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authorWillem de Bruijn <willemb@google.com>2014-08-04 22:11:47 -0400
committerDavid S. Miller <davem@davemloft.net>2014-08-05 16:35:54 -0700
commit09c2d251b70723650ba47e83571ff49281320f7c (patch)
treeb40d8ab4ed6533a357b885ca6184ab7e86537c22 /net
parentb9f40e21ef4298650ab33e35740fa85bd57706d5 (diff)
downloadlinux-09c2d251b70723650ba47e83571ff49281320f7c.tar.gz
net-timestamp: add key to disambiguate concurrent datagrams
Datagrams timestamped on transmission can coexist in the kernel stack and be reordered in packet scheduling. When reading looped datagrams from the socket error queue it is not always possible to unique correlate looped data with original send() call (for application level retransmits). Even if possible, it may be expensive and complex, requiring packet inspection. Introduce a data-independent ID mechanism to associate timestamps with send calls. Pass an ID alongside the timestamp in field ee_data of sock_extended_err. The ID is a simple 32 bit unsigned int that is associated with the socket and incremented on each send() call for which software tx timestamp generation is enabled. The feature is enabled only if SOF_TIMESTAMPING_OPT_ID is set, to avoid changing ee_data for existing applications that expect it 0. The counter is reset each time the flag is reenabled. Reenabling does not change the ID of already submitted data. It is possible to receive out of order IDs if the timestamp stream is not quiesced first. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/skbuff.c2
-rw-r--r--net/core/sock.c3
-rw-r--r--net/ipv4/ip_output.c6
-rw-r--r--net/ipv6/ip6_output.c9
4 files changed, 19 insertions, 1 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index c9f68802e992..0df4f1d14c5a 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3522,6 +3522,8 @@ void skb_tstamp_tx(struct sk_buff *orig_skb,
serr->ee.ee_errno = ENOMSG;
serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
serr->ee.ee_info = SCM_TSTAMP_SND;
+ if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
+ serr->ee.ee_data = skb_shinfo(skb)->tskey;
err = sock_queue_err_skb(sk, skb);
diff --git a/net/core/sock.c b/net/core/sock.c
index 47c9377e14b9..1e0f1c63ad6b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -848,6 +848,9 @@ set_rcvbuf:
ret = -EINVAL;
break;
}
+ if (val & SOF_TIMESTAMPING_OPT_ID &&
+ !(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID))
+ sk->sk_tskey = 0;
sk->sk_tsflags = val;
if (val & SOF_TIMESTAMPING_RX_SOFTWARE)
sock_enable_timestamp(sk,
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index b16556836d66..215af2b155cb 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -855,11 +855,15 @@ static int __ip_append_data(struct sock *sk,
unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
int csummode = CHECKSUM_NONE;
struct rtable *rt = (struct rtable *)cork->dst;
+ u32 tskey = 0;
skb = skb_peek_tail(queue);
exthdrlen = !skb ? rt->dst.header_len : 0;
mtu = cork->fragsize;
+ if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
+ sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
+ tskey = sk->sk_tskey++;
hh_len = LL_RESERVED_SPACE(rt->dst.dev);
@@ -976,6 +980,8 @@ alloc_new_skb:
/* only the initial fragment is time stamped */
skb_shinfo(skb)->tx_flags = cork->tx_flags;
cork->tx_flags = 0;
+ skb_shinfo(skb)->tskey = tskey;
+ tskey = 0;
/*
* Find where to start putting bytes.
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index f5dafe609f8b..315a55d66079 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1157,6 +1157,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
int err;
int offset = 0;
__u8 tx_flags = 0;
+ u32 tskey = 0;
if (flags&MSG_PROBE)
return 0;
@@ -1272,8 +1273,12 @@ emsgsize:
}
}
- if (sk->sk_type == SOCK_DGRAM || sk->sk_type == SOCK_RAW)
+ if (sk->sk_type == SOCK_DGRAM || sk->sk_type == SOCK_RAW) {
sock_tx_timestamp(sk, &tx_flags);
+ if (tx_flags & SKBTX_ANY_SW_TSTAMP &&
+ sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
+ tskey = sk->sk_tskey++;
+ }
/*
* Let's try using as much space as possible.
@@ -1397,6 +1402,8 @@ alloc_new_skb:
/* Only the initial fragment is time stamped */
skb_shinfo(skb)->tx_flags = tx_flags;
tx_flags = 0;
+ skb_shinfo(skb)->tskey = tskey;
+ tskey = 0;
/*
* Find where to start putting bytes