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Date: Thu, 27 Mar 2014 20:08:39 +0800 From: Lai Jiangshan <laijs@...fujitsu.com> To: Lai Jiangshan <laijs@...fujitsu.com> CC: Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org Subject: Re: [PATCH] workqueue: add __WQ_FREEZING and remove POOL_FREEZING On 03/25/2014 05:56 PM, Lai Jiangshan wrote: > freezing is nothing related to pools, but POOL_FREEZING adds a connection, > and causes freeze_workqueues_begin() and thaw_workqueues() complicated. > > Since freezing is workqueue instance attribute, so we introduce __WQ_FREEZING > to wq->flags instead and remove POOL_FREEZING. > > we set __WQ_FREEZING only when freezable(to simplify pwq_adjust_max_active()), > make freeze_workqueues_begin() and thaw_workqueues() fast skip non-freezable wq. > > Changed from previous patches(requested by tj): > 1) added the WARN_ON_ONCE() back > 2) merged the two patches as one Ping. Hi, Tejun You had reviewed this patch several rounds. I had applied all your requests(the last two is listed above) in your comments. I'm deeply sorry for responding so late. Thanks, Lai > > Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com> > --- > include/linux/workqueue.h | 1 + > kernel/workqueue.c | 43 ++++++++++++------------------------------- > 2 files changed, 13 insertions(+), 31 deletions(-) > > diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h > index 704f4f6..a45202b 100644 > --- a/include/linux/workqueue.h > +++ b/include/linux/workqueue.h > @@ -335,6 +335,7 @@ enum { > */ > WQ_POWER_EFFICIENT = 1 << 7, > > + __WQ_FREEZING = 1 << 15, /* internel: workqueue is freezing */ > __WQ_DRAINING = 1 << 16, /* internal: workqueue is draining */ > __WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */ > > diff --git a/kernel/workqueue.c b/kernel/workqueue.c > index 193e977..0c74979 100644 > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -70,7 +70,6 @@ enum { > */ > POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ > POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ > - POOL_FREEZING = 1 << 3, /* freeze in progress */ > > /* worker flags */ > WORKER_STARTED = 1 << 0, /* started */ > @@ -3632,9 +3631,6 @@ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) > if (!pool || init_worker_pool(pool) < 0) > goto fail; > > - if (workqueue_freezing) > - pool->flags |= POOL_FREEZING; > - > lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */ > copy_workqueue_attrs(pool->attrs, attrs); > > @@ -3730,18 +3726,13 @@ static void pwq_unbound_release_workfn(struct work_struct *work) > static void pwq_adjust_max_active(struct pool_workqueue *pwq) > { > struct workqueue_struct *wq = pwq->wq; > - bool freezable = wq->flags & WQ_FREEZABLE; > > - /* for @wq->saved_max_active */ > + /* for @wq->saved_max_active and @wq->flags */ > lockdep_assert_held(&wq->mutex); > > - /* fast exit for non-freezable wqs */ > - if (!freezable && pwq->max_active == wq->saved_max_active) > - return; > - > spin_lock_irq(&pwq->pool->lock); > > - if (!freezable || !(pwq->pool->flags & POOL_FREEZING)) { > + if (!(wq->flags & __WQ_FREEZING)) { > pwq->max_active = wq->saved_max_active; > > while (!list_empty(&pwq->delayed_works) && > @@ -4250,6 +4241,8 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt, > mutex_lock(&wq_pool_mutex); > > mutex_lock(&wq->mutex); > + if ((wq->flags & WQ_FREEZABLE) && workqueue_freezing) > + wq->flags |= __WQ_FREEZING; > for_each_pwq(pwq, wq) > pwq_adjust_max_active(pwq); > mutex_unlock(&wq->mutex); > @@ -4856,26 +4849,20 @@ EXPORT_SYMBOL_GPL(work_on_cpu); > */ > void freeze_workqueues_begin(void) > { > - struct worker_pool *pool; > struct workqueue_struct *wq; > struct pool_workqueue *pwq; > - int pi; > > mutex_lock(&wq_pool_mutex); > > WARN_ON_ONCE(workqueue_freezing); > workqueue_freezing = true; > > - /* set FREEZING */ > - for_each_pool(pool, pi) { > - spin_lock_irq(&pool->lock); > - WARN_ON_ONCE(pool->flags & POOL_FREEZING); > - pool->flags |= POOL_FREEZING; > - spin_unlock_irq(&pool->lock); > - } > - > list_for_each_entry(wq, &workqueues, list) { > + if (!(wq->flags & WQ_FREEZABLE)) > + continue; > mutex_lock(&wq->mutex); > + WARN_ON_ONCE(wq->flags & __WQ_FREEZING); > + wq->flags |= __WQ_FREEZING; > for_each_pwq(pwq, wq) > pwq_adjust_max_active(pwq); > mutex_unlock(&wq->mutex); > @@ -4943,25 +4930,19 @@ void thaw_workqueues(void) > { > struct workqueue_struct *wq; > struct pool_workqueue *pwq; > - struct worker_pool *pool; > - int pi; > > mutex_lock(&wq_pool_mutex); > > if (!workqueue_freezing) > goto out_unlock; > > - /* clear FREEZING */ > - for_each_pool(pool, pi) { > - spin_lock_irq(&pool->lock); > - WARN_ON_ONCE(!(pool->flags & POOL_FREEZING)); > - pool->flags &= ~POOL_FREEZING; > - spin_unlock_irq(&pool->lock); > - } > - > /* restore max_active and repopulate worklist */ > list_for_each_entry(wq, &workqueues, list) { > + if (!(wq->flags & WQ_FREEZABLE)) > + continue; > mutex_lock(&wq->mutex); > + WARN_ON_ONCE(!(wq->flags & __WQ_FREEZING)); > + wq->flags &= ~__WQ_FREEZING; > for_each_pwq(pwq, wq) > pwq_adjust_max_active(pwq); > mutex_unlock(&wq->mutex); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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