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| author | Matthieu Baerts (NGI0) <matttbe@kernel.org> | 2024-11-15 17:52:34 +0100 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2024-11-18 18:50:13 -0800 |
| commit | 3fbb27b7f87e60324cec7d2d10a40884182c99d4 (patch) | |
| tree | 722f9df80b4cc5e248ed6e03a8ae36b29fe42941 /net/mptcp | |
| parent | cc84d89ad8d411d52ec4d000c3ed5cce52683fbd (diff) | |
| download | linux-stable-3fbb27b7f87e60324cec7d2d10a40884182c99d4.tar.gz linux-stable-3fbb27b7f87e60324cec7d2d10a40884182c99d4.tar.bz2 linux-stable-3fbb27b7f87e60324cec7d2d10a40884182c99d4.zip | |
mptcp: pm: lockless list traversal to dump endp
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.
Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20241115-net-next-mptcp-pm-lockless-dump-v1-1-f4a1bcb4ca2c@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/mptcp')
| -rw-r--r-- | net/mptcp/pm_netlink.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 758a0dbfcf78..2b005ddfd2d3 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -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; |