| From 0a94efb5acbb6980d7c9ab604372d93cd507e4d8 Mon Sep 17 00:00:00 2001 |
| From: Tejun Heo <tj@kernel.org> |
| Date: Sun, 23 Jul 2017 08:36:15 -0400 |
| Subject: workqueue: implicit ordered attribute should be overridable |
| |
| From: Tejun Heo <tj@kernel.org> |
| |
| commit 0a94efb5acbb6980d7c9ab604372d93cd507e4d8 upstream. |
| |
| 5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1 to be |
| ordered") automatically enabled ordered attribute for unbound |
| workqueues w/ max_active == 1. Because ordered workqueues reject |
| max_active and some attribute changes, this implicit ordered mode |
| broke cases where the user creates an unbound workqueue w/ max_active |
| == 1 and later explicitly changes the related attributes. |
| |
| This patch distinguishes explicit and implicit ordered setting and |
| overrides from attribute changes if implict. |
| |
| Signed-off-by: Tejun Heo <tj@kernel.org> |
| Fixes: 5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered") |
| Cc: Holger Hoffstรคtte <holger@applied-asynchrony.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| include/linux/workqueue.h | 4 +++- |
| kernel/workqueue.c | 13 +++++++++---- |
| 2 files changed, 12 insertions(+), 5 deletions(-) |
| |
| --- a/include/linux/workqueue.h |
| +++ b/include/linux/workqueue.h |
| @@ -311,6 +311,7 @@ enum { |
| |
| __WQ_DRAINING = 1 << 16, /* internal: workqueue is draining */ |
| __WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */ |
| + __WQ_ORDERED_EXPLICIT = 1 << 18, /* internal: alloc_ordered_workqueue() */ |
| |
| WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */ |
| WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */ |
| @@ -408,7 +409,8 @@ __alloc_workqueue_key(const char *fmt, u |
| * Pointer to the allocated workqueue on success, %NULL on failure. |
| */ |
| #define alloc_ordered_workqueue(fmt, flags, args...) \ |
| - alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | (flags), 1, ##args) |
| + alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | \ |
| + __WQ_ORDERED_EXPLICIT | (flags), 1, ##args) |
| |
| #define create_workqueue(name) \ |
| alloc_workqueue("%s", WQ_MEM_RECLAIM, 1, (name)) |
| --- a/kernel/workqueue.c |
| +++ b/kernel/workqueue.c |
| @@ -3647,8 +3647,12 @@ static int apply_workqueue_attrs_locked( |
| return -EINVAL; |
| |
| /* creating multiple pwqs breaks ordering guarantee */ |
| - if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs))) |
| - return -EINVAL; |
| + if (!list_empty(&wq->pwqs)) { |
| + if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) |
| + return -EINVAL; |
| + |
| + wq->flags &= ~__WQ_ORDERED; |
| + } |
| |
| ctx = apply_wqattrs_prepare(wq, attrs); |
| |
| @@ -4032,13 +4036,14 @@ void workqueue_set_max_active(struct wor |
| struct pool_workqueue *pwq; |
| |
| /* disallow meddling with max_active for ordered workqueues */ |
| - if (WARN_ON(wq->flags & __WQ_ORDERED)) |
| + if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) |
| return; |
| |
| max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); |
| |
| mutex_lock(&wq->mutex); |
| |
| + wq->flags &= ~__WQ_ORDERED; |
| wq->saved_max_active = max_active; |
| |
| for_each_pwq(pwq, wq) |
| @@ -5164,7 +5169,7 @@ int workqueue_sysfs_register(struct work |
| * attributes breaks ordering guarantee. Disallow exposing ordered |
| * workqueues. |
| */ |
| - if (WARN_ON(wq->flags & __WQ_ORDERED)) |
| + if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) |
| return -EINVAL; |
| |
| wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); |