Re: [PATCH] sched: core: Remove unnecessary ‘NULL’ values from core_rq
From: kernel test robot
Date: Tue May 28 2024 - 06:50:02 EST
Hi Li,
kernel test robot noticed the following build warnings:
[auto build test WARNING on tip/sched/core]
[also build test WARNING on peterz-queue/sched/core linus/master v6.10-rc1 next-20240528]
[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/Li-zeming/sched-core-Remove-unnecessary-NULL-values-from-core_rq/20240528-152109
base: tip/sched/core
patch link: https://lore.kernel.org/r/20240528071446.59197-1-zeming%40nfschina.com
patch subject: [PATCH] sched: core: Remove unnecessary ‘NULL’ values from core_rq
config: s390-defconfig (https://download.01.org/0day-ci/archive/20240528/202405281844.8oxr5i5s-lkp@xxxxxxxxx/config)
compiler: clang version 19.0.0git (https://github.com/llvm/llvm-project bafda89a0944d947fc4b3b5663185e07a397ac30)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240528/202405281844.8oxr5i5s-lkp@xxxxxxxxx/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@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405281844.8oxr5i5s-lkp@xxxxxxxxx/
All warnings (new ones prefixed by >>):
In file included from kernel/sched/core.c:10:
In file included from include/linux/highmem.h:10:
In file included from include/linux/mm.h:2253:
include/linux/vmstat.h:500:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
500 | return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~ ^
501 | item];
| ~~~~
include/linux/vmstat.h:507:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
507 | return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~ ^
508 | NR_VM_NUMA_EVENT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~~
include/linux/vmstat.h:514:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
514 | return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
| ~~~~~~~~~~~ ^ ~~~
include/linux/vmstat.h:519:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
519 | return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~ ^
520 | NR_VM_NUMA_EVENT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~~
include/linux/vmstat.h:528:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
528 | return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~ ^
529 | NR_VM_NUMA_EVENT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~~
In file included from kernel/sched/core.c:34:
In file included from include/linux/sched/isolation.h:7:
In file included from include/linux/tick.h:8:
In file included from include/linux/clockchips.h:14:
In file included from include/linux/clocksource.h:22:
In file included from arch/s390/include/asm/io.h:93:
include/asm-generic/io.h:548:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
548 | val = __raw_readb(PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:561:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
561 | val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
| ~~~~~~~~~~ ^
include/uapi/linux/byteorder/big_endian.h:37:59: note: expanded from macro '__le16_to_cpu'
37 | #define __le16_to_cpu(x) __swab16((__force __u16)(__le16)(x))
| ^
include/uapi/linux/swab.h:102:54: note: expanded from macro '__swab16'
102 | #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
| ^
In file included from kernel/sched/core.c:34:
In file included from include/linux/sched/isolation.h:7:
In file included from include/linux/tick.h:8:
In file included from include/linux/clockchips.h:14:
In file included from include/linux/clocksource.h:22:
In file included from arch/s390/include/asm/io.h:93:
include/asm-generic/io.h:574:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
574 | val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
| ~~~~~~~~~~ ^
include/uapi/linux/byteorder/big_endian.h:35:59: note: expanded from macro '__le32_to_cpu'
35 | #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
| ^
include/uapi/linux/swab.h:115:54: note: expanded from macro '__swab32'
115 | #define __swab32(x) (__u32)__builtin_bswap32((__u32)(x))
| ^
In file included from kernel/sched/core.c:34:
In file included from include/linux/sched/isolation.h:7:
In file included from include/linux/tick.h:8:
In file included from include/linux/clockchips.h:14:
In file included from include/linux/clocksource.h:22:
In file included from arch/s390/include/asm/io.h:93:
include/asm-generic/io.h:585:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
585 | __raw_writeb(value, PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:595:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
595 | __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:605:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
605 | __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:693:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
693 | readsb(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:701:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
701 | readsw(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:709:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
709 | readsl(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:718:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
718 | writesb(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:727:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
727 | writesw(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:736:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
736 | writesl(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
>> kernel/sched/core.c:6288:2: warning: variable 'core_rq' is used uninitialized whenever 'for' loop exits because its condition is false [-Wsometimes-uninitialized]
6288 | for_each_cpu(t, smt_mask) {
| ^~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/cpumask.h:300:2: note: expanded from macro 'for_each_cpu'
300 | for_each_set_bit(cpu, cpumask_bits(mask), small_cpumask_bits)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/find.h:586:18: note: expanded from macro 'for_each_set_bit'
586 | for ((bit) = 0; (bit) = find_next_bit((addr), (size), (bit)), (bit) < (size); (bit)++)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/sched/core.c:6295:20: note: uninitialized use occurs here
6295 | if (WARN_ON_ONCE(!core_rq)) /* impossible */
| ^~~~~~~
include/asm-generic/bug.h:111:25: note: expanded from macro 'WARN_ON_ONCE'
111 | int __ret_warn_on = !!(condition); \
| ^~~~~~~~~
kernel/sched/core.c:6288:2: note: remove the condition if it is always true
6288 | for_each_cpu(t, smt_mask) {
| ^
include/linux/cpumask.h:300:2: note: expanded from macro 'for_each_cpu'
300 | for_each_set_bit(cpu, cpumask_bits(mask), small_cpumask_bits)
| ^
include/linux/find.h:586:18: note: expanded from macro 'for_each_set_bit'
586 | for ((bit) = 0; (bit) = find_next_bit((addr), (size), (bit)), (bit) < (size); (bit)++)
| ^
kernel/sched/core.c:6272:39: note: initialize the variable 'core_rq' to silence this warning
6272 | struct rq *rq = cpu_rq(cpu), *core_rq;
| ^
| = NULL
kernel/sched/core.c:6225:1: warning: unused function 'class_core_lock_lock_ptr' [-Wunused-function]
6225 | DEFINE_LOCK_GUARD_1(core_lock, int,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6226 | sched_core_lock(*_T->lock, &_T->flags),
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6227 | sched_core_unlock(*_T->lock, &_T->flags),
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6228 | unsigned long flags)
| ~~~~~~~~~~~~~~~~~~~~
include/linux/cleanup.h:232:65: note: expanded from macro 'DEFINE_LOCK_GUARD_1'
232 | #define DEFINE_LOCK_GUARD_1(_name, _type, _lock, _unlock, ...) \
| ^
233 | __DEFINE_UNLOCK_GUARD(_name, _type, _unlock, __VA_ARGS__) \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/cleanup.h:209:21: note: expanded from macro '\
__DEFINE_UNLOCK_GUARD'
209 | static inline void *class_##_name##_lock_ptr(class_##_name##_t *_T) \
| ^~~~~~~~~~~~~~~~~~~~~~~~
<scratch space>:76:1: note: expanded from here
76 | class_core_lock_lock_ptr
| ^~~~~~~~~~~~~~~~~~~~~~~~
19 warnings generated.
vim +6288 kernel/sched/core.c
3c474b3239f12f Peter Zijlstra 2021-08-19 6268
3c474b3239f12f Peter Zijlstra 2021-08-19 6269 static void sched_core_cpu_deactivate(unsigned int cpu)
3c474b3239f12f Peter Zijlstra 2021-08-19 6270 {
3c474b3239f12f Peter Zijlstra 2021-08-19 6271 const struct cpumask *smt_mask = cpu_smt_mask(cpu);
ca27ccef75e13e Li zeming 2024-05-28 6272 struct rq *rq = cpu_rq(cpu), *core_rq;
3c474b3239f12f Peter Zijlstra 2021-08-19 6273 int t;
3c474b3239f12f Peter Zijlstra 2021-08-19 6274
7170509cadbb76 Peter Zijlstra 2023-08-01 6275 guard(core_lock)(&cpu);
3c474b3239f12f Peter Zijlstra 2021-08-19 6276
3c474b3239f12f Peter Zijlstra 2021-08-19 6277 /* if we're the last man standing, nothing to do */
3c474b3239f12f Peter Zijlstra 2021-08-19 6278 if (cpumask_weight(smt_mask) == 1) {
3c474b3239f12f Peter Zijlstra 2021-08-19 6279 WARN_ON_ONCE(rq->core != rq);
7170509cadbb76 Peter Zijlstra 2023-08-01 6280 return;
9edeaea1bc4523 Peter Zijlstra 2020-11-17 6281 }
3c474b3239f12f Peter Zijlstra 2021-08-19 6282
3c474b3239f12f Peter Zijlstra 2021-08-19 6283 /* if we're not the leader, nothing to do */
3c474b3239f12f Peter Zijlstra 2021-08-19 6284 if (rq->core != rq)
7170509cadbb76 Peter Zijlstra 2023-08-01 6285 return;
3c474b3239f12f Peter Zijlstra 2021-08-19 6286
3c474b3239f12f Peter Zijlstra 2021-08-19 6287 /* find a new leader */
3c474b3239f12f Peter Zijlstra 2021-08-19 @6288 for_each_cpu(t, smt_mask) {
3c474b3239f12f Peter Zijlstra 2021-08-19 6289 if (t == cpu)
3c474b3239f12f Peter Zijlstra 2021-08-19 6290 continue;
3c474b3239f12f Peter Zijlstra 2021-08-19 6291 core_rq = cpu_rq(t);
3c474b3239f12f Peter Zijlstra 2021-08-19 6292 break;
9edeaea1bc4523 Peter Zijlstra 2020-11-17 6293 }
3c474b3239f12f Peter Zijlstra 2021-08-19 6294
3c474b3239f12f Peter Zijlstra 2021-08-19 6295 if (WARN_ON_ONCE(!core_rq)) /* impossible */
7170509cadbb76 Peter Zijlstra 2023-08-01 6296 return;
3c474b3239f12f Peter Zijlstra 2021-08-19 6297
3c474b3239f12f Peter Zijlstra 2021-08-19 6298 /* copy the shared state to the new leader */
3c474b3239f12f Peter Zijlstra 2021-08-19 6299 core_rq->core_task_seq = rq->core_task_seq;
3c474b3239f12f Peter Zijlstra 2021-08-19 6300 core_rq->core_pick_seq = rq->core_pick_seq;
3c474b3239f12f Peter Zijlstra 2021-08-19 6301 core_rq->core_cookie = rq->core_cookie;
4feee7d12603de Josh Don 2021-10-18 6302 core_rq->core_forceidle_count = rq->core_forceidle_count;
3c474b3239f12f Peter Zijlstra 2021-08-19 6303 core_rq->core_forceidle_seq = rq->core_forceidle_seq;
4feee7d12603de Josh Don 2021-10-18 6304 core_rq->core_forceidle_occupation = rq->core_forceidle_occupation;
4feee7d12603de Josh Don 2021-10-18 6305
4feee7d12603de Josh Don 2021-10-18 6306 /*
4feee7d12603de Josh Don 2021-10-18 6307 * Accounting edge for forced idle is handled in pick_next_task().
4feee7d12603de Josh Don 2021-10-18 6308 * Don't need another one here, since the hotplug thread shouldn't
4feee7d12603de Josh Don 2021-10-18 6309 * have a cookie.
4feee7d12603de Josh Don 2021-10-18 6310 */
4feee7d12603de Josh Don 2021-10-18 6311 core_rq->core_forceidle_start = 0;
3c474b3239f12f Peter Zijlstra 2021-08-19 6312
3c474b3239f12f Peter Zijlstra 2021-08-19 6313 /* install new leader */
3c474b3239f12f Peter Zijlstra 2021-08-19 6314 for_each_cpu(t, smt_mask) {
3c474b3239f12f Peter Zijlstra 2021-08-19 6315 rq = cpu_rq(t);
3c474b3239f12f Peter Zijlstra 2021-08-19 6316 rq->core = core_rq;
3c474b3239f12f Peter Zijlstra 2021-08-19 6317 }
3c474b3239f12f Peter Zijlstra 2021-08-19 6318 }
3c474b3239f12f Peter Zijlstra 2021-08-19 6319
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki