Re: [PATCH v3 2/2] rcu: Simplify the code logic of rcu_init_nohz()
From: kernel test robot
Date: Wed Aug 17 2022 - 21:20:01 EST
Hi Zhen,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on paulmck-rcu/dev]
[also build test ERROR on linus/master v6.0-rc1 next-20220817]
[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/Zhen-Lei/rcu-nocb-Delete-local-variable-need_rcu_nocb_mask-in-rcu_init_nohz/20220816-205131
base: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev
config: hexagon-randconfig-r041-20220818 (https://download.01.org/0day-ci/archive/20220818/202208180940.Jks0rOXz-lkp@xxxxxxxxx/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project aed5e3bea138ce581d682158eb61c27b3cfdd6ec)
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
# https://github.com/intel-lab-lkp/linux/commit/a1d5079765918764de3ff6e3e63fa2db7f7c14df
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Zhen-Lei/rcu-nocb-Delete-local-variable-need_rcu_nocb_mask-in-rcu_init_nohz/20220816-205131
git checkout a1d5079765918764de3ff6e3e63fa2db7f7c14df
# 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=hexagon SHELL=/bin/bash kernel/
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>
All errors (new ones prefixed by >>):
In file included from kernel/rcu/tree.c:4801:
>> kernel/rcu/tree_nocb.h:1216:10: error: assigning to 'struct cpumask *' from 'const struct cpumask *' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
cpumask = cpu_possible_mask;
^ ~~~~~~~~~~~~~~~~~
1 error generated.
vim +1216 kernel/rcu/tree_nocb.h
1208
1209 void __init rcu_init_nohz(void)
1210 {
1211 int cpu;
1212 struct rcu_data *rdp;
1213 struct cpumask *cpumask = NULL;
1214
1215 #if defined(CONFIG_RCU_NOCB_CPU_DEFAULT_ALL)
> 1216 cpumask = cpu_possible_mask;
1217 #elif defined(CONFIG_NO_HZ_FULL)
1218 if (tick_nohz_full_running && !cpumask_empty(tick_nohz_full_mask))
1219 cpumask = tick_nohz_full_mask;
1220 #endif
1221
1222 if (cpumask) {
1223 if (!cpumask_available(rcu_nocb_mask)) {
1224 if (!zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL)) {
1225 pr_info("rcu_nocb_mask allocation failed, callback offloading disabled.\n");
1226 return;
1227 }
1228 }
1229
1230 cpumask_or(rcu_nocb_mask, rcu_nocb_mask, cpumask);
1231 }
1232
1233 if (!cpumask_available(rcu_nocb_mask))
1234 return;
1235
1236 if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
1237 pr_info("\tNote: kernel parameter 'rcu_nocbs=', 'nohz_full', or 'isolcpus=' contains nonexistent CPUs.\n");
1238 cpumask_and(rcu_nocb_mask, cpu_possible_mask,
1239 rcu_nocb_mask);
1240 }
1241 if (cpumask_empty(rcu_nocb_mask))
1242 pr_info("\tOffload RCU callbacks from CPUs: (none).\n");
1243 else
1244 pr_info("\tOffload RCU callbacks from CPUs: %*pbl.\n",
1245 cpumask_pr_args(rcu_nocb_mask));
1246 if (rcu_nocb_poll)
1247 pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
1248
1249 for_each_cpu(cpu, rcu_nocb_mask) {
1250 rdp = per_cpu_ptr(&rcu_data, cpu);
1251 if (rcu_segcblist_empty(&rdp->cblist))
1252 rcu_segcblist_init(&rdp->cblist);
1253 rcu_segcblist_offload(&rdp->cblist, true);
1254 rcu_segcblist_set_flags(&rdp->cblist, SEGCBLIST_KTHREAD_CB | SEGCBLIST_KTHREAD_GP);
1255 rcu_segcblist_clear_flags(&rdp->cblist, SEGCBLIST_RCU_CORE);
1256 }
1257 rcu_organize_nocb_kthreads();
1258 }
1259
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