linux-kernel - [PATCH 7/8] rcu/srcutiny: don't return before reenabling preemption

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Message-ID: <20241106145911.35503-8-frederic@kernel.org>
Date: Wed,  6 Nov 2024 15:59:10 +0100
From: Frederic Weisbecker <frederic@...nel.org>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Michal Schmidt <mschmidt@...hat.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Joel Fernandes <joel@...lfernandes.org>,
	Josh Triplett <josh@...htriplett.org>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Neeraj Upadhyay <neeraj.upadhyay@....com>,
	"Paul E . McKenney" <paulmck@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Zqiang <qiang.zhang1211@...il.com>,
	rcu <rcu@...r.kernel.org>,
	Frederic Weisbecker <frederic@...nel.org>
Subject: [PATCH 7/8] rcu/srcutiny: don't return before reenabling preemption

From: Michal Schmidt <mschmidt@...hat.com>

Code after the return statement is dead. Enable preemption before
returning from srcu_drive_gp().

This will be important when/if PREEMPT_AUTO (lazy resched) gets merged.

Fixes: 65b4a59557f6 ("srcu: Make Tiny SRCU explicitly disable preemption")
Reviewed-by: Paul E. McKenney <paulmck@...nel.org>
Signed-off-by: Michal Schmidt <mschmidt@...hat.com>
Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
---
 kernel/rcu/srcutiny.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c
index 549c03336ee9..4dcbf8aa80ff 100644
--- a/kernel/rcu/srcutiny.c
+++ b/kernel/rcu/srcutiny.c
@@ -122,8 +122,8 @@ void srcu_drive_gp(struct work_struct *wp)
 	ssp = container_of(wp, struct srcu_struct, srcu_work);
 	preempt_disable();  // Needed for PREEMPT_AUTO
 	if (ssp->srcu_gp_running || ULONG_CMP_GE(ssp->srcu_idx, READ_ONCE(ssp->srcu_idx_max))) {
+		preempt_enable();
 		return; /* Already running or nothing to do. */
-		preempt_enable();
 	}
 
 	/* Remove recently arrived callbacks and wait for readers. */
-- 
2.46.0