From d2bf22865663c260c9eb4ca2cba63dbac9e258f9 Mon Sep 17 00:00:00 2001
From: Jozsef Kadlecsik <kadlec@netfilter.org>
Date: Fri, 1 Nov 2019 15:40:33 +0100
Subject: Fix compatibility support for netlink extended ACK and add
 synchronize_rcu_bh() checking

---
 configure.ac                                            | 13 ++++++++++++-
 kernel/include/linux/netfilter/ipset/ip_set_compat.h.in |  5 +++++
 kernel/net/netfilter/ipset/ip_set_hash_gen.h            |  2 +-
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index 75f43c7..5a0f18a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -581,7 +581,7 @@ fi
 
 AC_MSG_CHECKING([kernel source for netlink extended ACK])
 if test -f $ksourcedir/include/linux/netlink.h && \
-   $AWK '/^extern void netlink_ack\(/,/\)/' $ksourcedir/include/linux/netlink.h | $GREP -q 'const struct netlink_ext_ack'; then
+   $AWK '/void netlink_ack\(/,/\)/' $ksourcedir/include/linux/netlink.h | $GREP -q 'const struct netlink_ext_ack'; then
 	AC_MSG_RESULT(yes)
 	AC_SUBST(HAVE_NETLINK_EXTENDED_ACK, define)
 else
@@ -649,6 +649,17 @@ else
 	AC_SUBST(HAVE_STRSCPY, undef)
 fi
 
+AC_MSG_CHECKING([kernel source for synchronize_rcu_bh() in rcutiny.h and rcupdate.h])
+if test -f $ksourcedir/include/linux/rcupdate.h && \
+   $GREP -q 'static inline void synchronize_rcu_bh' \
+	$ksourcedir/include/linux/rcutiny.h $ksourcedir/include/linux/rcupdate.h; then
+	AC_MSG_RESULT(yes)
+	AC_SUBST(HAVE_SYNCHRONIZE_RCU_BH, define)
+else
+	AC_MSG_RESULT(no)
+	AC_SUBST(HAVE_SYNCHRONIZE_RCU_BH, undef)
+fi
+
 AC_MSG_CHECKING([kernel source for struct net_generic])
 if test -f $ksourcedir/include/net/netns/generic.h && \
    $GREP -q 'struct net_generic' $ksourcedir/include/net/netns/generic.h; then
diff --git a/kernel/include/linux/netfilter/ipset/ip_set_compat.h.in b/kernel/include/linux/netfilter/ipset/ip_set_compat.h.in
index 415104d..5f12ad8 100644
--- a/kernel/include/linux/netfilter/ipset/ip_set_compat.h.in
+++ b/kernel/include/linux/netfilter/ipset/ip_set_compat.h.in
@@ -48,6 +48,7 @@
 #@HAVE_TYPEDEF_SCTP_SCTPHDR_T@ HAVE_TYPEDEF_SCTP_SCTPHDR_T
 #@HAVE_TIMER_SETUP@ HAVE_TIMER_SETUP
 #@HAVE_STRSCPY@ HAVE_STRSCPY
+#@HAVE_SYNCHRONIZE_RCU_BH@ HAVE_SYNCHRONIZE_RCU_BH
 #@HAVE_LOCKDEP_NFNL_IS_HELD@ HAVE_LOCKDEP_NFNL_IS_HELD
 
 #ifdef HAVE_EXPORT_SYMBOL_GPL_IN_MODULE_H
@@ -82,6 +83,10 @@
 #include <linux/version.h>
 #include <linux/netlink.h>
 
+#ifdef HAVE_SYNCHRONIZE_RCU_BH
+#define synchronize_rcu()		synchronize_rcu_bh()
+#endif
+
 #ifndef rcu_dereference_bh
 #define rcu_dereference_bh(p)		rcu_dereference(p)
 #endif
diff --git a/kernel/net/netfilter/ipset/ip_set_hash_gen.h b/kernel/net/netfilter/ipset/ip_set_hash_gen.h
index cc0e754..1767fed 100644
--- a/kernel/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/kernel/net/netfilter/ipset/ip_set_hash_gen.h
@@ -663,7 +663,7 @@ retry:
 	spin_unlock_bh(&set->lock);
 
 	/* Give time to other readers of the set */
-	synchronize_rcu_bh();
+	synchronize_rcu();
 
 	pr_debug("set %s resized from %u (%p) to %u (%p)\n", set->name,
 		 orig->htable_bits, orig, t->htable_bits, t);
-- 
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