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Merge branch 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 

Pull workqueue updates from Tejun Heo:
 "rcu_work addition and a couple trivial changes"

* 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: remove the comment about the old manager_arb mutex
  workqueue: fix the comments of nr_idle
  fs/aio: Use rcu_work instead of explicit rcu and work item
  cgroup: Use rcu_work instead of explicit rcu and work item
  RCU, workqueue: Implement rcu_work
This commit is contained in:
Linus Torvalds 2018-04-03 18:00:13 -07:00
parent a23867f1d2 f75da8a8a9
commit d92cd810e6
5 changed files with 93 additions and 34 deletions
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21
fs/aio.c
View File

@ -115,8 +115,7 @@ struct kioctx {
struct page **ring_pages;
long nr_pages;
struct rcu_head free_rcu;
struct work_struct free_work; /* see free_ioctx() */
struct rcu_work free_rwork; /* see free_ioctx() */
/*
* signals when all in-flight requests are done
@ -592,13 +591,12 @@ static int kiocb_cancel(struct aio_kiocb *kiocb)
/*
* free_ioctx() should be RCU delayed to synchronize against the RCU
* protected lookup_ioctx() and also needs process context to call
* aio_free_ring(), so the double bouncing through kioctx->free_rcu and
* ->free_work.
* aio_free_ring(). Use rcu_work.
*/
static void free_ioctx(struct work_struct *work)
{
struct kioctx *ctx = container_of(work, struct kioctx, free_work);
struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
free_rwork);
pr_debug("freeing %p\n", ctx);
aio_free_ring(ctx);
@ -608,14 +606,6 @@ static void free_ioctx(struct work_struct *work)
kmem_cache_free(kioctx_cachep, ctx);
}
static void free_ioctx_rcufn(struct rcu_head *head)
{
struct kioctx *ctx = container_of(head, struct kioctx, free_rcu);
INIT_WORK(&ctx->free_work, free_ioctx);
schedule_work(&ctx->free_work);
}
static void free_ioctx_reqs(struct percpu_ref *ref)
{
struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
@ -625,7 +615,8 @@ static void free_ioctx_reqs(struct percpu_ref *ref)
complete(&ctx->rq_wait->comp);
/* Synchronize against RCU protected table->table[] dereferences */
call_rcu(&ctx->free_rcu, free_ioctx_rcufn);
INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
queue_rcu_work(system_wq, &ctx->free_rwork);
}
/*

2
include/linux/cgroup-defs.h
View File

@ -151,8 +151,8 @@ struct cgroup_subsys_state {
atomic_t online_cnt;
/* percpu_ref killing and RCU release */
struct rcu_head rcu_head;
struct work_struct destroy_work;
struct rcu_work destroy_rwork;
/*
* PI: the parent css. Placed here for cache proximity to following

23
include/linux/workqueue.h
View File

@ -13,6 +13,7 @@
#include <linux/threads.h>
#include <linux/atomic.h>
#include <linux/cpumask.h>
#include <linux/rcupdate.h>
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);
@ -462,6 +483,8 @@ 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);

21
kernel/cgroup/cgroup.c
View File

@ -4524,10 +4524,10 @@ static struct cftype cgroup_base_files[] = {
* and thus involve punting to css->destroy_work adding two additional
* steps to the already complex sequence.
*/
static void css_free_work_fn(struct work_struct *work)
static void css_free_rwork_fn(struct work_struct *work)
{
struct cgroup_subsys_state *css =
container_of(work, struct cgroup_subsys_state, destroy_work);
struct cgroup_subsys_state *css = container_of(to_rcu_work(work),
struct cgroup_subsys_state, destroy_rwork);
struct cgroup_subsys *ss = css->ss;
struct cgroup *cgrp = css->cgroup;
@ -4573,15 +4573,6 @@ static void css_free_work_fn(struct work_struct *work)
}
}
static void css_free_rcu_fn(struct rcu_head *rcu_head)
{
struct cgroup_subsys_state *css =
container_of(rcu_head, struct cgroup_subsys_state, rcu_head);
INIT_WORK(&css->destroy_work, css_free_work_fn);
queue_work(cgroup_destroy_wq, &css->destroy_work);
}
static void css_release_work_fn(struct work_struct *work)
{
struct cgroup_subsys_state *css =
@ -4631,7 +4622,8 @@ static void css_release_work_fn(struct work_struct *work)
mutex_unlock(&cgroup_mutex);
call_rcu(&css->rcu_head, css_free_rcu_fn);
INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn);
queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork);
}
static void css_release(struct percpu_ref *ref)
@ -4765,7 +4757,8 @@ static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
err_list_del:
list_del_rcu(&css->sibling);
err_free_css:
call_rcu(&css->rcu_head, css_free_rcu_fn);
INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn);
queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork);
return ERR_PTR(err);
}

60
kernel/workqueue.c
View File

@ -153,10 +153,9 @@ struct worker_pool {
unsigned long watchdog_ts; /* L: watchdog timestamp */
struct list_head worklist; /* L: list of pending works */
int nr_workers; /* L: total number of workers */
/* nr_idle includes the ones off idle_list for rebinding */
int nr_idle; /* L: currently idle ones */
int nr_workers; /* L: total number of workers */
int nr_idle; /* L: currently idle workers */
struct list_head idle_list; /* X: list of idle workers */
struct timer_list idle_timer; /* L: worker idle timeout */
@ -166,7 +165,6 @@ struct worker_pool {
DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
/* L: hash of busy workers */
/* see manage_workers() for details on the two manager mutexes */
struct worker *manager; /* L: purely informational */
struct mutex attach_mutex; /* attach/detach exclusion */
struct list_head workers; /* A: attached workers */
@ -1604,6 +1602,40 @@ bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
}
EXPORT_SYMBOL_GPL(mod_delayed_work_on);
static void rcu_work_rcufn(struct rcu_head *rcu)
{
struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu);
/* read the comment in __queue_work() */
local_irq_disable();
__queue_work(WORK_CPU_UNBOUND, rwork->wq, &rwork->work);
local_irq_enable();
}
/**
* queue_rcu_work - queue work after a RCU grace period
* @wq: workqueue to use
* @rwork: work to queue
*
* Return: %false if @rwork was already pending, %true otherwise. Note
* that a full RCU grace period is guaranteed only after a %true return.
* While @rwork is guarnateed to be executed after a %false return, the
* execution may happen before a full RCU grace period has passed.
*/
bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork)
{
struct work_struct *work = &rwork->work;
if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
rwork->wq = wq;
call_rcu(&rwork->rcu, rcu_work_rcufn);
return true;
}
return false;
}
EXPORT_SYMBOL(queue_rcu_work);
/**
* worker_enter_idle - enter idle state
* @worker: worker which is entering idle state
@ -3001,6 +3033,26 @@ bool flush_delayed_work(struct delayed_work *dwork)
}
EXPORT_SYMBOL(flush_delayed_work);
/**
* flush_rcu_work - wait for a rwork to finish executing the last queueing
* @rwork: the rcu work to flush
*
* Return:
* %true if flush_rcu_work() waited for the work to finish execution,
* %false if it was already idle.
*/
bool flush_rcu_work(struct rcu_work *rwork)
{
if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) {
rcu_barrier();
flush_work(&rwork->work);
return true;
} else {
return flush_work(&rwork->work);
}
}
EXPORT_SYMBOL(flush_rcu_work);
static bool __cancel_work(struct work_struct *work, bool is_dwork)
{
unsigned long flags;