From: Atsushi Nemoto <[EMAIL PROTECTED]>
This patch is to make netif_receive_skb() robust on NAPI+NETPOLL case.
1. netpoll_send_skb() calls netpoll_poll() with interrupt disabled.
2. netpoll_poll() calls poll_napi().
3. poll_napi() calls dev->poll().
4. dev->poll() (for example rtl8139_poll()) calls rtl8139_rx().
5. rtl8139_rx() calls netif_receive_skb().
6. netif_receive_skb() calls netpoll_rx().
If netpoll_rx() returned 1, no problem. If netpoll_rx() returned 0,
netif_receive_skb() continues to processing the skb with interrupt
disabled. It might cause some problems, for example,
netif_receive_skb() -> deliver_skb() -> arp_rcv() -> arp_process() ->
neigh_lookup() -> read_unlock_bh() -> local_bh_enable() ->
WARN_ON_ONCE(irqs_disabled()).
The patch tries to avoid this by redirecting skb to netif_rx() if
netif_receive_skb() was called from irq context or irq disabled.
Signed-off-by: Atsushi Nemoto <[EMAIL PROTECTED]>
Cc: Jeff Garzik <[EMAIL PROTECTED]>
Cc: Francois Romieu <[EMAIL PROTECTED]>
Cc: "David S. Miller" <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
---
net/core/dev.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff -puN net/core/dev.c~fix-irq-problem-with-napi-netpoll net/core/dev.c
--- a/net/core/dev.c~fix-irq-problem-with-napi-netpoll
+++ a/net/core/dev.c
@@ -1769,8 +1769,15 @@ int netif_receive_skb(struct sk_buff *sk
__be16 type;
/* if we've gotten here through NAPI, check netpoll */
- if (skb->dev->poll && netpoll_rx(skb))
- return NET_RX_DROP;
+#ifdef CONFIG_NET_POLL_CONTROLLER
+ if (skb->dev->poll && skb->dev->poll_controller) {
+ /* NAPI poll might be called in irq context on NETPOLL */
+ if (in_irq() || irqs_disabled())
+ return netif_rx(skb);
+ if (netpoll_rx(skb))
+ return NET_RX_DROP;
+ }
+#endif
if (!skb->tstamp.off_sec)
net_timestamp(skb);
_
-
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