workqueue: introduce workqueue_attrs

Introduce struct workqueue_attrs which carries worker attributes -
currently the nice level and allowed cpumask along with helper
routines alloc_workqueue_attrs() and free_workqueue_attrs().

Each worker_pool now carries ->attrs describing the attributes of its
workers.  All functions dealing with cpumask and nice level of workers
are updated to follow worker_pool->attrs instead of determining them
from other characteristics of the worker_pool, and init_workqueues()
is updated to set worker_pool->attrs appropriately for all standard
pools.

Note that create_worker() is updated to always perform set_user_nice()
and use set_cpus_allowed_ptr() combined with manual assertion of
PF_THREAD_BOUND instead of kthread_bind().  This simplifies handling
random attributes without affecting the outcome.

This patch doesn't introduce any behavior changes.

v2: Missing cpumask_var_t definition caused build failure on some
    archs.  linux/cpumask.h included.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 899be6636d20..00c1b9ba8252 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -11,6 +11,7 @@
 #include <linux/lockdep.h>
 #include <linux/threads.h>
 #include <linux/atomic.h>
+#include <linux/cpumask.h>
 
 struct workqueue_struct;
 
@@ -115,6 +116,15 @@ struct delayed_work {
         int cpu;
 };
 
+/*
+ * A struct for workqueue attributes.  This can be used to change
+ * attributes of an unbound workqueue.
+ */
+struct workqueue_attrs {
+        int                     nice;           /* nice level */
+        cpumask_var_t           cpumask;        /* allowed CPUs */
+};
+
 static inline struct delayed_work *to_delayed_work(struct work_struct *work)
 {
         return container_of(work, struct delayed_work, work);
@@ -399,6 +409,9 @@ __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
 
 extern void destroy_workqueue(struct workqueue_struct *wq);
 
+struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask);
+void free_workqueue_attrs(struct workqueue_attrs *attrs);
+
 extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
                         struct work_struct *work);
 extern bool queue_work(struct workqueue_struct *wq, struct work_struct *work);