[PATCH] xfrm: replace xfrm_policy_afinfo_lock spinlock with mutex

[PATCH] xfrm: replace xfrm_policy_afinfo_lock spinlock with mutex

[Fan Du]

Signed-off-by: Fan Du <fan.du@windriver.com>
---
 net/xfrm/xfrm_policy.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index e52cab3..27768ba 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -46,7 +46,7 @@ static DEFINE_SPINLOCK(xfrm_policy_sk_bundle_lock);
 static struct dst_entry *xfrm_policy_sk_bundles;
 static DEFINE_RWLOCK(xfrm_policy_lock);
 
-static DEFINE_SPINLOCK(xfrm_policy_afinfo_lock);
+static DEFINE_MUTEX(xfrm_policy_afinfo_lock);
 static struct xfrm_policy_afinfo __rcu *xfrm_policy_afinfo[NPROTO]
 						__read_mostly;
 
@@ -2687,7 +2687,7 @@ int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo)
 		return -EINVAL;
 	if (unlikely(afinfo->family >= NPROTO))
 		return -EAFNOSUPPORT;
-	spin_lock(&xfrm_policy_afinfo_lock);
+	mutex_lock(&xfrm_policy_afinfo_lock);
 	if (unlikely(xfrm_policy_afinfo[afinfo->family] != NULL))
 		err = -ENOBUFS;
 	else {
@@ -2710,7 +2710,7 @@ int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo)
 			afinfo->garbage_collect = xfrm_garbage_collect_deferred;
 		rcu_assign_pointer(xfrm_policy_afinfo[afinfo->family], afinfo);
 	}
-	spin_unlock(&xfrm_policy_afinfo_lock);
+	mutex_unlock(&xfrm_policy_afinfo_lock);
 
 	rtnl_lock();
 	for_each_net(net) {
@@ -2743,7 +2743,7 @@ int xfrm_policy_unregister_afinfo(struct xfrm_policy_afinfo *afinfo)
 		return -EINVAL;
 	if (unlikely(afinfo->family >= NPROTO))
 		return -EAFNOSUPPORT;
-	spin_lock(&xfrm_policy_afinfo_lock);
+	mutex_lock(&xfrm_policy_afinfo_lock);
 	if (likely(xfrm_policy_afinfo[afinfo->family] != NULL)) {
 		if (unlikely(xfrm_policy_afinfo[afinfo->family] != afinfo))
 			err = -EINVAL;
@@ -2751,7 +2751,7 @@ int xfrm_policy_unregister_afinfo(struct xfrm_policy_afinfo *afinfo)
 			RCU_INIT_POINTER(xfrm_policy_afinfo[afinfo->family],
 					 NULL);
 	}
-	spin_unlock(&xfrm_policy_afinfo_lock);
+	mutex_unlock(&xfrm_policy_afinfo_lock);
 	if (!err) {
 		struct dst_ops *dst_ops = afinfo->dst_ops;
 
-- 
1.7.1

Re: [PATCH] xfrm: replace xfrm_policy_afinfo_lock spinlock with mutex

[Cong Wang]

On Thu, 04 Jul 2013 at 06:53 GMT, Fan Du <fan.du@windriver.com> wrote:
> Signed-off-by: Fan Du <fan.du@windriver.com>

Reason?
What problem did you meet?

Re: [PATCH] xfrm: replace xfrm_policy_afinfo_lock spinlock with mutex

[Eric Dumazet]

On Thu, 2013-07-04 at 14:53 +0800, Fan Du wrote:
> Signed-off-by: Fan Du <fan.du@windriver.com>
> ---
>  net/xfrm/xfrm_policy.c |   10 +++++-----
>  1 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
> index e52cab3..27768ba 100644
> --- a/net/xfrm/xfrm_policy.c
> +++ b/net/xfrm/xfrm_policy.c
> @@ -46,7 +46,7 @@ static DEFINE_SPINLOCK(xfrm_policy_sk_bundle_lock);
>  static struct dst_entry *xfrm_policy_sk_bundles;
>  static DEFINE_RWLOCK(xfrm_policy_lock);
>  
> -static DEFINE_SPINLOCK(xfrm_policy_afinfo_lock);
> +static DEFINE_MUTEX(xfrm_policy_afinfo_lock);

Why is it needed, and why is it safe ?

Is it a bug fix ? If answer is no please read : 

http://www.spinics.net/lists/netdev/msg242161.html

This mutex or spinlock is not really needed anyway.

Check commit e0386005ff2a729 for a starting point.
("net: inet_add_protocol() can use cmpxchg()")

But do not send a patch until David reopens net-next.