Current code always set 'Unbound && max_active == 1' workqueues to ordered
implicitly, while this may be not an expected behaviour for some use cases.
E.g some scsi and iscsi workqueues(unbound && max_active = 1) want to be bind
to different cpu so as to get better isolation, but their cpumask can't be
changed because WQ_ORDERED is set implicitly.
This patch adds a flag __WQ_ORDERED_DISABLE and also
create_singlethread_workqueue_noorder() to offer an new option.
Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
---
include/linux/workqueue.h | 4 ++++
kernel/workqueue.c | 4 +++-
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index e48554e..4c86913 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -344,6 +344,7 @@ enum {
__WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */
__WQ_LEGACY = 1 << 18, /* internal: create*_workqueue() */
__WQ_ORDERED_EXPLICIT = 1 << 19, /* internal: alloc_ordered_workqueue() */
+ __WQ_ORDERED_DISABLE = 1 << 20, /* internal: don't set __WQ_ORDERED implicitly */
WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */
WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
@@ -433,6 +434,9 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
#define create_singlethread_workqueue(name) \
alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
+#define create_singlethread_workqueue_noorder(name) \
+ alloc_workqueue("%s", WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | \
+ WQ_UNBOUND | __WQ_ORDERED_DISABLE, 1, (name))
extern void destroy_workqueue(struct workqueue_struct *wq);
struct workqueue_attrs *alloc_workqueue_attrs(void);
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 4e01c44..2167013 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4237,7 +4237,9 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
* on NUMA.
*/
if ((flags & WQ_UNBOUND) && max_active == 1)
- flags |= __WQ_ORDERED;
+ /* the caller may don't want __WQ_ORDERED to be set implicitly. */
+ if (!(flags & __WQ_ORDERED_DISABLE))
+ flags |= __WQ_ORDERED;
/* see the comment above the definition of WQ_POWER_EFFICIENT */
if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
--
2.9.5
