From 05f0fe6b74dbd7690a4cbd61810948b7d575576a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 14 Mar 2018 12:45:13 -0700 Subject: RCU, workqueue: Implement rcu_work There are cases where RCU callback needs to be bounced to a sleepable context. This is currently done by the RCU callback queueing a work item, which can be cumbersome to write and confusing to read. This patch introduces rcu_work, a workqueue work variant which gets executed after a RCU grace period, and converts the open coded bouncing in fs/aio and kernel/cgroup. v3: Dropped queue_rcu_work_on(). Documented rcu grace period behavior after queue_rcu_work(). v2: Use rcu_barrier() instead of synchronize_rcu() to wait for completion of previously queued rcu callback as per Paul. Signed-off-by: Tejun Heo Acked-by: "Paul E. McKenney" Cc: Linus Torvalds --- include/linux/workqueue.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'include/linux/workqueue.h') diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index bc0cda180c8b..d026f8f818cc 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -13,6 +13,7 @@ #include #include #include +#include struct workqueue_struct; @@ -120,6 +121,14 @@ struct delayed_work { int cpu; }; +struct rcu_work { + struct work_struct work; + struct rcu_head rcu; + + /* target workqueue ->rcu uses to queue ->work */ + struct workqueue_struct *wq; +}; + /** * struct workqueue_attrs - A struct for workqueue attributes. * @@ -151,6 +160,11 @@ static inline struct delayed_work *to_delayed_work(struct work_struct *work) return container_of(work, struct delayed_work, work); } +static inline struct rcu_work *to_rcu_work(struct work_struct *work) +{ + return container_of(work, struct rcu_work, work); +} + struct execute_work { struct work_struct work; }; @@ -266,6 +280,12 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; } #define INIT_DEFERRABLE_WORK_ONSTACK(_work, _func) \ __INIT_DELAYED_WORK_ONSTACK(_work, _func, TIMER_DEFERRABLE) +#define INIT_RCU_WORK(_work, _func) \ + INIT_WORK(&(_work)->work, (_func)) + +#define INIT_RCU_WORK_ONSTACK(_work, _func) \ + INIT_WORK_ONSTACK(&(_work)->work, (_func)) + /** * work_pending - Find out whether a work item is currently pending * @work: The work item in question @@ -447,6 +467,7 @@ extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, struct delayed_work *work, unsigned long delay); extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, struct delayed_work *dwork, unsigned long delay); +extern bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork); extern void flush_workqueue(struct workqueue_struct *wq); extern void drain_workqueue(struct workqueue_struct *wq); @@ -463,6 +484,8 @@ extern bool flush_delayed_work(struct delayed_work *dwork); extern bool cancel_delayed_work(struct delayed_work *dwork); extern bool cancel_delayed_work_sync(struct delayed_work *dwork); +extern bool flush_rcu_work(struct rcu_work *rwork); + extern void workqueue_set_max_active(struct workqueue_struct *wq, int max_active); extern struct work_struct *current_work(void); -- cgit v1.2.1