[PATCH v2 4/7] rcu: drop redundant defer_qs_pending clear in irqrestore handler

[Joel Fernandes]

With __note_gp_changes() now clearing defer_qs_pending at every
per-CPU GP advance, the per-irqrestore clear is redundant.  Remove it.

Effect: PENDING now stays set from arming until the next per-CPU GP
advance, future arming attempts on the same CPU within the same GP are
gated by the rcu_read_unlock_special().

This serves both as an optimization (should not need new irq_work again
this GP - for the compounded section case, we detect and clear it there),
and reduces risks of recursion due to clearing too aggressively.

Signed-off-by: Joel Fernandes <joelagnelf@xxxxxxxxxx>
---
 kernel/rcu/tree_plugin.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 2da009dbe64c..bb5f955a06df 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -487,8 +487,6 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags)
 	union rcu_special special;
 
 	rdp = this_cpu_ptr(&rcu_data);
-	if (rdp->defer_qs_pending == DEFER_QS_PENDING)
-		rcu_defer_qs_clear(rdp);
 
 	/*
 	 * If RCU core is waiting for this CPU to exit its critical section,
-- 
2.34.1