From 983e0e4e87bdf465e8424b1902e41bfe51ba128a Mon Sep 17 00:00:00 2001 From: Pauli Virtanen Date: Tue, 18 Mar 2025 21:06:42 +0200 Subject: [PATCH] net-timestamp: COMPLETION timestamp on packet tx completion Add SOF_TIMESTAMPING_TX_COMPLETION, for requesting a software timestamp when hardware reports a packet completed. Completion tstamp is useful for Bluetooth, as hardware timestamps do not exist in the HCI specification except for ISO packets, and the hardware has a queue where packets may wait. In this case the software SND timestamp only reflects the kernel-side part of the total latency (usually small) and queue length (usually 0 unless HW buffers congested), whereas the completion report time is more informative of the true latency. It may also be useful in other cases where HW TX timestamps cannot be obtained and user wants to estimate an upper bound to when the TX probably happened. Signed-off-by: Pauli Virtanen Reviewed-by: Willem de Bruijn Signed-off-by: Luiz Augusto von Dentz --- Documentation/networking/timestamping.rst | 8 ++++++++ include/linux/skbuff.h | 7 ++++--- include/uapi/linux/errqueue.h | 1 + include/uapi/linux/net_tstamp.h | 6 ++++-- net/core/skbuff.c | 2 ++ net/ethtool/common.c | 1 + net/socket.c | 3 +++ 7 files changed, 23 insertions(+), 5 deletions(-) diff --git a/Documentation/networking/timestamping.rst b/Documentation/networking/timestamping.rst index 61ef9da10e284..b8fef8101176d 100644 --- a/Documentation/networking/timestamping.rst +++ b/Documentation/networking/timestamping.rst @@ -140,6 +140,14 @@ SOF_TIMESTAMPING_TX_ACK: cumulative acknowledgment. The mechanism ignores SACK and FACK. This flag can be enabled via both socket options and control messages. +SOF_TIMESTAMPING_TX_COMPLETION: + Request tx timestamps on packet tx completion. The completion + timestamp is generated by the kernel when it receives packet a + completion report from the hardware. Hardware may report multiple + packets at once, and completion timestamps reflect the timing of the + report and not actual tx time. This flag can be enabled via both + socket options and control messages. + 1.3.2 Timestamp Reporting ^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index cd8294cdc2496..b974a277975a8 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -478,8 +478,8 @@ enum { /* device driver is going to provide hardware time stamp */ SKBTX_IN_PROGRESS = 1 << 2, - /* reserved */ - SKBTX_RESERVED = 1 << 3, + /* generate software time stamp on packet tx completion */ + SKBTX_COMPLETION_TSTAMP = 1 << 3, /* generate wifi status information (where possible) */ SKBTX_WIFI_STATUS = 1 << 4, @@ -498,7 +498,8 @@ enum { #define SKBTX_ANY_SW_TSTAMP (SKBTX_SW_TSTAMP | \ SKBTX_SCHED_TSTAMP | \ - SKBTX_BPF) + SKBTX_BPF | \ + SKBTX_COMPLETION_TSTAMP) #define SKBTX_ANY_TSTAMP (SKBTX_HW_TSTAMP | \ SKBTX_ANY_SW_TSTAMP) diff --git a/include/uapi/linux/errqueue.h b/include/uapi/linux/errqueue.h index 3c70e8ac14b8d..1ea47309d7726 100644 --- a/include/uapi/linux/errqueue.h +++ b/include/uapi/linux/errqueue.h @@ -73,6 +73,7 @@ enum { SCM_TSTAMP_SND, /* driver passed skb to NIC, or HW */ SCM_TSTAMP_SCHED, /* data entered the packet scheduler */ SCM_TSTAMP_ACK, /* data acknowledged by peer */ + SCM_TSTAMP_COMPLETION, /* packet tx completion */ }; #endif /* _UAPI_LINUX_ERRQUEUE_H */ diff --git a/include/uapi/linux/net_tstamp.h b/include/uapi/linux/net_tstamp.h index 55b0ab51096c1..383213de612a8 100644 --- a/include/uapi/linux/net_tstamp.h +++ b/include/uapi/linux/net_tstamp.h @@ -44,8 +44,9 @@ enum { SOF_TIMESTAMPING_BIND_PHC = (1 << 15), SOF_TIMESTAMPING_OPT_ID_TCP = (1 << 16), SOF_TIMESTAMPING_OPT_RX_FILTER = (1 << 17), + SOF_TIMESTAMPING_TX_COMPLETION = (1 << 18), - SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_RX_FILTER, + SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_TX_COMPLETION, SOF_TIMESTAMPING_MASK = (SOF_TIMESTAMPING_LAST - 1) | SOF_TIMESTAMPING_LAST }; @@ -58,7 +59,8 @@ enum { #define SOF_TIMESTAMPING_TX_RECORD_MASK (SOF_TIMESTAMPING_TX_HARDWARE | \ SOF_TIMESTAMPING_TX_SOFTWARE | \ SOF_TIMESTAMPING_TX_SCHED | \ - SOF_TIMESTAMPING_TX_ACK) + SOF_TIMESTAMPING_TX_ACK | \ + SOF_TIMESTAMPING_TX_COMPLETION) /** * struct so_timestamping - SO_TIMESTAMPING parameter diff --git a/net/core/skbuff.c b/net/core/skbuff.c index ab8acb737b932..6cbf77bc61fce 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -5523,6 +5523,8 @@ static bool skb_tstamp_tx_report_so_timestamping(struct sk_buff *skb, SKBTX_SW_TSTAMP); case SCM_TSTAMP_ACK: return TCP_SKB_CB(skb)->txstamp_ack & TSTAMP_ACK_SK; + case SCM_TSTAMP_COMPLETION: + return skb_shinfo(skb)->tx_flags & SKBTX_COMPLETION_TSTAMP; } return false; diff --git a/net/ethtool/common.c b/net/ethtool/common.c index 7e3c16856c1a8..0cb6da1f692a0 100644 --- a/net/ethtool/common.c +++ b/net/ethtool/common.c @@ -476,6 +476,7 @@ const char sof_timestamping_names[][ETH_GSTRING_LEN] = { [const_ilog2(SOF_TIMESTAMPING_BIND_PHC)] = "bind-phc", [const_ilog2(SOF_TIMESTAMPING_OPT_ID_TCP)] = "option-id-tcp", [const_ilog2(SOF_TIMESTAMPING_OPT_RX_FILTER)] = "option-rx-filter", + [const_ilog2(SOF_TIMESTAMPING_TX_COMPLETION)] = "tx-completion", }; static_assert(ARRAY_SIZE(sof_timestamping_names) == __SOF_TIMESTAMPING_CNT); diff --git a/net/socket.c b/net/socket.c index b64ecf2722e7b..e3d879b532781 100644 --- a/net/socket.c +++ b/net/socket.c @@ -689,6 +689,9 @@ void __sock_tx_timestamp(__u32 tsflags, __u8 *tx_flags) if (tsflags & SOF_TIMESTAMPING_TX_SCHED) flags |= SKBTX_SCHED_TSTAMP; + if (tsflags & SOF_TIMESTAMPING_TX_COMPLETION) + flags |= SKBTX_COMPLETION_TSTAMP; + *tx_flags = flags; } EXPORT_SYMBOL(__sock_tx_timestamp);