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Message-Id: <20220501111836.10910-5-gerhard@engleder-embedded.com>
Date: Sun, 1 May 2022 13:18:34 +0200
From: Gerhard Engleder <gerhard@...leder-embedded.com>
To: richardcochran@...il.com, vinicius.gomes@...el.com,
yangbo.lu@....com, davem@...emloft.net, kuba@...nel.org
Cc: mlichvar@...hat.com, netdev@...r.kernel.org,
Gerhard Engleder <gerhard@...leder-embedded.com>
Subject: [PATCH net-next v3 4/6] ptp: Support late timestamp determination
If a physical clock supports a free running cycle counter, then
timestamps shall be based on this time too. For TX it is known in
advance before the transmission if a timestamp based on the free running
cycle counter is needed. For RX it is impossible to know which timestamp
is needed before the packet is received and assigned to a socket.
Support late timestamp determination by a network device. Therefore, an
address/cookie is stored within the new netdev_data field of struct
skb_shared_hwtstamps. This address/cookie is provided to a new network
device function called ndo_get_tstamp(), which returns a timestamp based
on the normal/adjustable time or based on the free running cycle
counter. If function is not supported, then timestamp handling is not
changed.
Signed-off-by: Gerhard Engleder <gerhard@...leder-embedded.com>
---
include/linux/netdevice.h | 21 ++++++++++++++++++++
include/linux/skbuff.h | 16 ++++++++++++---
net/socket.c | 42 +++++++++++++++++++++++++++++----------
3 files changed, 66 insertions(+), 13 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 4aba92a4042a..47dca9adfb17 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1356,6 +1356,12 @@ struct netdev_net_notifier {
* The caller must be under RCU read context.
* int (*ndo_fill_forward_path)(struct net_device_path_ctx *ctx, struct net_device_path *path);
* Get the forwarding path to reach the real device from the HW destination address
+ * ktime_t (*ndo_get_tstamp)(struct net_device *dev,
+ * const struct skb_shared_hwtstamps *hwtstamps,
+ * bool cycles);
+ * Get hardware timestamp based on normal/adjustable time or free running
+ * cycle counter. This function is required if physical clock supports a
+ * free running cycle counter.
*/
struct net_device_ops {
int (*ndo_init)(struct net_device *dev);
@@ -1578,6 +1584,9 @@ struct net_device_ops {
struct net_device * (*ndo_get_peer_dev)(struct net_device *dev);
int (*ndo_fill_forward_path)(struct net_device_path_ctx *ctx,
struct net_device_path *path);
+ ktime_t (*ndo_get_tstamp)(struct net_device *dev,
+ const struct skb_shared_hwtstamps *hwtstamps,
+ bool cycles);
};
/**
@@ -4738,6 +4747,18 @@ static inline void netdev_rx_csum_fault(struct net_device *dev,
void net_enable_timestamp(void);
void net_disable_timestamp(void);
+static inline ktime_t netdev_get_tstamp(struct net_device *dev,
+ const struct skb_shared_hwtstamps *hwtstamps,
+ bool cycles)
+{
+ const struct net_device_ops *ops = dev->netdev_ops;
+
+ if (ops->ndo_get_tstamp)
+ return ops->ndo_get_tstamp(dev, hwtstamps, cycles);
+
+ return hwtstamps->hwtstamp;
+}
+
static inline netdev_tx_t __netdev_start_xmit(const struct net_device_ops *ops,
struct sk_buff *skb, struct net_device *dev,
bool more)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index fa03e02b761d..732b995fe54e 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -588,8 +588,10 @@ static inline bool skb_frag_must_loop(struct page *p)
/**
* struct skb_shared_hwtstamps - hardware time stamps
- * @hwtstamp: hardware time stamp transformed into duration
- * since arbitrary point in time
+ * @hwtstamp: hardware time stamp transformed into duration
+ * since arbitrary point in time
+ * @netdev_data: address/cookie of network device driver used as
+ * reference to actual hardware time stamp
*
* Software time stamps generated by ktime_get_real() are stored in
* skb->tstamp.
@@ -601,7 +603,10 @@ static inline bool skb_frag_must_loop(struct page *p)
* &skb_shared_info. Use skb_hwtstamps() to get a pointer.
*/
struct skb_shared_hwtstamps {
- ktime_t hwtstamp;
+ union {
+ ktime_t hwtstamp;
+ void *netdev_data;
+ };
};
/* Definitions for tx_flags in struct skb_shared_info */
@@ -620,6 +625,11 @@ enum {
*/
SKBTX_HW_TSTAMP_USE_CYCLES = 1 << 3,
+ /* determine hardware time stamp based on time or cycles, flag is used
+ * only for RX path
+ */
+ SKBTX_HW_TSTAMP_NETDEV = 1 << 3,
+
/* generate wifi status information (where possible) */
SKBTX_WIFI_STATUS = 1 << 4,
diff --git a/net/socket.c b/net/socket.c
index 0f680c7d968a..ee81e25e9b98 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -805,7 +805,8 @@ static bool skb_is_swtx_tstamp(const struct sk_buff *skb, int false_tstamp)
return skb->tstamp && !false_tstamp && skb_is_err_queue(skb);
}
-static void put_ts_pktinfo(struct msghdr *msg, struct sk_buff *skb)
+static void put_ts_pktinfo(struct msghdr *msg, struct sk_buff *skb,
+ int if_index)
{
struct scm_ts_pktinfo ts_pktinfo;
struct net_device *orig_dev;
@@ -815,11 +816,15 @@ static void put_ts_pktinfo(struct msghdr *msg, struct sk_buff *skb)
memset(&ts_pktinfo, 0, sizeof(ts_pktinfo));
- rcu_read_lock();
- orig_dev = dev_get_by_napi_id(skb_napi_id(skb));
- if (orig_dev)
- ts_pktinfo.if_index = orig_dev->ifindex;
- rcu_read_unlock();
+ if (if_index == -1) {
+ rcu_read_lock();
+ orig_dev = dev_get_by_napi_id(skb_napi_id(skb));
+ if (orig_dev)
+ ts_pktinfo.if_index = orig_dev->ifindex;
+ rcu_read_unlock();
+ } else {
+ ts_pktinfo.if_index = if_index;
+ }
ts_pktinfo.pkt_length = skb->len - skb_mac_offset(skb);
put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMPING_PKTINFO,
@@ -839,6 +844,8 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
int empty = 1, false_tstamp = 0;
struct skb_shared_hwtstamps *shhwtstamps =
skb_hwtstamps(skb);
+ struct net_device *orig_dev;
+ int if_index = -1;
ktime_t hwtstamp;
/* Race occurred between timestamp enabling and packet
@@ -887,18 +894,33 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
if (shhwtstamps &&
(sk->sk_tsflags & SOF_TIMESTAMPING_RAW_HARDWARE) &&
!skb_is_swtx_tstamp(skb, false_tstamp)) {
+ if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP_NETDEV) {
+ rcu_read_lock();
+ orig_dev = dev_get_by_napi_id(skb_napi_id(skb));
+ if (orig_dev) {
+ if_index = orig_dev->ifindex;
+ hwtstamp = netdev_get_tstamp(orig_dev,
+ shhwtstamps,
+ sk->sk_tsflags &
+ SOF_TIMESTAMPING_BIND_PHC);
+ } else {
+ hwtstamp = shhwtstamps->hwtstamp;
+ }
+ rcu_read_unlock();
+ } else {
+ hwtstamp = shhwtstamps->hwtstamp;
+ }
+
if (sk->sk_tsflags & SOF_TIMESTAMPING_BIND_PHC)
- hwtstamp = ptp_convert_timestamp(&shhwtstamps->hwtstamp,
+ hwtstamp = ptp_convert_timestamp(&hwtstamp,
sk->sk_bind_phc);
- else
- hwtstamp = shhwtstamps->hwtstamp;
if (ktime_to_timespec64_cond(hwtstamp, tss.ts + 2)) {
empty = 0;
if ((sk->sk_tsflags & SOF_TIMESTAMPING_OPT_PKTINFO) &&
!skb_is_err_queue(skb))
- put_ts_pktinfo(msg, skb);
+ put_ts_pktinfo(msg, skb, if_index);
}
}
if (!empty) {
--
2.20.1
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