Commit fb286bb2 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

[NET]: Detect hardware rx checksum faults correctly 



Here is the patch that introduces the generic skb_checksum_complete
which also checks for hardware RX checksum faults.  If that happens,
it'll call netdev_rx_csum_fault which currently prints out a stack
trace with the device name.  In future it can turn off RX checksum.

I've converted every spot under net/ that does RX checksum checks to
use skb_checksum_complete or __skb_checksum_complete with the
exceptions of:

* Those places where checksums are done bit by bit.  These will call
netdev_rx_csum_fault directly.

* The following have not been completely checked/converted:

ipmr
ip_vs
netfilter
dccp

This patch is based on patches and suggestions from Stephen Hemminger
and David S. Miller.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1064e944

include/linux/netdevice.h

+7 −0
Original line number Diff line number Diff line
@@ -927,6 +927,13 @@ extern int netdev_max_backlog; 
extern int		weight_p;

extern int		netdev_set_master(struct net_device *dev, struct net_device *master);

extern int skb_checksum_help(struct sk_buff *skb, int inward);

#ifdef CONFIG_BUG

extern void netdev_rx_csum_fault(struct net_device *dev);

#else

static inline void netdev_rx_csum_fault(struct net_device *dev)

{

}

#endif

/* rx skb timestamps */

extern void		net_enable_timestamp(void);

extern void		net_disable_timestamp(void);

include/linux/skbuff.h

+25 −2
Original line number Diff line number Diff line
@@ -1236,8 +1236,7 @@ extern unsigned int datagram_poll(struct file *file, struct socket *sock, 
extern int	       skb_copy_datagram_iovec(const struct sk_buff *from,

					       int offset, struct iovec *to,

					       int size);

extern int	       skb_copy_and_csum_datagram_iovec(const

							struct sk_buff *skb,

extern int	       skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,

							int hlen,

							struct iovec *iov);

extern void	       skb_free_datagram(struct sock *sk, struct sk_buff *skb);
@@ -1305,6 +1304,30 @@ static inline void skb_set_timestamp(struct sk_buff *skb, const struct timeval * 


extern void __net_timestamp(struct sk_buff *skb);



extern unsigned int __skb_checksum_complete(struct sk_buff *skb);



/**

 *	skb_checksum_complete - Calculate checksum of an entire packet

 *	@skb: packet to process

 *

 *	This function calculates the checksum over the entire packet plus

 *	the value of skb->csum.  The latter can be used to supply the

 *	checksum of a pseudo header as used by TCP/UDP.  It returns the

 *	checksum.

 *

 *	For protocols that contain complete checksums such as ICMP/TCP/UDP,

 *	this function can be used to verify that checksum on received

 *	packets.  In that case the function should return zero if the

 *	checksum is correct.  In particular, this function will return zero

 *	if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the

 *	hardware has already verified the correctness of the checksum.

 */

static inline unsigned int skb_checksum_complete(struct sk_buff *skb)

{

	return skb->ip_summed != CHECKSUM_UNNECESSARY &&

		__skb_checksum_complete(skb);

}



#ifdef CONFIG_NETFILTER

static inline void nf_conntrack_put(struct nf_conntrack *nfct)

{

include/net/tcp.h

+2 −1
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <linux/slab.h>

#include <linux/cache.h>

#include <linux/percpu.h>

#include <linux/skbuff.h>



#include <net/inet_connection_sock.h>

#include <net/inet_timewait_sock.h>
@@ -852,7 +853,7 @@ static __inline__ u16 tcp_v4_check(struct tcphdr *th, int len, 


static __inline__ int __tcp_checksum_complete(struct sk_buff *skb)

{

	return (unsigned short)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum));

	return __skb_checksum_complete(skb);

}



static __inline__ int tcp_checksum_complete(struct sk_buff *skb)

net/core/datagram.c

+18 −3
Original line number Diff line number Diff line
@@ -350,6 +350,20 @@ fault: 
	return -EFAULT;

}



unsigned int __skb_checksum_complete(struct sk_buff *skb)

{

	unsigned int sum;



	sum = (u16)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum));

	if (likely(!sum)) {

		if (unlikely(skb->ip_summed == CHECKSUM_HW))

			netdev_rx_csum_fault(skb->dev);

		skb->ip_summed = CHECKSUM_UNNECESSARY;

	}

	return sum;

}

EXPORT_SYMBOL(__skb_checksum_complete);



/**

 *	skb_copy_and_csum_datagram_iovec - Copy and checkum skb to user iovec.

 *	@skb: skbuff
@@ -363,7 +377,7 @@ fault: 
 *		 -EFAULT - fault during copy. Beware, in this case iovec

 *			   can be modified!

 */

int skb_copy_and_csum_datagram_iovec(const struct sk_buff *skb,

int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,

				     int hlen, struct iovec *iov)

{

	unsigned int csum;
@@ -376,8 +390,7 @@ int skb_copy_and_csum_datagram_iovec(const struct sk_buff *skb, 
		iov++;



	if (iov->iov_len < chunk) {

		if ((unsigned short)csum_fold(skb_checksum(skb, 0, chunk + hlen,

							   skb->csum)))

		if (__skb_checksum_complete(skb))

			goto csum_error;

		if (skb_copy_datagram_iovec(skb, hlen, iov, chunk))

			goto fault;
@@ -388,6 +401,8 @@ int skb_copy_and_csum_datagram_iovec(const struct sk_buff *skb, 
			goto fault;

		if ((unsigned short)csum_fold(csum))

			goto csum_error;

		if (unlikely(skb->ip_summed == CHECKSUM_HW))

			netdev_rx_csum_fault(skb->dev);

		iov->iov_len -= chunk;

		iov->iov_base += chunk;

	}

net/core/dev.c

+12 −0
Original line number Diff line number Diff line
@@ -1108,6 +1108,18 @@ out: 
	return ret;

}



/* Take action when hardware reception checksum errors are detected. */

#ifdef CONFIG_BUG

void netdev_rx_csum_fault(struct net_device *dev)

{

	if (net_ratelimit()) {

		printk(KERN_ERR "%s: hw csum failure.\n", dev->name);

		dump_stack();

	}

}

EXPORT_SYMBOL(netdev_rx_csum_fault);

#endif



#ifdef CONFIG_HIGHMEM

/* Actually, we should eliminate this check as soon as we know, that:

 * 1. IOMMU is present and allows to map all the memory.

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