[PATCH 06/15] xfrm: add and use xfrm_state_afinfo_get_rcu

[Steffen Klassert]

From: Florian Westphal <f...@strlen.de>

xfrm_init_tempstate is always called from within rcu read side section.
We can thus use a simpler function that doesn't call rcu_read_lock
again.

While at it, also make xfrm_init_tempstate return value void, the
return value was never tested.

A followup patch will replace remaining callers of xfrm_state_get_afinfo
with xfrm_state_afinfo_get_rcu variant and then remove the 'old'
get_afinfo interface.

Signed-off-by: Florian Westphal <f...@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klass...@secunet.com>
---
 include/net/xfrm.h    |  1 +
 net/xfrm/xfrm_state.c | 25 +++++++++++++++----------
 2 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 957d0cc..c52197c 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -343,6 +343,7 @@ struct xfrm_state_afinfo {
 int xfrm_state_register_afinfo(struct xfrm_state_afinfo *afinfo);
 int xfrm_state_unregister_afinfo(struct xfrm_state_afinfo *afinfo);
 struct xfrm_state_afinfo *xfrm_state_get_afinfo(unsigned int family);
+struct xfrm_state_afinfo *xfrm_state_afinfo_get_rcu(unsigned int family);
 
 struct xfrm_input_afinfo {
        unsigned int            family;
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 7830844..b5dad89 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -639,26 +639,23 @@ void xfrm_sad_getinfo(struct net *net, struct 
xfrmk_sadinfo *si)
 }
 EXPORT_SYMBOL(xfrm_sad_getinfo);
 
-static int
+static void
 xfrm_init_tempstate(struct xfrm_state *x, const struct flowi *fl,
                    const struct xfrm_tmpl *tmpl,
                    const xfrm_address_t *daddr, const xfrm_address_t *saddr,
                    unsigned short family)
 {
-       struct xfrm_state_afinfo *afinfo = xfrm_state_get_afinfo(family);
-       if (!afinfo)
-               return -1;
-       afinfo->init_tempsel(&x->sel, fl);
+       struct xfrm_state_afinfo *afinfo = xfrm_state_afinfo_get_rcu(family);
+
+       if (afinfo)
+               afinfo->init_tempsel(&x->sel, fl);
 
        if (family != tmpl->encap_family) {
-               rcu_read_unlock();
-               afinfo = xfrm_state_get_afinfo(tmpl->encap_family);
+               afinfo = xfrm_state_afinfo_get_rcu(tmpl->encap_family);
                if (!afinfo)
-                       return -1;
+                       return;
        }
        afinfo->init_temprop(x, tmpl, daddr, saddr);
-       rcu_read_unlock();
-       return 0;
 }
 
 static struct xfrm_state *__xfrm_state_lookup(struct net *net, u32 mark,
@@ -1966,6 +1963,14 @@ int xfrm_state_unregister_afinfo(struct 
xfrm_state_afinfo *afinfo)
 }
 EXPORT_SYMBOL(xfrm_state_unregister_afinfo);
 
+struct xfrm_state_afinfo *xfrm_state_afinfo_get_rcu(unsigned int family)
+{
+       if (unlikely(family >= NPROTO))
+               return NULL;
+
+       return rcu_dereference(xfrm_state_afinfo[family]);
+}
+
 struct xfrm_state_afinfo *xfrm_state_get_afinfo(unsigned int family)
 {
        struct xfrm_state_afinfo *afinfo;
-- 
1.9.1