diff --git a/include/linux/preempt.h b/include/linux/preempt.h index 7d013e887f95..e7b538244afc 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -150,6 +150,14 @@ do { \ set_preempt_need_resched(); \ } while (0) +#ifdef CONFIG_SMP +extern void migrate_disable(void); +extern void migrate_enable(void); +#else +# define migrate_disable() barrier() +# define migrate_enable() barrier() +#endif + #ifdef CONFIG_PREEMPT_RT_FULL # define preempt_disable_rt() preempt_disable() # define preempt_enable_rt() preempt_enable() diff --git a/include/linux/sched.h b/include/linux/sched.h index f3a1c15af802..09d5a7d379cc 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1202,6 +1202,7 @@ struct task_struct { #endif unsigned int policy; + int migrate_disable; int nr_cpus_allowed; cpumask_t cpus_allowed; @@ -1613,9 +1614,6 @@ struct task_struct { #endif }; -/* Future-safe accessor for struct task_struct's cpus_allowed. */ -#define tsk_cpus_allowed(tsk) (&(tsk)->cpus_allowed) - #define TNF_MIGRATED 0x01 #define TNF_NO_GROUP 0x02 #define TNF_SHARED 0x04 @@ -2980,6 +2978,15 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu) #endif /* CONFIG_SMP */ +/* Future-safe accessor for struct task_struct's cpus_allowed. */ +static inline const struct cpumask *tsk_cpus_allowed(struct task_struct *p) +{ + if (p->migrate_disable) + return cpumask_of(task_cpu(p)); + + return &p->cpus_allowed; +} + extern long sched_setaffinity(pid_t pid, const struct cpumask *new_mask); extern long sched_getaffinity(pid_t pid, struct cpumask *mask); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 650ee9d4cbdb..43597499d254 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4654,11 +4654,12 @@ void init_idle(struct task_struct *idle, int cpu) #ifdef CONFIG_SMP void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) { - if (p->sched_class && p->sched_class->set_cpus_allowed) - p->sched_class->set_cpus_allowed(p, new_mask); - + if (!p->migrate_disable) { + if (p->sched_class && p->sched_class->set_cpus_allowed) + p->sched_class->set_cpus_allowed(p, new_mask); + p->nr_cpus_allowed = cpumask_weight(new_mask); + } cpumask_copy(&p->cpus_allowed, new_mask); - p->nr_cpus_allowed = cpumask_weight(new_mask); } /* @@ -4704,7 +4705,7 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) do_set_cpus_allowed(p, new_mask); /* Can the task run on the task's current CPU? If so, we're done */ - if (cpumask_test_cpu(task_cpu(p), new_mask)) + if (cpumask_test_cpu(task_cpu(p), new_mask) || p->migrate_disable) goto out; dest_cpu = cpumask_any_and(cpu_active_mask, new_mask); @@ -4723,6 +4724,83 @@ out: } EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); +void migrate_disable(void) +{ + struct task_struct *p = current; + const struct cpumask *mask; + unsigned long flags; + struct rq *rq; + + preempt_disable(); + if (p->migrate_disable) { + p->migrate_disable++; + preempt_enable(); + return; + } + + pin_current_cpu(); + if (unlikely(!scheduler_running)) { + p->migrate_disable = 1; + preempt_enable(); + return; + } + rq = task_rq_lock(p, &flags); + p->migrate_disable = 1; + mask = tsk_cpus_allowed(p); + + WARN_ON(!cpumask_test_cpu(smp_processor_id(), mask)); + + if (!cpumask_equal(&p->cpus_allowed, mask)) { + if (p->sched_class->set_cpus_allowed) + p->sched_class->set_cpus_allowed(p, mask); + p->nr_cpus_allowed = cpumask_weight(mask); + } + task_rq_unlock(rq, p, &flags); + preempt_enable(); +} +EXPORT_SYMBOL(migrate_disable); + +void migrate_enable(void) +{ + struct task_struct *p = current; + const struct cpumask *mask; + unsigned long flags; + struct rq *rq; + + WARN_ON_ONCE(p->migrate_disable <= 0); + + preempt_disable(); + if (p->migrate_disable > 1) { + p->migrate_disable--; + preempt_enable(); + return; + } + + if (unlikely(!scheduler_running)) { + p->migrate_disable = 0; + unpin_current_cpu(); + preempt_enable(); + return; + } + + rq = task_rq_lock(p, &flags); + p->migrate_disable = 0; + mask = tsk_cpus_allowed(p); + + WARN_ON(!cpumask_test_cpu(smp_processor_id(), mask)); + + if (!cpumask_equal(&p->cpus_allowed, mask)) { + if (p->sched_class->set_cpus_allowed) + p->sched_class->set_cpus_allowed(p, mask); + p->nr_cpus_allowed = cpumask_weight(mask); + } + + task_rq_unlock(rq, p, &flags); + unpin_current_cpu(); + preempt_enable(); +} +EXPORT_SYMBOL(migrate_enable); + /* * Move (not current) task off this cpu, onto dest cpu. We're doing * this because either it can't run here any more (set_cpus_allowed() diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c index 04abe53f12a1..a82eaa4b0623 100644 --- a/lib/smp_processor_id.c +++ b/lib/smp_processor_id.c @@ -38,9 +38,9 @@ notrace unsigned int debug_smp_processor_id(void) if (!printk_ratelimit()) goto out_enable; - printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] " - "code: %s/%d\n", - preempt_count() - 1, current->comm, current->pid); + printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x %08x] " + "code: %s/%d\n", preempt_count() - 1, + current->migrate_disable, current->comm, current->pid); print_symbol("caller is %s\n", (long)__builtin_return_address(0)); dump_stack();