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| author | Eric Dumazet <edumazet@google.com> | 2012-07-29 23:20:37 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-07-30 14:53:22 -0700 |
| commit | 404e0a8b6a55d5e1cd138c6deb1bca9abdf75d8c (patch) | |
| tree | 38e9748d38c415cc97b973fecb9279cd43f76393 /net/ipv4/fib_semantics.c | |
| parent | cca32e4bf999a34ac08d959f351f2b30bcd02460 (diff) | |
| download | op-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.c | 4 |
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); |
