Messages in this thread Patch in this message | | | From | "Paul E. McKenney" <> | Subject | [PATCH tip/core/rcu 4/8] rcu: Remove preemption disabling from expedited CPU selection | Date | Wed, 9 Jan 2019 13:41:38 -0800 |
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It turns out that it is queue_delayed_work_on() rather than queue_work_on() that has difficulties when used concurrently with CPU-hotplug removal operations. It is therefore unnecessary to protect CPU identification and queue_work_on() with preempt_disable().
This commit therefore removes the preempt_disable() and preempt_enable() from sync_rcu_exp_select_cpus(), which has the further benefit of reducing the number of changes that must be maintained in the -rt patchset.
Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Sebastian Siewior <bigeasy@linutronix.de> Suggested-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> --- kernel/rcu/tree_exp.h | 2 -- 1 file changed, 2 deletions(-)
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 928fe5893a57..f42c999f4d2d 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -449,7 +449,6 @@ static void sync_rcu_exp_select_cpus(smp_call_func_t func) continue; } INIT_WORK(&rnp->rew.rew_work, sync_rcu_exp_select_node_cpus); - preempt_disable(); cpu = find_next_bit(&rnp->ffmask, BITS_PER_LONG, -1); /* If all offline, queue the work on an unbound CPU. */ if (unlikely(cpu > rnp->grphi - rnp->grplo)) @@ -457,7 +456,6 @@ static void sync_rcu_exp_select_cpus(smp_call_func_t func) else cpu += rnp->grplo; queue_work_on(cpu, rcu_par_gp_wq, &rnp->rew.rew_work); - preempt_enable(); rnp->exp_need_flush = true; } -- 2.17.1
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