path: root/net/ipv4/fib_semantics.c
diff options
authorWei Wang <weiwan@google.com>2017-06-17 10:42:29 -0700
committerDavid S. Miller <davem@davemloft.net>2017-06-17 22:53:59 -0400
commit0830106c53900181d336350581119af09e123bf3 (patch)
tree23954c6a70cb21f051b24492757c4c2a2daa34ac /net/ipv4/fib_semantics.c
parentnet: introduce a new function dst_dev_put() (diff)
ipv4: take dst->__refcnt when caching dst in fib
In IPv4 routing code, fib_nh and fib_nh_exception can hold pointers to struct rtable but they never increment dst->__refcnt. This leads to the need of the dst garbage collector because when user is done with this dst and calls dst_release(), it can only decrement dst->__refcnt and can not free the dst even it sees dst->__refcnt drops from 1 to 0 (unless DST_NOCACHE flag is set) because the routing code might still hold reference to it. And when the routing code tries to delete a route, it has to put the dst to the gc_list if dst->__refcnt is not yet 0 and have a gc thread running periodically to check on dst->__refcnt and finally to free dst when refcnt becomes 0. This patch increments dst->__refcnt when fib_nh/fib_nh_exception holds reference to this dst and properly release the dst when fib_nh/fib_nh_exception has been updated with a new dst. This patch is a preparation in order to fully get rid of dst gc later. Signed-off-by: Wei Wang <weiwan@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/fib_semantics.c')
1 files changed, 4 insertions, 1 deletions
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 2157dc08c407..53b3e9c2da4c 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -152,6 +152,7 @@ static void rt_fibinfo_free(struct rtable __rcu **rtp)
* free_fib_info_rcu()
+ dst_release(&rt->dst);
@@ -194,8 +195,10 @@ static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
struct rtable *rt;
rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
- if (rt)
+ if (rt) {
+ dst_release(&rt->dst);
+ }