Re: [PATCH v2 tip/core/rcu 07/13] ipv6/ip6_tunnel: Applyrcu_access_pointer() to avoid sparse false positive

[Eric Dumazet]

On Wed, 2013-10-09 at 15:36 -0700, Paul E. McKenney wrote:

> That would work, though it would probably give sparse complaints.

No sparse error here, as I said types are correct and SPARSE_RCU ready :

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 583b77e..28f8495 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -245,7 +245,7 @@ ip6_tnl_unlink(struct ip6_tnl_net *ip6n, struct ip6_tnl *t)
             (iter = rtnl_dereference(*tp)) != NULL;
             tp = &iter->next) {
                if (t == iter) {
-                       rcu_assign_pointer(*tp, t->next);
+                       ACCESS_ONCE(*tp) = t->next;
                        break;
                }
        }

root@edumazet-glaptop:/usr/src/net-next# grep CONFIG_SPARSE_RCU_POINTER .config
CONFIG_SPARSE_RCU_POINTER=y

root@edumazet-glaptop:/usr/src/net-next# make C=2 net/ipv6/ip6_tunnel.o
make[1]: Nothing to be done for `all'.
make[1]: Nothing to be done for `relocs'.
  CHK     include/config/kernel.release
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
  CALL    scripts/checksyscalls.sh
  CHECK   scripts/mod/empty.c
  CHECK   net/ipv6/ip6_tunnel.c


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