netpoll: warning for ndo_start_xmit returns with interrupts enabled

WARN_ONCE for ndo_start_xmit() enable interrupts in netpoll_send_skb(),
because the NETPOLL API requires that interrupts remain disabled in
netpoll_send_skb().

Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 0 deletions

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index df30feb2fc72..1b76eb11deb4 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -319,6 +319,11 @@ static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 
                         udelay(USEC_PER_POLL);
                 }
+
+                WARN_ONCE(!irqs_disabled(),
+                        "netpoll_send_skb(): %s enabled interrupts in poll (%pF)\n",
+                        dev->name, ops->ndo_start_xmit);
+
                 local_irq_restore(flags);
         }