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authorSebastian Andrzej Siewior <bigeasy@linutronix.de>2019-04-23 16:26:36 +0200
committerIngo Molnar <mingo@kernel.org>2019-06-03 11:49:37 +0200
commit3bd3706251ee8ab67e69d9340ac2abdca217e733 (patch)
tree4431aa630d095905d840ace6a0b86e266395f71a /kernel/sched/cpupri.c
parentf2c7c76c5d0a443053e94adb9f0918fa2fb85c3a (diff)
downloadlinux-3bd3706251ee8ab67e69d9340ac2abdca217e733.tar.bz2
sched/core: Provide a pointer to the valid CPU mask
In commit: 4b53a3412d66 ("sched/core: Remove the tsk_nr_cpus_allowed() wrapper") the tsk_nr_cpus_allowed() wrapper was removed. There was not much difference in !RT but in RT we used this to implement migrate_disable(). Within a migrate_disable() section the CPU mask is restricted to single CPU while the "normal" CPU mask remains untouched. As an alternative implementation Ingo suggested to use: struct task_struct { const cpumask_t *cpus_ptr; cpumask_t cpus_mask; }; with t->cpus_ptr = &t->cpus_mask; In -RT we then can switch the cpus_ptr to: t->cpus_ptr = &cpumask_of(task_cpu(p)); in a migration disabled region. The rules are simple: - Code that 'uses' ->cpus_allowed would use the pointer. - Code that 'modifies' ->cpus_allowed would use the direct mask. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20190423142636.14347-1-bigeasy@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/cpupri.c')
-rw-r--r--kernel/sched/cpupri.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/sched/cpupri.c b/kernel/sched/cpupri.c
index daaadf939ccb..f7d2c10b4c92 100644
--- a/kernel/sched/cpupri.c
+++ b/kernel/sched/cpupri.c
@@ -98,11 +98,11 @@ int cpupri_find(struct cpupri *cp, struct task_struct *p,
if (skip)
continue;
- if (cpumask_any_and(&p->cpus_allowed, vec->mask) >= nr_cpu_ids)
+ if (cpumask_any_and(p->cpus_ptr, vec->mask) >= nr_cpu_ids)
continue;
if (lowest_mask) {
- cpumask_and(lowest_mask, &p->cpus_allowed, vec->mask);
+ cpumask_and(lowest_mask, p->cpus_ptr, vec->mask);
/*
* We have to ensure that we have at least one bit