Patchwork [net-next,1/2] xfrm: replace rwlock on xfrm_state_afinfo with rcu

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Submitter Amerigo Wang
Date Jan. 16, 2013, 8:05 a.m.
Message ID <1358323506-19571-1-git-send-email-amwang@redhat.com>
Download mbox | patch
Permalink /patch/212421/
State Awaiting Upstream
Delegated to: David Miller
Headers show

Comments

Amerigo Wang - Jan. 16, 2013, 8:05 a.m.
From: Cong Wang <amwang@redhat.com>

Similar to commit 418a99ac6ad487dc9c42e6b0e85f941af56330f2
(Replace rwlock on xfrm_policy_afinfo with rcu), the rwlock
on xfrm_state_afinfo can be replaced by RCU too.

Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
 net/xfrm/xfrm_state.c |   33 ++++++++++++++++-----------------
 1 files changed, 16 insertions(+), 17 deletions(-)
YOSHIFUJI Hideaki / 吉藤英明 - Jan. 16, 2013, 1:57 p.m.
Cong Wang wrote:
> From: Cong Wang <amwang@redhat.com>
> 
> Similar to commit 418a99ac6ad487dc9c42e6b0e85f941af56330f2
> (Replace rwlock on xfrm_policy_afinfo with rcu), the rwlock
> on xfrm_state_afinfo can be replaced by RCU too.
> 
> Cc: Steffen Klassert <steffen.klassert@secunet.com>
> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> Cc: "David S. Miller" <davem@davemloft.net>
> Signed-off-by: Cong Wang <amwang@redhat.com>
> ---
>  net/xfrm/xfrm_state.c |   33 ++++++++++++++++-----------------
>  1 files changed, 16 insertions(+), 17 deletions(-)
> 
> diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
> index 3459692..f567716 100644
> --- a/net/xfrm/xfrm_state.c
> +++ b/net/xfrm/xfrm_state.c
:
> @@ -173,17 +173,16 @@ static struct xfrm_state_afinfo *xfrm_state_lock_afinfo(unsigned int family)
>  	struct xfrm_state_afinfo *afinfo;
>  	if (unlikely(family >= NPROTO))
>  		return NULL;
> -	write_lock_bh(&xfrm_state_afinfo_lock);
> +	spin_lock_bh(&xfrm_state_afinfo_lock);
>  	afinfo = xfrm_state_afinfo[family];
>  	if (unlikely(!afinfo))
> -		write_unlock_bh(&xfrm_state_afinfo_lock);
> +		spin_unlock_bh(&xfrm_state_afinfo_lock);
>  	return afinfo;
>  }
>  
>  static void xfrm_state_unlock_afinfo(struct xfrm_state_afinfo *afinfo)
> -	__releases(xfrm_state_afinfo_lock)
>  {
> -	write_unlock_bh(&xfrm_state_afinfo_lock);
> +	spin_unlock_bh(&xfrm_state_afinfo_lock);
>  }
>  
>  int xfrm_register_type(const struct xfrm_type *type, unsigned short family)

Why removing __releases() hint?

--yoshfuji

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Amerigo Wang - Jan. 17, 2013, 6:22 a.m.
On Wed, 2013-01-16 at 22:57 +0900, YOSHIFUJI Hideaki wrote:
> Cong Wang wrote:
> >  
> >  static void xfrm_state_unlock_afinfo(struct xfrm_state_afinfo *afinfo)
> > -	__releases(xfrm_state_afinfo_lock)
> >  {
> > -	write_unlock_bh(&xfrm_state_afinfo_lock);
> > +	spin_unlock_bh(&xfrm_state_afinfo_lock);
> >  }
> >  
> >  int xfrm_register_type(const struct xfrm_type *type, unsigned short family)
> 
> Why removing __releases() hint?

There is no __acquires matched:
% git grep __acquires -- net/xfrm 
<nothing output>


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Patch

diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 3459692..f567716 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -158,8 +158,8 @@  out_unlock:
 	mutex_unlock(&hash_resize_mutex);
 }
 
-static DEFINE_RWLOCK(xfrm_state_afinfo_lock);
-static struct xfrm_state_afinfo *xfrm_state_afinfo[NPROTO];
+static DEFINE_SPINLOCK(xfrm_state_afinfo_lock);
+static struct xfrm_state_afinfo __rcu *xfrm_state_afinfo[NPROTO];
 
 static DEFINE_SPINLOCK(xfrm_state_gc_lock);
 
@@ -173,17 +173,16 @@  static struct xfrm_state_afinfo *xfrm_state_lock_afinfo(unsigned int family)
 	struct xfrm_state_afinfo *afinfo;
 	if (unlikely(family >= NPROTO))
 		return NULL;
-	write_lock_bh(&xfrm_state_afinfo_lock);
+	spin_lock_bh(&xfrm_state_afinfo_lock);
 	afinfo = xfrm_state_afinfo[family];
 	if (unlikely(!afinfo))
-		write_unlock_bh(&xfrm_state_afinfo_lock);
+		spin_unlock_bh(&xfrm_state_afinfo_lock);
 	return afinfo;
 }
 
 static void xfrm_state_unlock_afinfo(struct xfrm_state_afinfo *afinfo)
-	__releases(xfrm_state_afinfo_lock)
 {
-	write_unlock_bh(&xfrm_state_afinfo_lock);
+	spin_unlock_bh(&xfrm_state_afinfo_lock);
 }
 
 int xfrm_register_type(const struct xfrm_type *type, unsigned short family)
@@ -1848,12 +1847,12 @@  int xfrm_state_register_afinfo(struct xfrm_state_afinfo *afinfo)
 		return -EINVAL;
 	if (unlikely(afinfo->family >= NPROTO))
 		return -EAFNOSUPPORT;
-	write_lock_bh(&xfrm_state_afinfo_lock);
+	spin_lock_bh(&xfrm_state_afinfo_lock);
 	if (unlikely(xfrm_state_afinfo[afinfo->family] != NULL))
 		err = -ENOBUFS;
 	else
-		xfrm_state_afinfo[afinfo->family] = afinfo;
-	write_unlock_bh(&xfrm_state_afinfo_lock);
+		rcu_assign_pointer(xfrm_state_afinfo[afinfo->family], afinfo);
+	spin_unlock_bh(&xfrm_state_afinfo_lock);
 	return err;
 }
 EXPORT_SYMBOL(xfrm_state_register_afinfo);
@@ -1865,14 +1864,15 @@  int xfrm_state_unregister_afinfo(struct xfrm_state_afinfo *afinfo)
 		return -EINVAL;
 	if (unlikely(afinfo->family >= NPROTO))
 		return -EAFNOSUPPORT;
-	write_lock_bh(&xfrm_state_afinfo_lock);
+	spin_lock_bh(&xfrm_state_afinfo_lock);
 	if (likely(xfrm_state_afinfo[afinfo->family] != NULL)) {
 		if (unlikely(xfrm_state_afinfo[afinfo->family] != afinfo))
 			err = -EINVAL;
 		else
-			xfrm_state_afinfo[afinfo->family] = NULL;
+			RCU_INIT_POINTER(xfrm_state_afinfo[afinfo->family], NULL);
 	}
-	write_unlock_bh(&xfrm_state_afinfo_lock);
+	spin_unlock_bh(&xfrm_state_afinfo_lock);
+	synchronize_rcu();
 	return err;
 }
 EXPORT_SYMBOL(xfrm_state_unregister_afinfo);
@@ -1882,17 +1882,16 @@  static struct xfrm_state_afinfo *xfrm_state_get_afinfo(unsigned int family)
 	struct xfrm_state_afinfo *afinfo;
 	if (unlikely(family >= NPROTO))
 		return NULL;
-	read_lock(&xfrm_state_afinfo_lock);
-	afinfo = xfrm_state_afinfo[family];
+	rcu_read_lock();
+	afinfo = rcu_dereference(xfrm_state_afinfo[family]);
 	if (unlikely(!afinfo))
-		read_unlock(&xfrm_state_afinfo_lock);
+		rcu_read_unlock();
 	return afinfo;
 }
 
 static void xfrm_state_put_afinfo(struct xfrm_state_afinfo *afinfo)
-	__releases(xfrm_state_afinfo_lock)
 {
-	read_unlock(&xfrm_state_afinfo_lock);
+	rcu_read_unlock();
 }
 
 /* Temporarily located here until net/xfrm/xfrm_tunnel.c is created */