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>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 477f0f6..0e35b3a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -278,6 +278,7 @@
unsigned short gso_type;
struct sk_buff *frag_list;
struct skb_shared_hwtstamps hwtstamps;
+ u32 tskey;
__be32 ip6_frag_id;
/*
diff --git a/include/net/sock.h b/include/net/sock.h
index a211297..52fe0bc 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -280,6 +280,7 @@
* @sk_timer: sock cleanup timer
* @sk_stamp: time stamp of last packet received
* @sk_tsflags: SO_TIMESTAMPING socket options
+ * @sk_tskey: counter to disambiguate concurrent tstamp requests
* @sk_socket: Identd and reporting IO signals
* @sk_user_data: RPC layer private data
* @sk_frag: cached page frag
@@ -414,6 +415,7 @@
struct timer_list sk_timer;
ktime_t sk_stamp;
u16 sk_tsflags;
+ u32 sk_tskey;
struct socket *sk_socket;
void *sk_user_data;
struct page_frag sk_frag;
diff --git a/include/uapi/linux/net_tstamp.h b/include/uapi/linux/net_tstamp.h
index f53879c..1e861d2 100644
--- a/include/uapi/linux/net_tstamp.h
+++ b/include/uapi/linux/net_tstamp.h
@@ -20,9 +20,11 @@
SOF_TIMESTAMPING_SOFTWARE = (1<<4),
SOF_TIMESTAMPING_SYS_HARDWARE = (1<<5),
SOF_TIMESTAMPING_RAW_HARDWARE = (1<<6),
- SOF_TIMESTAMPING_MASK =
- (SOF_TIMESTAMPING_RAW_HARDWARE - 1) |
- SOF_TIMESTAMPING_RAW_HARDWARE
+ SOF_TIMESTAMPING_OPT_ID = (1<<7),
+
+ SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_ID,
+ SOF_TIMESTAMPING_MASK = (SOF_TIMESTAMPING_LAST - 1) |
+ SOF_TIMESTAMPING_LAST
};
/**