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authorMartin KaFai Lau <kafai@fb.com>2015-08-14 11:05:53 -0700
committerDavid S. Miller <davem@davemloft.net>2015-08-17 14:28:03 -0700
commita73e4195636c17f310b8530643a576f42b82385f (patch)
tree084823d7d514bc015523526b8317ae05db15e629
parentad706862890171e02df1d7391b05599fb676ec18 (diff)
ipv6: Add rt6_make_pcpu_route()
It is a prep work for fixing a potential deadlock when creating a pcpu rt. The current rt6_get_pcpu_route() will also create a pcpu rt if one does not exist. This patch moves the pcpu rt creation logic into another function, rt6_make_pcpu_route(). Signed-off-by: Martin KaFai Lau <kafai@fb.com> CC: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv6/route.c20
1 files changed, 16 insertions, 4 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index c95c3197c186..0a82653efc88 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -993,13 +993,21 @@ static struct rt6_info *ip6_rt_pcpu_alloc(struct rt6_info *rt)
/* It should be called with read_lock_bh(&tb6_lock) acquired */
static struct rt6_info *rt6_get_pcpu_route(struct rt6_info *rt)
{
- struct rt6_info *pcpu_rt, *prev, **p;
+ struct rt6_info *pcpu_rt, **p;
p = this_cpu_ptr(rt->rt6i_pcpu);
pcpu_rt = *p;
- if (pcpu_rt)
- goto done;
+ if (pcpu_rt) {
+ dst_hold(&pcpu_rt->dst);
+ rt6_dst_from_metrics_check(pcpu_rt);
+ }
+ return pcpu_rt;
+}
+
+static struct rt6_info *rt6_make_pcpu_route(struct rt6_info *rt)
+{
+ struct rt6_info *pcpu_rt, *prev, **p;
pcpu_rt = ip6_rt_pcpu_alloc(rt);
if (!pcpu_rt) {
@@ -1009,6 +1017,7 @@ static struct rt6_info *rt6_get_pcpu_route(struct rt6_info *rt)
goto done;
}
+ p = this_cpu_ptr(rt->rt6i_pcpu);
prev = cmpxchg(p, NULL, pcpu_rt);
if (prev) {
/* If someone did it before us, return prev instead */
@@ -1093,8 +1102,11 @@ redo_rt6_select:
rt->dst.lastuse = jiffies;
rt->dst.__use++;
pcpu_rt = rt6_get_pcpu_route(rt);
- read_unlock_bh(&table->tb6_lock);
+ if (!pcpu_rt)
+ pcpu_rt = rt6_make_pcpu_route(rt);
+
+ read_unlock_bh(&table->tb6_lock);
return pcpu_rt;
}
}