linux-kernel - [PATCH] macvlan.c: schedule port->bc

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Date:   Mon, 25 Nov 2019 14:59:03 +0800
From:   Menglong Dong <dong.menglong@....com.cn>
To:     davem@...emloft.net
Cc:     petrm@...lanox.com, jiri@...lanox.com, gustavo@...eddedor.com,
        liuhangbin@...il.com, ap420073@...il.com, jwi@...ux.ibm.com,
        mcroce@...hat.com, tglx@...utronix.de, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, xue.zhihong@....com.cn,
        wang.yi59@....com.cn, jiang.xuexin@....com.cn,
        Menglong Dong <dong.menglong@....com.cn>
Subject: [PATCH] macvlan.c: schedule port->bc_work even if error

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()

Signed-off-by: Menglong Dong <dong.menglong@....com.cn>
---
 drivers/net/macvlan.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 940192c..ef2c4f7 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -359,10 +359,11 @@ static void macvlan_broadcast_enqueue(struct macvlan_port *port,
 	}
 	spin_unlock(&port->bc_queue.lock);

+	schedule_work(&port->bc_work);
+
 	if (err)
 		goto free_nskb;
-
-	schedule_work(&port->bc_work);
+
 	return;

 free_nskb:
-- 
2.11.0