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Commit d9452e9f authored by David S. Miller's avatar David S. Miller
Browse files

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



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

This reverts 33f807ba ("[NETPOLL]:
Kill NETPOLL_RX_DROP, set but never tested.")  and
c7b6ea24 ("[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: default avatarDavid S. Miller <davem@davemloft.net>
parent ec9b6add

include/linux/netpoll.h

+4 −3
Original line number Diff line number Diff line
@@ -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);

net/core/netpoll.c

+8 −4
Original line number Diff line number Diff line
@@ -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);

			}