workqueue: replace use of system_wq with system_percpu_wq

Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.

This lack of consistentcy cannot be addressed without refactoring the API.

system_wq is a per-CPU worqueue, yet nothing in its name tells about that
CPU affinity constraint, which is very often not required by users. Make
it clear by adding a system_percpu_wq.

queue_work() / queue_delayed_work() mod_delayed_work() will now use the
new per-cpu wq: whether the user still stick on the old name a warn will
be printed along a wq redirect to the new one.

This patch add the new system_percpu_wq except for mm, fs and net
subsystem, whom are handled in separated patches.

The old wq will be kept for a few release cylces.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index af860e8f848145810e376fd56e86cc9351afdbec..b6834b7aee4bce98fc5d93170bd7031c4dd813dc 100644 (file)
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -434,10 +434,10 @@ enum wq_consts {
  * short queue flush time.  Don't queue works which can run for too
  * long.
  *
- * system_highpri_wq is similar to system_wq but for work items which
+ * system_highpri_wq is similar to system_percpu_wq but for work items which
  * require WQ_HIGHPRI.
  *
- * system_long_wq is similar to system_wq but may host long running
+ * system_long_wq is similar to system_percpu_wq but may host long running
  * works.  Queue flushing might take relatively long.
  *
  * system_dfl_wq is unbound workqueue.  Workers are not bound to
@@ -445,13 +445,13 @@ enum wq_consts {
  * executed immediately as long as max_active limit is not reached and
  * resources are available.
  *
- * system_freezable_wq is equivalent to system_wq except that it's
+ * system_freezable_wq is equivalent to system_percpu_wq except that it's
  * freezable.
  *
  * *_power_efficient_wq are inclined towards saving power and converted
  * into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
  * they are same as their non-power-efficient counterparts - e.g.
- * system_power_efficient_wq is identical to system_wq if
+ * system_power_efficient_wq is identical to system_percpu_wq if
  * 'wq_power_efficient' is disabled.  See WQ_POWER_EFFICIENT for more info.
  *
  * system_bh[_highpri]_wq are convenience interface to softirq. BH work items
@@ -708,7 +708,7 @@ static inline bool mod_delayed_work(struct workqueue_struct *wq,
  */
 static inline bool schedule_work_on(int cpu, struct work_struct *work)
 {
-       return queue_work_on(cpu, system_wq, work);
+       return queue_work_on(cpu, system_percpu_wq, work);
 }
 
 /**
@@ -727,7 +727,7 @@ static inline bool schedule_work_on(int cpu, struct work_struct *work)
  */
 static inline bool schedule_work(struct work_struct *work)
 {
-       return queue_work(system_wq, work);
+       return queue_work(system_percpu_wq, work);
 }
 
 /**
@@ -770,15 +770,15 @@ extern void __warn_flushing_systemwide_wq(void)
 #define flush_scheduled_work()                                         \
 ({                                                                     \
        __warn_flushing_systemwide_wq();                                \
-       __flush_workqueue(system_wq);                                   \
+       __flush_workqueue(system_percpu_wq);                                    \
 })
 
 #define flush_workqueue(wq)                                            \
 ({                                                                     \
        struct workqueue_struct *_wq = (wq);                            \
                                                                        \
-       if ((__builtin_constant_p(_wq == system_wq) &&                  \
-            _wq == system_wq) ||                                       \
+       if ((__builtin_constant_p(_wq == system_percpu_wq) &&                   \
+            _wq == system_percpu_wq) ||                                        \
            (__builtin_constant_p(_wq == system_highpri_wq) &&          \
             _wq == system_highpri_wq) ||                               \
            (__builtin_constant_p(_wq == system_long_wq) &&             \
@@ -807,7 +807,7 @@ extern void __warn_flushing_systemwide_wq(void)
 static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
                                            unsigned long delay)
 {
-       return queue_delayed_work_on(cpu, system_wq, dwork, delay);
+       return queue_delayed_work_on(cpu, system_percpu_wq, dwork, delay);
 }
 
 /**
@@ -821,7 +821,7 @@ static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
 static inline bool schedule_delayed_work(struct delayed_work *dwork,
                                         unsigned long delay)
 {
-       return queue_delayed_work(system_wq, dwork, delay);
+       return queue_delayed_work(system_percpu_wq, dwork, delay);
 }
 
 #ifndef CONFIG_SMP

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 2888f4399acdbdd36edc9a76e859aa9c6591ae77..90db8cf015c2fbafef1137850037f1a2eb5087bd 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -7668,7 +7668,7 @@ static int wq_watchdog_param_set_thresh(const char *val,
        if (ret)
                return ret;
 
-       if (system_wq)
+       if (system_percpu_wq)
                wq_watchdog_set_thresh(thresh);
        else
                wq_watchdog_thresh = thresh;