@@ -512,7 +512,8 @@ __lookup_addr_by_id(struct pm_nl_pernet *pernet, unsigned int id)
{
struct mptcp_pm_addr_entry *entry;
- list_for_each_entry(entry, &pernet->local_addr_list, list) {
+ list_for_each_entry_rcu(entry, &pernet->local_addr_list, list,
+ lockdep_is_held(&pernet->lock)) {
if (entry->addr.id == id)
return entry;
}
@@ -1824,7 +1825,7 @@ int mptcp_pm_nl_get_addr(struct sk_buff *skb, struct genl_info *info)
goto fail;
}
- spin_lock_bh(&pernet->lock);
+ rcu_read_lock();
entry = __lookup_addr_by_id(pernet, addr.addr.id);
if (!entry) {
GENL_SET_ERR_MSG(info, "address not found");
@@ -1838,11 +1839,11 @@ int mptcp_pm_nl_get_addr(struct sk_buff *skb, struct genl_info *info)
genlmsg_end(msg, reply);
ret = genlmsg_reply(msg, info);
- spin_unlock_bh(&pernet->lock);
+ rcu_read_unlock();
return ret;
unlock_fail:
- spin_unlock_bh(&pernet->lock);
+ rcu_read_unlock();
fail:
nlmsg_free(msg);
@@ -1866,7 +1867,7 @@ int mptcp_pm_nl_dump_addr(struct sk_buff *msg,
pernet = pm_nl_get_pernet(net);
- spin_lock_bh(&pernet->lock);
+ rcu_read_lock();
for (i = id; i < MPTCP_PM_MAX_ADDR_ID + 1; i++) {
if (test_bit(i, pernet->id_bitmap)) {
entry = __lookup_addr_by_id(pernet, i);
@@ -1891,7 +1892,7 @@ int mptcp_pm_nl_dump_addr(struct sk_buff *msg,
genlmsg_end(msg, hdr);
}
}
- spin_unlock_bh(&pernet->lock);
+ rcu_read_unlock();
cb->args[0] = id;
return msg->len;
To return an endpoint to the userspace via Netlink, and to dump all of them, the endpoint list was iterated while holding the pernet->lock, but only to read the content of the list. In these cases, the spin locks can be replaced by RCU read ones, and use the _rcu variants to iterate over the entries list in a lockless way. Note that the __lookup_addr_by_id() helper has been modified to use the _rcu variants of list_for_each_entry(), but with an extra conditions, so it can be called either while the RCU read lock is held, or when the associated pernet->lock is held. Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> --- Notes: - This is not a fix, a small improvement for -next. - v3: - Use list_for_each_entry_rcu() with lockdep_is_held() instead of duplicating the helper. So no need to rename the helper with _rcu suffix. - No copy of the bitmap in dump_addr() (Mat) - No need to modify set flags. (Paolo) --- net/mptcp/pm_netlink.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)