistics *stats =  __schedstats_from_se(se);
      |                                         ^~~~~

Caused by commit

  cb3e971c435d ("sched: Make struct sched_statistics independent of fair sched class")

# CONFIG_SCHEDSTATS is not set
   

Thanks for the report.

We have discussed this issue before[1].
This warning happens when CONFIG_SCHEDSTATS is not set and
schedstat_enabled() is 0, so the whole scope should be not compiled.
It seems that we don't need to fix this warning.

[1]. https://lore.kernel.org/lkml/20210911082505.115758-1-laoar.shao@gmail.com/ (local)  

Clearly it will be compiled if CONFIG_SCHEDSTATS is not set as that is
exactly what this build has ... even sections of code guarded by "if
(0)" are compiled, they may just not produce any output in the binary.

Also, I do not have W=1 for this build.

If you turned schedstat_val() into a static inline function, then this
warning would go away.  That also means that argument types and return
values will be better checked.

I take it back, that won't work :-(

So, please fix this.

Still it needs to be fixed to keep unnecessary warnings out of our builds.
-- 
Cheers,
Stephen Rothwell