From: kernel test robot <lkp@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: llvm@lists.linux.dev, oe-kbuild-all@lists.linux.dev
Subject: [peterz-queue:sched/scx 41/42] kernel/sched/core.c:6072:7: warning: variable 'p' is used uninitialized whenever 'if' condition is true
Date: Wed, 24 Jul 2024 06:58:17 +0800 [thread overview]
Message-ID: <202407240955.E1PWz6eH-lkp@intel.com> (raw)
tree: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/scx
head: df64e1ce653e6748aff3f6d7dea17a02c7905075
commit: 929779e3c90a5ca107489bf418463d952bc1a194 [41/42] sched: Add put_prev_task(.change_class)
config: s390-allmodconfig (https://download.01.org/0day-ci/archive/20240724/202407240955.E1PWz6eH-lkp@intel.com/config)
compiler: clang version 19.0.0git (https://github.com/llvm/llvm-project ad154281230d83ee551e12d5be48bb956ef47ed3)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240724/202407240955.E1PWz6eH-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/202407240955.E1PWz6eH-lkp@intel.com/
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:2221:
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:6072:7: warning: variable 'p' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
6072 | if (!next->core_cookie) {
| ^~~~~~~~~~~~~~~~~~
kernel/sched/core.c:6200:35: note: uninitialized use occurs here
6200 | put_prev_set_next_task(rq, prev, p);
| ^
kernel/sched/core.c:6072:3: note: remove the 'if' if its condition is always false
6072 | if (!next->core_cookie) {
| ^~~~~~~~~~~~~~~~~~~~~~~~~
6073 | rq->core_pick = NULL;
| ~~~~~~~~~~~~~~~~~~~~~
6074 | /*
| ~~
6075 | * For robustness, update the min_vruntime_fi for
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6076 | * unconstrained picks as well.
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6077 | */
| ~~
6078 | WARN_ON_ONCE(fi_before);
| ~~~~~~~~~~~~~~~~~~~~~~~~
6079 | task_vruntime_update(rq, next, false);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6080 | goto out_set_next;
| ~~~~~~~~~~~~~~~~~~
6081 | }
| ~
kernel/sched/core.c:5984:30: note: initialize the variable 'p' to silence this warning
5984 | struct task_struct *next, *p, *max = NULL;
| ^
| = NULL
kernel/sched/core.c:6316:1: warning: unused function 'class_core_lock_lock_ptr' [-Wunused-function]
6316 | DEFINE_LOCK_GUARD_1(core_lock, int,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6317 | sched_core_lock(*_T->lock, &_T->flags),
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6318 | sched_core_unlock(*_T->lock, &_T->flags),
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6319 | unsigned long flags)
| ~~~~~~~~~~~~~~~~~~~~
include/linux/cleanup.h:235:65: note: expanded from macro 'DEFINE_LOCK_GUARD_1'
235 | #define DEFINE_LOCK_GUARD_1(_name, _type, _lock, _unlock, ...) \
| ^
236 | __DEFINE_UNLOCK_GUARD(_name, _type, _unlock, __VA_ARGS__) \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/cleanup.h:212:21: note: expanded from macro '\
__DEFINE_UNLOCK_GUARD'
212 | static inline void *class_##_name##_lock_ptr(class_##_name##_t *_T) \
| ^~~~~~~~~~~~~~~~~~~~~~~~
<scratch space>:124:1: note: expanded from here
124 | class_core_lock_lock_ptr
| ^~~~~~~~~~~~~~~~~~~~~~~~
19 warnings generated.
vim +6072 kernel/sched/core.c
5b6547ed97f4f5 Peter Zijlstra 2022-03-16 5980
539f65125d20aa Peter Zijlstra 2020-11-17 5981 static struct task_struct *
539f65125d20aa Peter Zijlstra 2020-11-17 5982 pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
539f65125d20aa Peter Zijlstra 2020-11-17 5983 {
bc9ffef31bf598 Peter Zijlstra 2021-08-24 5984 struct task_struct *next, *p, *max = NULL;
539f65125d20aa Peter Zijlstra 2020-11-17 5985 const struct cpumask *smt_mask;
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 5986) bool fi_before = false;
4feee7d12603de Josh Don 2021-10-18 5987 bool core_clock_updated = (rq == rq->core);
bc9ffef31bf598 Peter Zijlstra 2021-08-24 5988 unsigned long cookie;
bc9ffef31bf598 Peter Zijlstra 2021-08-24 5989 int i, cpu, occ = 0;
bc9ffef31bf598 Peter Zijlstra 2021-08-24 5990 struct rq *rq_i;
539f65125d20aa Peter Zijlstra 2020-11-17 5991 bool need_sync;
539f65125d20aa Peter Zijlstra 2020-11-17 5992
539f65125d20aa Peter Zijlstra 2020-11-17 5993 if (!sched_core_enabled(rq))
539f65125d20aa Peter Zijlstra 2020-11-17 5994 return __pick_next_task(rq, prev, rf);
539f65125d20aa Peter Zijlstra 2020-11-17 5995
539f65125d20aa Peter Zijlstra 2020-11-17 5996 cpu = cpu_of(rq);
539f65125d20aa Peter Zijlstra 2020-11-17 5997
539f65125d20aa Peter Zijlstra 2020-11-17 5998 /* Stopper task is switching into idle, no need core-wide selection. */
539f65125d20aa Peter Zijlstra 2020-11-17 5999 if (cpu_is_offline(cpu)) {
539f65125d20aa Peter Zijlstra 2020-11-17 6000 /*
539f65125d20aa Peter Zijlstra 2020-11-17 6001 * Reset core_pick so that we don't enter the fastpath when
539f65125d20aa Peter Zijlstra 2020-11-17 6002 * coming online. core_pick would already be migrated to
539f65125d20aa Peter Zijlstra 2020-11-17 6003 * another cpu during offline.
539f65125d20aa Peter Zijlstra 2020-11-17 6004 */
539f65125d20aa Peter Zijlstra 2020-11-17 6005 rq->core_pick = NULL;
539f65125d20aa Peter Zijlstra 2020-11-17 6006 return __pick_next_task(rq, prev, rf);
539f65125d20aa Peter Zijlstra 2020-11-17 6007 }
539f65125d20aa Peter Zijlstra 2020-11-17 6008
539f65125d20aa Peter Zijlstra 2020-11-17 6009 /*
539f65125d20aa Peter Zijlstra 2020-11-17 6010 * If there were no {en,de}queues since we picked (IOW, the task
539f65125d20aa Peter Zijlstra 2020-11-17 6011 * pointers are all still valid), and we haven't scheduled the last
539f65125d20aa Peter Zijlstra 2020-11-17 6012 * pick yet, do so now.
539f65125d20aa Peter Zijlstra 2020-11-17 6013 *
539f65125d20aa Peter Zijlstra 2020-11-17 6014 * rq->core_pick can be NULL if no selection was made for a CPU because
539f65125d20aa Peter Zijlstra 2020-11-17 6015 * it was either offline or went offline during a sibling's core-wide
539f65125d20aa Peter Zijlstra 2020-11-17 6016 * selection. In this case, do a core-wide selection.
539f65125d20aa Peter Zijlstra 2020-11-17 6017 */
539f65125d20aa Peter Zijlstra 2020-11-17 6018 if (rq->core->core_pick_seq == rq->core->core_task_seq &&
539f65125d20aa Peter Zijlstra 2020-11-17 6019 rq->core->core_pick_seq != rq->core_sched_seq &&
539f65125d20aa Peter Zijlstra 2020-11-17 6020 rq->core_pick) {
539f65125d20aa Peter Zijlstra 2020-11-17 6021 WRITE_ONCE(rq->core_sched_seq, rq->core->core_pick_seq);
539f65125d20aa Peter Zijlstra 2020-11-17 6022
539f65125d20aa Peter Zijlstra 2020-11-17 6023 next = rq->core_pick;
539f65125d20aa Peter Zijlstra 2020-11-17 6024 if (next != prev) {
539f65125d20aa Peter Zijlstra 2020-11-17 6025 put_prev_task(rq, prev);
539f65125d20aa Peter Zijlstra 2020-11-17 6026 set_next_task(rq, next);
539f65125d20aa Peter Zijlstra 2020-11-17 6027 }
539f65125d20aa Peter Zijlstra 2020-11-17 6028
539f65125d20aa Peter Zijlstra 2020-11-17 6029 rq->core_pick = NULL;
5b6547ed97f4f5 Peter Zijlstra 2022-03-16 6030 goto out;
539f65125d20aa Peter Zijlstra 2020-11-17 6031 }
539f65125d20aa Peter Zijlstra 2020-11-17 6032
6bef643d2583b2 Peter Zijlstra 2024-07-22 6033 prev_balance(rq, prev, rf);
6bef643d2583b2 Peter Zijlstra 2024-07-22 6034
539f65125d20aa Peter Zijlstra 2020-11-17 6035 smt_mask = cpu_smt_mask(cpu);
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6036) need_sync = !!rq->core->core_cookie;
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6037)
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6038) /* reset state */
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6039) rq->core->core_cookie = 0UL;
4feee7d12603de Josh Don 2021-10-18 6040 if (rq->core->core_forceidle_count) {
4feee7d12603de Josh Don 2021-10-18 6041 if (!core_clock_updated) {
4feee7d12603de Josh Don 2021-10-18 6042 update_rq_clock(rq->core);
4feee7d12603de Josh Don 2021-10-18 6043 core_clock_updated = true;
4feee7d12603de Josh Don 2021-10-18 6044 }
4feee7d12603de Josh Don 2021-10-18 6045 sched_core_account_forceidle(rq);
4feee7d12603de Josh Don 2021-10-18 6046 /* reset after accounting force idle */
4feee7d12603de Josh Don 2021-10-18 6047 rq->core->core_forceidle_start = 0;
4feee7d12603de Josh Don 2021-10-18 6048 rq->core->core_forceidle_count = 0;
4feee7d12603de Josh Don 2021-10-18 6049 rq->core->core_forceidle_occupation = 0;
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6050) need_sync = true;
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6051) fi_before = true;
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6052) }
539f65125d20aa Peter Zijlstra 2020-11-17 6053
539f65125d20aa Peter Zijlstra 2020-11-17 6054 /*
539f65125d20aa Peter Zijlstra 2020-11-17 6055 * core->core_task_seq, core->core_pick_seq, rq->core_sched_seq
539f65125d20aa Peter Zijlstra 2020-11-17 6056 *
539f65125d20aa Peter Zijlstra 2020-11-17 6057 * @task_seq guards the task state ({en,de}queues)
539f65125d20aa Peter Zijlstra 2020-11-17 6058 * @pick_seq is the @task_seq we did a selection on
539f65125d20aa Peter Zijlstra 2020-11-17 6059 * @sched_seq is the @pick_seq we scheduled
539f65125d20aa Peter Zijlstra 2020-11-17 6060 *
539f65125d20aa Peter Zijlstra 2020-11-17 6061 * However, preemptions can cause multiple picks on the same task set.
539f65125d20aa Peter Zijlstra 2020-11-17 6062 * 'Fix' this by also increasing @task_seq for every pick.
539f65125d20aa Peter Zijlstra 2020-11-17 6063 */
539f65125d20aa Peter Zijlstra 2020-11-17 6064 rq->core->core_task_seq++;
539f65125d20aa Peter Zijlstra 2020-11-17 6065
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6066) /*
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6067) * Optimize for common case where this CPU has no cookies
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6068) * and there are no cookied tasks running on siblings.
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6069) */
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6070) if (!need_sync) {
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6071 next = pick_task(rq);
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 @6072) if (!next->core_cookie) {
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6073) rq->core_pick = NULL;
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6074) /*
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6075) * For robustness, update the min_vruntime_fi for
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6076) * unconstrained picks as well.
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6077) */
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6078) WARN_ON_ONCE(fi_before);
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6079) task_vruntime_update(rq, next, false);
5b6547ed97f4f5 Peter Zijlstra 2022-03-16 6080 goto out_set_next;
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6081) }
8039e96fcc1de3 Vineeth Pillai 2020-11-17 6082 }
7afbba119f0da0 Joel Fernandes (Google 2020-11-17 6083)
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6084 /*
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6085 * For each thread: do the regular task pick and find the max prio task
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6086 * amongst them.
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6087 *
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6088 * Tie-break prio towards the current CPU
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6089 */
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6090 for_each_cpu_wrap(i, smt_mask, cpu) {
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6091 rq_i = cpu_rq(i);
539f65125d20aa Peter Zijlstra 2020-11-17 6092
4feee7d12603de Josh Don 2021-10-18 6093 /*
4feee7d12603de Josh Don 2021-10-18 6094 * Current cpu always has its clock updated on entrance to
4feee7d12603de Josh Don 2021-10-18 6095 * pick_next_task(). If the current cpu is not the core,
4feee7d12603de Josh Don 2021-10-18 6096 * the core may also have been updated above.
4feee7d12603de Josh Don 2021-10-18 6097 */
4feee7d12603de Josh Don 2021-10-18 6098 if (i != cpu && (rq_i != rq->core || !core_clock_updated))
539f65125d20aa Peter Zijlstra 2020-11-17 6099 update_rq_clock(rq_i);
539f65125d20aa Peter Zijlstra 2020-11-17 6100
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6101 p = rq_i->core_pick = pick_task(rq_i);
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6102 if (!max || prio_less(max, p, fi_before))
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6103 max = p;
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6104 }
539f65125d20aa Peter Zijlstra 2020-11-17 6105
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6106 cookie = rq->core->core_cookie = max->core_cookie;
539f65125d20aa Peter Zijlstra 2020-11-17 6107
539f65125d20aa Peter Zijlstra 2020-11-17 6108 /*
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6109 * For each thread: try and find a runnable task that matches @max or
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6110 * force idle.
539f65125d20aa Peter Zijlstra 2020-11-17 6111 */
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6112 for_each_cpu(i, smt_mask) {
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6113 rq_i = cpu_rq(i);
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6114 p = rq_i->core_pick;
539f65125d20aa Peter Zijlstra 2020-11-17 6115
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6116 if (!cookie_equals(p, cookie)) {
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6117 p = NULL;
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6118 if (cookie)
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6119 p = sched_core_find(rq_i, cookie);
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6120 if (!p)
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6121 p = idle_sched_class.pick_task(rq_i);
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6122 }
d2dfa17bc7de67 Peter Zijlstra 2020-11-17 6123
539f65125d20aa Peter Zijlstra 2020-11-17 6124 rq_i->core_pick = p;
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6125
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6126 if (p == rq_i->idle) {
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6127 if (rq_i->nr_running) {
4feee7d12603de Josh Don 2021-10-18 6128 rq->core->core_forceidle_count++;
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6129) if (!fi_before)
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6130) rq->core->core_forceidle_seq++;
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6131) }
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6132 } else {
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6133 occ++;
539f65125d20aa Peter Zijlstra 2020-11-17 6134 }
539f65125d20aa Peter Zijlstra 2020-11-17 6135 }
539f65125d20aa Peter Zijlstra 2020-11-17 6136
4feee7d12603de Josh Don 2021-10-18 6137 if (schedstat_enabled() && rq->core->core_forceidle_count) {
4feee7d12603de Josh Don 2021-10-18 6138 rq->core->core_forceidle_start = rq_clock(rq->core);
4feee7d12603de Josh Don 2021-10-18 6139 rq->core->core_forceidle_occupation = occ;
4feee7d12603de Josh Don 2021-10-18 6140 }
4feee7d12603de Josh Don 2021-10-18 6141
539f65125d20aa Peter Zijlstra 2020-11-17 6142 rq->core->core_pick_seq = rq->core->core_task_seq;
539f65125d20aa Peter Zijlstra 2020-11-17 6143 next = rq->core_pick;
539f65125d20aa Peter Zijlstra 2020-11-17 6144 rq->core_sched_seq = rq->core->core_pick_seq;
539f65125d20aa Peter Zijlstra 2020-11-17 6145
539f65125d20aa Peter Zijlstra 2020-11-17 6146 /* Something should have been selected for current CPU */
539f65125d20aa Peter Zijlstra 2020-11-17 6147 WARN_ON_ONCE(!next);
539f65125d20aa Peter Zijlstra 2020-11-17 6148
539f65125d20aa Peter Zijlstra 2020-11-17 6149 /*
539f65125d20aa Peter Zijlstra 2020-11-17 6150 * Reschedule siblings
539f65125d20aa Peter Zijlstra 2020-11-17 6151 *
539f65125d20aa Peter Zijlstra 2020-11-17 6152 * NOTE: L1TF -- at this point we're no longer running the old task and
539f65125d20aa Peter Zijlstra 2020-11-17 6153 * sending an IPI (below) ensures the sibling will no longer be running
539f65125d20aa Peter Zijlstra 2020-11-17 6154 * their task. This ensures there is no inter-sibling overlap between
539f65125d20aa Peter Zijlstra 2020-11-17 6155 * non-matching user state.
539f65125d20aa Peter Zijlstra 2020-11-17 6156 */
539f65125d20aa Peter Zijlstra 2020-11-17 6157 for_each_cpu(i, smt_mask) {
bc9ffef31bf598 Peter Zijlstra 2021-08-24 6158 rq_i = cpu_rq(i);
539f65125d20aa Peter Zijlstra 2020-11-17 6159
539f65125d20aa Peter Zijlstra 2020-11-17 6160 /*
539f65125d20aa Peter Zijlstra 2020-11-17 6161 * An online sibling might have gone offline before a task
539f65125d20aa Peter Zijlstra 2020-11-17 6162 * could be picked for it, or it might be offline but later
539f65125d20aa Peter Zijlstra 2020-11-17 6163 * happen to come online, but its too late and nothing was
539f65125d20aa Peter Zijlstra 2020-11-17 6164 * picked for it. That's Ok - it will pick tasks for itself,
539f65125d20aa Peter Zijlstra 2020-11-17 6165 * so ignore it.
539f65125d20aa Peter Zijlstra 2020-11-17 6166 */
539f65125d20aa Peter Zijlstra 2020-11-17 6167 if (!rq_i->core_pick)
539f65125d20aa Peter Zijlstra 2020-11-17 6168 continue;
539f65125d20aa Peter Zijlstra 2020-11-17 6169
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6170) /*
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6171) * Update for new !FI->FI transitions, or if continuing to be in !FI:
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6172) * fi_before fi update?
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6173) * 0 0 1
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6174) * 0 1 1
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6175) * 1 0 1
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6176) * 1 1 0
c6047c2e3af68d Joel Fernandes (Google 2020-11-17 6177) */
4feee7d12603de Josh Don 2021-10-18 6178 if (!(fi_before && rq->core->core_forceidle_count))
4feee7d12603de Josh Don 2021-10-18 6179 task_vruntime_update(rq_i, rq_i->core_pick, !!rq->core->core_forceidle_count);
539f65125d20aa Peter Zijlstra 2020-11-17 6180
d2dfa17bc7de67 Peter Zijlstra 2020-11-17 6181 rq_i->core_pick->core_occupation = occ;
d2dfa17bc7de67 Peter Zijlstra 2020-11-17 6182
539f65125d20aa Peter Zijlstra 2020-11-17 6183 if (i == cpu) {
539f65125d20aa Peter Zijlstra 2020-11-17 6184 rq_i->core_pick = NULL;
539f65125d20aa Peter Zijlstra 2020-11-17 6185 continue;
539f65125d20aa Peter Zijlstra 2020-11-17 6186 }
539f65125d20aa Peter Zijlstra 2020-11-17 6187
539f65125d20aa Peter Zijlstra 2020-11-17 6188 /* Did we break L1TF mitigation requirements? */
539f65125d20aa Peter Zijlstra 2020-11-17 6189 WARN_ON_ONCE(!cookie_match(next, rq_i->core_pick));
539f65125d20aa Peter Zijlstra 2020-11-17 6190
539f65125d20aa Peter Zijlstra 2020-11-17 6191 if (rq_i->curr == rq_i->core_pick) {
539f65125d20aa Peter Zijlstra 2020-11-17 6192 rq_i->core_pick = NULL;
539f65125d20aa Peter Zijlstra 2020-11-17 6193 continue;
539f65125d20aa Peter Zijlstra 2020-11-17 6194 }
539f65125d20aa Peter Zijlstra 2020-11-17 6195
539f65125d20aa Peter Zijlstra 2020-11-17 6196 resched_curr(rq_i);
539f65125d20aa Peter Zijlstra 2020-11-17 6197 }
539f65125d20aa Peter Zijlstra 2020-11-17 6198
5b6547ed97f4f5 Peter Zijlstra 2022-03-16 6199 out_set_next:
4dc9ef89e52432 Peter Zijlstra 2024-07-22 6200 put_prev_set_next_task(rq, prev, p);
5b6547ed97f4f5 Peter Zijlstra 2022-03-16 6201 out:
5b6547ed97f4f5 Peter Zijlstra 2022-03-16 6202 if (rq->core->core_forceidle_count && next == rq->idle)
5b6547ed97f4f5 Peter Zijlstra 2022-03-16 6203 queue_core_balance(rq);
5b6547ed97f4f5 Peter Zijlstra 2022-03-16 6204
539f65125d20aa Peter Zijlstra 2020-11-17 6205 return next;
539f65125d20aa Peter Zijlstra 2020-11-17 6206 }
9edeaea1bc4523 Peter Zijlstra 2020-11-17 6207
:::::: The code at line 6072 was first introduced by commit
:::::: 7afbba119f0da09824d723f8081608ea1f74ff57 sched: Fix priority inversion of cookied task with sibling
:::::: TO: Joel Fernandes (Google) <joel@joelfernandes.org>
:::::: CC: Peter Zijlstra <peterz@infradead.org>
--
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