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Message-ID: <20211230172619.40603ff3@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net>
Date: Thu, 30 Dec 2021 17:26:19 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: menglong8.dong@...il.com
Cc: rostedt@...dmis.org, dsahern@...nel.org, mingo@...hat.com,
davem@...emloft.net, nhorman@...driver.com, edumazet@...gle.com,
yoshfuji@...ux-ipv6.org, jonathan.lemon@...il.com, alobakin@...me,
keescook@...omium.org, pabeni@...hat.com, talalahmad@...gle.com,
haokexin@...il.com, imagedong@...cent.com, atenart@...nel.org,
bigeasy@...utronix.de, weiwan@...gle.com, arnd@...db.de,
vvs@...tuozzo.com, cong.wang@...edance.com,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
mengensun@...cent.com, mungerjiang@...cent.com
Subject: Re: [PATCH v2 net-next 1/3] net: skb: introduce
kfree_skb_with_reason()
On Thu, 30 Dec 2021 17:32:38 +0800 menglong8.dong@...il.com wrote:
> From: Menglong Dong <imagedong@...cent.com>
>
> Introduce the interface kfree_skb_with_reason(), which is used to pass
> the reason why the skb is dropped to 'kfree_skb' tracepoint.
>
> Add the 'reason' field to 'trace_kfree_skb', therefor user can get
> more detail information about abnormal skb with 'drop_monitor' or
> eBPF.
> void skb_release_head_state(struct sk_buff *skb);
> void kfree_skb(struct sk_buff *skb);
Should this be turned into a static inline calling
kfree_skb_with_reason() now? BTW you should drop the
'_with'.
> +void kfree_skb_with_reason(struct sk_buff *skb,
> + enum skb_drop_reason reason);
continuation line is unaligned, please try checkpatch
> void kfree_skb_list(struct sk_buff *segs);
> void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt);
> void skb_tx_error(struct sk_buff *skb);
> diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
> index 9e92f22eb086..cab1c08a30cd 100644
> --- a/include/trace/events/skb.h
> +++ b/include/trace/events/skb.h
> @@ -9,29 +9,51 @@
> #include <linux/netdevice.h>
> #include <linux/tracepoint.h>
>
> +#define TRACE_SKB_DROP_REASON \
> + EM(SKB_DROP_REASON_NOT_SPECIFIED, NOT_SPECIFIED) \
> + EMe(SKB_DROP_REASON_MAX, HAHA_MAX)
HAHA_MAX ?
> +
> +#undef EM
> +#undef EMe
> +
> +#define EM(a, b) TRACE_DEFINE_ENUM(a);
> +#define EMe(a, b) TRACE_DEFINE_ENUM(a);
> +
> +TRACE_SKB_DROP_REASON
> +
> +#undef EM
> +#undef EMe
> +#define EM(a, b) { a, #b },
> +#define EMe(a, b) { a, #b }
> +
> +
double new line
> /*
> * Tracepoint for free an sk_buff:
> */
> TRACE_EVENT(kfree_skb,
>
> - TP_PROTO(struct sk_buff *skb, void *location),
> + TP_PROTO(struct sk_buff *skb, void *location,
> + enum skb_drop_reason reason),
>
> - TP_ARGS(skb, location),
> + TP_ARGS(skb, location, reason),
>
> TP_STRUCT__entry(
> - __field( void *, skbaddr )
> - __field( void *, location )
> - __field( unsigned short, protocol )
> + __field(void *, skbaddr)
> + __field(void *, location)
> + __field(unsigned short, protocol)
> + __field(enum skb_drop_reason, reason)
> ),
>
> TP_fast_assign(
> __entry->skbaddr = skb;
> __entry->location = location;
> __entry->protocol = ntohs(skb->protocol);
> + __entry->reason = reason;
> ),
>
> - TP_printk("skbaddr=%p protocol=%u location=%p",
> - __entry->skbaddr, __entry->protocol, __entry->location)
> + TP_printk("skbaddr=%p protocol=%u location=%p reason: %s",
> + __entry->skbaddr, __entry->protocol, __entry->location,
> + __print_symbolic(__entry->reason, TRACE_SKB_DROP_REASON))
> );
>
> TRACE_EVENT(consume_skb,
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 644b9c8be3a8..9464dbf9e3d6 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -4899,7 +4899,8 @@ static __latent_entropy void net_tx_action(struct softirq_action *h)
> if (likely(get_kfree_skb_cb(skb)->reason == SKB_REASON_CONSUMED))
> trace_consume_skb(skb);
> else
> - trace_kfree_skb(skb, net_tx_action);
> + trace_kfree_skb(skb, net_tx_action,
> + SKB_DROP_REASON_NOT_SPECIFIED);
>
> if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
> __kfree_skb(skb);
> diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
> index 3d0ab2eec916..7b288a121a41 100644
> --- a/net/core/drop_monitor.c
> +++ b/net/core/drop_monitor.c
> @@ -110,7 +110,8 @@ static u32 net_dm_queue_len = 1000;
>
> struct net_dm_alert_ops {
> void (*kfree_skb_probe)(void *ignore, struct sk_buff *skb,
> - void *location);
> + void *location,
> + enum skb_drop_reason reason);
> void (*napi_poll_probe)(void *ignore, struct napi_struct *napi,
> int work, int budget);
> void (*work_item_func)(struct work_struct *work);
> @@ -262,7 +263,9 @@ static void trace_drop_common(struct sk_buff *skb, void *location)
> spin_unlock_irqrestore(&data->lock, flags);
> }
>
> -static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location)
> +static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb,
> + void *location,
> + enum skb_drop_reason reason)
> {
> trace_drop_common(skb, location);
> }
> @@ -490,7 +493,8 @@ static const struct net_dm_alert_ops net_dm_alert_summary_ops = {
>
> static void net_dm_packet_trace_kfree_skb_hit(void *ignore,
> struct sk_buff *skb,
> - void *location)
> + void *location,
> + enum skb_drop_reason reason)
> {
> ktime_t tstamp = ktime_get_real();
> struct per_cpu_dm_data *data;
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 275f7b8416fe..570dc022a8a1 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -770,11 +770,31 @@ void kfree_skb(struct sk_buff *skb)
> if (!skb_unref(skb))
> return;
>
> - trace_kfree_skb(skb, __builtin_return_address(0));
> + trace_kfree_skb(skb, __builtin_return_address(0),
> + SKB_DROP_REASON_NOT_SPECIFIED);
> __kfree_skb(skb);
> }
> EXPORT_SYMBOL(kfree_skb);
>
> +/**
> + * kfree_skb_with_reason - free an sk_buff with reason
> + * @skb: buffer to free
> + * @reason: reason why this skb is dropped
> + *
> + * The same as kfree_skb() except that this function will pass
> + * the drop reason to 'kfree_skb' tracepoint.
> + */
> +void kfree_skb_with_reason(struct sk_buff *skb,
> + enum skb_drop_reason reason)
> +{
> + if (!skb_unref(skb))
> + return;
> +
> + trace_kfree_skb(skb, __builtin_return_address(0), reason);
> + __kfree_skb(skb);
> +}
> +EXPORT_SYMBOL(kfree_skb_with_reason);
> +
> void kfree_skb_list(struct sk_buff *segs)
> {
> while (segs) {
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