net: Add a flow_cache_flush_deferred function

flow_cach_flush() might sleep but can be called from
atomic context via the xfrm garbage collector. So add
a flow_cache_flush_deferred() function and use this if
the xfrm garbage colector is invoked from within the
packet path.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Timo Teräs <timo.teras@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 26 insertions, 4 deletions

diff --git a/net/core/flow.c b/net/core/flow.c
index 8ae42de9c79e..e318c7e98042 100644
--- a/net/core/flow.c
+++ b/net/core/flow.c
@@ -358,6 +358,18 @@ void flow_cache_flush(void)
         put_online_cpus();
 }
 
+static void flow_cache_flush_task(struct work_struct *work)
+{
+        flow_cache_flush();
+}
+
+static DECLARE_WORK(flow_cache_flush_work, flow_cache_flush_task);
+
+void flow_cache_flush_deferred(void)
+{
+        schedule_work(&flow_cache_flush_work);
+}
+
 static int __cpuinit flow_cache_cpu_prepare(struct flow_cache *fc, int cpu)
 {
         struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 2118d6446630..9049a5caeb25 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2276,8 +2276,6 @@ static void __xfrm_garbage_collect(struct net *net)
 {
         struct dst_entry *head, *next;
 
-        flow_cache_flush();
-
         spin_lock_bh(&xfrm_policy_sk_bundle_lock);
         head = xfrm_policy_sk_bundles;
         xfrm_policy_sk_bundles = NULL;
@@ -2290,6 +2288,18 @@ static void __xfrm_garbage_collect(struct net *net)
         }
 }
 
+static void xfrm_garbage_collect(struct net *net)
+{
+        flow_cache_flush();
+        __xfrm_garbage_collect(net);
+}
+
+static void xfrm_garbage_collect_deferred(struct net *net)
+{
+        flow_cache_flush_deferred();
+        __xfrm_garbage_collect(net);
+}
+
 static void xfrm_init_pmtu(struct dst_entry *dst)
 {
         do {
@@ -2422,7 +2432,7 @@ int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo)
                 if (likely(dst_ops->neigh_lookup == NULL))
                         dst_ops->neigh_lookup = xfrm_neigh_lookup;
                 if (likely(afinfo->garbage_collect == NULL))
-                        afinfo->garbage_collect = __xfrm_garbage_collect;
+                        afinfo->garbage_collect = xfrm_garbage_collect_deferred;
                 xfrm_policy_afinfo[afinfo->family] = afinfo;
         }
         write_unlock_bh(&xfrm_policy_afinfo_lock);
@@ -2516,7 +2526,7 @@ static int xfrm_dev_event(struct notifier_block *this, unsigned long event, void
 
         switch (event) {
         case NETDEV_DOWN:
-                __xfrm_garbage_collect(dev_net(dev));
+                xfrm_garbage_collect(dev_net(dev));
         }
         return NOTIFY_DONE;
 }