From f03a60088486149956230c80a05f3127d2269c77 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 11 Aug 2011 15:14:58 +0200 Subject: [PATCH] sched: Generic migrate_disable Make migrate_disable() be a preempt_disable() for !rt kernels. This allows generic code to use it but still enforces that these code sections stay relatively small. A preemptible migrate_disable() accessible for general use would allow people growing arbitrary per-cpu crap instead of clean these things up. Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/n/tip-275i87sl8e1jcamtchmehonm@git.kernel.org --- include/linux/preempt.h | 21 +++++++++------------ include/linux/sched.h | 13 +++++++++++++ include/linux/smp.h | 9 ++------- kernel/sched/core.c | 6 ++++-- kernel/trace/trace.c | 2 +- lib/smp_processor_id.c | 2 +- 6 files changed, 30 insertions(+), 23 deletions(-) diff --git a/include/linux/preempt.h b/include/linux/preempt.h index 93c5da839fd2..11df024a2175 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -150,28 +150,25 @@ 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() # define preempt_disable_nort() barrier() # define preempt_enable_nort() barrier() -# define migrate_disable_rt() migrate_disable() -# define migrate_enable_rt() migrate_enable() +# ifdef CONFIG_SMP + extern void migrate_disable(void); + extern void migrate_enable(void); +# else /* CONFIG_SMP */ +# define migrate_disable() barrier() +# define migrate_enable() barrier() +# endif /* CONFIG_SMP */ #else # define preempt_disable_rt() barrier() # define preempt_enable_rt() barrier() # define preempt_disable_nort() preempt_disable() # define preempt_enable_nort() preempt_enable() -# define migrate_disable_rt() barrier() -# define migrate_enable_rt() barrier() +# define migrate_disable() preempt_disable() +# define migrate_enable() preempt_enable() #endif #ifdef CONFIG_PREEMPT_NOTIFIERS diff --git a/include/linux/sched.h b/include/linux/sched.h index 09d5a7d379cc..1644c4e55673 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1202,7 +1202,9 @@ struct task_struct { #endif unsigned int policy; +#ifdef CONFIG_PREEMPT_RT_FULL int migrate_disable; +#endif int nr_cpus_allowed; cpumask_t cpus_allowed; @@ -2978,11 +2980,22 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu) #endif /* CONFIG_SMP */ +static inline int __migrate_disabled(struct task_struct *p) +{ +#ifdef CONFIG_PREEMPT_RT_FULL + return p->migrate_disable; +#else + return 0; +#endif +} + /* Future-safe accessor for struct task_struct's cpus_allowed. */ static inline const struct cpumask *tsk_cpus_allowed(struct task_struct *p) { +#ifdef CONFIG_PREEMPT_RT_FULL if (p->migrate_disable) return cpumask_of(task_cpu(p)); +#endif return &p->cpus_allowed; } diff --git a/include/linux/smp.h b/include/linux/smp.h index 42ff4feddd2b..225260914a3e 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -182,13 +182,8 @@ static inline void kick_all_cpus_sync(void) { } #define get_cpu() ({ preempt_disable(); smp_processor_id(); }) #define put_cpu() preempt_enable() -#ifndef CONFIG_PREEMPT_RT_FULL -# define get_cpu_light() get_cpu() -# define put_cpu_light() put_cpu() -#else -# define get_cpu_light() ({ migrate_disable(); smp_processor_id(); }) -# define put_cpu_light() migrate_enable() -#endif +#define get_cpu_light() ({ migrate_disable(); smp_processor_id(); }) +#define put_cpu_light() migrate_enable() /* * Callback to arch code if there's nosmp or maxcpus=0 on the diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a87710a85c55..7ce02e39d296 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4654,7 +4654,7 @@ 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->migrate_disable) { + if (!__migrate_disabled(p)) { 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); @@ -4705,7 +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) || p->migrate_disable) + if (cpumask_test_cpu(task_cpu(p), new_mask) || __migrate_disabled(p)) goto out; dest_cpu = cpumask_any_and(cpu_active_mask, new_mask); @@ -4724,6 +4724,7 @@ out: } EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); +#ifdef CONFIG_PREEMPT_RT_FULL void migrate_disable(void) { struct task_struct *p = current; @@ -4816,6 +4817,7 @@ void migrate_enable(void) preempt_enable(); } EXPORT_SYMBOL(migrate_enable); +#endif /* CONFIG_PREEMPT_RT_FULL */ /* * Move (not current) task off this cpu, onto dest cpu. We're doing diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 55bdfb3b999a..83aa646902c1 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1566,7 +1566,7 @@ tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags, (tif_need_resched() ? TRACE_FLAG_NEED_RESCHED : 0) | (test_preempt_need_resched() ? TRACE_FLAG_PREEMPT_RESCHED : 0); - entry->migrate_disable = (tsk) ? tsk->migrate_disable & 0xFF : 0; + entry->migrate_disable = (tsk) ? __migrate_disabled(tsk) & 0xFF : 0; } EXPORT_SYMBOL_GPL(tracing_generic_entry_update); diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c index a82eaa4b0623..1154792f6bbd 100644 --- a/lib/smp_processor_id.c +++ b/lib/smp_processor_id.c @@ -40,7 +40,7 @@ notrace unsigned int debug_smp_processor_id(void) 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); + __migrate_disabled(current), current->comm, current->pid); print_symbol("caller is %s\n", (long)__builtin_return_address(0)); dump_stack();