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From: Frederic Weisbecker <frederic@kernel.org>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Michal Schmidt <mschmidt@redhat.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Neeraj Upadhyay <neeraj.upadhyay@amd.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Uladzislau Rezki <urezki@gmail.com>,
	Zqiang <qiang.zhang1211@gmail.com>, rcu <rcu@vger.kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>
Subject: [PATCH 7/8] rcu/srcutiny: don't return before reenabling preemption
Date: Wed,  6 Nov 2024 15:59:10 +0100	[thread overview]
Message-ID: <20241106145911.35503-8-frederic@kernel.org> (raw)
In-Reply-To: <20241106145911.35503-1-frederic@kernel.org>

From: Michal Schmidt <mschmidt@redhat.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@kernel.org>
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.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


  parent reply	other threads:[~2024-11-06 14:59 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-11-06 14:59 [PATCH 0/8] RCU fixes for v6.13 Frederic Weisbecker
2024-11-06 14:59 ` [PATCH 1/8] doc: Add rcuog kthreads to kernel-per-CPU-kthreads.rst Frederic Weisbecker
2024-11-06 14:59 ` [PATCH 2/8] rcu: Allow short-circuiting of synchronize_rcu_tasks_rude() Frederic Weisbecker
2024-11-06 14:59 ` [PATCH 3/8] rcu: Permit start_poll_synchronize_rcu*() with interrupts disabled Frederic Weisbecker
2024-11-06 14:59 ` [PATCH 4/8] rcutorture: Test start-poll primitives " Frederic Weisbecker
2024-11-06 14:59 ` [PATCH 5/8] doc: Remove kernel-parameters.txt entry for rcutorture.read_exit Frederic Weisbecker
2024-11-06 14:59 ` [PATCH 6/8] rcu-tasks: Remove open-coded one-byte cmpxchg() emulation Frederic Weisbecker
2024-11-06 14:59 ` Frederic Weisbecker [this message]
2024-11-06 14:59 ` [PATCH 8/8] rcu/kvfree: Fix data-race in __mod_timer / kvfree_call_rcu Frederic Weisbecker
2024-11-11 17:32 ` [PATCH 0/8] RCU fixes for v6.13 Neeraj Upadhyay

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