Re: [PATCH 3/3] udp: make use of static_key_slow_set_true() interface

[Jason Baron]

On 06/28/2013 11:13 PM, Steven Rostedt wrote:
> On Fri, 2013-06-28 at 22:30 +0000, jbaron@xxxxxxxxxx wrote:
> > Make use of the simpler API.
> Need to make the change log much more descriptive. Never assume someone
> in the future that looks up a change to this file will know about other
> commits that led to this. Each change log should be sufficient to stand
> on its own.
>
> Explain why this patch is needed. And it's not about the use of a
> simpler API.
>
> It actually fixes a real bug.
>
>
> > Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx>
> > ---
> >   net/ipv4/udp.c |    9 ++++-----
> >   net/ipv6/udp.c |    9 ++++-----
> >   2 files changed, 8 insertions(+), 10 deletions(-)
> >
> > diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> > index 0bf5d39..b8d0029 100644
> > --- a/net/ipv4/udp.c
> > +++ b/net/ipv4/udp.c
> > @@ -1421,11 +1421,10 @@ static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> >   
> >   }
> >   
> > -static struct static_key udp_encap_needed __read_mostly;
> > +static struct static_key_boolean udp_encap_needed __read_mostly;
> >   void udp_encap_enable(void)
> >   {
> > -	if (!static_key_enabled(&udp_encap_needed))
> > -		static_key_slow_inc(&udp_encap_needed);
> > +	static_key_slow_set_true(&udp_encap_needed);
> >   }
> >   EXPORT_SYMBOL(udp_encap_enable);
> >   
> > @@ -1450,7 +1449,7 @@ int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> >   		goto drop;
> >   	nf_reset(skb);
> >   
> > -	if (static_key_false(&udp_encap_needed) && up->encap_type) {
> > +	if (static_key_false(&udp_encap_needed.key) && up->encap_type) {
> I wonder if we should add a static_bool_key_false(), because that added
> ".key" is a bit confusing.
>
> -- Steve

Yeah - that is sort of ugly, but it avoids introducing a new branch API 
call. That said, a 'static_bool_key_false()' would probably be a simple 
wrapper function.

-Jason


> >   		int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
> >   
> >   		/*
> > @@ -1773,7 +1772,7 @@ void udp_destroy_sock(struct sock *sk)
> >   	bool slow = lock_sock_fast(sk);
> >   	udp_flush_pending_frames(sk);
> >   	unlock_sock_fast(sk, slow);
> > -	if (static_key_false(&udp_encap_needed) && up->encap_type) {
> > +	if (static_key_false(&udp_encap_needed.key) && up->encap_type) {
> >   		void (*encap_destroy)(struct sock *sk);
> >   		encap_destroy = ACCESS_ONCE(up->encap_destroy);
> >   		if (encap_destroy)
> > diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> > index 42923b1..94a4091 100644
> > --- a/net/ipv6/udp.c
> > +++ b/net/ipv6/udp.c
> > @@ -573,11 +573,10 @@ static __inline__ void udpv6_err(struct sk_buff *skb,
> >   	__udp6_lib_err(skb, opt, type, code, offset, info, &udp_table);
> >   }
> >   
> > -static struct static_key udpv6_encap_needed __read_mostly;
> > +static struct static_key_boolean udpv6_encap_needed __read_mostly;
> >   void udpv6_encap_enable(void)
> >   {
> > -	if (!static_key_enabled(&udpv6_encap_needed))
> > -		static_key_slow_inc(&udpv6_encap_needed);
> > +	static_key_slow_set_true(&udpv6_encap_needed);
> >   }
> >   EXPORT_SYMBOL(udpv6_encap_enable);
> >   
> > @@ -590,7 +589,7 @@ int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> >   	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
> >   		goto drop;
> >   
> > -	if (static_key_false(&udpv6_encap_needed) && up->encap_type) {
> > +	if (static_key_false(&udpv6_encap_needed.key) && up->encap_type) {
> >   		int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
> >   
> >   		/*
> > @@ -1300,7 +1299,7 @@ void udpv6_destroy_sock(struct sock *sk)
> >   	udp_v6_flush_pending_frames(sk);
> >   	release_sock(sk);
> >   
> > -	if (static_key_false(&udpv6_encap_needed) && up->encap_type) {
> > +	if (static_key_false(&udpv6_encap_needed.key) && up->encap_type) {
> >   		void (*encap_destroy)(struct sock *sk);
> >   		encap_destroy = ACCESS_ONCE(up->encap_destroy);
> >   		if (encap_destroy)

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