[NETPOLL]: Revert two bogus cleanups that broke netconsole.

Based upon a report by Andrew Morton and code analysis done
by Jarek Poplawski.

This reverts 33f807ba0d9259e7c75c7a2ce8bd2787e5b540c7 ("[NETPOLL]:
Kill NETPOLL_RX_DROP, set but never tested.")  and
c7b6ea24b43afb5749cb704e143df19d70e23dea ("[NETPOLL]: Don't need
rx_flags.").

The rx_flags did get tested for zero vs. non-zero and therefore we do
need those tests and that code which sets NETPOLL_RX_DROP et al.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 4 deletions

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 6faa128a4c8e..4b7e756181c9 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -39,6 +39,8 @@ static struct sk_buff_head skb_pool;
 static atomic_t trapped;
 
 #define USEC_PER_POLL   50
+#define NETPOLL_RX_ENABLED  1
+#define NETPOLL_RX_DROP     2
 
 #define MAX_SKB_SIZE \
                 (MAX_UDP_CHUNK + sizeof(struct udphdr) + \
@@ -126,11 +128,13 @@ static int poll_one_napi(struct netpoll_info *npinfo,
         if (!test_bit(NAPI_STATE_SCHED, &napi->state))
                 return budget;
 
+        npinfo->rx_flags |= NETPOLL_RX_DROP;
         atomic_inc(&trapped);
 
         work = napi->poll(napi, budget);
 
         atomic_dec(&trapped);
+        npinfo->rx_flags &= ~NETPOLL_RX_DROP;
 
         return budget - work;
 }
@@ -472,7 +476,7 @@ int __netpoll_rx(struct sk_buff *skb)
         if (skb->dev->type != ARPHRD_ETHER)
                 goto out;
 
-        /* if receive ARP during middle of NAPI poll, then queue */
+        /* check if netpoll clients need ARP */
         if (skb->protocol == htons(ETH_P_ARP) &&
             atomic_read(&trapped)) {
                 skb_queue_tail(&npi->arp_tx, skb);
@@ -534,9 +538,6 @@ int __netpoll_rx(struct sk_buff *skb)
         return 1;
 
 out:
-        /* If packet received while already in poll then just
-         * silently drop.
-         */
         if (atomic_read(&trapped)) {
                 kfree_skb(skb);
                 return 1;
@@ -675,6 +676,7 @@ int netpoll_setup(struct netpoll *np)
                         goto release;
                 }
 
+                npinfo->rx_flags = 0;
                 npinfo->rx_np = NULL;
 
                 spin_lock_init(&npinfo->rx_lock);
@@ -756,6 +758,7 @@ int netpoll_setup(struct netpoll *np)
 
         if (np->rx_hook) {
                 spin_lock_irqsave(&npinfo->rx_lock, flags);
+                npinfo->rx_flags |= NETPOLL_RX_ENABLED;
                 npinfo->rx_np = np;
                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
         }
@@ -797,6 +800,7 @@ void netpoll_cleanup(struct netpoll *np)
                         if (npinfo->rx_np == np) {
                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
                                 npinfo->rx_np = NULL;
+                                npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
                         }