diff options
| -rw-r--r-- | include/linux/rcupdate.h | 3 | ||||
| -rw-r--r-- | kernel/exit.c | 3 | ||||
| -rw-r--r-- | kernel/rcu/update.c | 21 |
3 files changed, 27 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 640152fedcde..54b2ebb20313 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -321,6 +321,8 @@ static inline void rcu_user_hooks_switch(struct task_struct *prev, * macro rather than an inline function to avoid #include hell. */ #ifdef CONFIG_TASKS_RCU +#define TASKS_RCU(x) x +extern struct srcu_struct tasks_rcu_exit_srcu; #define rcu_note_voluntary_context_switch(t) \ do { \ preempt_disable(); /* Exclude synchronize_sched(); */ \ @@ -329,6 +331,7 @@ static inline void rcu_user_hooks_switch(struct task_struct *prev, preempt_enable(); \ } while (0) #else /* #ifdef CONFIG_TASKS_RCU */ +#define TASKS_RCU(x) do { } while (0) #define rcu_note_voluntary_context_switch(t) do { } while (0) #endif /* #else #ifdef CONFIG_TASKS_RCU */ diff --git a/kernel/exit.c b/kernel/exit.c index 32c58f7433a3..d13f2eec4bb8 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -667,6 +667,7 @@ void do_exit(long code) { struct task_struct *tsk = current; int group_dead; + TASKS_RCU(int tasks_rcu_i); profile_task_exit(tsk); @@ -775,6 +776,7 @@ void do_exit(long code) */ flush_ptrace_hw_breakpoint(tsk); + TASKS_RCU(tasks_rcu_i = __srcu_read_lock(&tasks_rcu_exit_srcu)); exit_notify(tsk, group_dead); proc_exit_connector(tsk); #ifdef CONFIG_NUMA @@ -814,6 +816,7 @@ void do_exit(long code) if (tsk->nr_dirtied) __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); exit_rcu(); + TASKS_RCU(__srcu_read_unlock(&tasks_rcu_exit_srcu, tasks_rcu_i)); /* * The setting of TASK_RUNNING by try_to_wake_up() may be delayed diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index 5fd1ddbfcc55..403fc4ae539e 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -367,6 +367,13 @@ static struct rcu_head *rcu_tasks_cbs_head; static struct rcu_head **rcu_tasks_cbs_tail = &rcu_tasks_cbs_head; static DEFINE_RAW_SPINLOCK(rcu_tasks_cbs_lock); +/* Track exiting tasks in order to allow them to be waited for. */ +DEFINE_SRCU(tasks_rcu_exit_srcu); + +/* Control stall timeouts. Disable with <= 0, otherwise jiffies till stall. */ +static int rcu_task_stall_timeout __read_mostly = HZ * 60 * 3; +module_param(rcu_task_stall_timeout, int, 0644); + /* Post an RCU-tasks callback. */ void call_rcu_tasks(struct rcu_head *rhp, void (*func)(struct rcu_head *rhp)) { @@ -518,6 +525,15 @@ static int __noreturn rcu_tasks_kthread(void *arg) rcu_read_unlock(); /* + * Wait for tasks that are in the process of exiting. + * This does only part of the job, ensuring that all + * tasks that were previously exiting reach the point + * where they have disabled preemption, allowing the + * later synchronize_sched() to finish the job. + */ + synchronize_srcu(&tasks_rcu_exit_srcu); + + /* * Each pass through the following loop scans the list * of holdout tasks, removing any that are no longer * holdouts. When the list is empty, we are done. @@ -546,6 +562,11 @@ static int __noreturn rcu_tasks_kthread(void *arg) * ->rcu_tasks_holdout accesses to be within the grace * period, avoiding the need for memory barriers for * ->rcu_tasks_holdout accesses. + * + * In addition, this synchronize_sched() waits for exiting + * tasks to complete their final preempt_disable() region + * of execution, cleaning up after the synchronize_srcu() + * above. */ synchronize_sched(); |