[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>

diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index a0525a1..e3d7959 100644 (file)
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -25,6 +25,7 @@ struct netpoll {
 
 struct netpoll_info {
        atomic_t refcnt;
+       int rx_flags;
        spinlock_t rx_lock;
        struct netpoll *rx_np; /* netpoll that registered an rx_hook */
        struct sk_buff_head arp_tx; /* list of arp requests to reply to */
@@ -50,12 +51,12 @@ static inline int netpoll_rx(struct sk_buff *skb)
        unsigned long flags;
        int ret = 0;
 
-       if (!npinfo || !npinfo->rx_np)
+       if (!npinfo || (!npinfo->rx_np && !npinfo->rx_flags))
                return 0;
 
        spin_lock_irqsave(&npinfo->rx_lock, flags);
-       /* check rx_np again with the lock held */
-       if (npinfo->rx_np && __netpoll_rx(skb))
+       /* check rx_flags again with the lock held */
+       if (npinfo->rx_flags && __netpoll_rx(skb))
                ret = 1;
        spin_unlock_irqrestore(&npinfo->rx_lock, flags);
 

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 6faa128..4b7e756 100644 (file)
--- 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);
                        }