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Date: Fri, 31 Dec 2021 14:35:31 +0800
From: Menglong Dong <menglong8.dong@...il.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>,
David Ahern <dsahern@...nel.org>, mingo@...hat.com,
David Miller <davem@...emloft.net>,
Neil Horman <nhorman@...driver.com>,
Eric Dumazet <edumazet@...gle.com>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
jonathan.lemon@...il.com, alobakin@...me,
Kees Cook <keescook@...omium.org>,
Paolo Abeni <pabeni@...hat.com>, talalahmad@...gle.com,
haokexin@...il.com, Menglong Dong <imagedong@...cent.com>,
atenart@...nel.org, bigeasy@...utronix.de,
Wei Wang <weiwan@...gle.com>, arnd@...db.de, vvs@...tuozzo.com,
Cong Wang <cong.wang@...edance.com>,
LKML <linux-kernel@...r.kernel.org>,
netdev <netdev@...r.kernel.org>,
Mengen Sun <mengensun@...cent.com>, mungerjiang@...cent.com
Subject: Re: [PATCH v2 net-next 1/3] net: skb: introduce kfree_skb_with_reason()
On Fri, Dec 31, 2021 at 9:26 AM Jakub Kicinski <kuba@...nel.org> wrote:
>
> 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'.
>
I thought about it before, but I'm a little afraid that some users may trace
kfree_skb() with kprobe, making it inline may not be friendly to them?
> > +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 ?
Enn......WOW_MAX? Just kidding, I'll make it 'MAX' (or remove this line,
as it won't be used).
>
> > +
> > +#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
Get it!
Thanks~
Menglong Dong
>
> > /*
> > * 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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