diff options
| -rw-r--r-- | include/linux/context_tracking.h | 10 | ||||
| -rw-r--r-- | include/linux/context_tracking_state.h | 1 | ||||
| -rw-r--r-- | include/linux/sched.h | 3 | ||||
| -rw-r--r-- | include/linux/tick.h | 7 | ||||
| -rw-r--r-- | kernel/context_tracking.c | 67 | ||||
| -rw-r--r-- | kernel/sched/core.c | 4 |
6 files changed, 59 insertions, 33 deletions
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h index 2821838256b4..b96bd299966f 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -14,8 +14,6 @@ extern void context_tracking_enter(enum ctx_state state); extern void context_tracking_exit(enum ctx_state state); extern void context_tracking_user_enter(void); extern void context_tracking_user_exit(void); -extern void __context_tracking_task_switch(struct task_struct *prev, - struct task_struct *next); static inline void user_enter(void) { @@ -51,19 +49,11 @@ static inline void exception_exit(enum ctx_state prev_ctx) } } -static inline void context_tracking_task_switch(struct task_struct *prev, - struct task_struct *next) -{ - if (context_tracking_is_enabled()) - __context_tracking_task_switch(prev, next); -} #else static inline void user_enter(void) { } static inline void user_exit(void) { } static inline enum ctx_state exception_enter(void) { return 0; } static inline void exception_exit(enum ctx_state prev_ctx) { } -static inline void context_tracking_task_switch(struct task_struct *prev, - struct task_struct *next) { } #endif /* !CONFIG_CONTEXT_TRACKING */ diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h index 6b7b96a32b75..678ecdf90cf6 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -12,6 +12,7 @@ struct context_tracking { * may be further optimized using static keys. */ bool active; + int recursion; enum ctx_state { CONTEXT_KERNEL = 0, CONTEXT_USER, diff --git a/include/linux/sched.h b/include/linux/sched.h index 30364cb58b1f..6633e83e608a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2599,6 +2599,9 @@ static inline unsigned long wait_task_inactive(struct task_struct *p, } #endif +#define tasklist_empty() \ + list_empty(&init_task.tasks) + #define next_task(p) \ list_entry_rcu((p)->tasks.next, struct task_struct, tasks) diff --git a/include/linux/tick.h b/include/linux/tick.h index f8492da57ad3..4191b5623a28 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -134,6 +134,12 @@ static inline bool tick_nohz_full_cpu(int cpu) return cpumask_test_cpu(cpu, tick_nohz_full_mask); } +static inline void tick_nohz_full_add_cpus_to(struct cpumask *mask) +{ + if (tick_nohz_full_enabled()) + cpumask_or(mask, mask, tick_nohz_full_mask); +} + extern void __tick_nohz_full_check(void); extern void tick_nohz_full_kick(void); extern void tick_nohz_full_kick_cpu(int cpu); @@ -142,6 +148,7 @@ extern void __tick_nohz_task_switch(struct task_struct *tsk); #else static inline bool tick_nohz_full_enabled(void) { return false; } static inline bool tick_nohz_full_cpu(int cpu) { return false; } +static inline void tick_nohz_full_add_cpus_to(struct cpumask *mask) { } static inline void __tick_nohz_full_check(void) { } static inline void tick_nohz_full_kick_cpu(int cpu) { } static inline void tick_nohz_full_kick(void) { } diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 72d59a1a6eb6..0a495ab35bc7 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -30,12 +30,23 @@ EXPORT_SYMBOL_GPL(context_tracking_enabled); DEFINE_PER_CPU(struct context_tracking, context_tracking); EXPORT_SYMBOL_GPL(context_tracking); -void context_tracking_cpu_set(int cpu) +static bool context_tracking_recursion_enter(void) { - if (!per_cpu(context_tracking.active, cpu)) { - per_cpu(context_tracking.active, cpu) = true; - static_key_slow_inc(&context_tracking_enabled); - } + int recursion; + + recursion = __this_cpu_inc_return(context_tracking.recursion); + if (recursion == 1) + return true; + + WARN_ONCE((recursion < 1), "Invalid context tracking recursion value %d\n", recursion); + __this_cpu_dec(context_tracking.recursion); + + return false; +} + +static void context_tracking_recursion_exit(void) +{ + __this_cpu_dec(context_tracking.recursion); } /** @@ -75,6 +86,9 @@ void context_tracking_enter(enum ctx_state state) WARN_ON_ONCE(!current->mm); local_irq_save(flags); + if (!context_tracking_recursion_enter()) + goto out_irq_restore; + if ( __this_cpu_read(context_tracking.state) != state) { if (__this_cpu_read(context_tracking.active)) { /* @@ -105,6 +119,8 @@ void context_tracking_enter(enum ctx_state state) */ __this_cpu_write(context_tracking.state, state); } + context_tracking_recursion_exit(); +out_irq_restore: local_irq_restore(flags); } NOKPROBE_SYMBOL(context_tracking_enter); @@ -139,6 +155,9 @@ void context_tracking_exit(enum ctx_state state) return; local_irq_save(flags); + if (!context_tracking_recursion_enter()) + goto out_irq_restore; + if (__this_cpu_read(context_tracking.state) == state) { if (__this_cpu_read(context_tracking.active)) { /* @@ -153,6 +172,8 @@ void context_tracking_exit(enum ctx_state state) } __this_cpu_write(context_tracking.state, CONTEXT_KERNEL); } + context_tracking_recursion_exit(); +out_irq_restore: local_irq_restore(flags); } NOKPROBE_SYMBOL(context_tracking_exit); @@ -164,24 +185,26 @@ void context_tracking_user_exit(void) } NOKPROBE_SYMBOL(context_tracking_user_exit); -/** - * __context_tracking_task_switch - context switch the syscall callbacks - * @prev: the task that is being switched out - * @next: the task that is being switched in - * - * The context tracking uses the syscall slow path to implement its user-kernel - * boundaries probes on syscalls. This way it doesn't impact the syscall fast - * path on CPUs that don't do context tracking. - * - * But we need to clear the flag on the previous task because it may later - * migrate to some CPU that doesn't do the context tracking. As such the TIF - * flag may not be desired there. - */ -void __context_tracking_task_switch(struct task_struct *prev, - struct task_struct *next) +void __init context_tracking_cpu_set(int cpu) { - clear_tsk_thread_flag(prev, TIF_NOHZ); - set_tsk_thread_flag(next, TIF_NOHZ); + static __initdata bool initialized = false; + + if (!per_cpu(context_tracking.active, cpu)) { + per_cpu(context_tracking.active, cpu) = true; + static_key_slow_inc(&context_tracking_enabled); + } + + if (initialized) + return; + + /* + * Set TIF_NOHZ to init/0 and let it propagate to all tasks through fork + * This assumes that init is the only task at this early boot stage. + */ + set_tsk_thread_flag(&init_task, TIF_NOHZ); + WARN_ON_ONCE(!tasklist_empty()); + + initialized = true; } #ifdef CONFIG_CONTEXT_TRACKING_FORCE diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c9a707b59331..c86935a7f1f8 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2374,7 +2374,6 @@ context_switch(struct rq *rq, struct task_struct *prev, */ spin_release(&rq->lock.dep_map, 1, _THIS_IP_); - context_tracking_task_switch(prev, next); /* Here we just switch the register state and the stack. */ switch_to(prev, next, prev); barrier(); @@ -7068,6 +7067,9 @@ void __init sched_init_smp(void) alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL); alloc_cpumask_var(&fallback_doms, GFP_KERNEL); + /* nohz_full won't take effect without isolating the cpus. */ + tick_nohz_full_add_cpus_to(cpu_isolated_map); + sched_init_numa(); /* |