linux-kernel - [PATCH rcu 14/14] rxrpc: Use call_rcu_flush() instead of call

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Message-Id: <20221019225144.2500095-14-paulmck@kernel.org>
Date:   Wed, 19 Oct 2022 15:51:44 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com,
        rostedt@...dmis.org,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: [PATCH rcu 14/14] rxrpc: Use call_rcu_flush() instead of call_rcu()

From: "Joel Fernandes (Google)" <joel@...lfernandes.org>

call_rcu() changes to save power may cause slowness. Use the
call_rcu_flush() API instead which reverts to the old behavior.

We find this via inspection that the RCU callback does a wakeup of a
thread. This usually indicates that something is waiting on it. To be
safe, let us use call_rcu_flush() here instead.

Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 net/rxrpc/conn_object.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/rxrpc/conn_object.c b/net/rxrpc/conn_object.c
index 22089e37e97f0..fdcfb509cc443 100644
--- a/net/rxrpc/conn_object.c
+++ b/net/rxrpc/conn_object.c
@@ -253,7 +253,7 @@ void rxrpc_kill_connection(struct rxrpc_connection *conn)
 	 * must carry a ref on the connection to prevent us getting here whilst
 	 * it is queued or running.
 	 */
-	call_rcu(&conn->rcu, rxrpc_destroy_connection);
+	call_rcu_flush(&conn->rcu, rxrpc_destroy_connection);
 }
 
 /*
-- 
2.31.1.189.g2e36527f23