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Subject[PATCH v1 net 10/16] inetpeer: Fix data-races around sysctl.
Date
While reading sysctl variables, they can be changed concurrently.  So, we
need to add READ_ONCE(). Then we can set lockless variants as the handler
to mark them safe.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
net/ipv4/inetpeer.c | 13 ++++++++-----
net/ipv4/sysctl_net_ipv4.c | 6 +++---
2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index da21dfce24d7..69e1342a9068 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -141,16 +141,19 @@ static void inet_peer_gc(struct inet_peer_base *base,
struct inet_peer *gc_stack[],
unsigned int gc_cnt)
{
+ int i, peer_threshold, peer_maxttl, peer_minttl;
struct inet_peer *p;
__u32 delta, ttl;
- int i;

- if (base->total >= inet_peer_threshold)
+ peer_threshold = READ_ONCE(inet_peer_threshold);
+ peer_maxttl = READ_ONCE(inet_peer_maxttl);
+ peer_minttl = READ_ONCE(inet_peer_minttl);
+
+ if (base->total >= peer_threshold)
ttl = 0; /* be aggressive */
else
- ttl = inet_peer_maxttl
- - (inet_peer_maxttl - inet_peer_minttl) / HZ *
- base->total / inet_peer_threshold * HZ;
+ ttl = peer_maxttl - (peer_maxttl - peer_minttl) / HZ *
+ base->total / peer_threshold * HZ;
for (i = 0; i < gc_cnt; i++) {
p = gc_stack[i];

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index aa5adf136556..eea11218a663 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -483,21 +483,21 @@ static struct ctl_table ipv4_table[] = {
.data = &inet_peer_threshold,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec
+ .proc_handler = proc_dointvec_lockless,
},
{
.procname = "inet_peer_minttl",
.data = &inet_peer_minttl,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec_jiffies,
+ .proc_handler = proc_dointvec_jiffies_lockless,
},
{
.procname = "inet_peer_maxttl",
.data = &inet_peer_maxttl,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec_jiffies,
+ .proc_handler = proc_dointvec_jiffies_lockless,
},
{
.procname = "tcp_mem",
--
2.30.2
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