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mptcp: use WRITE_ONCE/READ_ONCE for the pernet *_max
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This patch uses WRITE_ONCE() and READ_ONCE for all the pernet
add_addr_signal_max, add_addr_accept_max, local_addr_max and
subflows_max fields in struct pm_nl_pernet to avoid concurrency
issues.

Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
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@geliangtang @jenkins-tessares
geliangtang authored and jenkins-tessares committed Jan 21, 2021
1 parent de8c81b commit 38a01ce
Showing 1 changed file with 23 additions and 13 deletions.
36 changes: 23 additions & 13 deletions net/mptcp/pm_netlink.c
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Original file line number Diff line number Diff line change
Expand Up @@ -572,6 +572,7 @@ static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet,
struct mptcp_pm_addr_entry *entry)
{
struct mptcp_pm_addr_entry *cur;
unsigned int addr_max;
int ret = -EINVAL;

spin_lock_bh(&pernet->lock);
Expand Down Expand Up @@ -614,10 +615,14 @@ static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet,
if (entry->addr.id > pernet->next_id)
pernet->next_id = entry->addr.id;

if (entry->addr.flags & MPTCP_PM_ADDR_FLAG_SIGNAL)
pernet->add_addr_signal_max++;
if (entry->addr.flags & MPTCP_PM_ADDR_FLAG_SUBFLOW)
pernet->local_addr_max++;
if (entry->addr.flags & MPTCP_PM_ADDR_FLAG_SIGNAL) {
addr_max = READ_ONCE(pernet->add_addr_signal_max);
WRITE_ONCE(pernet->add_addr_signal_max, addr_max + 1);
}
if (entry->addr.flags & MPTCP_PM_ADDR_FLAG_SUBFLOW) {
addr_max = READ_ONCE(pernet->local_addr_max);
WRITE_ONCE(pernet->local_addr_max, addr_max + 1);
}

pernet->addrs++;
list_add_tail_rcu(&entry->list, &pernet->local_addr_list);
Expand Down Expand Up @@ -912,6 +917,7 @@ static int mptcp_nl_cmd_del_addr(struct sk_buff *skb, struct genl_info *info)
struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_ADDR];
struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
struct mptcp_pm_addr_entry addr, *entry;
unsigned int addr_max;
int ret;

ret = mptcp_pm_parse_addr(attr, info, false, &addr);
Expand All @@ -925,10 +931,14 @@ static int mptcp_nl_cmd_del_addr(struct sk_buff *skb, struct genl_info *info)
spin_unlock_bh(&pernet->lock);
return -EINVAL;
}
if (entry->addr.flags & MPTCP_PM_ADDR_FLAG_SIGNAL)
pernet->add_addr_signal_max--;
if (entry->addr.flags & MPTCP_PM_ADDR_FLAG_SUBFLOW)
pernet->local_addr_max--;
if (entry->addr.flags & MPTCP_PM_ADDR_FLAG_SIGNAL) {
addr_max = READ_ONCE(pernet->add_addr_signal_max);
WRITE_ONCE(pernet->add_addr_signal_max, addr_max - 1);
}
if (entry->addr.flags & MPTCP_PM_ADDR_FLAG_SUBFLOW) {
addr_max = READ_ONCE(pernet->local_addr_max);
WRITE_ONCE(pernet->local_addr_max, addr_max - 1);
}

pernet->addrs--;
list_del_rcu(&entry->list);
Expand Down Expand Up @@ -956,9 +966,9 @@ static void __flush_addrs(struct net *net, struct list_head *list)

static void __reset_counters(struct pm_nl_pernet *pernet)
{
pernet->add_addr_signal_max = 0;
pernet->add_addr_accept_max = 0;
pernet->local_addr_max = 0;
WRITE_ONCE(pernet->add_addr_signal_max, 0);
WRITE_ONCE(pernet->add_addr_accept_max, 0);
WRITE_ONCE(pernet->local_addr_max, 0);
pernet->addrs = 0;
}

Expand Down Expand Up @@ -1130,12 +1140,12 @@ mptcp_nl_cmd_set_limits(struct sk_buff *skb, struct genl_info *info)
int ret;

spin_lock_bh(&pernet->lock);
rcv_addrs = pernet->add_addr_accept_max;
rcv_addrs = READ_ONCE(pernet->add_addr_accept_max);
ret = parse_limit(info, MPTCP_PM_ATTR_RCV_ADD_ADDRS, &rcv_addrs);
if (ret)
goto unlock;

subflows = pernet->subflows_max;
subflows = READ_ONCE(pernet->subflows_max);
ret = parse_limit(info, MPTCP_PM_ATTR_SUBFLOWS, &subflows);
if (ret)
goto unlock;
Expand Down

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