Jason Xing wrote:
> From: Jason Xing <kernelxing@xxxxxxxxxxx>
>
> It's a prep for bpf print function later. This patch only puts the
> original generating logic into one function, so that we integrate
> bpf print easily. No functional changes here.
>
> Signed-off-by: Jason Xing <kernelxing@xxxxxxxxxxx>
> ---
> include/linux/skbuff.h | 4 ++--
> net/core/dev.c | 3 +--
> net/core/skbuff.c | 41 +++++++++++++++++++++++++++++++++++------
> 3 files changed, 38 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 58009fa66102..53c6913560e4 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -39,6 +39,7 @@
> #include <net/net_debug.h>
> #include <net/dropreason-core.h>
> #include <net/netmem.h>
> +#include <uapi/linux/errqueue.h>
>
> /**
> * DOC: skb checksums
> @@ -4535,8 +4536,7 @@ void skb_tstamp_tx(struct sk_buff *orig_skb,
> static inline void skb_tx_timestamp(struct sk_buff *skb)
> {
> skb_clone_tx_timestamp(skb);
> - if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP)
> - skb_tstamp_tx(skb, NULL);
> + __skb_tstamp_tx(skb, NULL, NULL, skb->sk, SCM_TSTAMP_SND);
> }
>
> /**
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 45a8c3dd4a64..5d584950564b 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -4350,8 +4350,7 @@ int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev)
> skb_reset_mac_header(skb);
> skb_assert_len(skb);
>
> - if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP))
> - __skb_tstamp_tx(skb, NULL, NULL, skb->sk, SCM_TSTAMP_SCHED);
> + __skb_tstamp_tx(skb, NULL, NULL, skb->sk, SCM_TSTAMP_SCHED);
This adds a function call in the hot path, as __skb_tstamp_tx is
defined in a .c file.
Currently this is only well predicted branch on a likely cache hot
variable.
>
> /* Disable soft irqs for various locks below. Also
> * stops preemption for RCU.
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 6841e61a6bd0..74b840ffaf94 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -5539,10 +5539,10 @@ void skb_complete_tx_timestamp(struct sk_buff *skb,
> }
> EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
>
> -void __skb_tstamp_tx(struct sk_buff *orig_skb,
> - const struct sk_buff *ack_skb,
> - struct skb_shared_hwtstamps *hwtstamps,
> - struct sock *sk, int tstype)
> +static void skb_tstamp_tx_output(struct sk_buff *orig_skb,
> + const struct sk_buff *ack_skb,
> + struct skb_shared_hwtstamps *hwtstamps,
> + struct sock *sk, int tstype)
> {
> struct sk_buff *skb;
> bool tsonly, opt_stats = false;
> @@ -5594,13 +5594,42 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb,
>
> __skb_complete_tx_timestamp(skb, sk, tstype, opt_stats);
> }
> +
> +static bool skb_tstamp_is_set(const struct sk_buff *skb, int tstype)
> +{
> + switch (tstype) {
> + case SCM_TSTAMP_SCHED:
> + if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP))
> + return true;
> + return false;
> + case SCM_TSTAMP_SND:
> + if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP))
> + return true;
Also true for SKBTX_HW_TSTAMP
> + return false;
> + case SCM_TSTAMP_ACK:
> + if (TCP_SKB_CB(skb)->txstamp_ack)
> + return true;
> + return false;
> + }
> +
> + return false;
> +}
> +
> +void __skb_tstamp_tx(struct sk_buff *orig_skb,
> + const struct sk_buff *ack_skb,
> + struct skb_shared_hwtstamps *hwtstamps,
> + struct sock *sk, int tstype)
> +{
> + if (unlikely(skb_tstamp_is_set(orig_skb, tstype)))
> + skb_tstamp_tx_output(orig_skb, ack_skb, hwtstamps, sk, tstype);
> +}
> EXPORT_SYMBOL_GPL(__skb_tstamp_tx);
>
> void skb_tstamp_tx(struct sk_buff *orig_skb,
> struct skb_shared_hwtstamps *hwtstamps)
> {
> - return __skb_tstamp_tx(orig_skb, NULL, hwtstamps, orig_skb->sk,
> - SCM_TSTAMP_SND);
> + return skb_tstamp_tx_output(orig_skb, NULL, hwtstamps, orig_skb->sk,
> + SCM_TSTAMP_SND);
> }
> EXPORT_SYMBOL_GPL(skb_tstamp_tx);
>
> --
> 2.37.3
>
