Some functions in the workqueue code uses local_irq_disable() for the
RCU sched critical sections. That is, to make sure updates are done
using synchronize_sched() will synchronize with reader locations.
Unfortunately, local_irq_disable() is not very descriptive of what it
is used to protect, and disables interrupts for locations that do not
require interrupts disabled.
By using rcu_read_lock_sched(), we not only allow interrupts to be disabled
for shorter amounts of time, but also it documents nicely how the critical
section is being protected.
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Index: linux-rt.git/kernel/workqueue.c
===================================================================
--- linux-rt.git.orig/kernel/workqueue.c
+++ linux-rt.git/kernel/workqueue.c
@@ -2766,14 +2766,15 @@ static bool start_flush_work(struct work
might_sleep();
- local_irq_disable();
+ rcu_read_lock_sched();
+
pool = get_work_pool(work);
if (!pool) {
- local_irq_enable();
+ rcu_read_unlock_sched();
return false;
}
- spin_lock(&pool->lock);
+ spin_lock_irq(&pool->lock);
/* see the comment in try_to_grab_pending() with the same code */
pwq = get_work_pwq(work);
if (pwq) {
@@ -2788,6 +2789,7 @@ static bool start_flush_work(struct work
insert_wq_barrier(pwq, barr, work, worker);
spin_unlock_irq(&pool->lock);
+ rcu_read_unlock_sched();
/*
* If @max_active is 1 or rescuer is in use, flushing another work
@@ -2804,6 +2806,7 @@ static bool start_flush_work(struct work
return true;
already_gone:
spin_unlock_irq(&pool->lock);
+ rcu_read_unlock_sched();
return false;
}
@@ -4366,7 +4369,7 @@ unsigned int work_busy(struct work_struc
if (work_pending(work))
ret |= WORK_BUSY_PENDING;
- local_irq_save(flags);
+ rcu_read_lock_sched();
pool = get_work_pool(work);
if (pool) {
spin_lock(&pool->lock);
@@ -4374,7 +4377,7 @@ unsigned int work_busy(struct work_struc
ret |= WORK_BUSY_RUNNING;
spin_unlock(&pool->lock);
}
- local_irq_restore(flags);
+ rcu_read_unlock_sched();
return ret;
}
--
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