Re: [linux-stable-rc:linux-5.10.y 499/9671] arch/powerpc/kernel/smp.c:1380:7: error: variable 'ret' set but not used

[Srikar Dronamraju <srikar@linux.vnet.ibm.com>]

* kernel test robot <lkp@intel.com> [2022-11-24 07:11:15]:

> Hi Srikar,
> 
> FYI, the error/warning still remains.
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-5.10.y
> head:   38866e257e18dbc209f4c355fe57123b0c2e0e4a
> commit: e91077cf1780108dc586cedf1d19f65b44fa3870 [499/9671] powerpc/smp: Update cpu_core_map on all PowerPc systems
> config: powerpc-randconfig-r002-20221121
> compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project af8c49dc1ec44339d915d988ffe0f38da68ca0e7)
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # install powerpc cross compiling tool for clang build
>         # apt-get install binutils-powerpc-linux-gnu
>         # https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit/?id=e91077cf1780108dc586cedf1d19f65b44fa3870
>         git remote add linux-stable-rc https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git
>         git fetch --no-tags linux-stable-rc linux-5.10.y
>         git checkout e91077cf1780108dc586cedf1d19f65b44fa3870
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash arch/powerpc/
> 
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> 

Thanks for your report.

1st Commit c47f892d7aa6 ("powerpc/smp: Reintroduce cpu_core_mask") 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch/?id=c47f892d7aa6
in upstream which is Commit bf6476152a0a ("powerpc/smp: Reintroduce
cpu_core_mask") in stable tree as is.

2nd Commit c1e53367dab1 ("powerpc/smp: Cache CPU to chip lookup") 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch/?id=c1e53367dab1

3rd Commit c47f892d7aa6 ("powerpc/smp: Reintroduce cpu_core_mask") 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch/?id=c47f892d7aa6
is Commit e91077cf1780("powerpc/smp: Reintroduce cpu_core_mask")  in stable
tree with some minor modifications.

However when the 3rd commit was picked, it mangled with the changes
introduced in the 2nd commit. (Since 2nd commit is not present in Stable
tree). 

Relevant hunk from commit 2 (c1e53367dab1)
@@ -1492,7 +1506,10 @@ static void add_cpu_to_masks(int cpu)
        if (has_coregroup_support())
                update_coregroup_mask(cpu, &mask);
 
-       if (chip_id == -1 || !ret) {
+       if (chip_id_lookup_table && ret)
+               chip_id = cpu_to_chip_id(cpu);
+
+       if (chip_id == -1) {
                cpumask_copy(per_cpu(cpu_core_map, cpu), cpu_cpu_mask(cpu));
                goto out;
        }

Relevant hunks from commit 3 (c47f892d7aa6)
@@ -1544,11 +1545,6 @@ static void add_cpu_to_masks(int cpu)
        if (chip_id_lookup_table && ret)
                chip_id = cpu_to_chip_id(cpu);
 
-       if (chip_id == -1) {
-               cpumask_copy(per_cpu(cpu_core_map, cpu), cpu_cpu_mask(cpu));
-               goto out;
-       }
-
        if (shared_caches)
                submask_fn = cpu_l2_cache_mask;


The way it was applied in Stable tree combining hunks in Commit 2 and Commit 3.

@@ -1399,11 +1400,6 @@ static void add_cpu_to_masks(int cpu)
 	if (has_coregroup_support())
 		update_coregroup_mask(cpu, &mask);
 
-	if (chip_id == -1 || !ret) {
-		cpumask_copy(per_cpu(cpu_core_map, cpu), cpu_cpu_mask(cpu));
-		goto out;
-	}
-
 	if (shared_caches)
 		submask_fn = cpu_l2_cache_mask;
 

Because of the above, we end up with this warning.

Please let me know, how do we proceed on the same.

-- 
Thanks and Regards
Srikar Dronamraju