From 176f8f7a52cc6d09d686f0d900abda6942a52fbb Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 4 Aug 2014 17:43:50 -0700 Subject: rcu: Make TASKS_RCU handle nohz_full= CPUs Currently TASKS_RCU would ignore a CPU running a task in nohz_full= usermode execution. There would be neither a context switch nor a scheduling-clock interrupt to tell TASKS_RCU that the task in question had passed through a quiescent state. The grace period would therefore extend indefinitely. This commit therefore makes RCU's dyntick-idle subsystem record the task_struct structure of the task that is running in dyntick-idle mode on each CPU. The TASKS_RCU grace period can then access this information and record a quiescent state on behalf of any CPU running in dyntick-idle usermode. Signed-off-by: Paul E. McKenney --- include/linux/init_task.h | 3 ++- include/linux/sched.h | 2 ++ 2 files changed, 4 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/init_task.h b/include/linux/init_task.h index dffd9258ee60..03b274873b06 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -121,7 +121,8 @@ extern struct group_info init_groups; #define INIT_TASK_RCU_TASKS(tsk) \ .rcu_tasks_holdout = false, \ .rcu_tasks_holdout_list = \ - LIST_HEAD_INIT(tsk.rcu_tasks_holdout_list), + LIST_HEAD_INIT(tsk.rcu_tasks_holdout_list), \ + .rcu_tasks_idle_cpu = -1, #else #define INIT_TASK_RCU_TASKS(tsk) #endif diff --git a/include/linux/sched.h b/include/linux/sched.h index eaacac4ae77d..ec8b34722bcc 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1274,6 +1274,7 @@ struct task_struct { unsigned long rcu_tasks_nvcsw; bool rcu_tasks_holdout; struct list_head rcu_tasks_holdout_list; + int rcu_tasks_idle_cpu; #endif /* #ifdef CONFIG_TASKS_RCU */ #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) @@ -2020,6 +2021,7 @@ static inline void rcu_copy_process(struct task_struct *p) #ifdef CONFIG_TASKS_RCU p->rcu_tasks_holdout = false; INIT_LIST_HEAD(&p->rcu_tasks_holdout_list); + p->rcu_tasks_idle_cpu = -1; #endif /* #ifdef CONFIG_TASKS_RCU */ } -- cgit v1.2.3