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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Menglong Dong <dong.menglong@zte.com.cn>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 5.4 17/46] macvlan: schedule bc_work even if error
Date:   Tue,  3 Dec 2019 23:35:37 +0100
Message-Id: <20191203212733.796192448@linuxfoundation.org>
In-Reply-To: <20191203212705.175425505@linuxfoundation.org>
References: <20191203212705.175425505@linuxfoundation.org>
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From: Menglong Dong <dong.menglong@zte.com.cn>

[ Upstream commit 1d7ea55668878bb350979c377fc72509dd6f5b21 ]

While enqueueing a broadcast skb to port->bc_queue, schedule_work()
is called to add port->bc_work, which processes the skbs in
bc_queue, to "events" work queue. If port->bc_queue is full, the
skb will be discarded and schedule_work(&port->bc_work) won't be
called. However, if port->bc_queue is full and port->bc_work is not
running or pending, port->bc_queue will keep full and schedule_work()
won't be called any more, and all broadcast skbs to macvlan will be
discarded. This case can happen:

macvlan_process_broadcast() is the pending function of port->bc_work,
it moves all the skbs in port->bc_queue to the queue "list", and
processes the skbs in "list". During this, new skbs will keep being
added to port->bc_queue in macvlan_broadcast_enqueue(), and
port->bc_queue may already full when macvlan_process_broadcast()
return. This may happen, especially when there are a lot of real-time
threads and the process is preempted.

Fix this by calling schedule_work(&port->bc_work) even if
port->bc_work is full in macvlan_broadcast_enqueue().

Fixes: 412ca1550cbe ("macvlan: Move broadcasts into a work queue")
Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/macvlan.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -359,10 +359,11 @@ static void macvlan_broadcast_enqueue(st
 	}
 	spin_unlock(&port->bc_queue.lock);
 
+	schedule_work(&port->bc_work);
+
 	if (err)
 		goto free_nskb;
 
-	schedule_work(&port->bc_work);
 	return;
 
 free_nskb: