rxrpc: Use call_rcu_flush() instead of call_rcu()

joelagnel · chantra · commit 42cdf96e8171 · 2022-10-19T22:12:38.000-07:00
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) &lt;joel@joelfernandes.org&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
diff --git 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);
 }
 
 /*

Original file line number	Diff line number	Diff line change
`@@ -253,7 +253,7 @@ void rxrpc_kill_connection(struct rxrpc_connection *conn)`
`253`	`253`	`* must carry a ref on the connection to prevent us getting here whilst`
`254`	`254`	`* it is queued or running.`
`255`	`255`	`*/`
`256`		`- call_rcu(&conn->rcu, rxrpc_destroy_connection);`
	`256`	`+ call_rcu_flush(&conn->rcu, rxrpc_destroy_connection);`
`257`	`257`	`}`
`258`	`258`
`259`	`259`	`/*`