From f0bdf6d473cf12a488a78422e15aafdfe77cf853 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Sat, 15 Feb 2020 14:52:32 -0800 Subject: [PATCH] rcu: Remove unused ->rcu_read_unlock_special.b.deferred_qs field The ->rcu_read_unlock_special.b.deferred_qs field is set to true in rcu_read_unlock_special() but never set to false. This is not particularly useful, so this commit removes this field. The only possible justification for this field is to ease debugging of RCU deferred quiscent states, but the combination of the other ->rcu_read_unlock_special fields plus ->rcu_blocked_node and of course ->rcu_read_lock_nesting should cover debugging needs. And if this last proves incorrect, this patch can always be reverted, along with the required setting of ->rcu_read_unlock_special.b.deferred_qs to false in rcu_preempt_deferred_qs_irqrestore(). Signed-off-by: Lai Jiangshan Signed-off-by: Paul E. McKenney --- include/linux/sched.h | 2 +- kernel/rcu/tree_plugin.h | 1 - 2 files changed, 1 insertion(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 4418f5cb8324..a4b727f57095 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -613,7 +613,7 @@ union rcu_special { u8 blocked; u8 need_qs; u8 exp_hint; /* Hint for performance. */ - u8 deferred_qs; + u8 pad; /* No garbage from compiler! */ } b; /* Bits. */ u32 s; /* Set of bits. */ }; diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 263c766b9dc1..f31c5992f842 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -634,7 +634,6 @@ static void rcu_read_unlock_special(struct task_struct *t) irq_work_queue_on(&rdp->defer_qs_iw, rdp->cpu); } } - t->rcu_read_unlock_special.b.deferred_qs = true; local_irq_restore(flags); return; } -- 2.39.5