[PATCH 1/1] netfilter/jump_label: use HAVE_JUMP_LABEL?

[PATCH 1/1] netfilter/jump_label: use HAVE_JUMP_LABEL?

[Zhouyi Zhou]

CONFIG_JUMP_LABEL doesn't ensure HAVE_JUMP_LABEL, if it
is not the case use maintainers's own mutex to guard
the modification of global values.

Signed-off-by: Zhouyi Zhou <yizhouzhou@ict.ac.cn>
---
 include/linux/netfilter.h |    5 +++--
 net/netfilter/core.c      |    6 +++---
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
index 2077489..83a1952 100644
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -9,6 +9,7 @@
 #include <linux/in6.h>
 #include <linux/wait.h>
 #include <linux/list.h>
+#include <linux/static_key.h>
 #include <uapi/linux/netfilter.h>
 #ifdef CONFIG_NETFILTER
 static inline int NF_DROP_GETERR(int verdict)
@@ -99,8 +100,8 @@ void nf_unregister_sockopt(struct nf_sockopt_ops *reg);
 
 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 
-#if defined(CONFIG_JUMP_LABEL)
-#include <linux/static_key.h>
+#ifdef HAVE_JUMP_LABEL
+
 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 {
diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index a93c97f..024a2e2 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -54,7 +54,7 @@ EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
 struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS] __read_mostly;
 EXPORT_SYMBOL(nf_hooks);
 
-#if defined(CONFIG_JUMP_LABEL)
+#ifdef HAVE_JUMP_LABEL
 struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 EXPORT_SYMBOL(nf_hooks_needed);
 #endif
@@ -72,7 +72,7 @@ int nf_register_hook(struct nf_hook_ops *reg)
 	}
 	list_add_rcu(&reg->list, elem->list.prev);
 	mutex_unlock(&nf_hook_mutex);
-#if defined(CONFIG_JUMP_LABEL)
+#ifdef HAVE_JUMP_LABEL
 	static_key_slow_inc(&nf_hooks_needed[reg->pf][reg->hooknum]);
 #endif
 	return 0;
@@ -84,7 +84,7 @@ void nf_unregister_hook(struct nf_hook_ops *reg)
 	mutex_lock(&nf_hook_mutex);
 	list_del_rcu(&reg->list);
 	mutex_unlock(&nf_hook_mutex);
-#if defined(CONFIG_JUMP_LABEL)
+#ifdef HAVE_JUMP_LABEL
 	static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
 #endif
 	synchronize_net();
-- 
1.7.10.4

Re: [PATCH 1/1] netfilter/jump_label: use HAVE_JUMP_LABEL?

[Florian Westphal]

Zhouyi Zhou <zhouzhouyi@gmail.com> wrote:
> 
> CONFIG_JUMP_LABEL doesn't ensure HAVE_JUMP_LABEL, if it
> is not the case use maintainers's own mutex to guard
> the modification of global values.

I don't understand this patch.

What is the problem you are fixing?

The intent is to only use static_key infrastructure
if user has enabled CONFIG_JUMP_LABEL.

Re: [PATCH 1/1] netfilter/jump_label: use HAVE_JUMP_LABEL?

[Zhouyi Zhou]

Thanks Florian for reviewing

> -----Original Messages-----
> From: "Florian Westphal" <fw@strlen.de>

> 
> Zhouyi Zhou <zhouzhouyi@gmail.com> wrote:
> > 
> > CONFIG_JUMP_LABEL doesn't ensure HAVE_JUMP_LABEL, if it
> > is not the case use maintainers's own mutex to guard
> > the modification of global values.

CONFIG_JUMP_LABEL says the user wants to use jump labels.
But we also need the toolchain to support it.

That is reflected in CC_HAVE_ASM_GOTO=y, and if both are
set then HAVE_JUMP_LABEL is set to true.

> I don't understand this patch.
> 
> What is the problem you are fixing?

There is basically no real problem here.
This patch only tries to make kernel code that using 
static_key infrastructure appears "unified"
> 
> The intent is to only use static_key infrastructure
> if user has enabled CONFIG_JUMP_LABEL.

The other parts of kernel either use #ifdef HAVE_JUMP_LABEL,
or use no "#ifdef" at all(the two exceptions are netfilter 
and powerpc modules which I send patches to both).

Jason has suggested me to make the patches:
https://lkml.org/lkml/2014/8/20/761

"Unified" is the reason, I guess :-)
so rookies like me can have unified examples to follow


 
Cheers
Zhouyi

Re: [PATCH 1/1] netfilter/jump_label: use HAVE_JUMP_LABEL?

[Florian Westphal]

Zhouyi Zhou <yizhouzhou@ict.ac.cn> wrote:
> > > 
> > > CONFIG_JUMP_LABEL doesn't ensure HAVE_JUMP_LABEL, if it
> > > is not the case use maintainers's own mutex to guard
> > > the modification of global values.
> 
> CONFIG_JUMP_LABEL says the user wants to use jump labels.
> But we also need the toolchain to support it.
> 
> That is reflected in CC_HAVE_ASM_GOTO=y, and if both are
> set then HAVE_JUMP_LABEL is set to true.

Please resubmit and update the changelog to reflect this,
e.g. add something like

Use HAVE_JUMP_LABEL as elsewhere in the kernel to ensure
that the toolchain has the required support in addition to
CONFIG_JUMP_LABEL being set.