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 <[email protected]> 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; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
