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authorEric Dumazet <edumazet@google.com>2012-07-29 23:20:37 +0000
committerDavid S. Miller <davem@davemloft.net>2012-07-30 14:53:22 -0700
commit404e0a8b6a55d5e1cd138c6deb1bca9abdf75d8c (patch)
tree38e9748d38c415cc97b973fecb9279cd43f76393 /net/ipv4/fib_semantics.c
parentcca32e4bf999a34ac08d959f351f2b30bcd02460 (diff)
downloadop-kernel-dev-404e0a8b6a55d5e1cd138c6deb1bca9abdf75d8c.zip
op-kernel-dev-404e0a8b6a55d5e1cd138c6deb1bca9abdf75d8c.tar.gz
net: ipv4: fix RCU races on dst refcounts
commit c6cffba4ffa2 (ipv4: Fix input route performance regression.) added various fatal races with dst refcounts. crashes happen on tcp workloads if routes are added/deleted at the same time. The dst_free() calls from free_fib_info_rcu() are clearly racy. We need instead regular dst refcounting (dst_release()) and make sure dst_release() is aware of RCU grace periods : Add DST_RCU_FREE flag so that dst_release() respects an RCU grace period before dst destruction for cached dst Introduce a new inet_sk_rx_dst_set() helper, using atomic_inc_not_zero() to make sure we dont increase a zero refcount (On a dst currently waiting an rcu grace period before destruction) rt_cache_route() must take a reference on the new cached route, and release it if was not able to install it. With this patch, my machines survive various benchmarks. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/fib_semantics.c')
-rw-r--r--net/ipv4/fib_semantics.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index da0cc2e..e55171f 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -172,9 +172,9 @@ static void free_fib_info_rcu(struct rcu_head *head)
if (nexthop_nh->nh_exceptions)
free_nh_exceptions(nexthop_nh);
if (nexthop_nh->nh_rth_output)
- dst_free(&nexthop_nh->nh_rth_output->dst);
+ dst_release(&nexthop_nh->nh_rth_output->dst);
if (nexthop_nh->nh_rth_input)
- dst_free(&nexthop_nh->nh_rth_input->dst);
+ dst_release(&nexthop_nh->nh_rth_input->dst);
} endfor_nexthops(fi);
release_net(fi->fib_net);
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