[PATCH v4 1/2] ipvs: add READ_ONCE barrier for ipvs->sysctl_amemthresh

[Alexander Mikhalitsyn]

Cc: Julian Anastasov <j...@ssi.bg>
Cc: Simon Horman <ho...@verge.net.au>
Cc: Pablo Neira Ayuso <pa...@netfilter.org>
Cc: Jozsef Kadlecsik <kad...@netfilter.org>
Cc: Florian Westphal <f...@strlen.de>
Suggested-by: Julian Anastasov <j...@ssi.bg>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalit...@canonical.com>
---
 net/netfilter/ipvs/ip_vs_ctl.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 50b5dbe40eb8..e122fa367b81 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -94,6 +94,7 @@ static void update_defense_level(struct netns_ipvs *ipvs)
 {
        struct sysinfo i;
        int availmem;
+       int amemthresh;
        int nomem;
        int to_change = -1;
 
@@ -105,7 +106,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
        /* si_swapinfo(&i); */
        /* availmem = availmem - (i.totalswap - i.freeswap); */
 
-       nomem = (availmem < ipvs->sysctl_amemthresh);
+       amemthresh = max(READ_ONCE(ipvs->sysctl_amemthresh), 0);
+       nomem = (availmem < amemthresh);
 
        local_bh_disable();
 
@@ -145,9 +147,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
                break;
        case 1:
                if (nomem) {
-                       ipvs->drop_rate = ipvs->drop_counter
-                               = ipvs->sysctl_amemthresh /
-                               (ipvs->sysctl_amemthresh-availmem);
+                       ipvs->drop_counter = amemthresh / (amemthresh - 
availmem);
+                       ipvs->drop_rate = ipvs->drop_counter;
                        ipvs->sysctl_drop_packet = 2;
                } else {
                        ipvs->drop_rate = 0;
@@ -155,9 +156,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
                break;
        case 2:
                if (nomem) {
-                       ipvs->drop_rate = ipvs->drop_counter
-                               = ipvs->sysctl_amemthresh /
-                               (ipvs->sysctl_amemthresh-availmem);
+                       ipvs->drop_counter = amemthresh / (amemthresh - 
availmem);
+                       ipvs->drop_rate = ipvs->drop_counter;
                } else {
                        ipvs->drop_rate = 0;
                        ipvs->sysctl_drop_packet = 1;
-- 
2.34.1